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 int pageno, 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 1/20 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_flags & B_INVAL)) { 1174 /* 1175 * Failed write, redirty. Must clear BIO_ERROR to prevent 1176 * pages from being scrapped. If B_INVAL is set then 1177 * this case is not run and the next case is run to 1178 * destroy the buffer. B_INVAL can occur if the buffer 1179 * is outside the range supported by the underlying device. 1180 */ 1181 bp->b_ioflags &= ~BIO_ERROR; 1182 bdirty(bp); 1183 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1184 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1185 /* 1186 * Either a failed I/O or we were asked to free or not 1187 * cache the buffer. 1188 */ 1189 bp->b_flags |= B_INVAL; 1190 if (!LIST_EMPTY(&bp->b_dep)) 1191 buf_deallocate(bp); 1192 if (bp->b_flags & B_DELWRI) { 1193 atomic_subtract_int(&numdirtybuffers, 1); 1194 numdirtywakeup(lodirtybuffers); 1195 } 1196 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1197 if ((bp->b_flags & B_VMIO) == 0) { 1198 if (bp->b_bufsize) 1199 allocbuf(bp, 0); 1200 if (bp->b_vp) 1201 brelvp(bp); 1202 } 1203 } 1204 1205 /* 1206 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1207 * is called with B_DELWRI set, the underlying pages may wind up 1208 * getting freed causing a previous write (bdwrite()) to get 'lost' 1209 * because pages associated with a B_DELWRI bp are marked clean. 1210 * 1211 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1212 * if B_DELWRI is set. 1213 * 1214 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1215 * on pages to return pages to the VM page queues. 1216 */ 1217 if (bp->b_flags & B_DELWRI) 1218 bp->b_flags &= ~B_RELBUF; 1219 else if (vm_page_count_severe()) { 1220 /* 1221 * XXX This lock may not be necessary since BKGRDINPROG 1222 * cannot be set while we hold the buf lock, it can only be 1223 * cleared if it is already pending. 1224 */ 1225 if (bp->b_vp) { 1226 BO_LOCK(bp->b_bufobj); 1227 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1228 bp->b_flags |= B_RELBUF; 1229 BO_UNLOCK(bp->b_bufobj); 1230 } else 1231 bp->b_flags |= B_RELBUF; 1232 } 1233 1234 /* 1235 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1236 * constituted, not even NFS buffers now. Two flags effect this. If 1237 * B_INVAL, the struct buf is invalidated but the VM object is kept 1238 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1239 * 1240 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1241 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1242 * buffer is also B_INVAL because it hits the re-dirtying code above. 1243 * 1244 * Normally we can do this whether a buffer is B_DELWRI or not. If 1245 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1246 * the commit state and we cannot afford to lose the buffer. If the 1247 * buffer has a background write in progress, we need to keep it 1248 * around to prevent it from being reconstituted and starting a second 1249 * background write. 1250 */ 1251 if ((bp->b_flags & B_VMIO) 1252 && !(bp->b_vp->v_mount != NULL && 1253 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1254 !vn_isdisk(bp->b_vp, NULL) && 1255 (bp->b_flags & B_DELWRI)) 1256 ) { 1257 1258 int i, j, resid; 1259 vm_page_t m; 1260 off_t foff; 1261 vm_pindex_t poff; 1262 vm_object_t obj; 1263 1264 obj = bp->b_bufobj->bo_object; 1265 1266 /* 1267 * Get the base offset and length of the buffer. Note that 1268 * in the VMIO case if the buffer block size is not 1269 * page-aligned then b_data pointer may not be page-aligned. 1270 * But our b_pages[] array *IS* page aligned. 1271 * 1272 * block sizes less then DEV_BSIZE (usually 512) are not 1273 * supported due to the page granularity bits (m->valid, 1274 * m->dirty, etc...). 1275 * 1276 * See man buf(9) for more information 1277 */ 1278 resid = bp->b_bufsize; 1279 foff = bp->b_offset; 1280 VM_OBJECT_LOCK(obj); 1281 for (i = 0; i < bp->b_npages; i++) { 1282 int had_bogus = 0; 1283 1284 m = bp->b_pages[i]; 1285 1286 /* 1287 * If we hit a bogus page, fixup *all* the bogus pages 1288 * now. 1289 */ 1290 if (m == bogus_page) { 1291 poff = OFF_TO_IDX(bp->b_offset); 1292 had_bogus = 1; 1293 1294 for (j = i; j < bp->b_npages; j++) { 1295 vm_page_t mtmp; 1296 mtmp = bp->b_pages[j]; 1297 if (mtmp == bogus_page) { 1298 mtmp = vm_page_lookup(obj, poff + j); 1299 if (!mtmp) { 1300 panic("brelse: page missing\n"); 1301 } 1302 bp->b_pages[j] = mtmp; 1303 } 1304 } 1305 1306 if ((bp->b_flags & B_INVAL) == 0) { 1307 pmap_qenter( 1308 trunc_page((vm_offset_t)bp->b_data), 1309 bp->b_pages, bp->b_npages); 1310 } 1311 m = bp->b_pages[i]; 1312 } 1313 if ((bp->b_flags & B_NOCACHE) || 1314 (bp->b_ioflags & BIO_ERROR)) { 1315 int poffset = foff & PAGE_MASK; 1316 int presid = resid > (PAGE_SIZE - poffset) ? 1317 (PAGE_SIZE - poffset) : resid; 1318 1319 KASSERT(presid >= 0, ("brelse: extra page")); 1320 vm_page_lock_queues(); 1321 vm_page_set_invalid(m, poffset, presid); 1322 vm_page_unlock_queues(); 1323 if (had_bogus) 1324 printf("avoided corruption bug in bogus_page/brelse code\n"); 1325 } 1326 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1327 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1328 } 1329 VM_OBJECT_UNLOCK(obj); 1330 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1331 vfs_vmio_release(bp); 1332 1333 } else if (bp->b_flags & B_VMIO) { 1334 1335 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1336 vfs_vmio_release(bp); 1337 } 1338 1339 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1340 if (bp->b_bufsize != 0) 1341 allocbuf(bp, 0); 1342 if (bp->b_vp != NULL) 1343 brelvp(bp); 1344 } 1345 1346 if (BUF_REFCNT(bp) > 1) { 1347 /* do not release to free list */ 1348 BUF_UNLOCK(bp); 1349 return; 1350 } 1351 1352 /* enqueue */ 1353 mtx_lock(&bqlock); 1354 /* Handle delayed bremfree() processing. */ 1355 if (bp->b_flags & B_REMFREE) 1356 bremfreel(bp); 1357 if (bp->b_qindex != QUEUE_NONE) 1358 panic("brelse: free buffer onto another queue???"); 1359 1360 /* buffers with no memory */ 1361 if (bp->b_bufsize == 0) { 1362 bp->b_flags |= B_INVAL; 1363 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1364 if (bp->b_vflags & BV_BKGRDINPROG) 1365 panic("losing buffer 1"); 1366 if (bp->b_kvasize) { 1367 bp->b_qindex = QUEUE_EMPTYKVA; 1368 } else { 1369 bp->b_qindex = QUEUE_EMPTY; 1370 } 1371 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1372 /* buffers with junk contents */ 1373 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1374 (bp->b_ioflags & BIO_ERROR)) { 1375 bp->b_flags |= B_INVAL; 1376 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1377 if (bp->b_vflags & BV_BKGRDINPROG) 1378 panic("losing buffer 2"); 1379 bp->b_qindex = QUEUE_CLEAN; 1380 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1381 /* remaining buffers */ 1382 } else { 1383 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1384 (B_DELWRI|B_NEEDSGIANT)) 1385 bp->b_qindex = QUEUE_DIRTY_GIANT; 1386 if (bp->b_flags & B_DELWRI) 1387 bp->b_qindex = QUEUE_DIRTY; 1388 else 1389 bp->b_qindex = QUEUE_CLEAN; 1390 if (bp->b_flags & B_AGE) 1391 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1392 else 1393 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1394 } 1395 mtx_unlock(&bqlock); 1396 1397 /* 1398 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1399 * placed the buffer on the correct queue. We must also disassociate 1400 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1401 * find it. 1402 */ 1403 if (bp->b_flags & B_INVAL) { 1404 if (bp->b_flags & B_DELWRI) 1405 bundirty(bp); 1406 if (bp->b_vp) 1407 brelvp(bp); 1408 } 1409 1410 /* 1411 * Fixup numfreebuffers count. The bp is on an appropriate queue 1412 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1413 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1414 * if B_INVAL is set ). 1415 */ 1416 1417 if (!(bp->b_flags & B_DELWRI)) 1418 bufcountwakeup(); 1419 1420 /* 1421 * Something we can maybe free or reuse 1422 */ 1423 if (bp->b_bufsize || bp->b_kvasize) 1424 bufspacewakeup(); 1425 1426 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1427 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1428 panic("brelse: not dirty"); 1429 /* unlock */ 1430 BUF_UNLOCK(bp); 1431 } 1432 1433 /* 1434 * Release a buffer back to the appropriate queue but do not try to free 1435 * it. The buffer is expected to be used again soon. 1436 * 1437 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1438 * biodone() to requeue an async I/O on completion. It is also used when 1439 * known good buffers need to be requeued but we think we may need the data 1440 * again soon. 1441 * 1442 * XXX we should be able to leave the B_RELBUF hint set on completion. 1443 */ 1444 void 1445 bqrelse(struct buf *bp) 1446 { 1447 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1448 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1449 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1450 1451 if (BUF_REFCNT(bp) > 1) { 1452 /* do not release to free list */ 1453 BUF_UNLOCK(bp); 1454 return; 1455 } 1456 1457 if (bp->b_flags & B_MANAGED) { 1458 if (bp->b_flags & B_REMFREE) { 1459 mtx_lock(&bqlock); 1460 bremfreel(bp); 1461 mtx_unlock(&bqlock); 1462 } 1463 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1464 BUF_UNLOCK(bp); 1465 return; 1466 } 1467 1468 mtx_lock(&bqlock); 1469 /* Handle delayed bremfree() processing. */ 1470 if (bp->b_flags & B_REMFREE) 1471 bremfreel(bp); 1472 if (bp->b_qindex != QUEUE_NONE) 1473 panic("bqrelse: free buffer onto another queue???"); 1474 /* buffers with stale but valid contents */ 1475 if (bp->b_flags & B_DELWRI) { 1476 if (bp->b_flags & B_NEEDSGIANT) 1477 bp->b_qindex = QUEUE_DIRTY_GIANT; 1478 else 1479 bp->b_qindex = QUEUE_DIRTY; 1480 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1481 } else { 1482 /* 1483 * XXX This lock may not be necessary since BKGRDINPROG 1484 * cannot be set while we hold the buf lock, it can only be 1485 * cleared if it is already pending. 1486 */ 1487 BO_LOCK(bp->b_bufobj); 1488 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1489 BO_UNLOCK(bp->b_bufobj); 1490 bp->b_qindex = QUEUE_CLEAN; 1491 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1492 b_freelist); 1493 } else { 1494 /* 1495 * We are too low on memory, we have to try to free 1496 * the buffer (most importantly: the wired pages 1497 * making up its backing store) *now*. 1498 */ 1499 BO_UNLOCK(bp->b_bufobj); 1500 mtx_unlock(&bqlock); 1501 brelse(bp); 1502 return; 1503 } 1504 } 1505 mtx_unlock(&bqlock); 1506 1507 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1508 bufcountwakeup(); 1509 1510 /* 1511 * Something we can maybe free or reuse. 1512 */ 1513 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1514 bufspacewakeup(); 1515 1516 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1517 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1518 panic("bqrelse: not dirty"); 1519 /* unlock */ 1520 BUF_UNLOCK(bp); 1521 } 1522 1523 /* Give pages used by the bp back to the VM system (where possible) */ 1524 static void 1525 vfs_vmio_release(struct buf *bp) 1526 { 1527 int i; 1528 vm_page_t m; 1529 1530 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1531 vm_page_lock_queues(); 1532 for (i = 0; i < bp->b_npages; i++) { 1533 m = bp->b_pages[i]; 1534 bp->b_pages[i] = NULL; 1535 /* 1536 * In order to keep page LRU ordering consistent, put 1537 * everything on the inactive queue. 1538 */ 1539 vm_page_unwire(m, 0); 1540 /* 1541 * We don't mess with busy pages, it is 1542 * the responsibility of the process that 1543 * busied the pages to deal with them. 1544 */ 1545 if ((m->oflags & VPO_BUSY) || (m->busy != 0)) 1546 continue; 1547 1548 if (m->wire_count == 0) { 1549 /* 1550 * Might as well free the page if we can and it has 1551 * no valid data. We also free the page if the 1552 * buffer was used for direct I/O 1553 */ 1554 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1555 m->hold_count == 0) { 1556 vm_page_free(m); 1557 } else if (bp->b_flags & B_DIRECT) { 1558 vm_page_try_to_free(m); 1559 } else if (vm_page_count_severe()) { 1560 vm_page_try_to_cache(m); 1561 } 1562 } 1563 } 1564 vm_page_unlock_queues(); 1565 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1566 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1567 1568 if (bp->b_bufsize) { 1569 bufspacewakeup(); 1570 bp->b_bufsize = 0; 1571 } 1572 bp->b_npages = 0; 1573 bp->b_flags &= ~B_VMIO; 1574 if (bp->b_vp) 1575 brelvp(bp); 1576 } 1577 1578 /* 1579 * Check to see if a block at a particular lbn is available for a clustered 1580 * write. 1581 */ 1582 static int 1583 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1584 { 1585 struct buf *bpa; 1586 int match; 1587 1588 match = 0; 1589 1590 /* If the buf isn't in core skip it */ 1591 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1592 return (0); 1593 1594 /* If the buf is busy we don't want to wait for it */ 1595 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1596 return (0); 1597 1598 /* Only cluster with valid clusterable delayed write buffers */ 1599 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1600 (B_DELWRI | B_CLUSTEROK)) 1601 goto done; 1602 1603 if (bpa->b_bufsize != size) 1604 goto done; 1605 1606 /* 1607 * Check to see if it is in the expected place on disk and that the 1608 * block has been mapped. 1609 */ 1610 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1611 match = 1; 1612 done: 1613 BUF_UNLOCK(bpa); 1614 return (match); 1615 } 1616 1617 /* 1618 * vfs_bio_awrite: 1619 * 1620 * Implement clustered async writes for clearing out B_DELWRI buffers. 1621 * This is much better then the old way of writing only one buffer at 1622 * a time. Note that we may not be presented with the buffers in the 1623 * correct order, so we search for the cluster in both directions. 1624 */ 1625 int 1626 vfs_bio_awrite(struct buf *bp) 1627 { 1628 int i; 1629 int j; 1630 daddr_t lblkno = bp->b_lblkno; 1631 struct vnode *vp = bp->b_vp; 1632 int ncl; 1633 int nwritten; 1634 int size; 1635 int maxcl; 1636 1637 /* 1638 * right now we support clustered writing only to regular files. If 1639 * we find a clusterable block we could be in the middle of a cluster 1640 * rather then at the beginning. 1641 */ 1642 if ((vp->v_type == VREG) && 1643 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1644 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1645 1646 size = vp->v_mount->mnt_stat.f_iosize; 1647 maxcl = MAXPHYS / size; 1648 1649 VI_LOCK(vp); 1650 for (i = 1; i < maxcl; i++) 1651 if (vfs_bio_clcheck(vp, size, lblkno + i, 1652 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1653 break; 1654 1655 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1656 if (vfs_bio_clcheck(vp, size, lblkno - j, 1657 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1658 break; 1659 1660 VI_UNLOCK(vp); 1661 --j; 1662 ncl = i + j; 1663 /* 1664 * this is a possible cluster write 1665 */ 1666 if (ncl != 1) { 1667 BUF_UNLOCK(bp); 1668 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1669 return nwritten; 1670 } 1671 } 1672 bremfree(bp); 1673 bp->b_flags |= B_ASYNC; 1674 /* 1675 * default (old) behavior, writing out only one block 1676 * 1677 * XXX returns b_bufsize instead of b_bcount for nwritten? 1678 */ 1679 nwritten = bp->b_bufsize; 1680 (void) bwrite(bp); 1681 1682 return nwritten; 1683 } 1684 1685 /* 1686 * getnewbuf: 1687 * 1688 * Find and initialize a new buffer header, freeing up existing buffers 1689 * in the bufqueues as necessary. The new buffer is returned locked. 1690 * 1691 * Important: B_INVAL is not set. If the caller wishes to throw the 1692 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1693 * 1694 * We block if: 1695 * We have insufficient buffer headers 1696 * We have insufficient buffer space 1697 * buffer_map is too fragmented ( space reservation fails ) 1698 * If we have to flush dirty buffers ( but we try to avoid this ) 1699 * 1700 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1701 * Instead we ask the buf daemon to do it for us. We attempt to 1702 * avoid piecemeal wakeups of the pageout daemon. 1703 */ 1704 1705 static struct buf * 1706 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1707 { 1708 struct buf *bp; 1709 struct buf *nbp; 1710 int defrag = 0; 1711 int nqindex; 1712 static int flushingbufs; 1713 1714 /* 1715 * We can't afford to block since we might be holding a vnode lock, 1716 * which may prevent system daemons from running. We deal with 1717 * low-memory situations by proactively returning memory and running 1718 * async I/O rather then sync I/O. 1719 */ 1720 1721 atomic_add_int(&getnewbufcalls, 1); 1722 atomic_subtract_int(&getnewbufrestarts, 1); 1723 restart: 1724 atomic_add_int(&getnewbufrestarts, 1); 1725 1726 /* 1727 * Setup for scan. If we do not have enough free buffers, 1728 * we setup a degenerate case that immediately fails. Note 1729 * that if we are specially marked process, we are allowed to 1730 * dip into our reserves. 1731 * 1732 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1733 * 1734 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1735 * However, there are a number of cases (defragging, reusing, ...) 1736 * where we cannot backup. 1737 */ 1738 mtx_lock(&bqlock); 1739 nqindex = QUEUE_EMPTYKVA; 1740 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1741 1742 if (nbp == NULL) { 1743 /* 1744 * If no EMPTYKVA buffers and we are either 1745 * defragging or reusing, locate a CLEAN buffer 1746 * to free or reuse. If bufspace useage is low 1747 * skip this step so we can allocate a new buffer. 1748 */ 1749 if (defrag || bufspace >= lobufspace) { 1750 nqindex = QUEUE_CLEAN; 1751 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1752 } 1753 1754 /* 1755 * If we could not find or were not allowed to reuse a 1756 * CLEAN buffer, check to see if it is ok to use an EMPTY 1757 * buffer. We can only use an EMPTY buffer if allocating 1758 * its KVA would not otherwise run us out of buffer space. 1759 */ 1760 if (nbp == NULL && defrag == 0 && 1761 bufspace + maxsize < hibufspace) { 1762 nqindex = QUEUE_EMPTY; 1763 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1764 } 1765 } 1766 1767 /* 1768 * Run scan, possibly freeing data and/or kva mappings on the fly 1769 * depending. 1770 */ 1771 1772 while ((bp = nbp) != NULL) { 1773 int qindex = nqindex; 1774 1775 /* 1776 * Calculate next bp ( we can only use it if we do not block 1777 * or do other fancy things ). 1778 */ 1779 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1780 switch(qindex) { 1781 case QUEUE_EMPTY: 1782 nqindex = QUEUE_EMPTYKVA; 1783 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1784 break; 1785 /* FALLTHROUGH */ 1786 case QUEUE_EMPTYKVA: 1787 nqindex = QUEUE_CLEAN; 1788 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1789 break; 1790 /* FALLTHROUGH */ 1791 case QUEUE_CLEAN: 1792 /* 1793 * nbp is NULL. 1794 */ 1795 break; 1796 } 1797 } 1798 /* 1799 * If we are defragging then we need a buffer with 1800 * b_kvasize != 0. XXX this situation should no longer 1801 * occur, if defrag is non-zero the buffer's b_kvasize 1802 * should also be non-zero at this point. XXX 1803 */ 1804 if (defrag && bp->b_kvasize == 0) { 1805 printf("Warning: defrag empty buffer %p\n", bp); 1806 continue; 1807 } 1808 1809 /* 1810 * Start freeing the bp. This is somewhat involved. nbp 1811 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1812 */ 1813 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1814 continue; 1815 if (bp->b_vp) { 1816 BO_LOCK(bp->b_bufobj); 1817 if (bp->b_vflags & BV_BKGRDINPROG) { 1818 BO_UNLOCK(bp->b_bufobj); 1819 BUF_UNLOCK(bp); 1820 continue; 1821 } 1822 BO_UNLOCK(bp->b_bufobj); 1823 } 1824 CTR6(KTR_BUF, 1825 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1826 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1827 bp->b_kvasize, bp->b_bufsize, qindex); 1828 1829 /* 1830 * Sanity Checks 1831 */ 1832 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1833 1834 /* 1835 * Note: we no longer distinguish between VMIO and non-VMIO 1836 * buffers. 1837 */ 1838 1839 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1840 1841 bremfreel(bp); 1842 mtx_unlock(&bqlock); 1843 1844 if (qindex == QUEUE_CLEAN) { 1845 if (bp->b_flags & B_VMIO) { 1846 bp->b_flags &= ~B_ASYNC; 1847 vfs_vmio_release(bp); 1848 } 1849 if (bp->b_vp) 1850 brelvp(bp); 1851 } 1852 1853 /* 1854 * NOTE: nbp is now entirely invalid. We can only restart 1855 * the scan from this point on. 1856 * 1857 * Get the rest of the buffer freed up. b_kva* is still 1858 * valid after this operation. 1859 */ 1860 1861 if (bp->b_rcred != NOCRED) { 1862 crfree(bp->b_rcred); 1863 bp->b_rcred = NOCRED; 1864 } 1865 if (bp->b_wcred != NOCRED) { 1866 crfree(bp->b_wcred); 1867 bp->b_wcred = NOCRED; 1868 } 1869 if (!LIST_EMPTY(&bp->b_dep)) 1870 buf_deallocate(bp); 1871 if (bp->b_vflags & BV_BKGRDINPROG) 1872 panic("losing buffer 3"); 1873 KASSERT(bp->b_vp == NULL, 1874 ("bp: %p still has vnode %p. qindex: %d", 1875 bp, bp->b_vp, qindex)); 1876 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1877 ("bp: %p still on a buffer list. xflags %X", 1878 bp, bp->b_xflags)); 1879 1880 if (bp->b_bufsize) 1881 allocbuf(bp, 0); 1882 1883 bp->b_flags = 0; 1884 bp->b_ioflags = 0; 1885 bp->b_xflags = 0; 1886 bp->b_vflags = 0; 1887 bp->b_vp = NULL; 1888 bp->b_blkno = bp->b_lblkno = 0; 1889 bp->b_offset = NOOFFSET; 1890 bp->b_iodone = 0; 1891 bp->b_error = 0; 1892 bp->b_resid = 0; 1893 bp->b_bcount = 0; 1894 bp->b_npages = 0; 1895 bp->b_dirtyoff = bp->b_dirtyend = 0; 1896 bp->b_bufobj = NULL; 1897 bp->b_pin_count = 0; 1898 bp->b_fsprivate1 = NULL; 1899 bp->b_fsprivate2 = NULL; 1900 bp->b_fsprivate3 = NULL; 1901 1902 LIST_INIT(&bp->b_dep); 1903 1904 /* 1905 * If we are defragging then free the buffer. 1906 */ 1907 if (defrag) { 1908 bp->b_flags |= B_INVAL; 1909 bfreekva(bp); 1910 brelse(bp); 1911 defrag = 0; 1912 goto restart; 1913 } 1914 1915 /* 1916 * Notify any waiters for the buffer lock about 1917 * identity change by freeing the buffer. 1918 */ 1919 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) { 1920 bp->b_flags |= B_INVAL; 1921 bfreekva(bp); 1922 brelse(bp); 1923 goto restart; 1924 } 1925 1926 /* 1927 * If we are overcomitted then recover the buffer and its 1928 * KVM space. This occurs in rare situations when multiple 1929 * processes are blocked in getnewbuf() or allocbuf(). 1930 */ 1931 if (bufspace >= hibufspace) 1932 flushingbufs = 1; 1933 if (flushingbufs && bp->b_kvasize != 0) { 1934 bp->b_flags |= B_INVAL; 1935 bfreekva(bp); 1936 brelse(bp); 1937 goto restart; 1938 } 1939 if (bufspace < lobufspace) 1940 flushingbufs = 0; 1941 break; 1942 } 1943 1944 /* 1945 * If we exhausted our list, sleep as appropriate. We may have to 1946 * wakeup various daemons and write out some dirty buffers. 1947 * 1948 * Generally we are sleeping due to insufficient buffer space. 1949 */ 1950 1951 if (bp == NULL) { 1952 int flags; 1953 char *waitmsg; 1954 1955 if (defrag) { 1956 flags = VFS_BIO_NEED_BUFSPACE; 1957 waitmsg = "nbufkv"; 1958 } else if (bufspace >= hibufspace) { 1959 waitmsg = "nbufbs"; 1960 flags = VFS_BIO_NEED_BUFSPACE; 1961 } else { 1962 waitmsg = "newbuf"; 1963 flags = VFS_BIO_NEED_ANY; 1964 } 1965 mtx_lock(&nblock); 1966 needsbuffer |= flags; 1967 mtx_unlock(&nblock); 1968 mtx_unlock(&bqlock); 1969 1970 bd_speedup(); /* heeeelp */ 1971 1972 mtx_lock(&nblock); 1973 while (needsbuffer & flags) { 1974 if (msleep(&needsbuffer, &nblock, 1975 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1976 mtx_unlock(&nblock); 1977 return (NULL); 1978 } 1979 } 1980 mtx_unlock(&nblock); 1981 } else { 1982 /* 1983 * We finally have a valid bp. We aren't quite out of the 1984 * woods, we still have to reserve kva space. In order 1985 * to keep fragmentation sane we only allocate kva in 1986 * BKVASIZE chunks. 1987 */ 1988 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1989 1990 if (maxsize != bp->b_kvasize) { 1991 vm_offset_t addr = 0; 1992 1993 bfreekva(bp); 1994 1995 vm_map_lock(buffer_map); 1996 if (vm_map_findspace(buffer_map, 1997 vm_map_min(buffer_map), maxsize, &addr)) { 1998 /* 1999 * Uh oh. Buffer map is to fragmented. We 2000 * must defragment the map. 2001 */ 2002 atomic_add_int(&bufdefragcnt, 1); 2003 vm_map_unlock(buffer_map); 2004 defrag = 1; 2005 bp->b_flags |= B_INVAL; 2006 brelse(bp); 2007 goto restart; 2008 } 2009 if (addr) { 2010 vm_map_insert(buffer_map, NULL, 0, 2011 addr, addr + maxsize, 2012 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2013 2014 bp->b_kvabase = (caddr_t) addr; 2015 bp->b_kvasize = maxsize; 2016 atomic_add_int(&bufspace, bp->b_kvasize); 2017 atomic_add_int(&bufreusecnt, 1); 2018 } 2019 vm_map_unlock(buffer_map); 2020 } 2021 bp->b_saveaddr = bp->b_kvabase; 2022 bp->b_data = bp->b_saveaddr; 2023 } 2024 return(bp); 2025 } 2026 2027 /* 2028 * buf_daemon: 2029 * 2030 * buffer flushing daemon. Buffers are normally flushed by the 2031 * update daemon but if it cannot keep up this process starts to 2032 * take the load in an attempt to prevent getnewbuf() from blocking. 2033 */ 2034 2035 static struct kproc_desc buf_kp = { 2036 "bufdaemon", 2037 buf_daemon, 2038 &bufdaemonproc 2039 }; 2040 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2041 2042 static void 2043 buf_daemon() 2044 { 2045 2046 /* 2047 * This process needs to be suspended prior to shutdown sync. 2048 */ 2049 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2050 SHUTDOWN_PRI_LAST); 2051 2052 /* 2053 * This process is allowed to take the buffer cache to the limit 2054 */ 2055 curthread->td_pflags |= TDP_NORUNNINGBUF; 2056 mtx_lock(&bdlock); 2057 for (;;) { 2058 bd_request = 0; 2059 mtx_unlock(&bdlock); 2060 2061 kthread_suspend_check(bufdaemonproc); 2062 2063 /* 2064 * Do the flush. Limit the amount of in-transit I/O we 2065 * allow to build up, otherwise we would completely saturate 2066 * the I/O system. Wakeup any waiting processes before we 2067 * normally would so they can run in parallel with our drain. 2068 */ 2069 while (numdirtybuffers > lodirtybuffers) { 2070 int flushed; 2071 2072 flushed = flushbufqueues(QUEUE_DIRTY, 0); 2073 /* The list empty check here is slightly racy */ 2074 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2075 mtx_lock(&Giant); 2076 flushed += flushbufqueues(QUEUE_DIRTY_GIANT, 0); 2077 mtx_unlock(&Giant); 2078 } 2079 if (flushed == 0) { 2080 /* 2081 * Could not find any buffers without rollback 2082 * dependencies, so just write the first one 2083 * in the hopes of eventually making progress. 2084 */ 2085 flushbufqueues(QUEUE_DIRTY, 1); 2086 if (!TAILQ_EMPTY( 2087 &bufqueues[QUEUE_DIRTY_GIANT])) { 2088 mtx_lock(&Giant); 2089 flushbufqueues(QUEUE_DIRTY_GIANT, 1); 2090 mtx_unlock(&Giant); 2091 } 2092 break; 2093 } 2094 uio_yield(); 2095 } 2096 2097 /* 2098 * Only clear bd_request if we have reached our low water 2099 * mark. The buf_daemon normally waits 1 second and 2100 * then incrementally flushes any dirty buffers that have 2101 * built up, within reason. 2102 * 2103 * If we were unable to hit our low water mark and couldn't 2104 * find any flushable buffers, we sleep half a second. 2105 * Otherwise we loop immediately. 2106 */ 2107 mtx_lock(&bdlock); 2108 if (numdirtybuffers <= lodirtybuffers) { 2109 /* 2110 * We reached our low water mark, reset the 2111 * request and sleep until we are needed again. 2112 * The sleep is just so the suspend code works. 2113 */ 2114 bd_request = 0; 2115 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2116 } else { 2117 /* 2118 * We couldn't find any flushable dirty buffers but 2119 * still have too many dirty buffers, we 2120 * have to sleep and try again. (rare) 2121 */ 2122 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2123 } 2124 } 2125 } 2126 2127 /* 2128 * flushbufqueues: 2129 * 2130 * Try to flush a buffer in the dirty queue. We must be careful to 2131 * free up B_INVAL buffers instead of write them, which NFS is 2132 * particularly sensitive to. 2133 */ 2134 static int flushwithdeps = 0; 2135 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2136 0, "Number of buffers flushed with dependecies that require rollbacks"); 2137 2138 static int 2139 flushbufqueues(int queue, int flushdeps) 2140 { 2141 struct thread *td = curthread; 2142 struct buf sentinel; 2143 struct vnode *vp; 2144 struct mount *mp; 2145 struct buf *bp; 2146 int hasdeps; 2147 int flushed; 2148 int target; 2149 2150 target = numdirtybuffers - lodirtybuffers; 2151 if (flushdeps && target > 2) 2152 target /= 2; 2153 flushed = 0; 2154 bp = NULL; 2155 mtx_lock(&bqlock); 2156 TAILQ_INSERT_TAIL(&bufqueues[queue], &sentinel, b_freelist); 2157 while (flushed != target) { 2158 bp = TAILQ_FIRST(&bufqueues[queue]); 2159 if (bp == &sentinel) 2160 break; 2161 TAILQ_REMOVE(&bufqueues[queue], bp, b_freelist); 2162 TAILQ_INSERT_TAIL(&bufqueues[queue], bp, b_freelist); 2163 2164 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2165 continue; 2166 if (bp->b_pin_count > 0) { 2167 BUF_UNLOCK(bp); 2168 continue; 2169 } 2170 BO_LOCK(bp->b_bufobj); 2171 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2172 (bp->b_flags & B_DELWRI) == 0) { 2173 BO_UNLOCK(bp->b_bufobj); 2174 BUF_UNLOCK(bp); 2175 continue; 2176 } 2177 BO_UNLOCK(bp->b_bufobj); 2178 if (bp->b_flags & B_INVAL) { 2179 bremfreel(bp); 2180 mtx_unlock(&bqlock); 2181 brelse(bp); 2182 flushed++; 2183 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2184 mtx_lock(&bqlock); 2185 continue; 2186 } 2187 2188 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2189 if (flushdeps == 0) { 2190 BUF_UNLOCK(bp); 2191 continue; 2192 } 2193 hasdeps = 1; 2194 } else 2195 hasdeps = 0; 2196 /* 2197 * We must hold the lock on a vnode before writing 2198 * one of its buffers. Otherwise we may confuse, or 2199 * in the case of a snapshot vnode, deadlock the 2200 * system. 2201 * 2202 * The lock order here is the reverse of the normal 2203 * of vnode followed by buf lock. This is ok because 2204 * the NOWAIT will prevent deadlock. 2205 */ 2206 vp = bp->b_vp; 2207 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2208 BUF_UNLOCK(bp); 2209 continue; 2210 } 2211 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2212 mtx_unlock(&bqlock); 2213 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2214 bp, bp->b_vp, bp->b_flags); 2215 vfs_bio_awrite(bp); 2216 vn_finished_write(mp); 2217 VOP_UNLOCK(vp, 0, td); 2218 flushwithdeps += hasdeps; 2219 flushed++; 2220 waitrunningbufspace(); 2221 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2222 mtx_lock(&bqlock); 2223 continue; 2224 } 2225 vn_finished_write(mp); 2226 BUF_UNLOCK(bp); 2227 } 2228 TAILQ_REMOVE(&bufqueues[queue], &sentinel, b_freelist); 2229 mtx_unlock(&bqlock); 2230 return (flushed); 2231 } 2232 2233 /* 2234 * Check to see if a block is currently memory resident. 2235 */ 2236 struct buf * 2237 incore(struct bufobj *bo, daddr_t blkno) 2238 { 2239 struct buf *bp; 2240 2241 BO_LOCK(bo); 2242 bp = gbincore(bo, blkno); 2243 BO_UNLOCK(bo); 2244 return (bp); 2245 } 2246 2247 /* 2248 * Returns true if no I/O is needed to access the 2249 * associated VM object. This is like incore except 2250 * it also hunts around in the VM system for the data. 2251 */ 2252 2253 static int 2254 inmem(struct vnode * vp, daddr_t blkno) 2255 { 2256 vm_object_t obj; 2257 vm_offset_t toff, tinc, size; 2258 vm_page_t m; 2259 vm_ooffset_t off; 2260 2261 ASSERT_VOP_LOCKED(vp, "inmem"); 2262 2263 if (incore(&vp->v_bufobj, blkno)) 2264 return 1; 2265 if (vp->v_mount == NULL) 2266 return 0; 2267 obj = vp->v_object; 2268 if (obj == NULL) 2269 return (0); 2270 2271 size = PAGE_SIZE; 2272 if (size > vp->v_mount->mnt_stat.f_iosize) 2273 size = vp->v_mount->mnt_stat.f_iosize; 2274 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2275 2276 VM_OBJECT_LOCK(obj); 2277 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2278 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2279 if (!m) 2280 goto notinmem; 2281 tinc = size; 2282 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2283 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2284 if (vm_page_is_valid(m, 2285 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2286 goto notinmem; 2287 } 2288 VM_OBJECT_UNLOCK(obj); 2289 return 1; 2290 2291 notinmem: 2292 VM_OBJECT_UNLOCK(obj); 2293 return (0); 2294 } 2295 2296 /* 2297 * vfs_setdirty: 2298 * 2299 * Sets the dirty range for a buffer based on the status of the dirty 2300 * bits in the pages comprising the buffer. 2301 * 2302 * The range is limited to the size of the buffer. 2303 * 2304 * This routine is primarily used by NFS, but is generalized for the 2305 * B_VMIO case. 2306 */ 2307 static void 2308 vfs_setdirty(struct buf *bp) 2309 { 2310 2311 /* 2312 * Degenerate case - empty buffer 2313 */ 2314 2315 if (bp->b_bufsize == 0) 2316 return; 2317 2318 /* 2319 * We qualify the scan for modified pages on whether the 2320 * object has been flushed yet. 2321 */ 2322 2323 if ((bp->b_flags & B_VMIO) == 0) 2324 return; 2325 2326 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2327 vfs_setdirty_locked_object(bp); 2328 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2329 } 2330 2331 static void 2332 vfs_setdirty_locked_object(struct buf *bp) 2333 { 2334 vm_object_t object; 2335 int i; 2336 2337 object = bp->b_bufobj->bo_object; 2338 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2339 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2340 vm_offset_t boffset; 2341 vm_offset_t eoffset; 2342 2343 vm_page_lock_queues(); 2344 /* 2345 * test the pages to see if they have been modified directly 2346 * by users through the VM system. 2347 */ 2348 for (i = 0; i < bp->b_npages; i++) 2349 vm_page_test_dirty(bp->b_pages[i]); 2350 2351 /* 2352 * Calculate the encompassing dirty range, boffset and eoffset, 2353 * (eoffset - boffset) bytes. 2354 */ 2355 2356 for (i = 0; i < bp->b_npages; i++) { 2357 if (bp->b_pages[i]->dirty) 2358 break; 2359 } 2360 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2361 2362 for (i = bp->b_npages - 1; i >= 0; --i) { 2363 if (bp->b_pages[i]->dirty) { 2364 break; 2365 } 2366 } 2367 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2368 2369 vm_page_unlock_queues(); 2370 /* 2371 * Fit it to the buffer. 2372 */ 2373 2374 if (eoffset > bp->b_bcount) 2375 eoffset = bp->b_bcount; 2376 2377 /* 2378 * If we have a good dirty range, merge with the existing 2379 * dirty range. 2380 */ 2381 2382 if (boffset < eoffset) { 2383 if (bp->b_dirtyoff > boffset) 2384 bp->b_dirtyoff = boffset; 2385 if (bp->b_dirtyend < eoffset) 2386 bp->b_dirtyend = eoffset; 2387 } 2388 } 2389 } 2390 2391 /* 2392 * getblk: 2393 * 2394 * Get a block given a specified block and offset into a file/device. 2395 * The buffers B_DONE bit will be cleared on return, making it almost 2396 * ready for an I/O initiation. B_INVAL may or may not be set on 2397 * return. The caller should clear B_INVAL prior to initiating a 2398 * READ. 2399 * 2400 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2401 * an existing buffer. 2402 * 2403 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2404 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2405 * and then cleared based on the backing VM. If the previous buffer is 2406 * non-0-sized but invalid, B_CACHE will be cleared. 2407 * 2408 * If getblk() must create a new buffer, the new buffer is returned with 2409 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2410 * case it is returned with B_INVAL clear and B_CACHE set based on the 2411 * backing VM. 2412 * 2413 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2414 * B_CACHE bit is clear. 2415 * 2416 * What this means, basically, is that the caller should use B_CACHE to 2417 * determine whether the buffer is fully valid or not and should clear 2418 * B_INVAL prior to issuing a read. If the caller intends to validate 2419 * the buffer by loading its data area with something, the caller needs 2420 * to clear B_INVAL. If the caller does this without issuing an I/O, 2421 * the caller should set B_CACHE ( as an optimization ), else the caller 2422 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2423 * a write attempt or if it was a successfull read. If the caller 2424 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2425 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2426 */ 2427 struct buf * 2428 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2429 int flags) 2430 { 2431 struct buf *bp; 2432 struct bufobj *bo; 2433 int error; 2434 2435 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2436 ASSERT_VOP_LOCKED(vp, "getblk"); 2437 if (size > MAXBSIZE) 2438 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2439 2440 bo = &vp->v_bufobj; 2441 loop: 2442 /* 2443 * Block if we are low on buffers. Certain processes are allowed 2444 * to completely exhaust the buffer cache. 2445 * 2446 * If this check ever becomes a bottleneck it may be better to 2447 * move it into the else, when gbincore() fails. At the moment 2448 * it isn't a problem. 2449 * 2450 * XXX remove if 0 sections (clean this up after its proven) 2451 */ 2452 if (numfreebuffers == 0) { 2453 if (TD_IS_IDLETHREAD(curthread)) 2454 return NULL; 2455 mtx_lock(&nblock); 2456 needsbuffer |= VFS_BIO_NEED_ANY; 2457 mtx_unlock(&nblock); 2458 } 2459 2460 BO_LOCK(bo); 2461 bp = gbincore(bo, blkno); 2462 if (bp != NULL) { 2463 int lockflags; 2464 /* 2465 * Buffer is in-core. If the buffer is not busy, it must 2466 * be on a queue. 2467 */ 2468 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2469 2470 if (flags & GB_LOCK_NOWAIT) 2471 lockflags |= LK_NOWAIT; 2472 2473 error = BUF_TIMELOCK(bp, lockflags, 2474 VI_MTX(vp), "getblk", slpflag, slptimeo); 2475 2476 /* 2477 * If we slept and got the lock we have to restart in case 2478 * the buffer changed identities. 2479 */ 2480 if (error == ENOLCK) 2481 goto loop; 2482 /* We timed out or were interrupted. */ 2483 else if (error) 2484 return (NULL); 2485 2486 /* 2487 * The buffer is locked. B_CACHE is cleared if the buffer is 2488 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2489 * and for a VMIO buffer B_CACHE is adjusted according to the 2490 * backing VM cache. 2491 */ 2492 if (bp->b_flags & B_INVAL) 2493 bp->b_flags &= ~B_CACHE; 2494 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2495 bp->b_flags |= B_CACHE; 2496 bremfree(bp); 2497 2498 /* 2499 * check for size inconsistancies for non-VMIO case. 2500 */ 2501 2502 if (bp->b_bcount != size) { 2503 if ((bp->b_flags & B_VMIO) == 0 || 2504 (size > bp->b_kvasize)) { 2505 if (bp->b_flags & B_DELWRI) { 2506 /* 2507 * If buffer is pinned and caller does 2508 * not want sleep waiting for it to be 2509 * unpinned, bail out 2510 * */ 2511 if (bp->b_pin_count > 0) { 2512 if (flags & GB_LOCK_NOWAIT) { 2513 bqrelse(bp); 2514 return (NULL); 2515 } else { 2516 bunpin_wait(bp); 2517 } 2518 } 2519 bp->b_flags |= B_NOCACHE; 2520 bwrite(bp); 2521 } else { 2522 if (LIST_EMPTY(&bp->b_dep)) { 2523 bp->b_flags |= B_RELBUF; 2524 brelse(bp); 2525 } else { 2526 bp->b_flags |= B_NOCACHE; 2527 bwrite(bp); 2528 } 2529 } 2530 goto loop; 2531 } 2532 } 2533 2534 /* 2535 * If the size is inconsistant in the VMIO case, we can resize 2536 * the buffer. This might lead to B_CACHE getting set or 2537 * cleared. If the size has not changed, B_CACHE remains 2538 * unchanged from its previous state. 2539 */ 2540 2541 if (bp->b_bcount != size) 2542 allocbuf(bp, size); 2543 2544 KASSERT(bp->b_offset != NOOFFSET, 2545 ("getblk: no buffer offset")); 2546 2547 /* 2548 * A buffer with B_DELWRI set and B_CACHE clear must 2549 * be committed before we can return the buffer in 2550 * order to prevent the caller from issuing a read 2551 * ( due to B_CACHE not being set ) and overwriting 2552 * it. 2553 * 2554 * Most callers, including NFS and FFS, need this to 2555 * operate properly either because they assume they 2556 * can issue a read if B_CACHE is not set, or because 2557 * ( for example ) an uncached B_DELWRI might loop due 2558 * to softupdates re-dirtying the buffer. In the latter 2559 * case, B_CACHE is set after the first write completes, 2560 * preventing further loops. 2561 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2562 * above while extending the buffer, we cannot allow the 2563 * buffer to remain with B_CACHE set after the write 2564 * completes or it will represent a corrupt state. To 2565 * deal with this we set B_NOCACHE to scrap the buffer 2566 * after the write. 2567 * 2568 * We might be able to do something fancy, like setting 2569 * B_CACHE in bwrite() except if B_DELWRI is already set, 2570 * so the below call doesn't set B_CACHE, but that gets real 2571 * confusing. This is much easier. 2572 */ 2573 2574 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2575 bp->b_flags |= B_NOCACHE; 2576 bwrite(bp); 2577 goto loop; 2578 } 2579 bp->b_flags &= ~B_DONE; 2580 } else { 2581 int bsize, maxsize, vmio; 2582 off_t offset; 2583 2584 /* 2585 * Buffer is not in-core, create new buffer. The buffer 2586 * returned by getnewbuf() is locked. Note that the returned 2587 * buffer is also considered valid (not marked B_INVAL). 2588 */ 2589 BO_UNLOCK(bo); 2590 /* 2591 * If the user does not want us to create the buffer, bail out 2592 * here. 2593 */ 2594 if (flags & GB_NOCREAT) 2595 return NULL; 2596 bsize = bo->bo_bsize; 2597 offset = blkno * bsize; 2598 vmio = vp->v_object != NULL; 2599 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2600 maxsize = imax(maxsize, bsize); 2601 2602 bp = getnewbuf(slpflag, slptimeo, size, maxsize); 2603 if (bp == NULL) { 2604 if (slpflag || slptimeo) 2605 return NULL; 2606 goto loop; 2607 } 2608 2609 /* 2610 * This code is used to make sure that a buffer is not 2611 * created while the getnewbuf routine is blocked. 2612 * This can be a problem whether the vnode is locked or not. 2613 * If the buffer is created out from under us, we have to 2614 * throw away the one we just created. 2615 * 2616 * Note: this must occur before we associate the buffer 2617 * with the vp especially considering limitations in 2618 * the splay tree implementation when dealing with duplicate 2619 * lblkno's. 2620 */ 2621 BO_LOCK(bo); 2622 if (gbincore(bo, blkno)) { 2623 BO_UNLOCK(bo); 2624 bp->b_flags |= B_INVAL; 2625 brelse(bp); 2626 goto loop; 2627 } 2628 2629 /* 2630 * Insert the buffer into the hash, so that it can 2631 * be found by incore. 2632 */ 2633 bp->b_blkno = bp->b_lblkno = blkno; 2634 bp->b_offset = offset; 2635 bgetvp(vp, bp); 2636 BO_UNLOCK(bo); 2637 2638 /* 2639 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2640 * buffer size starts out as 0, B_CACHE will be set by 2641 * allocbuf() for the VMIO case prior to it testing the 2642 * backing store for validity. 2643 */ 2644 2645 if (vmio) { 2646 bp->b_flags |= B_VMIO; 2647 #if defined(VFS_BIO_DEBUG) 2648 if (vn_canvmio(vp) != TRUE) 2649 printf("getblk: VMIO on vnode type %d\n", 2650 vp->v_type); 2651 #endif 2652 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2653 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2654 bp, vp->v_object, bp->b_bufobj->bo_object)); 2655 } else { 2656 bp->b_flags &= ~B_VMIO; 2657 KASSERT(bp->b_bufobj->bo_object == NULL, 2658 ("ARGH! has b_bufobj->bo_object %p %p\n", 2659 bp, bp->b_bufobj->bo_object)); 2660 } 2661 2662 allocbuf(bp, size); 2663 bp->b_flags &= ~B_DONE; 2664 } 2665 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2666 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2667 KASSERT(bp->b_bufobj == bo, 2668 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2669 return (bp); 2670 } 2671 2672 /* 2673 * Get an empty, disassociated buffer of given size. The buffer is initially 2674 * set to B_INVAL. 2675 */ 2676 struct buf * 2677 geteblk(int size) 2678 { 2679 struct buf *bp; 2680 int maxsize; 2681 2682 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2683 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2684 continue; 2685 allocbuf(bp, size); 2686 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2687 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2688 return (bp); 2689 } 2690 2691 2692 /* 2693 * This code constitutes the buffer memory from either anonymous system 2694 * memory (in the case of non-VMIO operations) or from an associated 2695 * VM object (in the case of VMIO operations). This code is able to 2696 * resize a buffer up or down. 2697 * 2698 * Note that this code is tricky, and has many complications to resolve 2699 * deadlock or inconsistant data situations. Tread lightly!!! 2700 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2701 * the caller. Calling this code willy nilly can result in the loss of data. 2702 * 2703 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2704 * B_CACHE for the non-VMIO case. 2705 */ 2706 2707 int 2708 allocbuf(struct buf *bp, int size) 2709 { 2710 int newbsize, mbsize; 2711 int i; 2712 2713 if (BUF_REFCNT(bp) == 0) 2714 panic("allocbuf: buffer not busy"); 2715 2716 if (bp->b_kvasize < size) 2717 panic("allocbuf: buffer too small"); 2718 2719 if ((bp->b_flags & B_VMIO) == 0) { 2720 caddr_t origbuf; 2721 int origbufsize; 2722 /* 2723 * Just get anonymous memory from the kernel. Don't 2724 * mess with B_CACHE. 2725 */ 2726 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2727 if (bp->b_flags & B_MALLOC) 2728 newbsize = mbsize; 2729 else 2730 newbsize = round_page(size); 2731 2732 if (newbsize < bp->b_bufsize) { 2733 /* 2734 * malloced buffers are not shrunk 2735 */ 2736 if (bp->b_flags & B_MALLOC) { 2737 if (newbsize) { 2738 bp->b_bcount = size; 2739 } else { 2740 free(bp->b_data, M_BIOBUF); 2741 if (bp->b_bufsize) { 2742 atomic_subtract_int( 2743 &bufmallocspace, 2744 bp->b_bufsize); 2745 bufspacewakeup(); 2746 bp->b_bufsize = 0; 2747 } 2748 bp->b_saveaddr = bp->b_kvabase; 2749 bp->b_data = bp->b_saveaddr; 2750 bp->b_bcount = 0; 2751 bp->b_flags &= ~B_MALLOC; 2752 } 2753 return 1; 2754 } 2755 vm_hold_free_pages( 2756 bp, 2757 (vm_offset_t) bp->b_data + newbsize, 2758 (vm_offset_t) bp->b_data + bp->b_bufsize); 2759 } else if (newbsize > bp->b_bufsize) { 2760 /* 2761 * We only use malloced memory on the first allocation. 2762 * and revert to page-allocated memory when the buffer 2763 * grows. 2764 */ 2765 /* 2766 * There is a potential smp race here that could lead 2767 * to bufmallocspace slightly passing the max. It 2768 * is probably extremely rare and not worth worrying 2769 * over. 2770 */ 2771 if ( (bufmallocspace < maxbufmallocspace) && 2772 (bp->b_bufsize == 0) && 2773 (mbsize <= PAGE_SIZE/2)) { 2774 2775 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2776 bp->b_bufsize = mbsize; 2777 bp->b_bcount = size; 2778 bp->b_flags |= B_MALLOC; 2779 atomic_add_int(&bufmallocspace, mbsize); 2780 return 1; 2781 } 2782 origbuf = NULL; 2783 origbufsize = 0; 2784 /* 2785 * If the buffer is growing on its other-than-first allocation, 2786 * then we revert to the page-allocation scheme. 2787 */ 2788 if (bp->b_flags & B_MALLOC) { 2789 origbuf = bp->b_data; 2790 origbufsize = bp->b_bufsize; 2791 bp->b_data = bp->b_kvabase; 2792 if (bp->b_bufsize) { 2793 atomic_subtract_int(&bufmallocspace, 2794 bp->b_bufsize); 2795 bufspacewakeup(); 2796 bp->b_bufsize = 0; 2797 } 2798 bp->b_flags &= ~B_MALLOC; 2799 newbsize = round_page(newbsize); 2800 } 2801 vm_hold_load_pages( 2802 bp, 2803 (vm_offset_t) bp->b_data + bp->b_bufsize, 2804 (vm_offset_t) bp->b_data + newbsize); 2805 if (origbuf) { 2806 bcopy(origbuf, bp->b_data, origbufsize); 2807 free(origbuf, M_BIOBUF); 2808 } 2809 } 2810 } else { 2811 int desiredpages; 2812 2813 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2814 desiredpages = (size == 0) ? 0 : 2815 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2816 2817 if (bp->b_flags & B_MALLOC) 2818 panic("allocbuf: VMIO buffer can't be malloced"); 2819 /* 2820 * Set B_CACHE initially if buffer is 0 length or will become 2821 * 0-length. 2822 */ 2823 if (size == 0 || bp->b_bufsize == 0) 2824 bp->b_flags |= B_CACHE; 2825 2826 if (newbsize < bp->b_bufsize) { 2827 /* 2828 * DEV_BSIZE aligned new buffer size is less then the 2829 * DEV_BSIZE aligned existing buffer size. Figure out 2830 * if we have to remove any pages. 2831 */ 2832 if (desiredpages < bp->b_npages) { 2833 vm_page_t m; 2834 2835 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2836 vm_page_lock_queues(); 2837 for (i = desiredpages; i < bp->b_npages; i++) { 2838 /* 2839 * the page is not freed here -- it 2840 * is the responsibility of 2841 * vnode_pager_setsize 2842 */ 2843 m = bp->b_pages[i]; 2844 KASSERT(m != bogus_page, 2845 ("allocbuf: bogus page found")); 2846 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2847 vm_page_lock_queues(); 2848 2849 bp->b_pages[i] = NULL; 2850 vm_page_unwire(m, 0); 2851 } 2852 vm_page_unlock_queues(); 2853 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2854 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2855 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2856 bp->b_npages = desiredpages; 2857 } 2858 } else if (size > bp->b_bcount) { 2859 /* 2860 * We are growing the buffer, possibly in a 2861 * byte-granular fashion. 2862 */ 2863 struct vnode *vp; 2864 vm_object_t obj; 2865 vm_offset_t toff; 2866 vm_offset_t tinc; 2867 2868 /* 2869 * Step 1, bring in the VM pages from the object, 2870 * allocating them if necessary. We must clear 2871 * B_CACHE if these pages are not valid for the 2872 * range covered by the buffer. 2873 */ 2874 2875 vp = bp->b_vp; 2876 obj = bp->b_bufobj->bo_object; 2877 2878 VM_OBJECT_LOCK(obj); 2879 while (bp->b_npages < desiredpages) { 2880 vm_page_t m; 2881 vm_pindex_t pi; 2882 2883 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2884 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2885 /* 2886 * note: must allocate system pages 2887 * since blocking here could intefere 2888 * with paging I/O, no matter which 2889 * process we are. 2890 */ 2891 m = vm_page_alloc(obj, pi, 2892 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2893 VM_ALLOC_WIRED); 2894 if (m == NULL) { 2895 atomic_add_int(&vm_pageout_deficit, 2896 desiredpages - bp->b_npages); 2897 VM_OBJECT_UNLOCK(obj); 2898 VM_WAIT; 2899 VM_OBJECT_LOCK(obj); 2900 } else { 2901 bp->b_flags &= ~B_CACHE; 2902 bp->b_pages[bp->b_npages] = m; 2903 ++bp->b_npages; 2904 } 2905 continue; 2906 } 2907 2908 /* 2909 * We found a page. If we have to sleep on it, 2910 * retry because it might have gotten freed out 2911 * from under us. 2912 * 2913 * We can only test VPO_BUSY here. Blocking on 2914 * m->busy might lead to a deadlock: 2915 * 2916 * vm_fault->getpages->cluster_read->allocbuf 2917 * 2918 */ 2919 vm_page_lock_queues(); 2920 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2921 continue; 2922 2923 /* 2924 * We have a good page. Should we wakeup the 2925 * page daemon? 2926 */ 2927 if ((curproc != pageproc) && 2928 (VM_PAGE_INQUEUE1(m, PQ_CACHE)) && 2929 ((cnt.v_free_count + cnt.v_cache_count) < 2930 (cnt.v_free_min + cnt.v_cache_min))) { 2931 pagedaemon_wakeup(); 2932 } 2933 vm_page_wire(m); 2934 vm_page_unlock_queues(); 2935 bp->b_pages[bp->b_npages] = m; 2936 ++bp->b_npages; 2937 } 2938 2939 /* 2940 * Step 2. We've loaded the pages into the buffer, 2941 * we have to figure out if we can still have B_CACHE 2942 * set. Note that B_CACHE is set according to the 2943 * byte-granular range ( bcount and size ), new the 2944 * aligned range ( newbsize ). 2945 * 2946 * The VM test is against m->valid, which is DEV_BSIZE 2947 * aligned. Needless to say, the validity of the data 2948 * needs to also be DEV_BSIZE aligned. Note that this 2949 * fails with NFS if the server or some other client 2950 * extends the file's EOF. If our buffer is resized, 2951 * B_CACHE may remain set! XXX 2952 */ 2953 2954 toff = bp->b_bcount; 2955 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2956 2957 while ((bp->b_flags & B_CACHE) && toff < size) { 2958 vm_pindex_t pi; 2959 2960 if (tinc > (size - toff)) 2961 tinc = size - toff; 2962 2963 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2964 PAGE_SHIFT; 2965 2966 vfs_buf_test_cache( 2967 bp, 2968 bp->b_offset, 2969 toff, 2970 tinc, 2971 bp->b_pages[pi] 2972 ); 2973 toff += tinc; 2974 tinc = PAGE_SIZE; 2975 } 2976 VM_OBJECT_UNLOCK(obj); 2977 2978 /* 2979 * Step 3, fixup the KVM pmap. Remember that 2980 * bp->b_data is relative to bp->b_offset, but 2981 * bp->b_offset may be offset into the first page. 2982 */ 2983 2984 bp->b_data = (caddr_t) 2985 trunc_page((vm_offset_t)bp->b_data); 2986 pmap_qenter( 2987 (vm_offset_t)bp->b_data, 2988 bp->b_pages, 2989 bp->b_npages 2990 ); 2991 2992 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2993 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2994 } 2995 } 2996 if (newbsize < bp->b_bufsize) 2997 bufspacewakeup(); 2998 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2999 bp->b_bcount = size; /* requested buffer size */ 3000 return 1; 3001 } 3002 3003 void 3004 biodone(struct bio *bp) 3005 { 3006 void (*done)(struct bio *); 3007 3008 mtx_lock(&bdonelock); 3009 bp->bio_flags |= BIO_DONE; 3010 done = bp->bio_done; 3011 if (done == NULL) 3012 wakeup(bp); 3013 mtx_unlock(&bdonelock); 3014 if (done != NULL) 3015 done(bp); 3016 } 3017 3018 /* 3019 * Wait for a BIO to finish. 3020 * 3021 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3022 * case is not yet clear. 3023 */ 3024 int 3025 biowait(struct bio *bp, const char *wchan) 3026 { 3027 3028 mtx_lock(&bdonelock); 3029 while ((bp->bio_flags & BIO_DONE) == 0) 3030 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3031 mtx_unlock(&bdonelock); 3032 if (bp->bio_error != 0) 3033 return (bp->bio_error); 3034 if (!(bp->bio_flags & BIO_ERROR)) 3035 return (0); 3036 return (EIO); 3037 } 3038 3039 void 3040 biofinish(struct bio *bp, struct devstat *stat, int error) 3041 { 3042 3043 if (error) { 3044 bp->bio_error = error; 3045 bp->bio_flags |= BIO_ERROR; 3046 } 3047 if (stat != NULL) 3048 devstat_end_transaction_bio(stat, bp); 3049 biodone(bp); 3050 } 3051 3052 /* 3053 * bufwait: 3054 * 3055 * Wait for buffer I/O completion, returning error status. The buffer 3056 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3057 * error and cleared. 3058 */ 3059 int 3060 bufwait(struct buf *bp) 3061 { 3062 if (bp->b_iocmd == BIO_READ) 3063 bwait(bp, PRIBIO, "biord"); 3064 else 3065 bwait(bp, PRIBIO, "biowr"); 3066 if (bp->b_flags & B_EINTR) { 3067 bp->b_flags &= ~B_EINTR; 3068 return (EINTR); 3069 } 3070 if (bp->b_ioflags & BIO_ERROR) { 3071 return (bp->b_error ? bp->b_error : EIO); 3072 } else { 3073 return (0); 3074 } 3075 } 3076 3077 /* 3078 * Call back function from struct bio back up to struct buf. 3079 */ 3080 static void 3081 bufdonebio(struct bio *bip) 3082 { 3083 struct buf *bp; 3084 3085 bp = bip->bio_caller2; 3086 bp->b_resid = bp->b_bcount - bip->bio_completed; 3087 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3088 bp->b_ioflags = bip->bio_flags; 3089 bp->b_error = bip->bio_error; 3090 if (bp->b_error) 3091 bp->b_ioflags |= BIO_ERROR; 3092 bufdone(bp); 3093 g_destroy_bio(bip); 3094 } 3095 3096 void 3097 dev_strategy(struct cdev *dev, struct buf *bp) 3098 { 3099 struct cdevsw *csw; 3100 struct bio *bip; 3101 3102 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3103 panic("b_iocmd botch"); 3104 for (;;) { 3105 bip = g_new_bio(); 3106 if (bip != NULL) 3107 break; 3108 /* Try again later */ 3109 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3110 } 3111 bip->bio_cmd = bp->b_iocmd; 3112 bip->bio_offset = bp->b_iooffset; 3113 bip->bio_length = bp->b_bcount; 3114 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3115 bip->bio_data = bp->b_data; 3116 bip->bio_done = bufdonebio; 3117 bip->bio_caller2 = bp; 3118 bip->bio_dev = dev; 3119 KASSERT(dev->si_refcount > 0, 3120 ("dev_strategy on un-referenced struct cdev *(%s)", 3121 devtoname(dev))); 3122 csw = dev_refthread(dev); 3123 if (csw == NULL) { 3124 g_destroy_bio(bip); 3125 bp->b_error = ENXIO; 3126 bp->b_ioflags = BIO_ERROR; 3127 bufdone(bp); 3128 return; 3129 } 3130 (*csw->d_strategy)(bip); 3131 dev_relthread(dev); 3132 } 3133 3134 /* 3135 * bufdone: 3136 * 3137 * Finish I/O on a buffer, optionally calling a completion function. 3138 * This is usually called from an interrupt so process blocking is 3139 * not allowed. 3140 * 3141 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3142 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3143 * assuming B_INVAL is clear. 3144 * 3145 * For the VMIO case, we set B_CACHE if the op was a read and no 3146 * read error occured, or if the op was a write. B_CACHE is never 3147 * set if the buffer is invalid or otherwise uncacheable. 3148 * 3149 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3150 * initiator to leave B_INVAL set to brelse the buffer out of existance 3151 * in the biodone routine. 3152 */ 3153 void 3154 bufdone(struct buf *bp) 3155 { 3156 struct bufobj *dropobj; 3157 void (*biodone)(struct buf *); 3158 3159 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3160 dropobj = NULL; 3161 3162 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3163 BUF_REFCNT(bp))); 3164 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3165 3166 runningbufwakeup(bp); 3167 if (bp->b_iocmd == BIO_WRITE) 3168 dropobj = bp->b_bufobj; 3169 /* call optional completion function if requested */ 3170 if (bp->b_iodone != NULL) { 3171 biodone = bp->b_iodone; 3172 bp->b_iodone = NULL; 3173 (*biodone) (bp); 3174 if (dropobj) 3175 bufobj_wdrop(dropobj); 3176 return; 3177 } 3178 3179 bufdone_finish(bp); 3180 3181 if (dropobj) 3182 bufobj_wdrop(dropobj); 3183 } 3184 3185 void 3186 bufdone_finish(struct buf *bp) 3187 { 3188 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3189 BUF_REFCNT(bp))); 3190 3191 if (!LIST_EMPTY(&bp->b_dep)) 3192 buf_complete(bp); 3193 3194 if (bp->b_flags & B_VMIO) { 3195 int i; 3196 vm_ooffset_t foff; 3197 vm_page_t m; 3198 vm_object_t obj; 3199 int iosize; 3200 struct vnode *vp = bp->b_vp; 3201 boolean_t are_queues_locked; 3202 3203 obj = bp->b_bufobj->bo_object; 3204 3205 #if defined(VFS_BIO_DEBUG) 3206 mp_fixme("usecount and vflag accessed without locks."); 3207 if (vp->v_usecount == 0) { 3208 panic("biodone: zero vnode ref count"); 3209 } 3210 3211 KASSERT(vp->v_object != NULL, 3212 ("biodone: vnode %p has no vm_object", vp)); 3213 #endif 3214 3215 foff = bp->b_offset; 3216 KASSERT(bp->b_offset != NOOFFSET, 3217 ("biodone: no buffer offset")); 3218 3219 VM_OBJECT_LOCK(obj); 3220 #if defined(VFS_BIO_DEBUG) 3221 if (obj->paging_in_progress < bp->b_npages) { 3222 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3223 obj->paging_in_progress, bp->b_npages); 3224 } 3225 #endif 3226 3227 /* 3228 * Set B_CACHE if the op was a normal read and no error 3229 * occured. B_CACHE is set for writes in the b*write() 3230 * routines. 3231 */ 3232 iosize = bp->b_bcount - bp->b_resid; 3233 if (bp->b_iocmd == BIO_READ && 3234 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3235 !(bp->b_ioflags & BIO_ERROR)) { 3236 bp->b_flags |= B_CACHE; 3237 } 3238 if (bp->b_iocmd == BIO_READ) { 3239 vm_page_lock_queues(); 3240 are_queues_locked = TRUE; 3241 } else 3242 are_queues_locked = FALSE; 3243 for (i = 0; i < bp->b_npages; i++) { 3244 int bogusflag = 0; 3245 int resid; 3246 3247 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3248 if (resid > iosize) 3249 resid = iosize; 3250 3251 /* 3252 * cleanup bogus pages, restoring the originals 3253 */ 3254 m = bp->b_pages[i]; 3255 if (m == bogus_page) { 3256 bogusflag = 1; 3257 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3258 if (m == NULL) 3259 panic("biodone: page disappeared!"); 3260 bp->b_pages[i] = m; 3261 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3262 bp->b_pages, bp->b_npages); 3263 } 3264 #if defined(VFS_BIO_DEBUG) 3265 if (OFF_TO_IDX(foff) != m->pindex) { 3266 printf( 3267 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3268 (intmax_t)foff, (uintmax_t)m->pindex); 3269 } 3270 #endif 3271 3272 /* 3273 * In the write case, the valid and clean bits are 3274 * already changed correctly ( see bdwrite() ), so we 3275 * only need to do this here in the read case. 3276 */ 3277 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3278 vfs_page_set_valid(bp, foff, i, m); 3279 } 3280 3281 /* 3282 * when debugging new filesystems or buffer I/O methods, this 3283 * is the most common error that pops up. if you see this, you 3284 * have not set the page busy flag correctly!!! 3285 */ 3286 if (m->busy == 0) { 3287 printf("biodone: page busy < 0, " 3288 "pindex: %d, foff: 0x(%x,%x), " 3289 "resid: %d, index: %d\n", 3290 (int) m->pindex, (int)(foff >> 32), 3291 (int) foff & 0xffffffff, resid, i); 3292 if (!vn_isdisk(vp, NULL)) 3293 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3294 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3295 (intmax_t) bp->b_lblkno, 3296 bp->b_flags, bp->b_npages); 3297 else 3298 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3299 (intmax_t) bp->b_lblkno, 3300 bp->b_flags, bp->b_npages); 3301 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3302 (u_long)m->valid, (u_long)m->dirty, 3303 m->wire_count); 3304 panic("biodone: page busy < 0\n"); 3305 } 3306 vm_page_io_finish(m); 3307 vm_object_pip_subtract(obj, 1); 3308 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3309 iosize -= resid; 3310 } 3311 if (are_queues_locked) 3312 vm_page_unlock_queues(); 3313 vm_object_pip_wakeupn(obj, 0); 3314 VM_OBJECT_UNLOCK(obj); 3315 } 3316 3317 /* 3318 * For asynchronous completions, release the buffer now. The brelse 3319 * will do a wakeup there if necessary - so no need to do a wakeup 3320 * here in the async case. The sync case always needs to do a wakeup. 3321 */ 3322 3323 if (bp->b_flags & B_ASYNC) { 3324 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3325 brelse(bp); 3326 else 3327 bqrelse(bp); 3328 } else 3329 bdone(bp); 3330 } 3331 3332 /* 3333 * This routine is called in lieu of iodone in the case of 3334 * incomplete I/O. This keeps the busy status for pages 3335 * consistant. 3336 */ 3337 void 3338 vfs_unbusy_pages(struct buf *bp) 3339 { 3340 int i; 3341 vm_object_t obj; 3342 vm_page_t m; 3343 3344 runningbufwakeup(bp); 3345 if (!(bp->b_flags & B_VMIO)) 3346 return; 3347 3348 obj = bp->b_bufobj->bo_object; 3349 VM_OBJECT_LOCK(obj); 3350 for (i = 0; i < bp->b_npages; i++) { 3351 m = bp->b_pages[i]; 3352 if (m == bogus_page) { 3353 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3354 if (!m) 3355 panic("vfs_unbusy_pages: page missing\n"); 3356 bp->b_pages[i] = m; 3357 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3358 bp->b_pages, bp->b_npages); 3359 } 3360 vm_object_pip_subtract(obj, 1); 3361 vm_page_io_finish(m); 3362 } 3363 vm_object_pip_wakeupn(obj, 0); 3364 VM_OBJECT_UNLOCK(obj); 3365 } 3366 3367 /* 3368 * vfs_page_set_valid: 3369 * 3370 * Set the valid bits in a page based on the supplied offset. The 3371 * range is restricted to the buffer's size. 3372 * 3373 * This routine is typically called after a read completes. 3374 */ 3375 static void 3376 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3377 { 3378 vm_ooffset_t soff, eoff; 3379 3380 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3381 /* 3382 * Start and end offsets in buffer. eoff - soff may not cross a 3383 * page boundry or cross the end of the buffer. The end of the 3384 * buffer, in this case, is our file EOF, not the allocation size 3385 * of the buffer. 3386 */ 3387 soff = off; 3388 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3389 if (eoff > bp->b_offset + bp->b_bcount) 3390 eoff = bp->b_offset + bp->b_bcount; 3391 3392 /* 3393 * Set valid range. This is typically the entire buffer and thus the 3394 * entire page. 3395 */ 3396 if (eoff > soff) { 3397 vm_page_set_validclean( 3398 m, 3399 (vm_offset_t) (soff & PAGE_MASK), 3400 (vm_offset_t) (eoff - soff) 3401 ); 3402 } 3403 } 3404 3405 /* 3406 * This routine is called before a device strategy routine. 3407 * It is used to tell the VM system that paging I/O is in 3408 * progress, and treat the pages associated with the buffer 3409 * almost as being VPO_BUSY. Also the object paging_in_progress 3410 * flag is handled to make sure that the object doesn't become 3411 * inconsistant. 3412 * 3413 * Since I/O has not been initiated yet, certain buffer flags 3414 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3415 * and should be ignored. 3416 */ 3417 void 3418 vfs_busy_pages(struct buf *bp, int clear_modify) 3419 { 3420 int i, bogus; 3421 vm_object_t obj; 3422 vm_ooffset_t foff; 3423 vm_page_t m; 3424 3425 if (!(bp->b_flags & B_VMIO)) 3426 return; 3427 3428 obj = bp->b_bufobj->bo_object; 3429 foff = bp->b_offset; 3430 KASSERT(bp->b_offset != NOOFFSET, 3431 ("vfs_busy_pages: no buffer offset")); 3432 VM_OBJECT_LOCK(obj); 3433 if (bp->b_bufsize != 0) 3434 vfs_setdirty_locked_object(bp); 3435 retry: 3436 for (i = 0; i < bp->b_npages; i++) { 3437 m = bp->b_pages[i]; 3438 3439 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3440 goto retry; 3441 } 3442 bogus = 0; 3443 vm_page_lock_queues(); 3444 for (i = 0; i < bp->b_npages; i++) { 3445 m = bp->b_pages[i]; 3446 3447 if ((bp->b_flags & B_CLUSTER) == 0) { 3448 vm_object_pip_add(obj, 1); 3449 vm_page_io_start(m); 3450 } 3451 /* 3452 * When readying a buffer for a read ( i.e 3453 * clear_modify == 0 ), it is important to do 3454 * bogus_page replacement for valid pages in 3455 * partially instantiated buffers. Partially 3456 * instantiated buffers can, in turn, occur when 3457 * reconstituting a buffer from its VM backing store 3458 * base. We only have to do this if B_CACHE is 3459 * clear ( which causes the I/O to occur in the 3460 * first place ). The replacement prevents the read 3461 * I/O from overwriting potentially dirty VM-backed 3462 * pages. XXX bogus page replacement is, uh, bogus. 3463 * It may not work properly with small-block devices. 3464 * We need to find a better way. 3465 */ 3466 pmap_remove_all(m); 3467 if (clear_modify) 3468 vfs_page_set_valid(bp, foff, i, m); 3469 else if (m->valid == VM_PAGE_BITS_ALL && 3470 (bp->b_flags & B_CACHE) == 0) { 3471 bp->b_pages[i] = bogus_page; 3472 bogus++; 3473 } 3474 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3475 } 3476 vm_page_unlock_queues(); 3477 VM_OBJECT_UNLOCK(obj); 3478 if (bogus) 3479 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3480 bp->b_pages, bp->b_npages); 3481 } 3482 3483 /* 3484 * Tell the VM system that the pages associated with this buffer 3485 * are clean. This is used for delayed writes where the data is 3486 * going to go to disk eventually without additional VM intevention. 3487 * 3488 * Note that while we only really need to clean through to b_bcount, we 3489 * just go ahead and clean through to b_bufsize. 3490 */ 3491 static void 3492 vfs_clean_pages(struct buf *bp) 3493 { 3494 int i; 3495 vm_ooffset_t foff, noff, eoff; 3496 vm_page_t m; 3497 3498 if (!(bp->b_flags & B_VMIO)) 3499 return; 3500 3501 foff = bp->b_offset; 3502 KASSERT(bp->b_offset != NOOFFSET, 3503 ("vfs_clean_pages: no buffer offset")); 3504 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3505 vm_page_lock_queues(); 3506 for (i = 0; i < bp->b_npages; i++) { 3507 m = bp->b_pages[i]; 3508 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3509 eoff = noff; 3510 3511 if (eoff > bp->b_offset + bp->b_bufsize) 3512 eoff = bp->b_offset + bp->b_bufsize; 3513 vfs_page_set_valid(bp, foff, i, m); 3514 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3515 foff = noff; 3516 } 3517 vm_page_unlock_queues(); 3518 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3519 } 3520 3521 /* 3522 * vfs_bio_set_validclean: 3523 * 3524 * Set the range within the buffer to valid and clean. The range is 3525 * relative to the beginning of the buffer, b_offset. Note that b_offset 3526 * itself may be offset from the beginning of the first page. 3527 * 3528 */ 3529 3530 void 3531 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3532 { 3533 int i, n; 3534 vm_page_t m; 3535 3536 if (!(bp->b_flags & B_VMIO)) 3537 return; 3538 /* 3539 * Fixup base to be relative to beginning of first page. 3540 * Set initial n to be the maximum number of bytes in the 3541 * first page that can be validated. 3542 */ 3543 3544 base += (bp->b_offset & PAGE_MASK); 3545 n = PAGE_SIZE - (base & PAGE_MASK); 3546 3547 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3548 vm_page_lock_queues(); 3549 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3550 m = bp->b_pages[i]; 3551 if (n > size) 3552 n = size; 3553 vm_page_set_validclean(m, base & PAGE_MASK, n); 3554 base += n; 3555 size -= n; 3556 n = PAGE_SIZE; 3557 } 3558 vm_page_unlock_queues(); 3559 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3560 } 3561 3562 /* 3563 * vfs_bio_clrbuf: 3564 * 3565 * clear a buffer. This routine essentially fakes an I/O, so we need 3566 * to clear BIO_ERROR and B_INVAL. 3567 * 3568 * Note that while we only theoretically need to clear through b_bcount, 3569 * we go ahead and clear through b_bufsize. 3570 */ 3571 3572 void 3573 vfs_bio_clrbuf(struct buf *bp) 3574 { 3575 int i, j, mask = 0; 3576 caddr_t sa, ea; 3577 3578 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3579 clrbuf(bp); 3580 return; 3581 } 3582 3583 bp->b_flags &= ~B_INVAL; 3584 bp->b_ioflags &= ~BIO_ERROR; 3585 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3586 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3587 (bp->b_offset & PAGE_MASK) == 0) { 3588 if (bp->b_pages[0] == bogus_page) 3589 goto unlock; 3590 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3591 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3592 if ((bp->b_pages[0]->valid & mask) == mask) 3593 goto unlock; 3594 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3595 ((bp->b_pages[0]->valid & mask) == 0)) { 3596 bzero(bp->b_data, bp->b_bufsize); 3597 bp->b_pages[0]->valid |= mask; 3598 goto unlock; 3599 } 3600 } 3601 ea = sa = bp->b_data; 3602 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3603 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3604 ea = (caddr_t)(vm_offset_t)ulmin( 3605 (u_long)(vm_offset_t)ea, 3606 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3607 if (bp->b_pages[i] == bogus_page) 3608 continue; 3609 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3610 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3611 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3612 if ((bp->b_pages[i]->valid & mask) == mask) 3613 continue; 3614 if ((bp->b_pages[i]->valid & mask) == 0) { 3615 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3616 bzero(sa, ea - sa); 3617 } else { 3618 for (; sa < ea; sa += DEV_BSIZE, j++) { 3619 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3620 (bp->b_pages[i]->valid & (1 << j)) == 0) 3621 bzero(sa, DEV_BSIZE); 3622 } 3623 } 3624 bp->b_pages[i]->valid |= mask; 3625 } 3626 unlock: 3627 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3628 bp->b_resid = 0; 3629 } 3630 3631 /* 3632 * vm_hold_load_pages and vm_hold_free_pages get pages into 3633 * a buffers address space. The pages are anonymous and are 3634 * not associated with a file object. 3635 */ 3636 static void 3637 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3638 { 3639 vm_offset_t pg; 3640 vm_page_t p; 3641 int index; 3642 3643 to = round_page(to); 3644 from = round_page(from); 3645 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3646 3647 VM_OBJECT_LOCK(kernel_object); 3648 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3649 tryagain: 3650 /* 3651 * note: must allocate system pages since blocking here 3652 * could intefere with paging I/O, no matter which 3653 * process we are. 3654 */ 3655 p = vm_page_alloc(kernel_object, 3656 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3657 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3658 if (!p) { 3659 atomic_add_int(&vm_pageout_deficit, 3660 (to - pg) >> PAGE_SHIFT); 3661 VM_OBJECT_UNLOCK(kernel_object); 3662 VM_WAIT; 3663 VM_OBJECT_LOCK(kernel_object); 3664 goto tryagain; 3665 } 3666 p->valid = VM_PAGE_BITS_ALL; 3667 pmap_qenter(pg, &p, 1); 3668 bp->b_pages[index] = p; 3669 } 3670 VM_OBJECT_UNLOCK(kernel_object); 3671 bp->b_npages = index; 3672 } 3673 3674 /* Return pages associated with this buf to the vm system */ 3675 static void 3676 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3677 { 3678 vm_offset_t pg; 3679 vm_page_t p; 3680 int index, newnpages; 3681 3682 from = round_page(from); 3683 to = round_page(to); 3684 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3685 3686 VM_OBJECT_LOCK(kernel_object); 3687 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3688 p = bp->b_pages[index]; 3689 if (p && (index < bp->b_npages)) { 3690 if (p->busy) { 3691 printf( 3692 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3693 (intmax_t)bp->b_blkno, 3694 (intmax_t)bp->b_lblkno); 3695 } 3696 bp->b_pages[index] = NULL; 3697 pmap_qremove(pg, 1); 3698 vm_page_lock_queues(); 3699 vm_page_unwire(p, 0); 3700 vm_page_free(p); 3701 vm_page_unlock_queues(); 3702 } 3703 } 3704 VM_OBJECT_UNLOCK(kernel_object); 3705 bp->b_npages = newnpages; 3706 } 3707 3708 /* 3709 * Map an IO request into kernel virtual address space. 3710 * 3711 * All requests are (re)mapped into kernel VA space. 3712 * Notice that we use b_bufsize for the size of the buffer 3713 * to be mapped. b_bcount might be modified by the driver. 3714 * 3715 * Note that even if the caller determines that the address space should 3716 * be valid, a race or a smaller-file mapped into a larger space may 3717 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3718 * check the return value. 3719 */ 3720 int 3721 vmapbuf(struct buf *bp) 3722 { 3723 caddr_t addr, kva; 3724 vm_prot_t prot; 3725 int pidx, i; 3726 struct vm_page *m; 3727 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3728 3729 if (bp->b_bufsize < 0) 3730 return (-1); 3731 prot = VM_PROT_READ; 3732 if (bp->b_iocmd == BIO_READ) 3733 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3734 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3735 addr < bp->b_data + bp->b_bufsize; 3736 addr += PAGE_SIZE, pidx++) { 3737 /* 3738 * Do the vm_fault if needed; do the copy-on-write thing 3739 * when reading stuff off device into memory. 3740 * 3741 * NOTE! Must use pmap_extract() because addr may be in 3742 * the userland address space, and kextract is only guarenteed 3743 * to work for the kernland address space (see: sparc64 port). 3744 */ 3745 retry: 3746 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3747 prot) < 0) { 3748 vm_page_lock_queues(); 3749 for (i = 0; i < pidx; ++i) { 3750 vm_page_unhold(bp->b_pages[i]); 3751 bp->b_pages[i] = NULL; 3752 } 3753 vm_page_unlock_queues(); 3754 return(-1); 3755 } 3756 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3757 if (m == NULL) 3758 goto retry; 3759 bp->b_pages[pidx] = m; 3760 } 3761 if (pidx > btoc(MAXPHYS)) 3762 panic("vmapbuf: mapped more than MAXPHYS"); 3763 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3764 3765 kva = bp->b_saveaddr; 3766 bp->b_npages = pidx; 3767 bp->b_saveaddr = bp->b_data; 3768 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3769 return(0); 3770 } 3771 3772 /* 3773 * Free the io map PTEs associated with this IO operation. 3774 * We also invalidate the TLB entries and restore the original b_addr. 3775 */ 3776 void 3777 vunmapbuf(struct buf *bp) 3778 { 3779 int pidx; 3780 int npages; 3781 3782 npages = bp->b_npages; 3783 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3784 vm_page_lock_queues(); 3785 for (pidx = 0; pidx < npages; pidx++) 3786 vm_page_unhold(bp->b_pages[pidx]); 3787 vm_page_unlock_queues(); 3788 3789 bp->b_data = bp->b_saveaddr; 3790 } 3791 3792 void 3793 bdone(struct buf *bp) 3794 { 3795 3796 mtx_lock(&bdonelock); 3797 bp->b_flags |= B_DONE; 3798 wakeup(bp); 3799 mtx_unlock(&bdonelock); 3800 } 3801 3802 void 3803 bwait(struct buf *bp, u_char pri, const char *wchan) 3804 { 3805 3806 mtx_lock(&bdonelock); 3807 while ((bp->b_flags & B_DONE) == 0) 3808 msleep(bp, &bdonelock, pri, wchan, 0); 3809 mtx_unlock(&bdonelock); 3810 } 3811 3812 int 3813 bufsync(struct bufobj *bo, int waitfor, struct thread *td) 3814 { 3815 3816 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td)); 3817 } 3818 3819 void 3820 bufstrategy(struct bufobj *bo, struct buf *bp) 3821 { 3822 int i = 0; 3823 struct vnode *vp; 3824 3825 vp = bp->b_vp; 3826 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3827 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3828 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3829 i = VOP_STRATEGY(vp, bp); 3830 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3831 } 3832 3833 void 3834 bufobj_wrefl(struct bufobj *bo) 3835 { 3836 3837 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3838 ASSERT_BO_LOCKED(bo); 3839 bo->bo_numoutput++; 3840 } 3841 3842 void 3843 bufobj_wref(struct bufobj *bo) 3844 { 3845 3846 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3847 BO_LOCK(bo); 3848 bo->bo_numoutput++; 3849 BO_UNLOCK(bo); 3850 } 3851 3852 void 3853 bufobj_wdrop(struct bufobj *bo) 3854 { 3855 3856 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3857 BO_LOCK(bo); 3858 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3859 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3860 bo->bo_flag &= ~BO_WWAIT; 3861 wakeup(&bo->bo_numoutput); 3862 } 3863 BO_UNLOCK(bo); 3864 } 3865 3866 int 3867 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3868 { 3869 int error; 3870 3871 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3872 ASSERT_BO_LOCKED(bo); 3873 error = 0; 3874 while (bo->bo_numoutput) { 3875 bo->bo_flag |= BO_WWAIT; 3876 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3877 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3878 if (error) 3879 break; 3880 } 3881 return (error); 3882 } 3883 3884 void 3885 bpin(struct buf *bp) 3886 { 3887 mtx_lock(&bpinlock); 3888 bp->b_pin_count++; 3889 mtx_unlock(&bpinlock); 3890 } 3891 3892 void 3893 bunpin(struct buf *bp) 3894 { 3895 mtx_lock(&bpinlock); 3896 if (--bp->b_pin_count == 0) 3897 wakeup(bp); 3898 mtx_unlock(&bpinlock); 3899 } 3900 3901 void 3902 bunpin_wait(struct buf *bp) 3903 { 3904 mtx_lock(&bpinlock); 3905 while (bp->b_pin_count > 0) 3906 msleep(bp, &bpinlock, PRIBIO, "bwunpin", 0); 3907 mtx_unlock(&bpinlock); 3908 } 3909 3910 #include "opt_ddb.h" 3911 #ifdef DDB 3912 #include <ddb/ddb.h> 3913 3914 /* DDB command to show buffer data */ 3915 DB_SHOW_COMMAND(buffer, db_show_buffer) 3916 { 3917 /* get args */ 3918 struct buf *bp = (struct buf *)addr; 3919 3920 if (!have_addr) { 3921 db_printf("usage: show buffer <addr>\n"); 3922 return; 3923 } 3924 3925 db_printf("buf at %p\n", bp); 3926 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3927 db_printf( 3928 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3929 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n", 3930 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3931 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno); 3932 if (bp->b_npages) { 3933 int i; 3934 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3935 for (i = 0; i < bp->b_npages; i++) { 3936 vm_page_t m; 3937 m = bp->b_pages[i]; 3938 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3939 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3940 if ((i + 1) < bp->b_npages) 3941 db_printf(","); 3942 } 3943 db_printf("\n"); 3944 } 3945 lockmgr_printinfo(&bp->b_lock); 3946 } 3947 3948 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 3949 { 3950 struct buf *bp; 3951 int i; 3952 3953 for (i = 0; i < nbuf; i++) { 3954 bp = &buf[i]; 3955 if (lockcount(&bp->b_lock)) { 3956 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 3957 db_printf("\n"); 3958 } 3959 } 3960 } 3961 #endif /* DDB */ 3962