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_compat.h" 73 #include "opt_directio.h" 74 #include "opt_swap.h" 75 76 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 77 78 struct bio_ops bioops; /* I/O operation notification */ 79 80 struct buf_ops buf_ops_bio = { 81 .bop_name = "buf_ops_bio", 82 .bop_write = bufwrite, 83 .bop_strategy = bufstrategy, 84 .bop_sync = bufsync, 85 .bop_bdflush = bufbdflush, 86 }; 87 88 /* 89 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 90 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 91 */ 92 struct buf *buf; /* buffer header pool */ 93 94 static struct proc *bufdaemonproc; 95 96 static int inmem(struct vnode *vp, daddr_t blkno); 97 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from, 98 vm_offset_t to); 99 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 100 vm_offset_t to); 101 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 102 vm_page_t m); 103 static void vfs_clean_pages(struct buf *bp); 104 static void vfs_setdirty(struct buf *bp); 105 static void vfs_setdirty_locked_object(struct buf *bp); 106 static void vfs_vmio_release(struct buf *bp); 107 static int vfs_bio_clcheck(struct vnode *vp, int size, 108 daddr_t lblkno, daddr_t blkno); 109 static int buf_do_flush(struct vnode *vp); 110 static int flushbufqueues(struct vnode *, int, int); 111 static void buf_daemon(void); 112 static void bremfreel(struct buf *bp); 113 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 114 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 115 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 116 #endif 117 118 int vmiodirenable = TRUE; 119 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 120 "Use the VM system for directory writes"); 121 long runningbufspace; 122 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 123 "Amount of presently outstanding async buffer io"); 124 static long bufspace; 125 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 126 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 127 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 128 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 129 #else 130 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 131 "Virtual memory used for buffers"); 132 #endif 133 static long maxbufspace; 134 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 135 "Maximum allowed value of bufspace (including buf_daemon)"); 136 static long bufmallocspace; 137 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 138 "Amount of malloced memory for buffers"); 139 static long maxbufmallocspace; 140 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 141 "Maximum amount of malloced memory for buffers"); 142 static long lobufspace; 143 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 144 "Minimum amount of buffers we want to have"); 145 long hibufspace; 146 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 147 "Maximum allowed value of bufspace (excluding buf_daemon)"); 148 static int bufreusecnt; 149 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 150 "Number of times we have reused a buffer"); 151 static int buffreekvacnt; 152 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 153 "Number of times we have freed the KVA space from some buffer"); 154 static int bufdefragcnt; 155 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 156 "Number of times we have had to repeat buffer allocation to defragment"); 157 static long lorunningspace; 158 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 159 "Minimum preferred space used for in-progress I/O"); 160 static long hirunningspace; 161 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 162 "Maximum amount of space to use for in-progress I/O"); 163 int dirtybufferflushes; 164 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 165 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 166 int bdwriteskip; 167 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 168 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 169 int altbufferflushes; 170 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 171 0, "Number of fsync flushes to limit dirty buffers"); 172 static int recursiveflushes; 173 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 174 0, "Number of flushes skipped due to being recursive"); 175 static int numdirtybuffers; 176 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 177 "Number of buffers that are dirty (has unwritten changes) at the moment"); 178 static int lodirtybuffers; 179 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 180 "How many buffers we want to have free before bufdaemon can sleep"); 181 static int hidirtybuffers; 182 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 183 "When the number of dirty buffers is considered severe"); 184 int dirtybufthresh; 185 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 186 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 187 static int numfreebuffers; 188 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 189 "Number of free buffers"); 190 static int lofreebuffers; 191 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 192 "XXX Unused"); 193 static int hifreebuffers; 194 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 195 "XXX Complicatedly unused"); 196 static int getnewbufcalls; 197 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 198 "Number of calls to getnewbuf"); 199 static int getnewbufrestarts; 200 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 201 "Number of times getnewbuf has had to restart a buffer aquisition"); 202 static int flushbufqtarget = 100; 203 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 204 "Amount of work to do in flushbufqueues when helping bufdaemon"); 205 static long notbufdflashes; 206 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0, 207 "Number of dirty buffer flushes done by the bufdaemon helpers"); 208 209 /* 210 * Wakeup point for bufdaemon, as well as indicator of whether it is already 211 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 212 * is idling. 213 */ 214 static int bd_request; 215 216 /* 217 * This lock synchronizes access to bd_request. 218 */ 219 static struct mtx bdlock; 220 221 /* 222 * bogus page -- for I/O to/from partially complete buffers 223 * this is a temporary solution to the problem, but it is not 224 * really that bad. it would be better to split the buffer 225 * for input in the case of buffers partially already in memory, 226 * but the code is intricate enough already. 227 */ 228 vm_page_t bogus_page; 229 230 /* 231 * Synchronization (sleep/wakeup) variable for active buffer space requests. 232 * Set when wait starts, cleared prior to wakeup(). 233 * Used in runningbufwakeup() and waitrunningbufspace(). 234 */ 235 static int runningbufreq; 236 237 /* 238 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 239 * waitrunningbufspace(). 240 */ 241 static struct mtx rbreqlock; 242 243 /* 244 * Synchronization (sleep/wakeup) variable for buffer requests. 245 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 246 * by and/or. 247 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 248 * getnewbuf(), and getblk(). 249 */ 250 static int needsbuffer; 251 252 /* 253 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 254 */ 255 static struct mtx nblock; 256 257 /* 258 * Definitions for the buffer free lists. 259 */ 260 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 261 262 #define QUEUE_NONE 0 /* on no queue */ 263 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 264 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 265 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 266 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 267 #define QUEUE_EMPTY 5 /* empty buffer headers */ 268 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 269 270 /* Queues for free buffers with various properties */ 271 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 272 273 /* Lock for the bufqueues */ 274 static struct mtx bqlock; 275 276 /* 277 * Single global constant for BUF_WMESG, to avoid getting multiple references. 278 * buf_wmesg is referred from macros. 279 */ 280 const char *buf_wmesg = BUF_WMESG; 281 282 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 283 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 284 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 285 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 286 287 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 288 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 289 static int 290 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 291 { 292 long lvalue; 293 int ivalue; 294 295 if (sizeof(int) == sizeof(long) || req->oldlen == sizeof(long)) 296 return (sysctl_handle_long(oidp, arg1, arg2, req)); 297 lvalue = *(long *)arg1; 298 if (lvalue > INT_MAX) 299 /* On overflow, still write out a long to trigger ENOMEM. */ 300 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 301 ivalue = lvalue; 302 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 303 } 304 #endif 305 306 #ifdef DIRECTIO 307 extern void ffs_rawread_setup(void); 308 #endif /* DIRECTIO */ 309 /* 310 * numdirtywakeup: 311 * 312 * If someone is blocked due to there being too many dirty buffers, 313 * and numdirtybuffers is now reasonable, wake them up. 314 */ 315 316 static __inline void 317 numdirtywakeup(int level) 318 { 319 320 if (numdirtybuffers <= level) { 321 mtx_lock(&nblock); 322 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 323 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 324 wakeup(&needsbuffer); 325 } 326 mtx_unlock(&nblock); 327 } 328 } 329 330 /* 331 * bufspacewakeup: 332 * 333 * Called when buffer space is potentially available for recovery. 334 * getnewbuf() will block on this flag when it is unable to free 335 * sufficient buffer space. Buffer space becomes recoverable when 336 * bp's get placed back in the queues. 337 */ 338 339 static __inline void 340 bufspacewakeup(void) 341 { 342 343 /* 344 * If someone is waiting for BUF space, wake them up. Even 345 * though we haven't freed the kva space yet, the waiting 346 * process will be able to now. 347 */ 348 mtx_lock(&nblock); 349 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 350 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 351 wakeup(&needsbuffer); 352 } 353 mtx_unlock(&nblock); 354 } 355 356 /* 357 * runningbufwakeup() - in-progress I/O accounting. 358 * 359 */ 360 void 361 runningbufwakeup(struct buf *bp) 362 { 363 364 if (bp->b_runningbufspace) { 365 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace); 366 bp->b_runningbufspace = 0; 367 mtx_lock(&rbreqlock); 368 if (runningbufreq && runningbufspace <= lorunningspace) { 369 runningbufreq = 0; 370 wakeup(&runningbufreq); 371 } 372 mtx_unlock(&rbreqlock); 373 } 374 } 375 376 /* 377 * bufcountwakeup: 378 * 379 * Called when a buffer has been added to one of the free queues to 380 * account for the buffer and to wakeup anyone waiting for free buffers. 381 * This typically occurs when large amounts of metadata are being handled 382 * by the buffer cache ( else buffer space runs out first, usually ). 383 */ 384 385 static __inline void 386 bufcountwakeup(void) 387 { 388 389 atomic_add_int(&numfreebuffers, 1); 390 mtx_lock(&nblock); 391 if (needsbuffer) { 392 needsbuffer &= ~VFS_BIO_NEED_ANY; 393 if (numfreebuffers >= hifreebuffers) 394 needsbuffer &= ~VFS_BIO_NEED_FREE; 395 wakeup(&needsbuffer); 396 } 397 mtx_unlock(&nblock); 398 } 399 400 /* 401 * waitrunningbufspace() 402 * 403 * runningbufspace is a measure of the amount of I/O currently 404 * running. This routine is used in async-write situations to 405 * prevent creating huge backups of pending writes to a device. 406 * Only asynchronous writes are governed by this function. 407 * 408 * Reads will adjust runningbufspace, but will not block based on it. 409 * The read load has a side effect of reducing the allowed write load. 410 * 411 * This does NOT turn an async write into a sync write. It waits 412 * for earlier writes to complete and generally returns before the 413 * caller's write has reached the device. 414 */ 415 void 416 waitrunningbufspace(void) 417 { 418 419 mtx_lock(&rbreqlock); 420 while (runningbufspace > hirunningspace) { 421 ++runningbufreq; 422 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 423 } 424 mtx_unlock(&rbreqlock); 425 } 426 427 428 /* 429 * vfs_buf_test_cache: 430 * 431 * Called when a buffer is extended. This function clears the B_CACHE 432 * bit if the newly extended portion of the buffer does not contain 433 * valid data. 434 */ 435 static __inline 436 void 437 vfs_buf_test_cache(struct buf *bp, 438 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 439 vm_page_t m) 440 { 441 442 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 443 if (bp->b_flags & B_CACHE) { 444 int base = (foff + off) & PAGE_MASK; 445 if (vm_page_is_valid(m, base, size) == 0) 446 bp->b_flags &= ~B_CACHE; 447 } 448 } 449 450 /* Wake up the buffer daemon if necessary */ 451 static __inline 452 void 453 bd_wakeup(int dirtybuflevel) 454 { 455 456 mtx_lock(&bdlock); 457 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 458 bd_request = 1; 459 wakeup(&bd_request); 460 } 461 mtx_unlock(&bdlock); 462 } 463 464 /* 465 * bd_speedup - speedup the buffer cache flushing code 466 */ 467 468 static __inline 469 void 470 bd_speedup(void) 471 { 472 473 bd_wakeup(1); 474 } 475 476 /* 477 * Calculating buffer cache scaling values and reserve space for buffer 478 * headers. This is called during low level kernel initialization and 479 * may be called more then once. We CANNOT write to the memory area 480 * being reserved at this time. 481 */ 482 caddr_t 483 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 484 { 485 int tuned_nbuf; 486 long maxbuf; 487 488 /* 489 * physmem_est is in pages. Convert it to kilobytes (assumes 490 * PAGE_SIZE is >= 1K) 491 */ 492 physmem_est = physmem_est * (PAGE_SIZE / 1024); 493 494 /* 495 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 496 * For the first 64MB of ram nominally allocate sufficient buffers to 497 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 498 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 499 * the buffer cache we limit the eventual kva reservation to 500 * maxbcache bytes. 501 * 502 * factor represents the 1/4 x ram conversion. 503 */ 504 if (nbuf == 0) { 505 int factor = 4 * BKVASIZE / 1024; 506 507 nbuf = 50; 508 if (physmem_est > 4096) 509 nbuf += min((physmem_est - 4096) / factor, 510 65536 / factor); 511 if (physmem_est > 65536) 512 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 513 514 if (maxbcache && nbuf > maxbcache / BKVASIZE) 515 nbuf = maxbcache / BKVASIZE; 516 tuned_nbuf = 1; 517 } else 518 tuned_nbuf = 0; 519 520 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 521 maxbuf = (LONG_MAX / 3) / BKVASIZE; 522 if (nbuf > maxbuf) { 523 if (!tuned_nbuf) 524 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 525 maxbuf); 526 nbuf = maxbuf; 527 } 528 529 /* 530 * swbufs are used as temporary holders for I/O, such as paging I/O. 531 * We have no less then 16 and no more then 256. 532 */ 533 nswbuf = max(min(nbuf/4, 256), 16); 534 #ifdef NSWBUF_MIN 535 if (nswbuf < NSWBUF_MIN) 536 nswbuf = NSWBUF_MIN; 537 #endif 538 #ifdef DIRECTIO 539 ffs_rawread_setup(); 540 #endif 541 542 /* 543 * Reserve space for the buffer cache buffers 544 */ 545 swbuf = (void *)v; 546 v = (caddr_t)(swbuf + nswbuf); 547 buf = (void *)v; 548 v = (caddr_t)(buf + nbuf); 549 550 return(v); 551 } 552 553 /* Initialize the buffer subsystem. Called before use of any buffers. */ 554 void 555 bufinit(void) 556 { 557 struct buf *bp; 558 int i; 559 560 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 561 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 562 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 563 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 564 565 /* next, make a null set of free lists */ 566 for (i = 0; i < BUFFER_QUEUES; i++) 567 TAILQ_INIT(&bufqueues[i]); 568 569 /* finally, initialize each buffer header and stick on empty q */ 570 for (i = 0; i < nbuf; i++) { 571 bp = &buf[i]; 572 bzero(bp, sizeof *bp); 573 bp->b_flags = B_INVAL; /* we're just an empty header */ 574 bp->b_rcred = NOCRED; 575 bp->b_wcred = NOCRED; 576 bp->b_qindex = QUEUE_EMPTY; 577 bp->b_vflags = 0; 578 bp->b_xflags = 0; 579 LIST_INIT(&bp->b_dep); 580 BUF_LOCKINIT(bp); 581 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 582 } 583 584 /* 585 * maxbufspace is the absolute maximum amount of buffer space we are 586 * allowed to reserve in KVM and in real terms. The absolute maximum 587 * is nominally used by buf_daemon. hibufspace is the nominal maximum 588 * used by most other processes. The differential is required to 589 * ensure that buf_daemon is able to run when other processes might 590 * be blocked waiting for buffer space. 591 * 592 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 593 * this may result in KVM fragmentation which is not handled optimally 594 * by the system. 595 */ 596 maxbufspace = (long)nbuf * BKVASIZE; 597 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 598 lobufspace = hibufspace - MAXBSIZE; 599 600 lorunningspace = 512 * 1024; 601 hirunningspace = 1024 * 1024; 602 603 /* 604 * Limit the amount of malloc memory since it is wired permanently into 605 * the kernel space. Even though this is accounted for in the buffer 606 * allocation, we don't want the malloced region to grow uncontrolled. 607 * The malloc scheme improves memory utilization significantly on average 608 * (small) directories. 609 */ 610 maxbufmallocspace = hibufspace / 20; 611 612 /* 613 * Reduce the chance of a deadlock occuring by limiting the number 614 * of delayed-write dirty buffers we allow to stack up. 615 */ 616 hidirtybuffers = nbuf / 4 + 20; 617 dirtybufthresh = hidirtybuffers * 9 / 10; 618 numdirtybuffers = 0; 619 /* 620 * To support extreme low-memory systems, make sure hidirtybuffers cannot 621 * eat up all available buffer space. This occurs when our minimum cannot 622 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 623 * BKVASIZE'd (8K) buffers. 624 */ 625 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 626 hidirtybuffers >>= 1; 627 } 628 lodirtybuffers = hidirtybuffers / 2; 629 630 /* 631 * Try to keep the number of free buffers in the specified range, 632 * and give special processes (e.g. like buf_daemon) access to an 633 * emergency reserve. 634 */ 635 lofreebuffers = nbuf / 18 + 5; 636 hifreebuffers = 2 * lofreebuffers; 637 numfreebuffers = nbuf; 638 639 /* 640 * Maximum number of async ops initiated per buf_daemon loop. This is 641 * somewhat of a hack at the moment, we really need to limit ourselves 642 * based on the number of bytes of I/O in-transit that were initiated 643 * from buf_daemon. 644 */ 645 646 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 647 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 648 } 649 650 /* 651 * bfreekva() - free the kva allocation for a buffer. 652 * 653 * Since this call frees up buffer space, we call bufspacewakeup(). 654 */ 655 static void 656 bfreekva(struct buf *bp) 657 { 658 659 if (bp->b_kvasize) { 660 atomic_add_int(&buffreekvacnt, 1); 661 atomic_subtract_long(&bufspace, bp->b_kvasize); 662 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, 663 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 664 bp->b_kvasize = 0; 665 bufspacewakeup(); 666 } 667 } 668 669 /* 670 * bremfree: 671 * 672 * Mark the buffer for removal from the appropriate free list in brelse. 673 * 674 */ 675 void 676 bremfree(struct buf *bp) 677 { 678 679 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 680 KASSERT((bp->b_flags & B_REMFREE) == 0, 681 ("bremfree: buffer %p already marked for delayed removal.", bp)); 682 KASSERT(bp->b_qindex != QUEUE_NONE, 683 ("bremfree: buffer %p not on a queue.", bp)); 684 BUF_ASSERT_HELD(bp); 685 686 bp->b_flags |= B_REMFREE; 687 /* Fixup numfreebuffers count. */ 688 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 689 atomic_subtract_int(&numfreebuffers, 1); 690 } 691 692 /* 693 * bremfreef: 694 * 695 * Force an immediate removal from a free list. Used only in nfs when 696 * it abuses the b_freelist pointer. 697 */ 698 void 699 bremfreef(struct buf *bp) 700 { 701 mtx_lock(&bqlock); 702 bremfreel(bp); 703 mtx_unlock(&bqlock); 704 } 705 706 /* 707 * bremfreel: 708 * 709 * Removes a buffer from the free list, must be called with the 710 * bqlock held. 711 */ 712 static void 713 bremfreel(struct buf *bp) 714 { 715 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 716 bp, bp->b_vp, bp->b_flags); 717 KASSERT(bp->b_qindex != QUEUE_NONE, 718 ("bremfreel: buffer %p not on a queue.", bp)); 719 BUF_ASSERT_HELD(bp); 720 mtx_assert(&bqlock, MA_OWNED); 721 722 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 723 bp->b_qindex = QUEUE_NONE; 724 /* 725 * If this was a delayed bremfree() we only need to remove the buffer 726 * from the queue and return the stats are already done. 727 */ 728 if (bp->b_flags & B_REMFREE) { 729 bp->b_flags &= ~B_REMFREE; 730 return; 731 } 732 /* 733 * Fixup numfreebuffers count. If the buffer is invalid or not 734 * delayed-write, the buffer was free and we must decrement 735 * numfreebuffers. 736 */ 737 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 738 atomic_subtract_int(&numfreebuffers, 1); 739 } 740 741 742 /* 743 * Get a buffer with the specified data. Look in the cache first. We 744 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 745 * is set, the buffer is valid and we do not have to do anything ( see 746 * getblk() ). This is really just a special case of breadn(). 747 */ 748 int 749 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 750 struct buf **bpp) 751 { 752 753 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 754 } 755 756 /* 757 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 758 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 759 * the buffer is valid and we do not have to do anything. 760 */ 761 void 762 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 763 int cnt, struct ucred * cred) 764 { 765 struct buf *rabp; 766 int i; 767 768 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 769 if (inmem(vp, *rablkno)) 770 continue; 771 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 772 773 if ((rabp->b_flags & B_CACHE) == 0) { 774 if (!TD_IS_IDLETHREAD(curthread)) 775 curthread->td_ru.ru_inblock++; 776 rabp->b_flags |= B_ASYNC; 777 rabp->b_flags &= ~B_INVAL; 778 rabp->b_ioflags &= ~BIO_ERROR; 779 rabp->b_iocmd = BIO_READ; 780 if (rabp->b_rcred == NOCRED && cred != NOCRED) 781 rabp->b_rcred = crhold(cred); 782 vfs_busy_pages(rabp, 0); 783 BUF_KERNPROC(rabp); 784 rabp->b_iooffset = dbtob(rabp->b_blkno); 785 bstrategy(rabp); 786 } else { 787 brelse(rabp); 788 } 789 } 790 } 791 792 /* 793 * Operates like bread, but also starts asynchronous I/O on 794 * read-ahead blocks. 795 */ 796 int 797 breadn(struct vnode * vp, daddr_t blkno, int size, 798 daddr_t * rablkno, int *rabsize, 799 int cnt, struct ucred * cred, struct buf **bpp) 800 { 801 struct buf *bp; 802 int rv = 0, readwait = 0; 803 804 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 805 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 806 807 /* if not found in cache, do some I/O */ 808 if ((bp->b_flags & B_CACHE) == 0) { 809 if (!TD_IS_IDLETHREAD(curthread)) 810 curthread->td_ru.ru_inblock++; 811 bp->b_iocmd = BIO_READ; 812 bp->b_flags &= ~B_INVAL; 813 bp->b_ioflags &= ~BIO_ERROR; 814 if (bp->b_rcred == NOCRED && cred != NOCRED) 815 bp->b_rcred = crhold(cred); 816 vfs_busy_pages(bp, 0); 817 bp->b_iooffset = dbtob(bp->b_blkno); 818 bstrategy(bp); 819 ++readwait; 820 } 821 822 breada(vp, rablkno, rabsize, cnt, cred); 823 824 if (readwait) { 825 rv = bufwait(bp); 826 } 827 return (rv); 828 } 829 830 /* 831 * Write, release buffer on completion. (Done by iodone 832 * if async). Do not bother writing anything if the buffer 833 * is invalid. 834 * 835 * Note that we set B_CACHE here, indicating that buffer is 836 * fully valid and thus cacheable. This is true even of NFS 837 * now so we set it generally. This could be set either here 838 * or in biodone() since the I/O is synchronous. We put it 839 * here. 840 */ 841 int 842 bufwrite(struct buf *bp) 843 { 844 int oldflags; 845 struct vnode *vp; 846 int vp_md; 847 848 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 849 if (bp->b_flags & B_INVAL) { 850 brelse(bp); 851 return (0); 852 } 853 854 oldflags = bp->b_flags; 855 856 BUF_ASSERT_HELD(bp); 857 858 if (bp->b_pin_count > 0) 859 bunpin_wait(bp); 860 861 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 862 ("FFS background buffer should not get here %p", bp)); 863 864 vp = bp->b_vp; 865 if (vp) 866 vp_md = vp->v_vflag & VV_MD; 867 else 868 vp_md = 0; 869 870 /* Mark the buffer clean */ 871 bundirty(bp); 872 873 bp->b_flags &= ~B_DONE; 874 bp->b_ioflags &= ~BIO_ERROR; 875 bp->b_flags |= B_CACHE; 876 bp->b_iocmd = BIO_WRITE; 877 878 bufobj_wref(bp->b_bufobj); 879 vfs_busy_pages(bp, 1); 880 881 /* 882 * Normal bwrites pipeline writes 883 */ 884 bp->b_runningbufspace = bp->b_bufsize; 885 atomic_add_long(&runningbufspace, bp->b_runningbufspace); 886 887 if (!TD_IS_IDLETHREAD(curthread)) 888 curthread->td_ru.ru_oublock++; 889 if (oldflags & B_ASYNC) 890 BUF_KERNPROC(bp); 891 bp->b_iooffset = dbtob(bp->b_blkno); 892 bstrategy(bp); 893 894 if ((oldflags & B_ASYNC) == 0) { 895 int rtval = bufwait(bp); 896 brelse(bp); 897 return (rtval); 898 } else { 899 /* 900 * don't allow the async write to saturate the I/O 901 * system. We will not deadlock here because 902 * we are blocking waiting for I/O that is already in-progress 903 * to complete. We do not block here if it is the update 904 * or syncer daemon trying to clean up as that can lead 905 * to deadlock. 906 */ 907 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 908 waitrunningbufspace(); 909 } 910 911 return (0); 912 } 913 914 void 915 bufbdflush(struct bufobj *bo, struct buf *bp) 916 { 917 struct buf *nbp; 918 919 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 920 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 921 altbufferflushes++; 922 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 923 BO_LOCK(bo); 924 /* 925 * Try to find a buffer to flush. 926 */ 927 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 928 if ((nbp->b_vflags & BV_BKGRDINPROG) || 929 BUF_LOCK(nbp, 930 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 931 continue; 932 if (bp == nbp) 933 panic("bdwrite: found ourselves"); 934 BO_UNLOCK(bo); 935 /* Don't countdeps with the bo lock held. */ 936 if (buf_countdeps(nbp, 0)) { 937 BO_LOCK(bo); 938 BUF_UNLOCK(nbp); 939 continue; 940 } 941 if (nbp->b_flags & B_CLUSTEROK) { 942 vfs_bio_awrite(nbp); 943 } else { 944 bremfree(nbp); 945 bawrite(nbp); 946 } 947 dirtybufferflushes++; 948 break; 949 } 950 if (nbp == NULL) 951 BO_UNLOCK(bo); 952 } 953 } 954 955 /* 956 * Delayed write. (Buffer is marked dirty). Do not bother writing 957 * anything if the buffer is marked invalid. 958 * 959 * Note that since the buffer must be completely valid, we can safely 960 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 961 * biodone() in order to prevent getblk from writing the buffer 962 * out synchronously. 963 */ 964 void 965 bdwrite(struct buf *bp) 966 { 967 struct thread *td = curthread; 968 struct vnode *vp; 969 struct bufobj *bo; 970 971 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 972 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 973 BUF_ASSERT_HELD(bp); 974 975 if (bp->b_flags & B_INVAL) { 976 brelse(bp); 977 return; 978 } 979 980 /* 981 * If we have too many dirty buffers, don't create any more. 982 * If we are wildly over our limit, then force a complete 983 * cleanup. Otherwise, just keep the situation from getting 984 * out of control. Note that we have to avoid a recursive 985 * disaster and not try to clean up after our own cleanup! 986 */ 987 vp = bp->b_vp; 988 bo = bp->b_bufobj; 989 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 990 td->td_pflags |= TDP_INBDFLUSH; 991 BO_BDFLUSH(bo, bp); 992 td->td_pflags &= ~TDP_INBDFLUSH; 993 } else 994 recursiveflushes++; 995 996 bdirty(bp); 997 /* 998 * Set B_CACHE, indicating that the buffer is fully valid. This is 999 * true even of NFS now. 1000 */ 1001 bp->b_flags |= B_CACHE; 1002 1003 /* 1004 * This bmap keeps the system from needing to do the bmap later, 1005 * perhaps when the system is attempting to do a sync. Since it 1006 * is likely that the indirect block -- or whatever other datastructure 1007 * that the filesystem needs is still in memory now, it is a good 1008 * thing to do this. Note also, that if the pageout daemon is 1009 * requesting a sync -- there might not be enough memory to do 1010 * the bmap then... So, this is important to do. 1011 */ 1012 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1013 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1014 } 1015 1016 /* 1017 * Set the *dirty* buffer range based upon the VM system dirty pages. 1018 */ 1019 vfs_setdirty(bp); 1020 1021 /* 1022 * We need to do this here to satisfy the vnode_pager and the 1023 * pageout daemon, so that it thinks that the pages have been 1024 * "cleaned". Note that since the pages are in a delayed write 1025 * buffer -- the VFS layer "will" see that the pages get written 1026 * out on the next sync, or perhaps the cluster will be completed. 1027 */ 1028 vfs_clean_pages(bp); 1029 bqrelse(bp); 1030 1031 /* 1032 * Wakeup the buffer flushing daemon if we have a lot of dirty 1033 * buffers (midpoint between our recovery point and our stall 1034 * point). 1035 */ 1036 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1037 1038 /* 1039 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1040 * due to the softdep code. 1041 */ 1042 } 1043 1044 /* 1045 * bdirty: 1046 * 1047 * Turn buffer into delayed write request. We must clear BIO_READ and 1048 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1049 * itself to properly update it in the dirty/clean lists. We mark it 1050 * B_DONE to ensure that any asynchronization of the buffer properly 1051 * clears B_DONE ( else a panic will occur later ). 1052 * 1053 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1054 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1055 * should only be called if the buffer is known-good. 1056 * 1057 * Since the buffer is not on a queue, we do not update the numfreebuffers 1058 * count. 1059 * 1060 * The buffer must be on QUEUE_NONE. 1061 */ 1062 void 1063 bdirty(struct buf *bp) 1064 { 1065 1066 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1067 bp, bp->b_vp, bp->b_flags); 1068 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1069 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1070 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1071 BUF_ASSERT_HELD(bp); 1072 bp->b_flags &= ~(B_RELBUF); 1073 bp->b_iocmd = BIO_WRITE; 1074 1075 if ((bp->b_flags & B_DELWRI) == 0) { 1076 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1077 reassignbuf(bp); 1078 atomic_add_int(&numdirtybuffers, 1); 1079 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1080 } 1081 } 1082 1083 /* 1084 * bundirty: 1085 * 1086 * Clear B_DELWRI for buffer. 1087 * 1088 * Since the buffer is not on a queue, we do not update the numfreebuffers 1089 * count. 1090 * 1091 * The buffer must be on QUEUE_NONE. 1092 */ 1093 1094 void 1095 bundirty(struct buf *bp) 1096 { 1097 1098 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1099 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1100 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1101 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1102 BUF_ASSERT_HELD(bp); 1103 1104 if (bp->b_flags & B_DELWRI) { 1105 bp->b_flags &= ~B_DELWRI; 1106 reassignbuf(bp); 1107 atomic_subtract_int(&numdirtybuffers, 1); 1108 numdirtywakeup(lodirtybuffers); 1109 } 1110 /* 1111 * Since it is now being written, we can clear its deferred write flag. 1112 */ 1113 bp->b_flags &= ~B_DEFERRED; 1114 } 1115 1116 /* 1117 * bawrite: 1118 * 1119 * Asynchronous write. Start output on a buffer, but do not wait for 1120 * it to complete. The buffer is released when the output completes. 1121 * 1122 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1123 * B_INVAL buffers. Not us. 1124 */ 1125 void 1126 bawrite(struct buf *bp) 1127 { 1128 1129 bp->b_flags |= B_ASYNC; 1130 (void) bwrite(bp); 1131 } 1132 1133 /* 1134 * bwillwrite: 1135 * 1136 * Called prior to the locking of any vnodes when we are expecting to 1137 * write. We do not want to starve the buffer cache with too many 1138 * dirty buffers so we block here. By blocking prior to the locking 1139 * of any vnodes we attempt to avoid the situation where a locked vnode 1140 * prevents the various system daemons from flushing related buffers. 1141 */ 1142 1143 void 1144 bwillwrite(void) 1145 { 1146 1147 if (numdirtybuffers >= hidirtybuffers) { 1148 mtx_lock(&nblock); 1149 while (numdirtybuffers >= hidirtybuffers) { 1150 bd_wakeup(1); 1151 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1152 msleep(&needsbuffer, &nblock, 1153 (PRIBIO + 4), "flswai", 0); 1154 } 1155 mtx_unlock(&nblock); 1156 } 1157 } 1158 1159 /* 1160 * Return true if we have too many dirty buffers. 1161 */ 1162 int 1163 buf_dirty_count_severe(void) 1164 { 1165 1166 return(numdirtybuffers >= hidirtybuffers); 1167 } 1168 1169 /* 1170 * brelse: 1171 * 1172 * Release a busy buffer and, if requested, free its resources. The 1173 * buffer will be stashed in the appropriate bufqueue[] allowing it 1174 * to be accessed later as a cache entity or reused for other purposes. 1175 */ 1176 void 1177 brelse(struct buf *bp) 1178 { 1179 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1180 bp, bp->b_vp, bp->b_flags); 1181 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1182 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1183 1184 if (bp->b_flags & B_MANAGED) { 1185 bqrelse(bp); 1186 return; 1187 } 1188 1189 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1190 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1191 /* 1192 * Failed write, redirty. Must clear BIO_ERROR to prevent 1193 * pages from being scrapped. If the error is anything 1194 * other than an I/O error (EIO), assume that retryingi 1195 * is futile. 1196 */ 1197 bp->b_ioflags &= ~BIO_ERROR; 1198 bdirty(bp); 1199 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1200 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1201 /* 1202 * Either a failed I/O or we were asked to free or not 1203 * cache the buffer. 1204 */ 1205 bp->b_flags |= B_INVAL; 1206 if (!LIST_EMPTY(&bp->b_dep)) 1207 buf_deallocate(bp); 1208 if (bp->b_flags & B_DELWRI) { 1209 atomic_subtract_int(&numdirtybuffers, 1); 1210 numdirtywakeup(lodirtybuffers); 1211 } 1212 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1213 if ((bp->b_flags & B_VMIO) == 0) { 1214 if (bp->b_bufsize) 1215 allocbuf(bp, 0); 1216 if (bp->b_vp) 1217 brelvp(bp); 1218 } 1219 } 1220 1221 /* 1222 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1223 * is called with B_DELWRI set, the underlying pages may wind up 1224 * getting freed causing a previous write (bdwrite()) to get 'lost' 1225 * because pages associated with a B_DELWRI bp are marked clean. 1226 * 1227 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1228 * if B_DELWRI is set. 1229 * 1230 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1231 * on pages to return pages to the VM page queues. 1232 */ 1233 if (bp->b_flags & B_DELWRI) 1234 bp->b_flags &= ~B_RELBUF; 1235 else if (vm_page_count_severe()) { 1236 /* 1237 * The locking of the BO_LOCK is not necessary since 1238 * BKGRDINPROG cannot be set while we hold the buf 1239 * lock, it can only be cleared if it is already 1240 * pending. 1241 */ 1242 if (bp->b_vp) { 1243 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1244 bp->b_flags |= B_RELBUF; 1245 } else 1246 bp->b_flags |= B_RELBUF; 1247 } 1248 1249 /* 1250 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1251 * constituted, not even NFS buffers now. Two flags effect this. If 1252 * B_INVAL, the struct buf is invalidated but the VM object is kept 1253 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1254 * 1255 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1256 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1257 * buffer is also B_INVAL because it hits the re-dirtying code above. 1258 * 1259 * Normally we can do this whether a buffer is B_DELWRI or not. If 1260 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1261 * the commit state and we cannot afford to lose the buffer. If the 1262 * buffer has a background write in progress, we need to keep it 1263 * around to prevent it from being reconstituted and starting a second 1264 * background write. 1265 */ 1266 if ((bp->b_flags & B_VMIO) 1267 && !(bp->b_vp->v_mount != NULL && 1268 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1269 !vn_isdisk(bp->b_vp, NULL) && 1270 (bp->b_flags & B_DELWRI)) 1271 ) { 1272 1273 int i, j, resid; 1274 vm_page_t m; 1275 off_t foff; 1276 vm_pindex_t poff; 1277 vm_object_t obj; 1278 1279 obj = bp->b_bufobj->bo_object; 1280 1281 /* 1282 * Get the base offset and length of the buffer. Note that 1283 * in the VMIO case if the buffer block size is not 1284 * page-aligned then b_data pointer may not be page-aligned. 1285 * But our b_pages[] array *IS* page aligned. 1286 * 1287 * block sizes less then DEV_BSIZE (usually 512) are not 1288 * supported due to the page granularity bits (m->valid, 1289 * m->dirty, etc...). 1290 * 1291 * See man buf(9) for more information 1292 */ 1293 resid = bp->b_bufsize; 1294 foff = bp->b_offset; 1295 VM_OBJECT_LOCK(obj); 1296 for (i = 0; i < bp->b_npages; i++) { 1297 int had_bogus = 0; 1298 1299 m = bp->b_pages[i]; 1300 1301 /* 1302 * If we hit a bogus page, fixup *all* the bogus pages 1303 * now. 1304 */ 1305 if (m == bogus_page) { 1306 poff = OFF_TO_IDX(bp->b_offset); 1307 had_bogus = 1; 1308 1309 for (j = i; j < bp->b_npages; j++) { 1310 vm_page_t mtmp; 1311 mtmp = bp->b_pages[j]; 1312 if (mtmp == bogus_page) { 1313 mtmp = vm_page_lookup(obj, poff + j); 1314 if (!mtmp) { 1315 panic("brelse: page missing\n"); 1316 } 1317 bp->b_pages[j] = mtmp; 1318 } 1319 } 1320 1321 if ((bp->b_flags & B_INVAL) == 0) { 1322 pmap_qenter( 1323 trunc_page((vm_offset_t)bp->b_data), 1324 bp->b_pages, bp->b_npages); 1325 } 1326 m = bp->b_pages[i]; 1327 } 1328 if ((bp->b_flags & B_NOCACHE) || 1329 (bp->b_ioflags & BIO_ERROR)) { 1330 int poffset = foff & PAGE_MASK; 1331 int presid = resid > (PAGE_SIZE - poffset) ? 1332 (PAGE_SIZE - poffset) : resid; 1333 1334 KASSERT(presid >= 0, ("brelse: extra page")); 1335 vm_page_lock_queues(); 1336 vm_page_set_invalid(m, poffset, presid); 1337 vm_page_unlock_queues(); 1338 if (had_bogus) 1339 printf("avoided corruption bug in bogus_page/brelse code\n"); 1340 } 1341 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1342 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1343 } 1344 VM_OBJECT_UNLOCK(obj); 1345 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1346 vfs_vmio_release(bp); 1347 1348 } else if (bp->b_flags & B_VMIO) { 1349 1350 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1351 vfs_vmio_release(bp); 1352 } 1353 1354 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1355 if (bp->b_bufsize != 0) 1356 allocbuf(bp, 0); 1357 if (bp->b_vp != NULL) 1358 brelvp(bp); 1359 } 1360 1361 if (BUF_LOCKRECURSED(bp)) { 1362 /* do not release to free list */ 1363 BUF_UNLOCK(bp); 1364 return; 1365 } 1366 1367 /* enqueue */ 1368 mtx_lock(&bqlock); 1369 /* Handle delayed bremfree() processing. */ 1370 if (bp->b_flags & B_REMFREE) 1371 bremfreel(bp); 1372 if (bp->b_qindex != QUEUE_NONE) 1373 panic("brelse: free buffer onto another queue???"); 1374 1375 /* 1376 * If the buffer has junk contents signal it and eventually 1377 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1378 * doesn't find it. 1379 */ 1380 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1381 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1382 bp->b_flags |= B_INVAL; 1383 if (bp->b_flags & B_INVAL) { 1384 if (bp->b_flags & B_DELWRI) 1385 bundirty(bp); 1386 if (bp->b_vp) 1387 brelvp(bp); 1388 } 1389 1390 /* buffers with no memory */ 1391 if (bp->b_bufsize == 0) { 1392 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1393 if (bp->b_vflags & BV_BKGRDINPROG) 1394 panic("losing buffer 1"); 1395 if (bp->b_kvasize) { 1396 bp->b_qindex = QUEUE_EMPTYKVA; 1397 } else { 1398 bp->b_qindex = QUEUE_EMPTY; 1399 } 1400 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1401 /* buffers with junk contents */ 1402 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1403 (bp->b_ioflags & BIO_ERROR)) { 1404 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1405 if (bp->b_vflags & BV_BKGRDINPROG) 1406 panic("losing buffer 2"); 1407 bp->b_qindex = QUEUE_CLEAN; 1408 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1409 /* remaining buffers */ 1410 } else { 1411 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1412 (B_DELWRI|B_NEEDSGIANT)) 1413 bp->b_qindex = QUEUE_DIRTY_GIANT; 1414 else if (bp->b_flags & B_DELWRI) 1415 bp->b_qindex = QUEUE_DIRTY; 1416 else 1417 bp->b_qindex = QUEUE_CLEAN; 1418 if (bp->b_flags & B_AGE) 1419 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1420 else 1421 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1422 } 1423 mtx_unlock(&bqlock); 1424 1425 /* 1426 * Fixup numfreebuffers count. The bp is on an appropriate queue 1427 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1428 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1429 * if B_INVAL is set ). 1430 */ 1431 1432 if (!(bp->b_flags & B_DELWRI)) 1433 bufcountwakeup(); 1434 1435 /* 1436 * Something we can maybe free or reuse 1437 */ 1438 if (bp->b_bufsize || bp->b_kvasize) 1439 bufspacewakeup(); 1440 1441 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1442 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1443 panic("brelse: not dirty"); 1444 /* unlock */ 1445 BUF_UNLOCK(bp); 1446 } 1447 1448 /* 1449 * Release a buffer back to the appropriate queue but do not try to free 1450 * it. The buffer is expected to be used again soon. 1451 * 1452 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1453 * biodone() to requeue an async I/O on completion. It is also used when 1454 * known good buffers need to be requeued but we think we may need the data 1455 * again soon. 1456 * 1457 * XXX we should be able to leave the B_RELBUF hint set on completion. 1458 */ 1459 void 1460 bqrelse(struct buf *bp) 1461 { 1462 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1463 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1464 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1465 1466 if (BUF_LOCKRECURSED(bp)) { 1467 /* do not release to free list */ 1468 BUF_UNLOCK(bp); 1469 return; 1470 } 1471 1472 if (bp->b_flags & B_MANAGED) { 1473 if (bp->b_flags & B_REMFREE) { 1474 mtx_lock(&bqlock); 1475 bremfreel(bp); 1476 mtx_unlock(&bqlock); 1477 } 1478 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1479 BUF_UNLOCK(bp); 1480 return; 1481 } 1482 1483 mtx_lock(&bqlock); 1484 /* Handle delayed bremfree() processing. */ 1485 if (bp->b_flags & B_REMFREE) 1486 bremfreel(bp); 1487 if (bp->b_qindex != QUEUE_NONE) 1488 panic("bqrelse: free buffer onto another queue???"); 1489 /* buffers with stale but valid contents */ 1490 if (bp->b_flags & B_DELWRI) { 1491 if (bp->b_flags & B_NEEDSGIANT) 1492 bp->b_qindex = QUEUE_DIRTY_GIANT; 1493 else 1494 bp->b_qindex = QUEUE_DIRTY; 1495 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1496 } else { 1497 /* 1498 * The locking of the BO_LOCK for checking of the 1499 * BV_BKGRDINPROG is not necessary since the 1500 * BV_BKGRDINPROG cannot be set while we hold the buf 1501 * lock, it can only be cleared if it is already 1502 * pending. 1503 */ 1504 if (!vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1505 bp->b_qindex = QUEUE_CLEAN; 1506 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1507 b_freelist); 1508 } else { 1509 /* 1510 * We are too low on memory, we have to try to free 1511 * the buffer (most importantly: the wired pages 1512 * making up its backing store) *now*. 1513 */ 1514 mtx_unlock(&bqlock); 1515 brelse(bp); 1516 return; 1517 } 1518 } 1519 mtx_unlock(&bqlock); 1520 1521 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1522 bufcountwakeup(); 1523 1524 /* 1525 * Something we can maybe free or reuse. 1526 */ 1527 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1528 bufspacewakeup(); 1529 1530 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1531 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1532 panic("bqrelse: not dirty"); 1533 /* unlock */ 1534 BUF_UNLOCK(bp); 1535 } 1536 1537 /* Give pages used by the bp back to the VM system (where possible) */ 1538 static void 1539 vfs_vmio_release(struct buf *bp) 1540 { 1541 int i; 1542 vm_page_t m; 1543 1544 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1545 vm_page_lock_queues(); 1546 for (i = 0; i < bp->b_npages; i++) { 1547 m = bp->b_pages[i]; 1548 bp->b_pages[i] = NULL; 1549 /* 1550 * In order to keep page LRU ordering consistent, put 1551 * everything on the inactive queue. 1552 */ 1553 vm_page_unwire(m, 0); 1554 /* 1555 * We don't mess with busy pages, it is 1556 * the responsibility of the process that 1557 * busied the pages to deal with them. 1558 */ 1559 if ((m->oflags & VPO_BUSY) || (m->busy != 0)) 1560 continue; 1561 1562 if (m->wire_count == 0) { 1563 /* 1564 * Might as well free the page if we can and it has 1565 * no valid data. We also free the page if the 1566 * buffer was used for direct I/O 1567 */ 1568 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1569 m->hold_count == 0) { 1570 vm_page_free(m); 1571 } else if (bp->b_flags & B_DIRECT) { 1572 vm_page_try_to_free(m); 1573 } else if (vm_page_count_severe()) { 1574 vm_page_try_to_cache(m); 1575 } 1576 } 1577 } 1578 vm_page_unlock_queues(); 1579 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1580 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1581 1582 if (bp->b_bufsize) { 1583 bufspacewakeup(); 1584 bp->b_bufsize = 0; 1585 } 1586 bp->b_npages = 0; 1587 bp->b_flags &= ~B_VMIO; 1588 if (bp->b_vp) 1589 brelvp(bp); 1590 } 1591 1592 /* 1593 * Check to see if a block at a particular lbn is available for a clustered 1594 * write. 1595 */ 1596 static int 1597 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1598 { 1599 struct buf *bpa; 1600 int match; 1601 1602 match = 0; 1603 1604 /* If the buf isn't in core skip it */ 1605 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1606 return (0); 1607 1608 /* If the buf is busy we don't want to wait for it */ 1609 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1610 return (0); 1611 1612 /* Only cluster with valid clusterable delayed write buffers */ 1613 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1614 (B_DELWRI | B_CLUSTEROK)) 1615 goto done; 1616 1617 if (bpa->b_bufsize != size) 1618 goto done; 1619 1620 /* 1621 * Check to see if it is in the expected place on disk and that the 1622 * block has been mapped. 1623 */ 1624 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1625 match = 1; 1626 done: 1627 BUF_UNLOCK(bpa); 1628 return (match); 1629 } 1630 1631 /* 1632 * vfs_bio_awrite: 1633 * 1634 * Implement clustered async writes for clearing out B_DELWRI buffers. 1635 * This is much better then the old way of writing only one buffer at 1636 * a time. Note that we may not be presented with the buffers in the 1637 * correct order, so we search for the cluster in both directions. 1638 */ 1639 int 1640 vfs_bio_awrite(struct buf *bp) 1641 { 1642 struct bufobj *bo; 1643 int i; 1644 int j; 1645 daddr_t lblkno = bp->b_lblkno; 1646 struct vnode *vp = bp->b_vp; 1647 int ncl; 1648 int nwritten; 1649 int size; 1650 int maxcl; 1651 1652 bo = &vp->v_bufobj; 1653 /* 1654 * right now we support clustered writing only to regular files. If 1655 * we find a clusterable block we could be in the middle of a cluster 1656 * rather then at the beginning. 1657 */ 1658 if ((vp->v_type == VREG) && 1659 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1660 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1661 1662 size = vp->v_mount->mnt_stat.f_iosize; 1663 maxcl = MAXPHYS / size; 1664 1665 BO_LOCK(bo); 1666 for (i = 1; i < maxcl; i++) 1667 if (vfs_bio_clcheck(vp, size, lblkno + i, 1668 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1669 break; 1670 1671 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1672 if (vfs_bio_clcheck(vp, size, lblkno - j, 1673 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1674 break; 1675 BO_UNLOCK(bo); 1676 --j; 1677 ncl = i + j; 1678 /* 1679 * this is a possible cluster write 1680 */ 1681 if (ncl != 1) { 1682 BUF_UNLOCK(bp); 1683 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1684 return nwritten; 1685 } 1686 } 1687 bremfree(bp); 1688 bp->b_flags |= B_ASYNC; 1689 /* 1690 * default (old) behavior, writing out only one block 1691 * 1692 * XXX returns b_bufsize instead of b_bcount for nwritten? 1693 */ 1694 nwritten = bp->b_bufsize; 1695 (void) bwrite(bp); 1696 1697 return nwritten; 1698 } 1699 1700 /* 1701 * getnewbuf: 1702 * 1703 * Find and initialize a new buffer header, freeing up existing buffers 1704 * in the bufqueues as necessary. The new buffer is returned locked. 1705 * 1706 * Important: B_INVAL is not set. If the caller wishes to throw the 1707 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1708 * 1709 * We block if: 1710 * We have insufficient buffer headers 1711 * We have insufficient buffer space 1712 * buffer_map is too fragmented ( space reservation fails ) 1713 * If we have to flush dirty buffers ( but we try to avoid this ) 1714 * 1715 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1716 * Instead we ask the buf daemon to do it for us. We attempt to 1717 * avoid piecemeal wakeups of the pageout daemon. 1718 */ 1719 1720 static struct buf * 1721 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 1722 int gbflags) 1723 { 1724 struct thread *td; 1725 struct buf *bp; 1726 struct buf *nbp; 1727 int defrag = 0; 1728 int nqindex; 1729 static int flushingbufs; 1730 1731 td = curthread; 1732 /* 1733 * We can't afford to block since we might be holding a vnode lock, 1734 * which may prevent system daemons from running. We deal with 1735 * low-memory situations by proactively returning memory and running 1736 * async I/O rather then sync I/O. 1737 */ 1738 atomic_add_int(&getnewbufcalls, 1); 1739 atomic_subtract_int(&getnewbufrestarts, 1); 1740 restart: 1741 atomic_add_int(&getnewbufrestarts, 1); 1742 1743 /* 1744 * Setup for scan. If we do not have enough free buffers, 1745 * we setup a degenerate case that immediately fails. Note 1746 * that if we are specially marked process, we are allowed to 1747 * dip into our reserves. 1748 * 1749 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1750 * 1751 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1752 * However, there are a number of cases (defragging, reusing, ...) 1753 * where we cannot backup. 1754 */ 1755 mtx_lock(&bqlock); 1756 nqindex = QUEUE_EMPTYKVA; 1757 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1758 1759 if (nbp == NULL) { 1760 /* 1761 * If no EMPTYKVA buffers and we are either 1762 * defragging or reusing, locate a CLEAN buffer 1763 * to free or reuse. If bufspace useage is low 1764 * skip this step so we can allocate a new buffer. 1765 */ 1766 if (defrag || bufspace >= lobufspace) { 1767 nqindex = QUEUE_CLEAN; 1768 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1769 } 1770 1771 /* 1772 * If we could not find or were not allowed to reuse a 1773 * CLEAN buffer, check to see if it is ok to use an EMPTY 1774 * buffer. We can only use an EMPTY buffer if allocating 1775 * its KVA would not otherwise run us out of buffer space. 1776 */ 1777 if (nbp == NULL && defrag == 0 && 1778 bufspace + maxsize < hibufspace) { 1779 nqindex = QUEUE_EMPTY; 1780 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1781 } 1782 } 1783 1784 /* 1785 * Run scan, possibly freeing data and/or kva mappings on the fly 1786 * depending. 1787 */ 1788 1789 while ((bp = nbp) != NULL) { 1790 int qindex = nqindex; 1791 1792 /* 1793 * Calculate next bp ( we can only use it if we do not block 1794 * or do other fancy things ). 1795 */ 1796 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1797 switch(qindex) { 1798 case QUEUE_EMPTY: 1799 nqindex = QUEUE_EMPTYKVA; 1800 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1801 break; 1802 /* FALLTHROUGH */ 1803 case QUEUE_EMPTYKVA: 1804 nqindex = QUEUE_CLEAN; 1805 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1806 break; 1807 /* FALLTHROUGH */ 1808 case QUEUE_CLEAN: 1809 /* 1810 * nbp is NULL. 1811 */ 1812 break; 1813 } 1814 } 1815 /* 1816 * If we are defragging then we need a buffer with 1817 * b_kvasize != 0. XXX this situation should no longer 1818 * occur, if defrag is non-zero the buffer's b_kvasize 1819 * should also be non-zero at this point. XXX 1820 */ 1821 if (defrag && bp->b_kvasize == 0) { 1822 printf("Warning: defrag empty buffer %p\n", bp); 1823 continue; 1824 } 1825 1826 /* 1827 * Start freeing the bp. This is somewhat involved. nbp 1828 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1829 */ 1830 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1831 continue; 1832 if (bp->b_vp) { 1833 BO_LOCK(bp->b_bufobj); 1834 if (bp->b_vflags & BV_BKGRDINPROG) { 1835 BO_UNLOCK(bp->b_bufobj); 1836 BUF_UNLOCK(bp); 1837 continue; 1838 } 1839 BO_UNLOCK(bp->b_bufobj); 1840 } 1841 CTR6(KTR_BUF, 1842 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1843 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1844 bp->b_kvasize, bp->b_bufsize, qindex); 1845 1846 /* 1847 * Sanity Checks 1848 */ 1849 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1850 1851 /* 1852 * Note: we no longer distinguish between VMIO and non-VMIO 1853 * buffers. 1854 */ 1855 1856 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1857 1858 bremfreel(bp); 1859 mtx_unlock(&bqlock); 1860 1861 if (qindex == QUEUE_CLEAN) { 1862 if (bp->b_flags & B_VMIO) { 1863 bp->b_flags &= ~B_ASYNC; 1864 vfs_vmio_release(bp); 1865 } 1866 if (bp->b_vp) 1867 brelvp(bp); 1868 } 1869 1870 /* 1871 * NOTE: nbp is now entirely invalid. We can only restart 1872 * the scan from this point on. 1873 * 1874 * Get the rest of the buffer freed up. b_kva* is still 1875 * valid after this operation. 1876 */ 1877 1878 if (bp->b_rcred != NOCRED) { 1879 crfree(bp->b_rcred); 1880 bp->b_rcred = NOCRED; 1881 } 1882 if (bp->b_wcred != NOCRED) { 1883 crfree(bp->b_wcred); 1884 bp->b_wcred = NOCRED; 1885 } 1886 if (!LIST_EMPTY(&bp->b_dep)) 1887 buf_deallocate(bp); 1888 if (bp->b_vflags & BV_BKGRDINPROG) 1889 panic("losing buffer 3"); 1890 KASSERT(bp->b_vp == NULL, 1891 ("bp: %p still has vnode %p. qindex: %d", 1892 bp, bp->b_vp, qindex)); 1893 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1894 ("bp: %p still on a buffer list. xflags %X", 1895 bp, bp->b_xflags)); 1896 1897 if (bp->b_bufsize) 1898 allocbuf(bp, 0); 1899 1900 bp->b_flags = 0; 1901 bp->b_ioflags = 0; 1902 bp->b_xflags = 0; 1903 bp->b_vflags = 0; 1904 bp->b_vp = NULL; 1905 bp->b_blkno = bp->b_lblkno = 0; 1906 bp->b_offset = NOOFFSET; 1907 bp->b_iodone = 0; 1908 bp->b_error = 0; 1909 bp->b_resid = 0; 1910 bp->b_bcount = 0; 1911 bp->b_npages = 0; 1912 bp->b_dirtyoff = bp->b_dirtyend = 0; 1913 bp->b_bufobj = NULL; 1914 bp->b_pin_count = 0; 1915 bp->b_fsprivate1 = NULL; 1916 bp->b_fsprivate2 = NULL; 1917 bp->b_fsprivate3 = NULL; 1918 1919 LIST_INIT(&bp->b_dep); 1920 1921 /* 1922 * If we are defragging then free the buffer. 1923 */ 1924 if (defrag) { 1925 bp->b_flags |= B_INVAL; 1926 bfreekva(bp); 1927 brelse(bp); 1928 defrag = 0; 1929 goto restart; 1930 } 1931 1932 /* 1933 * Notify any waiters for the buffer lock about 1934 * identity change by freeing the buffer. 1935 */ 1936 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 1937 bp->b_flags |= B_INVAL; 1938 bfreekva(bp); 1939 brelse(bp); 1940 goto restart; 1941 } 1942 1943 /* 1944 * If we are overcomitted then recover the buffer and its 1945 * KVM space. This occurs in rare situations when multiple 1946 * processes are blocked in getnewbuf() or allocbuf(). 1947 */ 1948 if (bufspace >= hibufspace) 1949 flushingbufs = 1; 1950 if (flushingbufs && bp->b_kvasize != 0) { 1951 bp->b_flags |= B_INVAL; 1952 bfreekva(bp); 1953 brelse(bp); 1954 goto restart; 1955 } 1956 if (bufspace < lobufspace) 1957 flushingbufs = 0; 1958 break; 1959 } 1960 1961 /* 1962 * If we exhausted our list, sleep as appropriate. We may have to 1963 * wakeup various daemons and write out some dirty buffers. 1964 * 1965 * Generally we are sleeping due to insufficient buffer space. 1966 */ 1967 1968 if (bp == NULL) { 1969 int flags, norunbuf; 1970 char *waitmsg; 1971 int fl; 1972 1973 if (defrag) { 1974 flags = VFS_BIO_NEED_BUFSPACE; 1975 waitmsg = "nbufkv"; 1976 } else if (bufspace >= hibufspace) { 1977 waitmsg = "nbufbs"; 1978 flags = VFS_BIO_NEED_BUFSPACE; 1979 } else { 1980 waitmsg = "newbuf"; 1981 flags = VFS_BIO_NEED_ANY; 1982 } 1983 mtx_lock(&nblock); 1984 needsbuffer |= flags; 1985 mtx_unlock(&nblock); 1986 mtx_unlock(&bqlock); 1987 1988 bd_speedup(); /* heeeelp */ 1989 if (gbflags & GB_NOWAIT_BD) 1990 return (NULL); 1991 1992 mtx_lock(&nblock); 1993 while (needsbuffer & flags) { 1994 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 1995 mtx_unlock(&nblock); 1996 /* 1997 * getblk() is called with a vnode 1998 * locked, and some majority of the 1999 * dirty buffers may as well belong to 2000 * the vnode. Flushing the buffers 2001 * there would make a progress that 2002 * cannot be achieved by the 2003 * buf_daemon, that cannot lock the 2004 * vnode. 2005 */ 2006 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2007 (td->td_pflags & TDP_NORUNNINGBUF); 2008 /* play bufdaemon */ 2009 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2010 fl = buf_do_flush(vp); 2011 td->td_pflags &= norunbuf; 2012 mtx_lock(&nblock); 2013 if (fl != 0) 2014 continue; 2015 if ((needsbuffer & flags) == 0) 2016 break; 2017 } 2018 if (msleep(&needsbuffer, &nblock, 2019 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 2020 mtx_unlock(&nblock); 2021 return (NULL); 2022 } 2023 } 2024 mtx_unlock(&nblock); 2025 } else { 2026 /* 2027 * We finally have a valid bp. We aren't quite out of the 2028 * woods, we still have to reserve kva space. In order 2029 * to keep fragmentation sane we only allocate kva in 2030 * BKVASIZE chunks. 2031 */ 2032 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2033 2034 if (maxsize != bp->b_kvasize) { 2035 vm_offset_t addr = 0; 2036 2037 bfreekva(bp); 2038 2039 vm_map_lock(buffer_map); 2040 if (vm_map_findspace(buffer_map, 2041 vm_map_min(buffer_map), maxsize, &addr)) { 2042 /* 2043 * Uh oh. Buffer map is to fragmented. We 2044 * must defragment the map. 2045 */ 2046 atomic_add_int(&bufdefragcnt, 1); 2047 vm_map_unlock(buffer_map); 2048 defrag = 1; 2049 bp->b_flags |= B_INVAL; 2050 brelse(bp); 2051 goto restart; 2052 } 2053 if (addr) { 2054 vm_map_insert(buffer_map, NULL, 0, 2055 addr, addr + maxsize, 2056 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2057 2058 bp->b_kvabase = (caddr_t) addr; 2059 bp->b_kvasize = maxsize; 2060 atomic_add_long(&bufspace, bp->b_kvasize); 2061 atomic_add_int(&bufreusecnt, 1); 2062 } 2063 vm_map_unlock(buffer_map); 2064 } 2065 bp->b_saveaddr = bp->b_kvabase; 2066 bp->b_data = bp->b_saveaddr; 2067 } 2068 return(bp); 2069 } 2070 2071 /* 2072 * buf_daemon: 2073 * 2074 * buffer flushing daemon. Buffers are normally flushed by the 2075 * update daemon but if it cannot keep up this process starts to 2076 * take the load in an attempt to prevent getnewbuf() from blocking. 2077 */ 2078 2079 static struct kproc_desc buf_kp = { 2080 "bufdaemon", 2081 buf_daemon, 2082 &bufdaemonproc 2083 }; 2084 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2085 2086 static int 2087 buf_do_flush(struct vnode *vp) 2088 { 2089 int flushed; 2090 2091 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2092 /* The list empty check here is slightly racy */ 2093 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2094 mtx_lock(&Giant); 2095 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0); 2096 mtx_unlock(&Giant); 2097 } 2098 if (flushed == 0) { 2099 /* 2100 * Could not find any buffers without rollback 2101 * dependencies, so just write the first one 2102 * in the hopes of eventually making progress. 2103 */ 2104 flushbufqueues(vp, QUEUE_DIRTY, 1); 2105 if (!TAILQ_EMPTY( 2106 &bufqueues[QUEUE_DIRTY_GIANT])) { 2107 mtx_lock(&Giant); 2108 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1); 2109 mtx_unlock(&Giant); 2110 } 2111 } 2112 return (flushed); 2113 } 2114 2115 static void 2116 buf_daemon() 2117 { 2118 2119 /* 2120 * This process needs to be suspended prior to shutdown sync. 2121 */ 2122 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2123 SHUTDOWN_PRI_LAST); 2124 2125 /* 2126 * This process is allowed to take the buffer cache to the limit 2127 */ 2128 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2129 mtx_lock(&bdlock); 2130 for (;;) { 2131 bd_request = 0; 2132 mtx_unlock(&bdlock); 2133 2134 kproc_suspend_check(bufdaemonproc); 2135 2136 /* 2137 * Do the flush. Limit the amount of in-transit I/O we 2138 * allow to build up, otherwise we would completely saturate 2139 * the I/O system. Wakeup any waiting processes before we 2140 * normally would so they can run in parallel with our drain. 2141 */ 2142 while (numdirtybuffers > lodirtybuffers) { 2143 if (buf_do_flush(NULL) == 0) 2144 break; 2145 uio_yield(); 2146 } 2147 2148 /* 2149 * Only clear bd_request if we have reached our low water 2150 * mark. The buf_daemon normally waits 1 second and 2151 * then incrementally flushes any dirty buffers that have 2152 * built up, within reason. 2153 * 2154 * If we were unable to hit our low water mark and couldn't 2155 * find any flushable buffers, we sleep half a second. 2156 * Otherwise we loop immediately. 2157 */ 2158 mtx_lock(&bdlock); 2159 if (numdirtybuffers <= lodirtybuffers) { 2160 /* 2161 * We reached our low water mark, reset the 2162 * request and sleep until we are needed again. 2163 * The sleep is just so the suspend code works. 2164 */ 2165 bd_request = 0; 2166 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2167 } else { 2168 /* 2169 * We couldn't find any flushable dirty buffers but 2170 * still have too many dirty buffers, we 2171 * have to sleep and try again. (rare) 2172 */ 2173 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2174 } 2175 } 2176 } 2177 2178 /* 2179 * flushbufqueues: 2180 * 2181 * Try to flush a buffer in the dirty queue. We must be careful to 2182 * free up B_INVAL buffers instead of write them, which NFS is 2183 * particularly sensitive to. 2184 */ 2185 static int flushwithdeps = 0; 2186 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2187 0, "Number of buffers flushed with dependecies that require rollbacks"); 2188 2189 static int 2190 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2191 { 2192 struct buf *sentinel; 2193 struct vnode *vp; 2194 struct mount *mp; 2195 struct buf *bp; 2196 int hasdeps; 2197 int flushed; 2198 int target; 2199 2200 if (lvp == NULL) { 2201 target = numdirtybuffers - lodirtybuffers; 2202 if (flushdeps && target > 2) 2203 target /= 2; 2204 } else 2205 target = flushbufqtarget; 2206 flushed = 0; 2207 bp = NULL; 2208 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2209 sentinel->b_qindex = QUEUE_SENTINEL; 2210 mtx_lock(&bqlock); 2211 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2212 while (flushed != target) { 2213 bp = TAILQ_NEXT(sentinel, b_freelist); 2214 if (bp != NULL) { 2215 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2216 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2217 b_freelist); 2218 } else 2219 break; 2220 /* 2221 * Skip sentinels inserted by other invocations of the 2222 * flushbufqueues(), taking care to not reorder them. 2223 */ 2224 if (bp->b_qindex == QUEUE_SENTINEL) 2225 continue; 2226 /* 2227 * Only flush the buffers that belong to the 2228 * vnode locked by the curthread. 2229 */ 2230 if (lvp != NULL && bp->b_vp != lvp) 2231 continue; 2232 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2233 continue; 2234 if (bp->b_pin_count > 0) { 2235 BUF_UNLOCK(bp); 2236 continue; 2237 } 2238 BO_LOCK(bp->b_bufobj); 2239 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2240 (bp->b_flags & B_DELWRI) == 0) { 2241 BO_UNLOCK(bp->b_bufobj); 2242 BUF_UNLOCK(bp); 2243 continue; 2244 } 2245 BO_UNLOCK(bp->b_bufobj); 2246 if (bp->b_flags & B_INVAL) { 2247 bremfreel(bp); 2248 mtx_unlock(&bqlock); 2249 brelse(bp); 2250 flushed++; 2251 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2252 mtx_lock(&bqlock); 2253 continue; 2254 } 2255 2256 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2257 if (flushdeps == 0) { 2258 BUF_UNLOCK(bp); 2259 continue; 2260 } 2261 hasdeps = 1; 2262 } else 2263 hasdeps = 0; 2264 /* 2265 * We must hold the lock on a vnode before writing 2266 * one of its buffers. Otherwise we may confuse, or 2267 * in the case of a snapshot vnode, deadlock the 2268 * system. 2269 * 2270 * The lock order here is the reverse of the normal 2271 * of vnode followed by buf lock. This is ok because 2272 * the NOWAIT will prevent deadlock. 2273 */ 2274 vp = bp->b_vp; 2275 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2276 BUF_UNLOCK(bp); 2277 continue; 2278 } 2279 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2280 mtx_unlock(&bqlock); 2281 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2282 bp, bp->b_vp, bp->b_flags); 2283 if (curproc == bufdaemonproc) 2284 vfs_bio_awrite(bp); 2285 else { 2286 bremfree(bp); 2287 bwrite(bp); 2288 notbufdflashes++; 2289 } 2290 vn_finished_write(mp); 2291 VOP_UNLOCK(vp, 0); 2292 flushwithdeps += hasdeps; 2293 flushed++; 2294 2295 /* 2296 * Sleeping on runningbufspace while holding 2297 * vnode lock leads to deadlock. 2298 */ 2299 if (curproc == bufdaemonproc) 2300 waitrunningbufspace(); 2301 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2302 mtx_lock(&bqlock); 2303 continue; 2304 } 2305 vn_finished_write(mp); 2306 BUF_UNLOCK(bp); 2307 } 2308 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2309 mtx_unlock(&bqlock); 2310 free(sentinel, M_TEMP); 2311 return (flushed); 2312 } 2313 2314 /* 2315 * Check to see if a block is currently memory resident. 2316 */ 2317 struct buf * 2318 incore(struct bufobj *bo, daddr_t blkno) 2319 { 2320 struct buf *bp; 2321 2322 BO_LOCK(bo); 2323 bp = gbincore(bo, blkno); 2324 BO_UNLOCK(bo); 2325 return (bp); 2326 } 2327 2328 /* 2329 * Returns true if no I/O is needed to access the 2330 * associated VM object. This is like incore except 2331 * it also hunts around in the VM system for the data. 2332 */ 2333 2334 static int 2335 inmem(struct vnode * vp, daddr_t blkno) 2336 { 2337 vm_object_t obj; 2338 vm_offset_t toff, tinc, size; 2339 vm_page_t m; 2340 vm_ooffset_t off; 2341 2342 ASSERT_VOP_LOCKED(vp, "inmem"); 2343 2344 if (incore(&vp->v_bufobj, blkno)) 2345 return 1; 2346 if (vp->v_mount == NULL) 2347 return 0; 2348 obj = vp->v_object; 2349 if (obj == NULL) 2350 return (0); 2351 2352 size = PAGE_SIZE; 2353 if (size > vp->v_mount->mnt_stat.f_iosize) 2354 size = vp->v_mount->mnt_stat.f_iosize; 2355 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2356 2357 VM_OBJECT_LOCK(obj); 2358 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2359 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2360 if (!m) 2361 goto notinmem; 2362 tinc = size; 2363 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2364 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2365 if (vm_page_is_valid(m, 2366 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2367 goto notinmem; 2368 } 2369 VM_OBJECT_UNLOCK(obj); 2370 return 1; 2371 2372 notinmem: 2373 VM_OBJECT_UNLOCK(obj); 2374 return (0); 2375 } 2376 2377 /* 2378 * vfs_setdirty: 2379 * 2380 * Sets the dirty range for a buffer based on the status of the dirty 2381 * bits in the pages comprising the buffer. 2382 * 2383 * The range is limited to the size of the buffer. 2384 * 2385 * This routine is primarily used by NFS, but is generalized for the 2386 * B_VMIO case. 2387 */ 2388 static void 2389 vfs_setdirty(struct buf *bp) 2390 { 2391 2392 /* 2393 * Degenerate case - empty buffer 2394 */ 2395 2396 if (bp->b_bufsize == 0) 2397 return; 2398 2399 /* 2400 * We qualify the scan for modified pages on whether the 2401 * object has been flushed yet. 2402 */ 2403 2404 if ((bp->b_flags & B_VMIO) == 0) 2405 return; 2406 2407 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2408 vfs_setdirty_locked_object(bp); 2409 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2410 } 2411 2412 static void 2413 vfs_setdirty_locked_object(struct buf *bp) 2414 { 2415 vm_object_t object; 2416 int i; 2417 2418 object = bp->b_bufobj->bo_object; 2419 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2420 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2421 vm_offset_t boffset; 2422 vm_offset_t eoffset; 2423 2424 vm_page_lock_queues(); 2425 /* 2426 * test the pages to see if they have been modified directly 2427 * by users through the VM system. 2428 */ 2429 for (i = 0; i < bp->b_npages; i++) 2430 vm_page_test_dirty(bp->b_pages[i]); 2431 2432 /* 2433 * Calculate the encompassing dirty range, boffset and eoffset, 2434 * (eoffset - boffset) bytes. 2435 */ 2436 2437 for (i = 0; i < bp->b_npages; i++) { 2438 if (bp->b_pages[i]->dirty) 2439 break; 2440 } 2441 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2442 2443 for (i = bp->b_npages - 1; i >= 0; --i) { 2444 if (bp->b_pages[i]->dirty) { 2445 break; 2446 } 2447 } 2448 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2449 2450 vm_page_unlock_queues(); 2451 /* 2452 * Fit it to the buffer. 2453 */ 2454 2455 if (eoffset > bp->b_bcount) 2456 eoffset = bp->b_bcount; 2457 2458 /* 2459 * If we have a good dirty range, merge with the existing 2460 * dirty range. 2461 */ 2462 2463 if (boffset < eoffset) { 2464 if (bp->b_dirtyoff > boffset) 2465 bp->b_dirtyoff = boffset; 2466 if (bp->b_dirtyend < eoffset) 2467 bp->b_dirtyend = eoffset; 2468 } 2469 } 2470 } 2471 2472 /* 2473 * getblk: 2474 * 2475 * Get a block given a specified block and offset into a file/device. 2476 * The buffers B_DONE bit will be cleared on return, making it almost 2477 * ready for an I/O initiation. B_INVAL may or may not be set on 2478 * return. The caller should clear B_INVAL prior to initiating a 2479 * READ. 2480 * 2481 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2482 * an existing buffer. 2483 * 2484 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2485 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2486 * and then cleared based on the backing VM. If the previous buffer is 2487 * non-0-sized but invalid, B_CACHE will be cleared. 2488 * 2489 * If getblk() must create a new buffer, the new buffer is returned with 2490 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2491 * case it is returned with B_INVAL clear and B_CACHE set based on the 2492 * backing VM. 2493 * 2494 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2495 * B_CACHE bit is clear. 2496 * 2497 * What this means, basically, is that the caller should use B_CACHE to 2498 * determine whether the buffer is fully valid or not and should clear 2499 * B_INVAL prior to issuing a read. If the caller intends to validate 2500 * the buffer by loading its data area with something, the caller needs 2501 * to clear B_INVAL. If the caller does this without issuing an I/O, 2502 * the caller should set B_CACHE ( as an optimization ), else the caller 2503 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2504 * a write attempt or if it was a successfull read. If the caller 2505 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2506 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2507 */ 2508 struct buf * 2509 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2510 int flags) 2511 { 2512 struct buf *bp; 2513 struct bufobj *bo; 2514 int error; 2515 2516 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2517 ASSERT_VOP_LOCKED(vp, "getblk"); 2518 if (size > MAXBSIZE) 2519 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2520 2521 bo = &vp->v_bufobj; 2522 loop: 2523 /* 2524 * Block if we are low on buffers. Certain processes are allowed 2525 * to completely exhaust the buffer cache. 2526 * 2527 * If this check ever becomes a bottleneck it may be better to 2528 * move it into the else, when gbincore() fails. At the moment 2529 * it isn't a problem. 2530 * 2531 * XXX remove if 0 sections (clean this up after its proven) 2532 */ 2533 if (numfreebuffers == 0) { 2534 if (TD_IS_IDLETHREAD(curthread)) 2535 return NULL; 2536 mtx_lock(&nblock); 2537 needsbuffer |= VFS_BIO_NEED_ANY; 2538 mtx_unlock(&nblock); 2539 } 2540 2541 BO_LOCK(bo); 2542 bp = gbincore(bo, blkno); 2543 if (bp != NULL) { 2544 int lockflags; 2545 /* 2546 * Buffer is in-core. If the buffer is not busy, it must 2547 * be on a queue. 2548 */ 2549 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2550 2551 if (flags & GB_LOCK_NOWAIT) 2552 lockflags |= LK_NOWAIT; 2553 2554 error = BUF_TIMELOCK(bp, lockflags, 2555 BO_MTX(bo), "getblk", slpflag, slptimeo); 2556 2557 /* 2558 * If we slept and got the lock we have to restart in case 2559 * the buffer changed identities. 2560 */ 2561 if (error == ENOLCK) 2562 goto loop; 2563 /* We timed out or were interrupted. */ 2564 else if (error) 2565 return (NULL); 2566 2567 /* 2568 * The buffer is locked. B_CACHE is cleared if the buffer is 2569 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2570 * and for a VMIO buffer B_CACHE is adjusted according to the 2571 * backing VM cache. 2572 */ 2573 if (bp->b_flags & B_INVAL) 2574 bp->b_flags &= ~B_CACHE; 2575 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2576 bp->b_flags |= B_CACHE; 2577 bremfree(bp); 2578 2579 /* 2580 * check for size inconsistancies for non-VMIO case. 2581 */ 2582 2583 if (bp->b_bcount != size) { 2584 if ((bp->b_flags & B_VMIO) == 0 || 2585 (size > bp->b_kvasize)) { 2586 if (bp->b_flags & B_DELWRI) { 2587 /* 2588 * If buffer is pinned and caller does 2589 * not want sleep waiting for it to be 2590 * unpinned, bail out 2591 * */ 2592 if (bp->b_pin_count > 0) { 2593 if (flags & GB_LOCK_NOWAIT) { 2594 bqrelse(bp); 2595 return (NULL); 2596 } else { 2597 bunpin_wait(bp); 2598 } 2599 } 2600 bp->b_flags |= B_NOCACHE; 2601 bwrite(bp); 2602 } else { 2603 if (LIST_EMPTY(&bp->b_dep)) { 2604 bp->b_flags |= B_RELBUF; 2605 brelse(bp); 2606 } else { 2607 bp->b_flags |= B_NOCACHE; 2608 bwrite(bp); 2609 } 2610 } 2611 goto loop; 2612 } 2613 } 2614 2615 /* 2616 * If the size is inconsistant in the VMIO case, we can resize 2617 * the buffer. This might lead to B_CACHE getting set or 2618 * cleared. If the size has not changed, B_CACHE remains 2619 * unchanged from its previous state. 2620 */ 2621 2622 if (bp->b_bcount != size) 2623 allocbuf(bp, size); 2624 2625 KASSERT(bp->b_offset != NOOFFSET, 2626 ("getblk: no buffer offset")); 2627 2628 /* 2629 * A buffer with B_DELWRI set and B_CACHE clear must 2630 * be committed before we can return the buffer in 2631 * order to prevent the caller from issuing a read 2632 * ( due to B_CACHE not being set ) and overwriting 2633 * it. 2634 * 2635 * Most callers, including NFS and FFS, need this to 2636 * operate properly either because they assume they 2637 * can issue a read if B_CACHE is not set, or because 2638 * ( for example ) an uncached B_DELWRI might loop due 2639 * to softupdates re-dirtying the buffer. In the latter 2640 * case, B_CACHE is set after the first write completes, 2641 * preventing further loops. 2642 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2643 * above while extending the buffer, we cannot allow the 2644 * buffer to remain with B_CACHE set after the write 2645 * completes or it will represent a corrupt state. To 2646 * deal with this we set B_NOCACHE to scrap the buffer 2647 * after the write. 2648 * 2649 * We might be able to do something fancy, like setting 2650 * B_CACHE in bwrite() except if B_DELWRI is already set, 2651 * so the below call doesn't set B_CACHE, but that gets real 2652 * confusing. This is much easier. 2653 */ 2654 2655 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2656 bp->b_flags |= B_NOCACHE; 2657 bwrite(bp); 2658 goto loop; 2659 } 2660 bp->b_flags &= ~B_DONE; 2661 } else { 2662 int bsize, maxsize, vmio; 2663 off_t offset; 2664 2665 /* 2666 * Buffer is not in-core, create new buffer. The buffer 2667 * returned by getnewbuf() is locked. Note that the returned 2668 * buffer is also considered valid (not marked B_INVAL). 2669 */ 2670 BO_UNLOCK(bo); 2671 /* 2672 * If the user does not want us to create the buffer, bail out 2673 * here. 2674 */ 2675 if (flags & GB_NOCREAT) 2676 return NULL; 2677 bsize = bo->bo_bsize; 2678 offset = blkno * bsize; 2679 vmio = vp->v_object != NULL; 2680 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2681 maxsize = imax(maxsize, bsize); 2682 2683 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 2684 if (bp == NULL) { 2685 if (slpflag || slptimeo) 2686 return NULL; 2687 goto loop; 2688 } 2689 2690 /* 2691 * This code is used to make sure that a buffer is not 2692 * created while the getnewbuf routine is blocked. 2693 * This can be a problem whether the vnode is locked or not. 2694 * If the buffer is created out from under us, we have to 2695 * throw away the one we just created. 2696 * 2697 * Note: this must occur before we associate the buffer 2698 * with the vp especially considering limitations in 2699 * the splay tree implementation when dealing with duplicate 2700 * lblkno's. 2701 */ 2702 BO_LOCK(bo); 2703 if (gbincore(bo, blkno)) { 2704 BO_UNLOCK(bo); 2705 bp->b_flags |= B_INVAL; 2706 brelse(bp); 2707 goto loop; 2708 } 2709 2710 /* 2711 * Insert the buffer into the hash, so that it can 2712 * be found by incore. 2713 */ 2714 bp->b_blkno = bp->b_lblkno = blkno; 2715 bp->b_offset = offset; 2716 bgetvp(vp, bp); 2717 BO_UNLOCK(bo); 2718 2719 /* 2720 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2721 * buffer size starts out as 0, B_CACHE will be set by 2722 * allocbuf() for the VMIO case prior to it testing the 2723 * backing store for validity. 2724 */ 2725 2726 if (vmio) { 2727 bp->b_flags |= B_VMIO; 2728 #if defined(VFS_BIO_DEBUG) 2729 if (vn_canvmio(vp) != TRUE) 2730 printf("getblk: VMIO on vnode type %d\n", 2731 vp->v_type); 2732 #endif 2733 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2734 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2735 bp, vp->v_object, bp->b_bufobj->bo_object)); 2736 } else { 2737 bp->b_flags &= ~B_VMIO; 2738 KASSERT(bp->b_bufobj->bo_object == NULL, 2739 ("ARGH! has b_bufobj->bo_object %p %p\n", 2740 bp, bp->b_bufobj->bo_object)); 2741 } 2742 2743 allocbuf(bp, size); 2744 bp->b_flags &= ~B_DONE; 2745 } 2746 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2747 BUF_ASSERT_HELD(bp); 2748 KASSERT(bp->b_bufobj == bo, 2749 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2750 return (bp); 2751 } 2752 2753 /* 2754 * Get an empty, disassociated buffer of given size. The buffer is initially 2755 * set to B_INVAL. 2756 */ 2757 struct buf * 2758 geteblk(int size, int flags) 2759 { 2760 struct buf *bp; 2761 int maxsize; 2762 2763 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2764 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 2765 if ((flags & GB_NOWAIT_BD) && 2766 (curthread->td_pflags & TDP_BUFNEED) != 0) 2767 return (NULL); 2768 } 2769 allocbuf(bp, size); 2770 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2771 BUF_ASSERT_HELD(bp); 2772 return (bp); 2773 } 2774 2775 2776 /* 2777 * This code constitutes the buffer memory from either anonymous system 2778 * memory (in the case of non-VMIO operations) or from an associated 2779 * VM object (in the case of VMIO operations). This code is able to 2780 * resize a buffer up or down. 2781 * 2782 * Note that this code is tricky, and has many complications to resolve 2783 * deadlock or inconsistant data situations. Tread lightly!!! 2784 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2785 * the caller. Calling this code willy nilly can result in the loss of data. 2786 * 2787 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2788 * B_CACHE for the non-VMIO case. 2789 */ 2790 2791 int 2792 allocbuf(struct buf *bp, int size) 2793 { 2794 int newbsize, mbsize; 2795 int i; 2796 2797 BUF_ASSERT_HELD(bp); 2798 2799 if (bp->b_kvasize < size) 2800 panic("allocbuf: buffer too small"); 2801 2802 if ((bp->b_flags & B_VMIO) == 0) { 2803 caddr_t origbuf; 2804 int origbufsize; 2805 /* 2806 * Just get anonymous memory from the kernel. Don't 2807 * mess with B_CACHE. 2808 */ 2809 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2810 if (bp->b_flags & B_MALLOC) 2811 newbsize = mbsize; 2812 else 2813 newbsize = round_page(size); 2814 2815 if (newbsize < bp->b_bufsize) { 2816 /* 2817 * malloced buffers are not shrunk 2818 */ 2819 if (bp->b_flags & B_MALLOC) { 2820 if (newbsize) { 2821 bp->b_bcount = size; 2822 } else { 2823 free(bp->b_data, M_BIOBUF); 2824 if (bp->b_bufsize) { 2825 atomic_subtract_long( 2826 &bufmallocspace, 2827 bp->b_bufsize); 2828 bufspacewakeup(); 2829 bp->b_bufsize = 0; 2830 } 2831 bp->b_saveaddr = bp->b_kvabase; 2832 bp->b_data = bp->b_saveaddr; 2833 bp->b_bcount = 0; 2834 bp->b_flags &= ~B_MALLOC; 2835 } 2836 return 1; 2837 } 2838 vm_hold_free_pages( 2839 bp, 2840 (vm_offset_t) bp->b_data + newbsize, 2841 (vm_offset_t) bp->b_data + bp->b_bufsize); 2842 } else if (newbsize > bp->b_bufsize) { 2843 /* 2844 * We only use malloced memory on the first allocation. 2845 * and revert to page-allocated memory when the buffer 2846 * grows. 2847 */ 2848 /* 2849 * There is a potential smp race here that could lead 2850 * to bufmallocspace slightly passing the max. It 2851 * is probably extremely rare and not worth worrying 2852 * over. 2853 */ 2854 if ( (bufmallocspace < maxbufmallocspace) && 2855 (bp->b_bufsize == 0) && 2856 (mbsize <= PAGE_SIZE/2)) { 2857 2858 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2859 bp->b_bufsize = mbsize; 2860 bp->b_bcount = size; 2861 bp->b_flags |= B_MALLOC; 2862 atomic_add_long(&bufmallocspace, mbsize); 2863 return 1; 2864 } 2865 origbuf = NULL; 2866 origbufsize = 0; 2867 /* 2868 * If the buffer is growing on its other-than-first allocation, 2869 * then we revert to the page-allocation scheme. 2870 */ 2871 if (bp->b_flags & B_MALLOC) { 2872 origbuf = bp->b_data; 2873 origbufsize = bp->b_bufsize; 2874 bp->b_data = bp->b_kvabase; 2875 if (bp->b_bufsize) { 2876 atomic_subtract_long(&bufmallocspace, 2877 bp->b_bufsize); 2878 bufspacewakeup(); 2879 bp->b_bufsize = 0; 2880 } 2881 bp->b_flags &= ~B_MALLOC; 2882 newbsize = round_page(newbsize); 2883 } 2884 vm_hold_load_pages( 2885 bp, 2886 (vm_offset_t) bp->b_data + bp->b_bufsize, 2887 (vm_offset_t) bp->b_data + newbsize); 2888 if (origbuf) { 2889 bcopy(origbuf, bp->b_data, origbufsize); 2890 free(origbuf, M_BIOBUF); 2891 } 2892 } 2893 } else { 2894 int desiredpages; 2895 2896 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2897 desiredpages = (size == 0) ? 0 : 2898 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2899 2900 if (bp->b_flags & B_MALLOC) 2901 panic("allocbuf: VMIO buffer can't be malloced"); 2902 /* 2903 * Set B_CACHE initially if buffer is 0 length or will become 2904 * 0-length. 2905 */ 2906 if (size == 0 || bp->b_bufsize == 0) 2907 bp->b_flags |= B_CACHE; 2908 2909 if (newbsize < bp->b_bufsize) { 2910 /* 2911 * DEV_BSIZE aligned new buffer size is less then the 2912 * DEV_BSIZE aligned existing buffer size. Figure out 2913 * if we have to remove any pages. 2914 */ 2915 if (desiredpages < bp->b_npages) { 2916 vm_page_t m; 2917 2918 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2919 vm_page_lock_queues(); 2920 for (i = desiredpages; i < bp->b_npages; i++) { 2921 /* 2922 * the page is not freed here -- it 2923 * is the responsibility of 2924 * vnode_pager_setsize 2925 */ 2926 m = bp->b_pages[i]; 2927 KASSERT(m != bogus_page, 2928 ("allocbuf: bogus page found")); 2929 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2930 vm_page_lock_queues(); 2931 2932 bp->b_pages[i] = NULL; 2933 vm_page_unwire(m, 0); 2934 } 2935 vm_page_unlock_queues(); 2936 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2937 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2938 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2939 bp->b_npages = desiredpages; 2940 } 2941 } else if (size > bp->b_bcount) { 2942 /* 2943 * We are growing the buffer, possibly in a 2944 * byte-granular fashion. 2945 */ 2946 struct vnode *vp; 2947 vm_object_t obj; 2948 vm_offset_t toff; 2949 vm_offset_t tinc; 2950 2951 /* 2952 * Step 1, bring in the VM pages from the object, 2953 * allocating them if necessary. We must clear 2954 * B_CACHE if these pages are not valid for the 2955 * range covered by the buffer. 2956 */ 2957 2958 vp = bp->b_vp; 2959 obj = bp->b_bufobj->bo_object; 2960 2961 VM_OBJECT_LOCK(obj); 2962 while (bp->b_npages < desiredpages) { 2963 vm_page_t m; 2964 vm_pindex_t pi; 2965 2966 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2967 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2968 /* 2969 * note: must allocate system pages 2970 * since blocking here could intefere 2971 * with paging I/O, no matter which 2972 * process we are. 2973 */ 2974 m = vm_page_alloc(obj, pi, 2975 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2976 VM_ALLOC_WIRED); 2977 if (m == NULL) { 2978 atomic_add_int(&vm_pageout_deficit, 2979 desiredpages - bp->b_npages); 2980 VM_OBJECT_UNLOCK(obj); 2981 VM_WAIT; 2982 VM_OBJECT_LOCK(obj); 2983 } else { 2984 if (m->valid == 0) 2985 bp->b_flags &= ~B_CACHE; 2986 bp->b_pages[bp->b_npages] = m; 2987 ++bp->b_npages; 2988 } 2989 continue; 2990 } 2991 2992 /* 2993 * We found a page. If we have to sleep on it, 2994 * retry because it might have gotten freed out 2995 * from under us. 2996 * 2997 * We can only test VPO_BUSY here. Blocking on 2998 * m->busy might lead to a deadlock: 2999 * 3000 * vm_fault->getpages->cluster_read->allocbuf 3001 * 3002 */ 3003 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 3004 continue; 3005 3006 /* 3007 * We have a good page. 3008 */ 3009 vm_page_lock_queues(); 3010 vm_page_wire(m); 3011 vm_page_unlock_queues(); 3012 bp->b_pages[bp->b_npages] = m; 3013 ++bp->b_npages; 3014 } 3015 3016 /* 3017 * Step 2. We've loaded the pages into the buffer, 3018 * we have to figure out if we can still have B_CACHE 3019 * set. Note that B_CACHE is set according to the 3020 * byte-granular range ( bcount and size ), new the 3021 * aligned range ( newbsize ). 3022 * 3023 * The VM test is against m->valid, which is DEV_BSIZE 3024 * aligned. Needless to say, the validity of the data 3025 * needs to also be DEV_BSIZE aligned. Note that this 3026 * fails with NFS if the server or some other client 3027 * extends the file's EOF. If our buffer is resized, 3028 * B_CACHE may remain set! XXX 3029 */ 3030 3031 toff = bp->b_bcount; 3032 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3033 3034 while ((bp->b_flags & B_CACHE) && toff < size) { 3035 vm_pindex_t pi; 3036 3037 if (tinc > (size - toff)) 3038 tinc = size - toff; 3039 3040 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3041 PAGE_SHIFT; 3042 3043 vfs_buf_test_cache( 3044 bp, 3045 bp->b_offset, 3046 toff, 3047 tinc, 3048 bp->b_pages[pi] 3049 ); 3050 toff += tinc; 3051 tinc = PAGE_SIZE; 3052 } 3053 VM_OBJECT_UNLOCK(obj); 3054 3055 /* 3056 * Step 3, fixup the KVM pmap. Remember that 3057 * bp->b_data is relative to bp->b_offset, but 3058 * bp->b_offset may be offset into the first page. 3059 */ 3060 3061 bp->b_data = (caddr_t) 3062 trunc_page((vm_offset_t)bp->b_data); 3063 pmap_qenter( 3064 (vm_offset_t)bp->b_data, 3065 bp->b_pages, 3066 bp->b_npages 3067 ); 3068 3069 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3070 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 3071 } 3072 } 3073 if (newbsize < bp->b_bufsize) 3074 bufspacewakeup(); 3075 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3076 bp->b_bcount = size; /* requested buffer size */ 3077 return 1; 3078 } 3079 3080 void 3081 biodone(struct bio *bp) 3082 { 3083 struct mtx *mtxp; 3084 void (*done)(struct bio *); 3085 3086 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3087 mtx_lock(mtxp); 3088 bp->bio_flags |= BIO_DONE; 3089 done = bp->bio_done; 3090 if (done == NULL) 3091 wakeup(bp); 3092 mtx_unlock(mtxp); 3093 if (done != NULL) 3094 done(bp); 3095 } 3096 3097 /* 3098 * Wait for a BIO to finish. 3099 * 3100 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3101 * case is not yet clear. 3102 */ 3103 int 3104 biowait(struct bio *bp, const char *wchan) 3105 { 3106 struct mtx *mtxp; 3107 3108 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3109 mtx_lock(mtxp); 3110 while ((bp->bio_flags & BIO_DONE) == 0) 3111 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3112 mtx_unlock(mtxp); 3113 if (bp->bio_error != 0) 3114 return (bp->bio_error); 3115 if (!(bp->bio_flags & BIO_ERROR)) 3116 return (0); 3117 return (EIO); 3118 } 3119 3120 void 3121 biofinish(struct bio *bp, struct devstat *stat, int error) 3122 { 3123 3124 if (error) { 3125 bp->bio_error = error; 3126 bp->bio_flags |= BIO_ERROR; 3127 } 3128 if (stat != NULL) 3129 devstat_end_transaction_bio(stat, bp); 3130 biodone(bp); 3131 } 3132 3133 /* 3134 * bufwait: 3135 * 3136 * Wait for buffer I/O completion, returning error status. The buffer 3137 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3138 * error and cleared. 3139 */ 3140 int 3141 bufwait(struct buf *bp) 3142 { 3143 if (bp->b_iocmd == BIO_READ) 3144 bwait(bp, PRIBIO, "biord"); 3145 else 3146 bwait(bp, PRIBIO, "biowr"); 3147 if (bp->b_flags & B_EINTR) { 3148 bp->b_flags &= ~B_EINTR; 3149 return (EINTR); 3150 } 3151 if (bp->b_ioflags & BIO_ERROR) { 3152 return (bp->b_error ? bp->b_error : EIO); 3153 } else { 3154 return (0); 3155 } 3156 } 3157 3158 /* 3159 * Call back function from struct bio back up to struct buf. 3160 */ 3161 static void 3162 bufdonebio(struct bio *bip) 3163 { 3164 struct buf *bp; 3165 3166 bp = bip->bio_caller2; 3167 bp->b_resid = bp->b_bcount - bip->bio_completed; 3168 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3169 bp->b_ioflags = bip->bio_flags; 3170 bp->b_error = bip->bio_error; 3171 if (bp->b_error) 3172 bp->b_ioflags |= BIO_ERROR; 3173 bufdone(bp); 3174 g_destroy_bio(bip); 3175 } 3176 3177 void 3178 dev_strategy(struct cdev *dev, struct buf *bp) 3179 { 3180 struct cdevsw *csw; 3181 struct bio *bip; 3182 3183 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3184 panic("b_iocmd botch"); 3185 for (;;) { 3186 bip = g_new_bio(); 3187 if (bip != NULL) 3188 break; 3189 /* Try again later */ 3190 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3191 } 3192 bip->bio_cmd = bp->b_iocmd; 3193 bip->bio_offset = bp->b_iooffset; 3194 bip->bio_length = bp->b_bcount; 3195 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3196 bip->bio_data = bp->b_data; 3197 bip->bio_done = bufdonebio; 3198 bip->bio_caller2 = bp; 3199 bip->bio_dev = dev; 3200 KASSERT(dev->si_refcount > 0, 3201 ("dev_strategy on un-referenced struct cdev *(%s)", 3202 devtoname(dev))); 3203 csw = dev_refthread(dev); 3204 if (csw == NULL) { 3205 g_destroy_bio(bip); 3206 bp->b_error = ENXIO; 3207 bp->b_ioflags = BIO_ERROR; 3208 bufdone(bp); 3209 return; 3210 } 3211 (*csw->d_strategy)(bip); 3212 dev_relthread(dev); 3213 } 3214 3215 /* 3216 * bufdone: 3217 * 3218 * Finish I/O on a buffer, optionally calling a completion function. 3219 * This is usually called from an interrupt so process blocking is 3220 * not allowed. 3221 * 3222 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3223 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3224 * assuming B_INVAL is clear. 3225 * 3226 * For the VMIO case, we set B_CACHE if the op was a read and no 3227 * read error occured, or if the op was a write. B_CACHE is never 3228 * set if the buffer is invalid or otherwise uncacheable. 3229 * 3230 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3231 * initiator to leave B_INVAL set to brelse the buffer out of existance 3232 * in the biodone routine. 3233 */ 3234 void 3235 bufdone(struct buf *bp) 3236 { 3237 struct bufobj *dropobj; 3238 void (*biodone)(struct buf *); 3239 3240 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3241 dropobj = NULL; 3242 3243 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3244 BUF_ASSERT_HELD(bp); 3245 3246 runningbufwakeup(bp); 3247 if (bp->b_iocmd == BIO_WRITE) 3248 dropobj = bp->b_bufobj; 3249 /* call optional completion function if requested */ 3250 if (bp->b_iodone != NULL) { 3251 biodone = bp->b_iodone; 3252 bp->b_iodone = NULL; 3253 (*biodone) (bp); 3254 if (dropobj) 3255 bufobj_wdrop(dropobj); 3256 return; 3257 } 3258 3259 bufdone_finish(bp); 3260 3261 if (dropobj) 3262 bufobj_wdrop(dropobj); 3263 } 3264 3265 void 3266 bufdone_finish(struct buf *bp) 3267 { 3268 BUF_ASSERT_HELD(bp); 3269 3270 if (!LIST_EMPTY(&bp->b_dep)) 3271 buf_complete(bp); 3272 3273 if (bp->b_flags & B_VMIO) { 3274 int i; 3275 vm_ooffset_t foff; 3276 vm_page_t m; 3277 vm_object_t obj; 3278 int iosize; 3279 struct vnode *vp = bp->b_vp; 3280 boolean_t are_queues_locked; 3281 3282 obj = bp->b_bufobj->bo_object; 3283 3284 #if defined(VFS_BIO_DEBUG) 3285 mp_fixme("usecount and vflag accessed without locks."); 3286 if (vp->v_usecount == 0) { 3287 panic("biodone: zero vnode ref count"); 3288 } 3289 3290 KASSERT(vp->v_object != NULL, 3291 ("biodone: vnode %p has no vm_object", vp)); 3292 #endif 3293 3294 foff = bp->b_offset; 3295 KASSERT(bp->b_offset != NOOFFSET, 3296 ("biodone: no buffer offset")); 3297 3298 VM_OBJECT_LOCK(obj); 3299 #if defined(VFS_BIO_DEBUG) 3300 if (obj->paging_in_progress < bp->b_npages) { 3301 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3302 obj->paging_in_progress, bp->b_npages); 3303 } 3304 #endif 3305 3306 /* 3307 * Set B_CACHE if the op was a normal read and no error 3308 * occured. B_CACHE is set for writes in the b*write() 3309 * routines. 3310 */ 3311 iosize = bp->b_bcount - bp->b_resid; 3312 if (bp->b_iocmd == BIO_READ && 3313 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3314 !(bp->b_ioflags & BIO_ERROR)) { 3315 bp->b_flags |= B_CACHE; 3316 } 3317 if (bp->b_iocmd == BIO_READ) { 3318 vm_page_lock_queues(); 3319 are_queues_locked = TRUE; 3320 } else 3321 are_queues_locked = FALSE; 3322 for (i = 0; i < bp->b_npages; i++) { 3323 int bogusflag = 0; 3324 int resid; 3325 3326 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3327 if (resid > iosize) 3328 resid = iosize; 3329 3330 /* 3331 * cleanup bogus pages, restoring the originals 3332 */ 3333 m = bp->b_pages[i]; 3334 if (m == bogus_page) { 3335 bogusflag = 1; 3336 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3337 if (m == NULL) 3338 panic("biodone: page disappeared!"); 3339 bp->b_pages[i] = m; 3340 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3341 bp->b_pages, bp->b_npages); 3342 } 3343 #if defined(VFS_BIO_DEBUG) 3344 if (OFF_TO_IDX(foff) != m->pindex) { 3345 printf( 3346 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3347 (intmax_t)foff, (uintmax_t)m->pindex); 3348 } 3349 #endif 3350 3351 /* 3352 * In the write case, the valid and clean bits are 3353 * already changed correctly ( see bdwrite() ), so we 3354 * only need to do this here in the read case. 3355 */ 3356 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3357 vfs_page_set_valid(bp, foff, m); 3358 } 3359 3360 /* 3361 * when debugging new filesystems or buffer I/O methods, this 3362 * is the most common error that pops up. if you see this, you 3363 * have not set the page busy flag correctly!!! 3364 */ 3365 if (m->busy == 0) { 3366 printf("biodone: page busy < 0, " 3367 "pindex: %d, foff: 0x(%x,%x), " 3368 "resid: %d, index: %d\n", 3369 (int) m->pindex, (int)(foff >> 32), 3370 (int) foff & 0xffffffff, resid, i); 3371 if (!vn_isdisk(vp, NULL)) 3372 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3373 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3374 (intmax_t) bp->b_lblkno, 3375 bp->b_flags, bp->b_npages); 3376 else 3377 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3378 (intmax_t) bp->b_lblkno, 3379 bp->b_flags, bp->b_npages); 3380 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3381 (u_long)m->valid, (u_long)m->dirty, 3382 m->wire_count); 3383 panic("biodone: page busy < 0\n"); 3384 } 3385 vm_page_io_finish(m); 3386 vm_object_pip_subtract(obj, 1); 3387 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3388 iosize -= resid; 3389 } 3390 if (are_queues_locked) 3391 vm_page_unlock_queues(); 3392 vm_object_pip_wakeupn(obj, 0); 3393 VM_OBJECT_UNLOCK(obj); 3394 } 3395 3396 /* 3397 * For asynchronous completions, release the buffer now. The brelse 3398 * will do a wakeup there if necessary - so no need to do a wakeup 3399 * here in the async case. The sync case always needs to do a wakeup. 3400 */ 3401 3402 if (bp->b_flags & B_ASYNC) { 3403 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3404 brelse(bp); 3405 else 3406 bqrelse(bp); 3407 } else 3408 bdone(bp); 3409 } 3410 3411 /* 3412 * This routine is called in lieu of iodone in the case of 3413 * incomplete I/O. This keeps the busy status for pages 3414 * consistant. 3415 */ 3416 void 3417 vfs_unbusy_pages(struct buf *bp) 3418 { 3419 int i; 3420 vm_object_t obj; 3421 vm_page_t m; 3422 3423 runningbufwakeup(bp); 3424 if (!(bp->b_flags & B_VMIO)) 3425 return; 3426 3427 obj = bp->b_bufobj->bo_object; 3428 VM_OBJECT_LOCK(obj); 3429 for (i = 0; i < bp->b_npages; i++) { 3430 m = bp->b_pages[i]; 3431 if (m == bogus_page) { 3432 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3433 if (!m) 3434 panic("vfs_unbusy_pages: page missing\n"); 3435 bp->b_pages[i] = m; 3436 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3437 bp->b_pages, bp->b_npages); 3438 } 3439 vm_object_pip_subtract(obj, 1); 3440 vm_page_io_finish(m); 3441 } 3442 vm_object_pip_wakeupn(obj, 0); 3443 VM_OBJECT_UNLOCK(obj); 3444 } 3445 3446 /* 3447 * vfs_page_set_valid: 3448 * 3449 * Set the valid bits in a page based on the supplied offset. The 3450 * range is restricted to the buffer's size. 3451 * 3452 * This routine is typically called after a read completes. 3453 */ 3454 static void 3455 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3456 { 3457 vm_ooffset_t soff, eoff; 3458 3459 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3460 /* 3461 * Start and end offsets in buffer. eoff - soff may not cross a 3462 * page boundry or cross the end of the buffer. The end of the 3463 * buffer, in this case, is our file EOF, not the allocation size 3464 * of the buffer. 3465 */ 3466 soff = off; 3467 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3468 if (eoff > bp->b_offset + bp->b_bcount) 3469 eoff = bp->b_offset + bp->b_bcount; 3470 3471 /* 3472 * Set valid range. This is typically the entire buffer and thus the 3473 * entire page. 3474 */ 3475 if (eoff > soff) { 3476 vm_page_set_validclean( 3477 m, 3478 (vm_offset_t) (soff & PAGE_MASK), 3479 (vm_offset_t) (eoff - soff) 3480 ); 3481 } 3482 } 3483 3484 /* 3485 * This routine is called before a device strategy routine. 3486 * It is used to tell the VM system that paging I/O is in 3487 * progress, and treat the pages associated with the buffer 3488 * almost as being VPO_BUSY. Also the object paging_in_progress 3489 * flag is handled to make sure that the object doesn't become 3490 * inconsistant. 3491 * 3492 * Since I/O has not been initiated yet, certain buffer flags 3493 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3494 * and should be ignored. 3495 */ 3496 void 3497 vfs_busy_pages(struct buf *bp, int clear_modify) 3498 { 3499 int i, bogus; 3500 vm_object_t obj; 3501 vm_ooffset_t foff; 3502 vm_page_t m; 3503 3504 if (!(bp->b_flags & B_VMIO)) 3505 return; 3506 3507 obj = bp->b_bufobj->bo_object; 3508 foff = bp->b_offset; 3509 KASSERT(bp->b_offset != NOOFFSET, 3510 ("vfs_busy_pages: no buffer offset")); 3511 VM_OBJECT_LOCK(obj); 3512 if (bp->b_bufsize != 0) 3513 vfs_setdirty_locked_object(bp); 3514 retry: 3515 for (i = 0; i < bp->b_npages; i++) { 3516 m = bp->b_pages[i]; 3517 3518 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3519 goto retry; 3520 } 3521 bogus = 0; 3522 vm_page_lock_queues(); 3523 for (i = 0; i < bp->b_npages; i++) { 3524 m = bp->b_pages[i]; 3525 3526 if ((bp->b_flags & B_CLUSTER) == 0) { 3527 vm_object_pip_add(obj, 1); 3528 vm_page_io_start(m); 3529 } 3530 /* 3531 * When readying a buffer for a read ( i.e 3532 * clear_modify == 0 ), it is important to do 3533 * bogus_page replacement for valid pages in 3534 * partially instantiated buffers. Partially 3535 * instantiated buffers can, in turn, occur when 3536 * reconstituting a buffer from its VM backing store 3537 * base. We only have to do this if B_CACHE is 3538 * clear ( which causes the I/O to occur in the 3539 * first place ). The replacement prevents the read 3540 * I/O from overwriting potentially dirty VM-backed 3541 * pages. XXX bogus page replacement is, uh, bogus. 3542 * It may not work properly with small-block devices. 3543 * We need to find a better way. 3544 */ 3545 pmap_remove_all(m); 3546 if (clear_modify) 3547 vfs_page_set_valid(bp, foff, m); 3548 else if (m->valid == VM_PAGE_BITS_ALL && 3549 (bp->b_flags & B_CACHE) == 0) { 3550 bp->b_pages[i] = bogus_page; 3551 bogus++; 3552 } 3553 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3554 } 3555 vm_page_unlock_queues(); 3556 VM_OBJECT_UNLOCK(obj); 3557 if (bogus) 3558 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3559 bp->b_pages, bp->b_npages); 3560 } 3561 3562 /* 3563 * Tell the VM system that the pages associated with this buffer 3564 * are clean. This is used for delayed writes where the data is 3565 * going to go to disk eventually without additional VM intevention. 3566 * 3567 * Note that while we only really need to clean through to b_bcount, we 3568 * just go ahead and clean through to b_bufsize. 3569 */ 3570 static void 3571 vfs_clean_pages(struct buf *bp) 3572 { 3573 int i; 3574 vm_ooffset_t foff, noff, eoff; 3575 vm_page_t m; 3576 3577 if (!(bp->b_flags & B_VMIO)) 3578 return; 3579 3580 foff = bp->b_offset; 3581 KASSERT(bp->b_offset != NOOFFSET, 3582 ("vfs_clean_pages: no buffer offset")); 3583 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3584 vm_page_lock_queues(); 3585 for (i = 0; i < bp->b_npages; i++) { 3586 m = bp->b_pages[i]; 3587 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3588 eoff = noff; 3589 3590 if (eoff > bp->b_offset + bp->b_bufsize) 3591 eoff = bp->b_offset + bp->b_bufsize; 3592 vfs_page_set_valid(bp, foff, m); 3593 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3594 foff = noff; 3595 } 3596 vm_page_unlock_queues(); 3597 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3598 } 3599 3600 /* 3601 * vfs_bio_set_validclean: 3602 * 3603 * Set the range within the buffer to valid and clean. The range is 3604 * relative to the beginning of the buffer, b_offset. Note that b_offset 3605 * itself may be offset from the beginning of the first page. 3606 * 3607 */ 3608 3609 void 3610 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3611 { 3612 int i, n; 3613 vm_page_t m; 3614 3615 if (!(bp->b_flags & B_VMIO)) 3616 return; 3617 /* 3618 * Fixup base to be relative to beginning of first page. 3619 * Set initial n to be the maximum number of bytes in the 3620 * first page that can be validated. 3621 */ 3622 3623 base += (bp->b_offset & PAGE_MASK); 3624 n = PAGE_SIZE - (base & PAGE_MASK); 3625 3626 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3627 vm_page_lock_queues(); 3628 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3629 m = bp->b_pages[i]; 3630 if (n > size) 3631 n = size; 3632 vm_page_set_validclean(m, base & PAGE_MASK, n); 3633 base += n; 3634 size -= n; 3635 n = PAGE_SIZE; 3636 } 3637 vm_page_unlock_queues(); 3638 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3639 } 3640 3641 /* 3642 * vfs_bio_clrbuf: 3643 * 3644 * clear a buffer. This routine essentially fakes an I/O, so we need 3645 * to clear BIO_ERROR and B_INVAL. 3646 * 3647 * Note that while we only theoretically need to clear through b_bcount, 3648 * we go ahead and clear through b_bufsize. 3649 */ 3650 3651 void 3652 vfs_bio_clrbuf(struct buf *bp) 3653 { 3654 int i, j, mask = 0; 3655 caddr_t sa, ea; 3656 3657 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3658 clrbuf(bp); 3659 return; 3660 } 3661 3662 bp->b_flags &= ~B_INVAL; 3663 bp->b_ioflags &= ~BIO_ERROR; 3664 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3665 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3666 (bp->b_offset & PAGE_MASK) == 0) { 3667 if (bp->b_pages[0] == bogus_page) 3668 goto unlock; 3669 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3670 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3671 if ((bp->b_pages[0]->valid & mask) == mask) 3672 goto unlock; 3673 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3674 ((bp->b_pages[0]->valid & mask) == 0)) { 3675 bzero(bp->b_data, bp->b_bufsize); 3676 bp->b_pages[0]->valid |= mask; 3677 goto unlock; 3678 } 3679 } 3680 ea = sa = bp->b_data; 3681 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3682 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3683 ea = (caddr_t)(vm_offset_t)ulmin( 3684 (u_long)(vm_offset_t)ea, 3685 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3686 if (bp->b_pages[i] == bogus_page) 3687 continue; 3688 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3689 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3690 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3691 if ((bp->b_pages[i]->valid & mask) == mask) 3692 continue; 3693 if ((bp->b_pages[i]->valid & mask) == 0) { 3694 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3695 bzero(sa, ea - sa); 3696 } else { 3697 for (; sa < ea; sa += DEV_BSIZE, j++) { 3698 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3699 (bp->b_pages[i]->valid & (1 << j)) == 0) 3700 bzero(sa, DEV_BSIZE); 3701 } 3702 } 3703 bp->b_pages[i]->valid |= mask; 3704 } 3705 unlock: 3706 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3707 bp->b_resid = 0; 3708 } 3709 3710 /* 3711 * vm_hold_load_pages and vm_hold_free_pages get pages into 3712 * a buffers address space. The pages are anonymous and are 3713 * not associated with a file object. 3714 */ 3715 static void 3716 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3717 { 3718 vm_offset_t pg; 3719 vm_page_t p; 3720 int index; 3721 3722 to = round_page(to); 3723 from = round_page(from); 3724 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3725 3726 VM_OBJECT_LOCK(kernel_object); 3727 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3728 tryagain: 3729 /* 3730 * note: must allocate system pages since blocking here 3731 * could intefere with paging I/O, no matter which 3732 * process we are. 3733 */ 3734 p = vm_page_alloc(kernel_object, 3735 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3736 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3737 if (!p) { 3738 atomic_add_int(&vm_pageout_deficit, 3739 (to - pg) >> PAGE_SHIFT); 3740 VM_OBJECT_UNLOCK(kernel_object); 3741 VM_WAIT; 3742 VM_OBJECT_LOCK(kernel_object); 3743 goto tryagain; 3744 } 3745 p->valid = VM_PAGE_BITS_ALL; 3746 pmap_qenter(pg, &p, 1); 3747 bp->b_pages[index] = p; 3748 } 3749 VM_OBJECT_UNLOCK(kernel_object); 3750 bp->b_npages = index; 3751 } 3752 3753 /* Return pages associated with this buf to the vm system */ 3754 static void 3755 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3756 { 3757 vm_offset_t pg; 3758 vm_page_t p; 3759 int index, newnpages; 3760 3761 from = round_page(from); 3762 to = round_page(to); 3763 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3764 3765 VM_OBJECT_LOCK(kernel_object); 3766 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3767 p = bp->b_pages[index]; 3768 if (p && (index < bp->b_npages)) { 3769 if (p->busy) { 3770 printf( 3771 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3772 (intmax_t)bp->b_blkno, 3773 (intmax_t)bp->b_lblkno); 3774 } 3775 bp->b_pages[index] = NULL; 3776 pmap_qremove(pg, 1); 3777 vm_page_lock_queues(); 3778 vm_page_unwire(p, 0); 3779 vm_page_free(p); 3780 vm_page_unlock_queues(); 3781 } 3782 } 3783 VM_OBJECT_UNLOCK(kernel_object); 3784 bp->b_npages = newnpages; 3785 } 3786 3787 /* 3788 * Map an IO request into kernel virtual address space. 3789 * 3790 * All requests are (re)mapped into kernel VA space. 3791 * Notice that we use b_bufsize for the size of the buffer 3792 * to be mapped. b_bcount might be modified by the driver. 3793 * 3794 * Note that even if the caller determines that the address space should 3795 * be valid, a race or a smaller-file mapped into a larger space may 3796 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3797 * check the return value. 3798 */ 3799 int 3800 vmapbuf(struct buf *bp) 3801 { 3802 caddr_t addr, kva; 3803 vm_prot_t prot; 3804 int pidx, i; 3805 struct vm_page *m; 3806 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3807 3808 if (bp->b_bufsize < 0) 3809 return (-1); 3810 prot = VM_PROT_READ; 3811 if (bp->b_iocmd == BIO_READ) 3812 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3813 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3814 addr < bp->b_data + bp->b_bufsize; 3815 addr += PAGE_SIZE, pidx++) { 3816 /* 3817 * Do the vm_fault if needed; do the copy-on-write thing 3818 * when reading stuff off device into memory. 3819 * 3820 * NOTE! Must use pmap_extract() because addr may be in 3821 * the userland address space, and kextract is only guarenteed 3822 * to work for the kernland address space (see: sparc64 port). 3823 */ 3824 retry: 3825 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3826 prot) < 0) { 3827 vm_page_lock_queues(); 3828 for (i = 0; i < pidx; ++i) { 3829 vm_page_unhold(bp->b_pages[i]); 3830 bp->b_pages[i] = NULL; 3831 } 3832 vm_page_unlock_queues(); 3833 return(-1); 3834 } 3835 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3836 if (m == NULL) 3837 goto retry; 3838 bp->b_pages[pidx] = m; 3839 } 3840 if (pidx > btoc(MAXPHYS)) 3841 panic("vmapbuf: mapped more than MAXPHYS"); 3842 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3843 3844 kva = bp->b_saveaddr; 3845 bp->b_npages = pidx; 3846 bp->b_saveaddr = bp->b_data; 3847 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3848 return(0); 3849 } 3850 3851 /* 3852 * Free the io map PTEs associated with this IO operation. 3853 * We also invalidate the TLB entries and restore the original b_addr. 3854 */ 3855 void 3856 vunmapbuf(struct buf *bp) 3857 { 3858 int pidx; 3859 int npages; 3860 3861 npages = bp->b_npages; 3862 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3863 vm_page_lock_queues(); 3864 for (pidx = 0; pidx < npages; pidx++) 3865 vm_page_unhold(bp->b_pages[pidx]); 3866 vm_page_unlock_queues(); 3867 3868 bp->b_data = bp->b_saveaddr; 3869 } 3870 3871 void 3872 bdone(struct buf *bp) 3873 { 3874 struct mtx *mtxp; 3875 3876 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3877 mtx_lock(mtxp); 3878 bp->b_flags |= B_DONE; 3879 wakeup(bp); 3880 mtx_unlock(mtxp); 3881 } 3882 3883 void 3884 bwait(struct buf *bp, u_char pri, const char *wchan) 3885 { 3886 struct mtx *mtxp; 3887 3888 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3889 mtx_lock(mtxp); 3890 while ((bp->b_flags & B_DONE) == 0) 3891 msleep(bp, mtxp, pri, wchan, 0); 3892 mtx_unlock(mtxp); 3893 } 3894 3895 int 3896 bufsync(struct bufobj *bo, int waitfor) 3897 { 3898 3899 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 3900 } 3901 3902 void 3903 bufstrategy(struct bufobj *bo, struct buf *bp) 3904 { 3905 int i = 0; 3906 struct vnode *vp; 3907 3908 vp = bp->b_vp; 3909 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3910 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3911 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3912 i = VOP_STRATEGY(vp, bp); 3913 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3914 } 3915 3916 void 3917 bufobj_wrefl(struct bufobj *bo) 3918 { 3919 3920 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3921 ASSERT_BO_LOCKED(bo); 3922 bo->bo_numoutput++; 3923 } 3924 3925 void 3926 bufobj_wref(struct bufobj *bo) 3927 { 3928 3929 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3930 BO_LOCK(bo); 3931 bo->bo_numoutput++; 3932 BO_UNLOCK(bo); 3933 } 3934 3935 void 3936 bufobj_wdrop(struct bufobj *bo) 3937 { 3938 3939 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3940 BO_LOCK(bo); 3941 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3942 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3943 bo->bo_flag &= ~BO_WWAIT; 3944 wakeup(&bo->bo_numoutput); 3945 } 3946 BO_UNLOCK(bo); 3947 } 3948 3949 int 3950 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3951 { 3952 int error; 3953 3954 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3955 ASSERT_BO_LOCKED(bo); 3956 error = 0; 3957 while (bo->bo_numoutput) { 3958 bo->bo_flag |= BO_WWAIT; 3959 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3960 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3961 if (error) 3962 break; 3963 } 3964 return (error); 3965 } 3966 3967 void 3968 bpin(struct buf *bp) 3969 { 3970 struct mtx *mtxp; 3971 3972 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3973 mtx_lock(mtxp); 3974 bp->b_pin_count++; 3975 mtx_unlock(mtxp); 3976 } 3977 3978 void 3979 bunpin(struct buf *bp) 3980 { 3981 struct mtx *mtxp; 3982 3983 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3984 mtx_lock(mtxp); 3985 if (--bp->b_pin_count == 0) 3986 wakeup(bp); 3987 mtx_unlock(mtxp); 3988 } 3989 3990 void 3991 bunpin_wait(struct buf *bp) 3992 { 3993 struct mtx *mtxp; 3994 3995 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3996 mtx_lock(mtxp); 3997 while (bp->b_pin_count > 0) 3998 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 3999 mtx_unlock(mtxp); 4000 } 4001 4002 #include "opt_ddb.h" 4003 #ifdef DDB 4004 #include <ddb/ddb.h> 4005 4006 /* DDB command to show buffer data */ 4007 DB_SHOW_COMMAND(buffer, db_show_buffer) 4008 { 4009 /* get args */ 4010 struct buf *bp = (struct buf *)addr; 4011 4012 if (!have_addr) { 4013 db_printf("usage: show buffer <addr>\n"); 4014 return; 4015 } 4016 4017 db_printf("buf at %p\n", bp); 4018 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 4019 db_printf( 4020 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4021 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_dep = %p\n", 4022 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4023 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4024 bp->b_dep.lh_first); 4025 if (bp->b_npages) { 4026 int i; 4027 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4028 for (i = 0; i < bp->b_npages; i++) { 4029 vm_page_t m; 4030 m = bp->b_pages[i]; 4031 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4032 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4033 if ((i + 1) < bp->b_npages) 4034 db_printf(","); 4035 } 4036 db_printf("\n"); 4037 } 4038 db_printf(" "); 4039 lockmgr_printinfo(&bp->b_lock); 4040 } 4041 4042 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4043 { 4044 struct buf *bp; 4045 int i; 4046 4047 for (i = 0; i < nbuf; i++) { 4048 bp = &buf[i]; 4049 if (BUF_ISLOCKED(bp)) { 4050 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4051 db_printf("\n"); 4052 } 4053 } 4054 } 4055 4056 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4057 { 4058 struct vnode *vp; 4059 struct buf *bp; 4060 4061 if (!have_addr) { 4062 db_printf("usage: show vnodebufs <addr>\n"); 4063 return; 4064 } 4065 vp = (struct vnode *)addr; 4066 db_printf("Clean buffers:\n"); 4067 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4068 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4069 db_printf("\n"); 4070 } 4071 db_printf("Dirty buffers:\n"); 4072 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4073 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4074 db_printf("\n"); 4075 } 4076 } 4077 #endif /* DDB */ 4078