1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * Copyright (c) 2013 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * this file contains a new buffer I/O scheme implementing a coherent 34 * VM object and buffer cache scheme. Pains have been taken to make 35 * sure that the performance degradation associated with schemes such 36 * as this is not realized. 37 * 38 * Author: John S. Dyson 39 * Significant help during the development and debugging phases 40 * had been provided by David Greenman, also of the FreeBSD core team. 41 * 42 * see man buf(9) for more info. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/bio.h> 51 #include <sys/conf.h> 52 #include <sys/buf.h> 53 #include <sys/devicestat.h> 54 #include <sys/eventhandler.h> 55 #include <sys/fail.h> 56 #include <sys/limits.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/mount.h> 60 #include <sys/mutex.h> 61 #include <sys/kernel.h> 62 #include <sys/kthread.h> 63 #include <sys/proc.h> 64 #include <sys/resourcevar.h> 65 #include <sys/rwlock.h> 66 #include <sys/sysctl.h> 67 #include <sys/vmmeter.h> 68 #include <sys/vnode.h> 69 #include <geom/geom.h> 70 #include <vm/vm.h> 71 #include <vm/vm_param.h> 72 #include <vm/vm_kern.h> 73 #include <vm/vm_pageout.h> 74 #include <vm/vm_page.h> 75 #include <vm/vm_object.h> 76 #include <vm/vm_extern.h> 77 #include <vm/vm_map.h> 78 #include "opt_compat.h" 79 #include "opt_directio.h" 80 #include "opt_swap.h" 81 82 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 83 84 struct bio_ops bioops; /* I/O operation notification */ 85 86 struct buf_ops buf_ops_bio = { 87 .bop_name = "buf_ops_bio", 88 .bop_write = bufwrite, 89 .bop_strategy = bufstrategy, 90 .bop_sync = bufsync, 91 .bop_bdflush = bufbdflush, 92 }; 93 94 /* 95 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 96 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 97 */ 98 struct buf *buf; /* buffer header pool */ 99 caddr_t unmapped_buf; 100 101 static struct proc *bufdaemonproc; 102 103 static int inmem(struct vnode *vp, daddr_t blkno); 104 static void vm_hold_free_pages(struct buf *bp, int newbsize); 105 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 106 vm_offset_t to); 107 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 108 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 109 vm_page_t m); 110 static void vfs_drain_busy_pages(struct buf *bp); 111 static void vfs_clean_pages_dirty_buf(struct buf *bp); 112 static void vfs_setdirty_locked_object(struct buf *bp); 113 static void vfs_vmio_release(struct buf *bp); 114 static int vfs_bio_clcheck(struct vnode *vp, int size, 115 daddr_t lblkno, daddr_t blkno); 116 static int buf_do_flush(struct vnode *vp); 117 static int flushbufqueues(struct vnode *, int, int); 118 static void buf_daemon(void); 119 static void bremfreel(struct buf *bp); 120 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 121 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 122 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 123 #endif 124 125 int vmiodirenable = TRUE; 126 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 127 "Use the VM system for directory writes"); 128 long runningbufspace; 129 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 130 "Amount of presently outstanding async buffer io"); 131 static long bufspace; 132 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 133 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 134 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 135 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 136 #else 137 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 138 "Virtual memory used for buffers"); 139 #endif 140 static long unmapped_bufspace; 141 SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD, 142 &unmapped_bufspace, 0, 143 "Amount of unmapped buffers, inclusive in the bufspace"); 144 static long maxbufspace; 145 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 146 "Maximum allowed value of bufspace (including buf_daemon)"); 147 static long bufmallocspace; 148 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 149 "Amount of malloced memory for buffers"); 150 static long maxbufmallocspace; 151 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 152 "Maximum amount of malloced memory for buffers"); 153 static long lobufspace; 154 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 155 "Minimum amount of buffers we want to have"); 156 long hibufspace; 157 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 158 "Maximum allowed value of bufspace (excluding buf_daemon)"); 159 static int bufreusecnt; 160 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 161 "Number of times we have reused a buffer"); 162 static int buffreekvacnt; 163 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 164 "Number of times we have freed the KVA space from some buffer"); 165 static int bufdefragcnt; 166 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 167 "Number of times we have had to repeat buffer allocation to defragment"); 168 static long lorunningspace; 169 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 170 "Minimum preferred space used for in-progress I/O"); 171 static long hirunningspace; 172 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 173 "Maximum amount of space to use for in-progress I/O"); 174 int dirtybufferflushes; 175 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 176 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 177 int bdwriteskip; 178 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 179 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 180 int altbufferflushes; 181 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 182 0, "Number of fsync flushes to limit dirty buffers"); 183 static int recursiveflushes; 184 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 185 0, "Number of flushes skipped due to being recursive"); 186 static int numdirtybuffers; 187 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 188 "Number of buffers that are dirty (has unwritten changes) at the moment"); 189 static int lodirtybuffers; 190 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 191 "How many buffers we want to have free before bufdaemon can sleep"); 192 static int hidirtybuffers; 193 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 194 "When the number of dirty buffers is considered severe"); 195 int dirtybufthresh; 196 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 197 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 198 static int numfreebuffers; 199 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 200 "Number of free buffers"); 201 static int lofreebuffers; 202 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 203 "XXX Unused"); 204 static int hifreebuffers; 205 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 206 "XXX Complicatedly unused"); 207 static int getnewbufcalls; 208 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 209 "Number of calls to getnewbuf"); 210 static int getnewbufrestarts; 211 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 212 "Number of times getnewbuf has had to restart a buffer aquisition"); 213 static int mappingrestarts; 214 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 215 "Number of times getblk has had to restart a buffer mapping for " 216 "unmapped buffer"); 217 static int flushbufqtarget = 100; 218 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 219 "Amount of work to do in flushbufqueues when helping bufdaemon"); 220 static long notbufdflashes; 221 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0, 222 "Number of dirty buffer flushes done by the bufdaemon helpers"); 223 static long barrierwrites; 224 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 225 "Number of barrier writes"); 226 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 227 &unmapped_buf_allowed, 0, 228 "Permit the use of the unmapped i/o"); 229 230 /* 231 * Wakeup point for bufdaemon, as well as indicator of whether it is already 232 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 233 * is idling. 234 */ 235 static int bd_request; 236 237 /* 238 * Request for the buf daemon to write more buffers than is indicated by 239 * lodirtybuf. This may be necessary to push out excess dependencies or 240 * defragment the address space where a simple count of the number of dirty 241 * buffers is insufficient to characterize the demand for flushing them. 242 */ 243 static int bd_speedupreq; 244 245 /* 246 * This lock synchronizes access to bd_request. 247 */ 248 static struct mtx bdlock; 249 250 /* 251 * bogus page -- for I/O to/from partially complete buffers 252 * this is a temporary solution to the problem, but it is not 253 * really that bad. it would be better to split the buffer 254 * for input in the case of buffers partially already in memory, 255 * but the code is intricate enough already. 256 */ 257 vm_page_t bogus_page; 258 259 /* 260 * Synchronization (sleep/wakeup) variable for active buffer space requests. 261 * Set when wait starts, cleared prior to wakeup(). 262 * Used in runningbufwakeup() and waitrunningbufspace(). 263 */ 264 static int runningbufreq; 265 266 /* 267 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 268 * waitrunningbufspace(). 269 */ 270 static struct mtx rbreqlock; 271 272 /* 273 * Synchronization (sleep/wakeup) variable for buffer requests. 274 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 275 * by and/or. 276 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 277 * getnewbuf(), and getblk(). 278 */ 279 static int needsbuffer; 280 281 /* 282 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 283 */ 284 static struct mtx nblock; 285 286 /* 287 * Definitions for the buffer free lists. 288 */ 289 #define BUFFER_QUEUES 5 /* number of free buffer queues */ 290 291 #define QUEUE_NONE 0 /* on no queue */ 292 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 293 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 294 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 295 #define QUEUE_EMPTY 4 /* empty buffer headers */ 296 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 297 298 /* Queues for free buffers with various properties */ 299 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 300 #ifdef INVARIANTS 301 static int bq_len[BUFFER_QUEUES]; 302 #endif 303 304 /* Lock for the bufqueues */ 305 static struct mtx bqlock; 306 307 /* 308 * Single global constant for BUF_WMESG, to avoid getting multiple references. 309 * buf_wmesg is referred from macros. 310 */ 311 const char *buf_wmesg = BUF_WMESG; 312 313 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 314 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 315 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 316 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 317 318 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 319 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 320 static int 321 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 322 { 323 long lvalue; 324 int ivalue; 325 326 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 327 return (sysctl_handle_long(oidp, arg1, arg2, req)); 328 lvalue = *(long *)arg1; 329 if (lvalue > INT_MAX) 330 /* On overflow, still write out a long to trigger ENOMEM. */ 331 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 332 ivalue = lvalue; 333 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 334 } 335 #endif 336 337 #ifdef DIRECTIO 338 extern void ffs_rawread_setup(void); 339 #endif /* DIRECTIO */ 340 /* 341 * numdirtywakeup: 342 * 343 * If someone is blocked due to there being too many dirty buffers, 344 * and numdirtybuffers is now reasonable, wake them up. 345 */ 346 347 static __inline void 348 numdirtywakeup(int level) 349 { 350 351 if (numdirtybuffers <= level) { 352 mtx_lock(&nblock); 353 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 354 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 355 wakeup(&needsbuffer); 356 } 357 mtx_unlock(&nblock); 358 } 359 } 360 361 /* 362 * bufspacewakeup: 363 * 364 * Called when buffer space is potentially available for recovery. 365 * getnewbuf() will block on this flag when it is unable to free 366 * sufficient buffer space. Buffer space becomes recoverable when 367 * bp's get placed back in the queues. 368 */ 369 370 static __inline void 371 bufspacewakeup(void) 372 { 373 374 /* 375 * If someone is waiting for BUF space, wake them up. Even 376 * though we haven't freed the kva space yet, the waiting 377 * process will be able to now. 378 */ 379 mtx_lock(&nblock); 380 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 381 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 382 wakeup(&needsbuffer); 383 } 384 mtx_unlock(&nblock); 385 } 386 387 /* 388 * runningbufwakeup() - in-progress I/O accounting. 389 * 390 */ 391 void 392 runningbufwakeup(struct buf *bp) 393 { 394 395 if (bp->b_runningbufspace) { 396 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace); 397 bp->b_runningbufspace = 0; 398 mtx_lock(&rbreqlock); 399 if (runningbufreq && runningbufspace <= lorunningspace) { 400 runningbufreq = 0; 401 wakeup(&runningbufreq); 402 } 403 mtx_unlock(&rbreqlock); 404 } 405 } 406 407 /* 408 * bufcountwakeup: 409 * 410 * Called when a buffer has been added to one of the free queues to 411 * account for the buffer and to wakeup anyone waiting for free buffers. 412 * This typically occurs when large amounts of metadata are being handled 413 * by the buffer cache ( else buffer space runs out first, usually ). 414 */ 415 416 static __inline void 417 bufcountwakeup(struct buf *bp) 418 { 419 int old; 420 421 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 422 ("buf %p already counted as free", bp)); 423 if (bp->b_bufobj != NULL) 424 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 425 bp->b_vflags |= BV_INFREECNT; 426 old = atomic_fetchadd_int(&numfreebuffers, 1); 427 KASSERT(old >= 0 && old < nbuf, 428 ("numfreebuffers climbed to %d", old + 1)); 429 mtx_lock(&nblock); 430 if (needsbuffer) { 431 needsbuffer &= ~VFS_BIO_NEED_ANY; 432 if (numfreebuffers >= hifreebuffers) 433 needsbuffer &= ~VFS_BIO_NEED_FREE; 434 wakeup(&needsbuffer); 435 } 436 mtx_unlock(&nblock); 437 } 438 439 /* 440 * waitrunningbufspace() 441 * 442 * runningbufspace is a measure of the amount of I/O currently 443 * running. This routine is used in async-write situations to 444 * prevent creating huge backups of pending writes to a device. 445 * Only asynchronous writes are governed by this function. 446 * 447 * Reads will adjust runningbufspace, but will not block based on it. 448 * The read load has a side effect of reducing the allowed write load. 449 * 450 * This does NOT turn an async write into a sync write. It waits 451 * for earlier writes to complete and generally returns before the 452 * caller's write has reached the device. 453 */ 454 void 455 waitrunningbufspace(void) 456 { 457 458 mtx_lock(&rbreqlock); 459 while (runningbufspace > hirunningspace) { 460 ++runningbufreq; 461 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 462 } 463 mtx_unlock(&rbreqlock); 464 } 465 466 467 /* 468 * vfs_buf_test_cache: 469 * 470 * Called when a buffer is extended. This function clears the B_CACHE 471 * bit if the newly extended portion of the buffer does not contain 472 * valid data. 473 */ 474 static __inline 475 void 476 vfs_buf_test_cache(struct buf *bp, 477 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 478 vm_page_t m) 479 { 480 481 VM_OBJECT_ASSERT_WLOCKED(m->object); 482 if (bp->b_flags & B_CACHE) { 483 int base = (foff + off) & PAGE_MASK; 484 if (vm_page_is_valid(m, base, size) == 0) 485 bp->b_flags &= ~B_CACHE; 486 } 487 } 488 489 /* Wake up the buffer daemon if necessary */ 490 static __inline 491 void 492 bd_wakeup(int dirtybuflevel) 493 { 494 495 mtx_lock(&bdlock); 496 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 497 bd_request = 1; 498 wakeup(&bd_request); 499 } 500 mtx_unlock(&bdlock); 501 } 502 503 /* 504 * bd_speedup - speedup the buffer cache flushing code 505 */ 506 507 void 508 bd_speedup(void) 509 { 510 int needwake; 511 512 mtx_lock(&bdlock); 513 needwake = 0; 514 if (bd_speedupreq == 0 || bd_request == 0) 515 needwake = 1; 516 bd_speedupreq = 1; 517 bd_request = 1; 518 if (needwake) 519 wakeup(&bd_request); 520 mtx_unlock(&bdlock); 521 } 522 523 /* 524 * Calculating buffer cache scaling values and reserve space for buffer 525 * headers. This is called during low level kernel initialization and 526 * may be called more then once. We CANNOT write to the memory area 527 * being reserved at this time. 528 */ 529 caddr_t 530 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 531 { 532 int tuned_nbuf; 533 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 534 535 /* 536 * physmem_est is in pages. Convert it to kilobytes (assumes 537 * PAGE_SIZE is >= 1K) 538 */ 539 physmem_est = physmem_est * (PAGE_SIZE / 1024); 540 541 /* 542 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 543 * For the first 64MB of ram nominally allocate sufficient buffers to 544 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 545 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 546 * the buffer cache we limit the eventual kva reservation to 547 * maxbcache bytes. 548 * 549 * factor represents the 1/4 x ram conversion. 550 */ 551 if (nbuf == 0) { 552 int factor = 4 * BKVASIZE / 1024; 553 554 nbuf = 50; 555 if (physmem_est > 4096) 556 nbuf += min((physmem_est - 4096) / factor, 557 65536 / factor); 558 if (physmem_est > 65536) 559 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 560 561 if (maxbcache && nbuf > maxbcache / BKVASIZE) 562 nbuf = maxbcache / BKVASIZE; 563 tuned_nbuf = 1; 564 } else 565 tuned_nbuf = 0; 566 567 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 568 maxbuf = (LONG_MAX / 3) / BKVASIZE; 569 if (nbuf > maxbuf) { 570 if (!tuned_nbuf) 571 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 572 maxbuf); 573 nbuf = maxbuf; 574 } 575 576 /* 577 * Ideal allocation size for the transient bio submap if 10% 578 * of the maximal space buffer map. This roughly corresponds 579 * to the amount of the buffer mapped for typical UFS load. 580 * 581 * Clip the buffer map to reserve space for the transient 582 * BIOs, if its extent is bigger than 90% of the maximum 583 * buffer map extent on the platform. 584 * 585 * The fall-back to the maxbuf in case of maxbcache unset, 586 * allows to not trim the buffer KVA for the architectures 587 * with ample KVA space. 588 */ 589 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 590 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 591 buf_sz = (long)nbuf * BKVASIZE; 592 if (buf_sz < maxbuf_sz / 10 * 9) { 593 /* 594 * There is more KVA than memory. Do not 595 * adjust buffer map size, and assign the rest 596 * of maxbuf to transient map. 597 */ 598 biotmap_sz = maxbuf_sz - buf_sz; 599 } else { 600 /* 601 * Buffer map spans all KVA we could afford on 602 * this platform. Give 10% of the buffer map 603 * to the transient bio map. 604 */ 605 biotmap_sz = buf_sz / 10; 606 buf_sz -= biotmap_sz; 607 } 608 if (biotmap_sz / INT_MAX > MAXPHYS) 609 bio_transient_maxcnt = INT_MAX; 610 else 611 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 612 /* 613 * Artifically limit to 1024 simultaneous in-flight I/Os 614 * using the transient mapping. 615 */ 616 if (bio_transient_maxcnt > 1024) 617 bio_transient_maxcnt = 1024; 618 if (tuned_nbuf) 619 nbuf = buf_sz / BKVASIZE; 620 } 621 622 /* 623 * swbufs are used as temporary holders for I/O, such as paging I/O. 624 * We have no less then 16 and no more then 256. 625 */ 626 nswbuf = max(min(nbuf/4, 256), 16); 627 #ifdef NSWBUF_MIN 628 if (nswbuf < NSWBUF_MIN) 629 nswbuf = NSWBUF_MIN; 630 #endif 631 #ifdef DIRECTIO 632 ffs_rawread_setup(); 633 #endif 634 635 /* 636 * Reserve space for the buffer cache buffers 637 */ 638 swbuf = (void *)v; 639 v = (caddr_t)(swbuf + nswbuf); 640 buf = (void *)v; 641 v = (caddr_t)(buf + nbuf); 642 643 return(v); 644 } 645 646 /* Initialize the buffer subsystem. Called before use of any buffers. */ 647 void 648 bufinit(void) 649 { 650 struct buf *bp; 651 int i; 652 653 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 654 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 655 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 656 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 657 658 /* next, make a null set of free lists */ 659 for (i = 0; i < BUFFER_QUEUES; i++) 660 TAILQ_INIT(&bufqueues[i]); 661 662 /* finally, initialize each buffer header and stick on empty q */ 663 for (i = 0; i < nbuf; i++) { 664 bp = &buf[i]; 665 bzero(bp, sizeof *bp); 666 bp->b_flags = B_INVAL; /* we're just an empty header */ 667 bp->b_rcred = NOCRED; 668 bp->b_wcred = NOCRED; 669 bp->b_qindex = QUEUE_EMPTY; 670 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */ 671 bp->b_xflags = 0; 672 LIST_INIT(&bp->b_dep); 673 BUF_LOCKINIT(bp); 674 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 675 #ifdef INVARIANTS 676 bq_len[QUEUE_EMPTY]++; 677 #endif 678 } 679 680 /* 681 * maxbufspace is the absolute maximum amount of buffer space we are 682 * allowed to reserve in KVM and in real terms. The absolute maximum 683 * is nominally used by buf_daemon. hibufspace is the nominal maximum 684 * used by most other processes. The differential is required to 685 * ensure that buf_daemon is able to run when other processes might 686 * be blocked waiting for buffer space. 687 * 688 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 689 * this may result in KVM fragmentation which is not handled optimally 690 * by the system. 691 */ 692 maxbufspace = (long)nbuf * BKVASIZE; 693 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 694 lobufspace = hibufspace - MAXBSIZE; 695 696 /* 697 * Note: The 16 MiB upper limit for hirunningspace was chosen 698 * arbitrarily and may need further tuning. It corresponds to 699 * 128 outstanding write IO requests (if IO size is 128 KiB), 700 * which fits with many RAID controllers' tagged queuing limits. 701 * The lower 1 MiB limit is the historical upper limit for 702 * hirunningspace. 703 */ 704 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 705 16 * 1024 * 1024), 1024 * 1024); 706 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 707 708 /* 709 * Limit the amount of malloc memory since it is wired permanently into 710 * the kernel space. Even though this is accounted for in the buffer 711 * allocation, we don't want the malloced region to grow uncontrolled. 712 * The malloc scheme improves memory utilization significantly on average 713 * (small) directories. 714 */ 715 maxbufmallocspace = hibufspace / 20; 716 717 /* 718 * Reduce the chance of a deadlock occuring by limiting the number 719 * of delayed-write dirty buffers we allow to stack up. 720 */ 721 hidirtybuffers = nbuf / 4 + 20; 722 dirtybufthresh = hidirtybuffers * 9 / 10; 723 numdirtybuffers = 0; 724 /* 725 * To support extreme low-memory systems, make sure hidirtybuffers cannot 726 * eat up all available buffer space. This occurs when our minimum cannot 727 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 728 * BKVASIZE'd buffers. 729 */ 730 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 731 hidirtybuffers >>= 1; 732 } 733 lodirtybuffers = hidirtybuffers / 2; 734 735 /* 736 * Try to keep the number of free buffers in the specified range, 737 * and give special processes (e.g. like buf_daemon) access to an 738 * emergency reserve. 739 */ 740 lofreebuffers = nbuf / 18 + 5; 741 hifreebuffers = 2 * lofreebuffers; 742 numfreebuffers = nbuf; 743 744 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 745 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 746 unmapped_buf = (caddr_t)kmem_alloc_nofault(kernel_map, MAXPHYS); 747 } 748 749 #ifdef INVARIANTS 750 static inline void 751 vfs_buf_check_mapped(struct buf *bp) 752 { 753 754 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 755 ("mapped buf %p %x", bp, bp->b_flags)); 756 KASSERT(bp->b_kvabase != unmapped_buf, 757 ("mapped buf: b_kvabase was not updated %p", bp)); 758 KASSERT(bp->b_data != unmapped_buf, 759 ("mapped buf: b_data was not updated %p", bp)); 760 } 761 762 static inline void 763 vfs_buf_check_unmapped(struct buf *bp) 764 { 765 766 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 767 ("unmapped buf %p %x", bp, bp->b_flags)); 768 KASSERT(bp->b_kvabase == unmapped_buf, 769 ("unmapped buf: corrupted b_kvabase %p", bp)); 770 KASSERT(bp->b_data == unmapped_buf, 771 ("unmapped buf: corrupted b_data %p", bp)); 772 } 773 774 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 775 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 776 #else 777 #define BUF_CHECK_MAPPED(bp) do {} while (0) 778 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 779 #endif 780 781 static void 782 bpmap_qenter(struct buf *bp) 783 { 784 785 BUF_CHECK_MAPPED(bp); 786 787 /* 788 * bp->b_data is relative to bp->b_offset, but 789 * bp->b_offset may be offset into the first page. 790 */ 791 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 792 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 793 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 794 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 795 } 796 797 /* 798 * bfreekva() - free the kva allocation for a buffer. 799 * 800 * Since this call frees up buffer space, we call bufspacewakeup(). 801 */ 802 static void 803 bfreekva(struct buf *bp) 804 { 805 806 if (bp->b_kvasize == 0) 807 return; 808 809 atomic_add_int(&buffreekvacnt, 1); 810 atomic_subtract_long(&bufspace, bp->b_kvasize); 811 if ((bp->b_flags & B_UNMAPPED) == 0) { 812 BUF_CHECK_MAPPED(bp); 813 vm_map_remove(buffer_map, (vm_offset_t)bp->b_kvabase, 814 (vm_offset_t)bp->b_kvabase + bp->b_kvasize); 815 } else { 816 BUF_CHECK_UNMAPPED(bp); 817 if ((bp->b_flags & B_KVAALLOC) != 0) { 818 vm_map_remove(buffer_map, (vm_offset_t)bp->b_kvaalloc, 819 (vm_offset_t)bp->b_kvaalloc + bp->b_kvasize); 820 } 821 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 822 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 823 } 824 bp->b_kvasize = 0; 825 bufspacewakeup(); 826 } 827 828 /* 829 * bremfree: 830 * 831 * Mark the buffer for removal from the appropriate free list in brelse. 832 * 833 */ 834 void 835 bremfree(struct buf *bp) 836 { 837 int old; 838 839 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 840 KASSERT((bp->b_flags & B_REMFREE) == 0, 841 ("bremfree: buffer %p already marked for delayed removal.", bp)); 842 KASSERT(bp->b_qindex != QUEUE_NONE, 843 ("bremfree: buffer %p not on a queue.", bp)); 844 BUF_ASSERT_HELD(bp); 845 846 bp->b_flags |= B_REMFREE; 847 /* Fixup numfreebuffers count. */ 848 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 849 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 850 ("buf %p not counted in numfreebuffers", bp)); 851 if (bp->b_bufobj != NULL) 852 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 853 bp->b_vflags &= ~BV_INFREECNT; 854 old = atomic_fetchadd_int(&numfreebuffers, -1); 855 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 856 } 857 } 858 859 /* 860 * bremfreef: 861 * 862 * Force an immediate removal from a free list. Used only in nfs when 863 * it abuses the b_freelist pointer. 864 */ 865 void 866 bremfreef(struct buf *bp) 867 { 868 mtx_lock(&bqlock); 869 bremfreel(bp); 870 mtx_unlock(&bqlock); 871 } 872 873 /* 874 * bremfreel: 875 * 876 * Removes a buffer from the free list, must be called with the 877 * bqlock held. 878 */ 879 static void 880 bremfreel(struct buf *bp) 881 { 882 int old; 883 884 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 885 bp, bp->b_vp, bp->b_flags); 886 KASSERT(bp->b_qindex != QUEUE_NONE, 887 ("bremfreel: buffer %p not on a queue.", bp)); 888 BUF_ASSERT_HELD(bp); 889 mtx_assert(&bqlock, MA_OWNED); 890 891 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 892 #ifdef INVARIANTS 893 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 894 bp->b_qindex)); 895 bq_len[bp->b_qindex]--; 896 #endif 897 bp->b_qindex = QUEUE_NONE; 898 /* 899 * If this was a delayed bremfree() we only need to remove the buffer 900 * from the queue and return the stats are already done. 901 */ 902 if (bp->b_flags & B_REMFREE) { 903 bp->b_flags &= ~B_REMFREE; 904 return; 905 } 906 /* 907 * Fixup numfreebuffers count. If the buffer is invalid or not 908 * delayed-write, the buffer was free and we must decrement 909 * numfreebuffers. 910 */ 911 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 912 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 913 ("buf %p not counted in numfreebuffers", bp)); 914 if (bp->b_bufobj != NULL) 915 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 916 bp->b_vflags &= ~BV_INFREECNT; 917 old = atomic_fetchadd_int(&numfreebuffers, -1); 918 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 919 } 920 } 921 922 /* 923 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 924 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 925 * the buffer is valid and we do not have to do anything. 926 */ 927 void 928 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 929 int cnt, struct ucred * cred) 930 { 931 struct buf *rabp; 932 int i; 933 934 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 935 if (inmem(vp, *rablkno)) 936 continue; 937 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 938 939 if ((rabp->b_flags & B_CACHE) == 0) { 940 if (!TD_IS_IDLETHREAD(curthread)) 941 curthread->td_ru.ru_inblock++; 942 rabp->b_flags |= B_ASYNC; 943 rabp->b_flags &= ~B_INVAL; 944 rabp->b_ioflags &= ~BIO_ERROR; 945 rabp->b_iocmd = BIO_READ; 946 if (rabp->b_rcred == NOCRED && cred != NOCRED) 947 rabp->b_rcred = crhold(cred); 948 vfs_busy_pages(rabp, 0); 949 BUF_KERNPROC(rabp); 950 rabp->b_iooffset = dbtob(rabp->b_blkno); 951 bstrategy(rabp); 952 } else { 953 brelse(rabp); 954 } 955 } 956 } 957 958 /* 959 * Entry point for bread() and breadn() via #defines in sys/buf.h. 960 * 961 * Get a buffer with the specified data. Look in the cache first. We 962 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 963 * is set, the buffer is valid and we do not have to do anything, see 964 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 965 */ 966 int 967 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 968 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 969 { 970 struct buf *bp; 971 int rv = 0, readwait = 0; 972 973 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 974 /* 975 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 976 */ 977 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 978 if (bp == NULL) 979 return (EBUSY); 980 981 /* if not found in cache, do some I/O */ 982 if ((bp->b_flags & B_CACHE) == 0) { 983 if (!TD_IS_IDLETHREAD(curthread)) 984 curthread->td_ru.ru_inblock++; 985 bp->b_iocmd = BIO_READ; 986 bp->b_flags &= ~B_INVAL; 987 bp->b_ioflags &= ~BIO_ERROR; 988 if (bp->b_rcred == NOCRED && cred != NOCRED) 989 bp->b_rcred = crhold(cred); 990 vfs_busy_pages(bp, 0); 991 bp->b_iooffset = dbtob(bp->b_blkno); 992 bstrategy(bp); 993 ++readwait; 994 } 995 996 breada(vp, rablkno, rabsize, cnt, cred); 997 998 if (readwait) { 999 rv = bufwait(bp); 1000 } 1001 return (rv); 1002 } 1003 1004 /* 1005 * Write, release buffer on completion. (Done by iodone 1006 * if async). Do not bother writing anything if the buffer 1007 * is invalid. 1008 * 1009 * Note that we set B_CACHE here, indicating that buffer is 1010 * fully valid and thus cacheable. This is true even of NFS 1011 * now so we set it generally. This could be set either here 1012 * or in biodone() since the I/O is synchronous. We put it 1013 * here. 1014 */ 1015 int 1016 bufwrite(struct buf *bp) 1017 { 1018 int oldflags; 1019 struct vnode *vp; 1020 int vp_md; 1021 1022 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1023 if (bp->b_flags & B_INVAL) { 1024 brelse(bp); 1025 return (0); 1026 } 1027 1028 if (bp->b_flags & B_BARRIER) 1029 barrierwrites++; 1030 1031 oldflags = bp->b_flags; 1032 1033 BUF_ASSERT_HELD(bp); 1034 1035 if (bp->b_pin_count > 0) 1036 bunpin_wait(bp); 1037 1038 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1039 ("FFS background buffer should not get here %p", bp)); 1040 1041 vp = bp->b_vp; 1042 if (vp) 1043 vp_md = vp->v_vflag & VV_MD; 1044 else 1045 vp_md = 0; 1046 1047 /* 1048 * Mark the buffer clean. Increment the bufobj write count 1049 * before bundirty() call, to prevent other thread from seeing 1050 * empty dirty list and zero counter for writes in progress, 1051 * falsely indicating that the bufobj is clean. 1052 */ 1053 bufobj_wref(bp->b_bufobj); 1054 bundirty(bp); 1055 1056 bp->b_flags &= ~B_DONE; 1057 bp->b_ioflags &= ~BIO_ERROR; 1058 bp->b_flags |= B_CACHE; 1059 bp->b_iocmd = BIO_WRITE; 1060 1061 vfs_busy_pages(bp, 1); 1062 1063 /* 1064 * Normal bwrites pipeline writes 1065 */ 1066 bp->b_runningbufspace = bp->b_bufsize; 1067 atomic_add_long(&runningbufspace, bp->b_runningbufspace); 1068 1069 if (!TD_IS_IDLETHREAD(curthread)) 1070 curthread->td_ru.ru_oublock++; 1071 if (oldflags & B_ASYNC) 1072 BUF_KERNPROC(bp); 1073 bp->b_iooffset = dbtob(bp->b_blkno); 1074 bstrategy(bp); 1075 1076 if ((oldflags & B_ASYNC) == 0) { 1077 int rtval = bufwait(bp); 1078 brelse(bp); 1079 return (rtval); 1080 } else { 1081 /* 1082 * don't allow the async write to saturate the I/O 1083 * system. We will not deadlock here because 1084 * we are blocking waiting for I/O that is already in-progress 1085 * to complete. We do not block here if it is the update 1086 * or syncer daemon trying to clean up as that can lead 1087 * to deadlock. 1088 */ 1089 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1090 waitrunningbufspace(); 1091 } 1092 1093 return (0); 1094 } 1095 1096 void 1097 bufbdflush(struct bufobj *bo, struct buf *bp) 1098 { 1099 struct buf *nbp; 1100 1101 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1102 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1103 altbufferflushes++; 1104 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1105 BO_LOCK(bo); 1106 /* 1107 * Try to find a buffer to flush. 1108 */ 1109 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1110 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1111 BUF_LOCK(nbp, 1112 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1113 continue; 1114 if (bp == nbp) 1115 panic("bdwrite: found ourselves"); 1116 BO_UNLOCK(bo); 1117 /* Don't countdeps with the bo lock held. */ 1118 if (buf_countdeps(nbp, 0)) { 1119 BO_LOCK(bo); 1120 BUF_UNLOCK(nbp); 1121 continue; 1122 } 1123 if (nbp->b_flags & B_CLUSTEROK) { 1124 vfs_bio_awrite(nbp); 1125 } else { 1126 bremfree(nbp); 1127 bawrite(nbp); 1128 } 1129 dirtybufferflushes++; 1130 break; 1131 } 1132 if (nbp == NULL) 1133 BO_UNLOCK(bo); 1134 } 1135 } 1136 1137 /* 1138 * Delayed write. (Buffer is marked dirty). Do not bother writing 1139 * anything if the buffer is marked invalid. 1140 * 1141 * Note that since the buffer must be completely valid, we can safely 1142 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1143 * biodone() in order to prevent getblk from writing the buffer 1144 * out synchronously. 1145 */ 1146 void 1147 bdwrite(struct buf *bp) 1148 { 1149 struct thread *td = curthread; 1150 struct vnode *vp; 1151 struct bufobj *bo; 1152 1153 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1154 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1155 KASSERT((bp->b_flags & B_BARRIER) == 0, 1156 ("Barrier request in delayed write %p", bp)); 1157 BUF_ASSERT_HELD(bp); 1158 1159 if (bp->b_flags & B_INVAL) { 1160 brelse(bp); 1161 return; 1162 } 1163 1164 /* 1165 * If we have too many dirty buffers, don't create any more. 1166 * If we are wildly over our limit, then force a complete 1167 * cleanup. Otherwise, just keep the situation from getting 1168 * out of control. Note that we have to avoid a recursive 1169 * disaster and not try to clean up after our own cleanup! 1170 */ 1171 vp = bp->b_vp; 1172 bo = bp->b_bufobj; 1173 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1174 td->td_pflags |= TDP_INBDFLUSH; 1175 BO_BDFLUSH(bo, bp); 1176 td->td_pflags &= ~TDP_INBDFLUSH; 1177 } else 1178 recursiveflushes++; 1179 1180 bdirty(bp); 1181 /* 1182 * Set B_CACHE, indicating that the buffer is fully valid. This is 1183 * true even of NFS now. 1184 */ 1185 bp->b_flags |= B_CACHE; 1186 1187 /* 1188 * This bmap keeps the system from needing to do the bmap later, 1189 * perhaps when the system is attempting to do a sync. Since it 1190 * is likely that the indirect block -- or whatever other datastructure 1191 * that the filesystem needs is still in memory now, it is a good 1192 * thing to do this. Note also, that if the pageout daemon is 1193 * requesting a sync -- there might not be enough memory to do 1194 * the bmap then... So, this is important to do. 1195 */ 1196 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1197 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1198 } 1199 1200 /* 1201 * Set the *dirty* buffer range based upon the VM system dirty 1202 * pages. 1203 * 1204 * Mark the buffer pages as clean. We need to do this here to 1205 * satisfy the vnode_pager and the pageout daemon, so that it 1206 * thinks that the pages have been "cleaned". Note that since 1207 * the pages are in a delayed write buffer -- the VFS layer 1208 * "will" see that the pages get written out on the next sync, 1209 * or perhaps the cluster will be completed. 1210 */ 1211 vfs_clean_pages_dirty_buf(bp); 1212 bqrelse(bp); 1213 1214 /* 1215 * Wakeup the buffer flushing daemon if we have a lot of dirty 1216 * buffers (midpoint between our recovery point and our stall 1217 * point). 1218 */ 1219 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1220 1221 /* 1222 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1223 * due to the softdep code. 1224 */ 1225 } 1226 1227 /* 1228 * bdirty: 1229 * 1230 * Turn buffer into delayed write request. We must clear BIO_READ and 1231 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1232 * itself to properly update it in the dirty/clean lists. We mark it 1233 * B_DONE to ensure that any asynchronization of the buffer properly 1234 * clears B_DONE ( else a panic will occur later ). 1235 * 1236 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1237 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1238 * should only be called if the buffer is known-good. 1239 * 1240 * Since the buffer is not on a queue, we do not update the numfreebuffers 1241 * count. 1242 * 1243 * The buffer must be on QUEUE_NONE. 1244 */ 1245 void 1246 bdirty(struct buf *bp) 1247 { 1248 1249 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1250 bp, bp->b_vp, bp->b_flags); 1251 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1252 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1253 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1254 BUF_ASSERT_HELD(bp); 1255 bp->b_flags &= ~(B_RELBUF); 1256 bp->b_iocmd = BIO_WRITE; 1257 1258 if ((bp->b_flags & B_DELWRI) == 0) { 1259 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1260 reassignbuf(bp); 1261 atomic_add_int(&numdirtybuffers, 1); 1262 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1263 } 1264 } 1265 1266 /* 1267 * bundirty: 1268 * 1269 * Clear B_DELWRI for buffer. 1270 * 1271 * Since the buffer is not on a queue, we do not update the numfreebuffers 1272 * count. 1273 * 1274 * The buffer must be on QUEUE_NONE. 1275 */ 1276 1277 void 1278 bundirty(struct buf *bp) 1279 { 1280 1281 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1282 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1283 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1284 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1285 BUF_ASSERT_HELD(bp); 1286 1287 if (bp->b_flags & B_DELWRI) { 1288 bp->b_flags &= ~B_DELWRI; 1289 reassignbuf(bp); 1290 atomic_subtract_int(&numdirtybuffers, 1); 1291 numdirtywakeup(lodirtybuffers); 1292 } 1293 /* 1294 * Since it is now being written, we can clear its deferred write flag. 1295 */ 1296 bp->b_flags &= ~B_DEFERRED; 1297 } 1298 1299 /* 1300 * bawrite: 1301 * 1302 * Asynchronous write. Start output on a buffer, but do not wait for 1303 * it to complete. The buffer is released when the output completes. 1304 * 1305 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1306 * B_INVAL buffers. Not us. 1307 */ 1308 void 1309 bawrite(struct buf *bp) 1310 { 1311 1312 bp->b_flags |= B_ASYNC; 1313 (void) bwrite(bp); 1314 } 1315 1316 /* 1317 * babarrierwrite: 1318 * 1319 * Asynchronous barrier write. Start output on a buffer, but do not 1320 * wait for it to complete. Place a write barrier after this write so 1321 * that this buffer and all buffers written before it are committed to 1322 * the disk before any buffers written after this write are committed 1323 * to the disk. The buffer is released when the output completes. 1324 */ 1325 void 1326 babarrierwrite(struct buf *bp) 1327 { 1328 1329 bp->b_flags |= B_ASYNC | B_BARRIER; 1330 (void) bwrite(bp); 1331 } 1332 1333 /* 1334 * bbarrierwrite: 1335 * 1336 * Synchronous barrier write. Start output on a buffer and wait for 1337 * it to complete. Place a write barrier after this write so that 1338 * this buffer and all buffers written before it are committed to 1339 * the disk before any buffers written after this write are committed 1340 * to the disk. The buffer is released when the output completes. 1341 */ 1342 int 1343 bbarrierwrite(struct buf *bp) 1344 { 1345 1346 bp->b_flags |= B_BARRIER; 1347 return (bwrite(bp)); 1348 } 1349 1350 /* 1351 * bwillwrite: 1352 * 1353 * Called prior to the locking of any vnodes when we are expecting to 1354 * write. We do not want to starve the buffer cache with too many 1355 * dirty buffers so we block here. By blocking prior to the locking 1356 * of any vnodes we attempt to avoid the situation where a locked vnode 1357 * prevents the various system daemons from flushing related buffers. 1358 */ 1359 1360 void 1361 bwillwrite(void) 1362 { 1363 1364 if (numdirtybuffers >= hidirtybuffers) { 1365 mtx_lock(&nblock); 1366 while (numdirtybuffers >= hidirtybuffers) { 1367 bd_wakeup(1); 1368 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1369 msleep(&needsbuffer, &nblock, 1370 (PRIBIO + 4), "flswai", 0); 1371 } 1372 mtx_unlock(&nblock); 1373 } 1374 } 1375 1376 /* 1377 * Return true if we have too many dirty buffers. 1378 */ 1379 int 1380 buf_dirty_count_severe(void) 1381 { 1382 1383 return(numdirtybuffers >= hidirtybuffers); 1384 } 1385 1386 static __noinline int 1387 buf_vm_page_count_severe(void) 1388 { 1389 1390 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1391 1392 return vm_page_count_severe(); 1393 } 1394 1395 /* 1396 * brelse: 1397 * 1398 * Release a busy buffer and, if requested, free its resources. The 1399 * buffer will be stashed in the appropriate bufqueue[] allowing it 1400 * to be accessed later as a cache entity or reused for other purposes. 1401 */ 1402 void 1403 brelse(struct buf *bp) 1404 { 1405 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1406 bp, bp->b_vp, bp->b_flags); 1407 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1408 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1409 1410 if (BUF_LOCKRECURSED(bp)) { 1411 /* 1412 * Do not process, in particular, do not handle the 1413 * B_INVAL/B_RELBUF and do not release to free list. 1414 */ 1415 BUF_UNLOCK(bp); 1416 return; 1417 } 1418 1419 if (bp->b_flags & B_MANAGED) { 1420 bqrelse(bp); 1421 return; 1422 } 1423 1424 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1425 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1426 /* 1427 * Failed write, redirty. Must clear BIO_ERROR to prevent 1428 * pages from being scrapped. If the error is anything 1429 * other than an I/O error (EIO), assume that retrying 1430 * is futile. 1431 */ 1432 bp->b_ioflags &= ~BIO_ERROR; 1433 bdirty(bp); 1434 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1435 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1436 /* 1437 * Either a failed I/O or we were asked to free or not 1438 * cache the buffer. 1439 */ 1440 bp->b_flags |= B_INVAL; 1441 if (!LIST_EMPTY(&bp->b_dep)) 1442 buf_deallocate(bp); 1443 if (bp->b_flags & B_DELWRI) { 1444 atomic_subtract_int(&numdirtybuffers, 1); 1445 numdirtywakeup(lodirtybuffers); 1446 } 1447 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1448 if ((bp->b_flags & B_VMIO) == 0) { 1449 if (bp->b_bufsize) 1450 allocbuf(bp, 0); 1451 if (bp->b_vp) 1452 brelvp(bp); 1453 } 1454 } 1455 1456 /* 1457 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1458 * is called with B_DELWRI set, the underlying pages may wind up 1459 * getting freed causing a previous write (bdwrite()) to get 'lost' 1460 * because pages associated with a B_DELWRI bp are marked clean. 1461 * 1462 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1463 * if B_DELWRI is set. 1464 * 1465 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1466 * on pages to return pages to the VM page queues. 1467 */ 1468 if (bp->b_flags & B_DELWRI) 1469 bp->b_flags &= ~B_RELBUF; 1470 else if (buf_vm_page_count_severe()) { 1471 /* 1472 * The locking of the BO_LOCK is not necessary since 1473 * BKGRDINPROG cannot be set while we hold the buf 1474 * lock, it can only be cleared if it is already 1475 * pending. 1476 */ 1477 if (bp->b_vp) { 1478 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1479 bp->b_flags |= B_RELBUF; 1480 } else 1481 bp->b_flags |= B_RELBUF; 1482 } 1483 1484 /* 1485 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1486 * constituted, not even NFS buffers now. Two flags effect this. If 1487 * B_INVAL, the struct buf is invalidated but the VM object is kept 1488 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1489 * 1490 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1491 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1492 * buffer is also B_INVAL because it hits the re-dirtying code above. 1493 * 1494 * Normally we can do this whether a buffer is B_DELWRI or not. If 1495 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1496 * the commit state and we cannot afford to lose the buffer. If the 1497 * buffer has a background write in progress, we need to keep it 1498 * around to prevent it from being reconstituted and starting a second 1499 * background write. 1500 */ 1501 if ((bp->b_flags & B_VMIO) 1502 && !(bp->b_vp->v_mount != NULL && 1503 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1504 !vn_isdisk(bp->b_vp, NULL) && 1505 (bp->b_flags & B_DELWRI)) 1506 ) { 1507 1508 int i, j, resid; 1509 vm_page_t m; 1510 off_t foff; 1511 vm_pindex_t poff; 1512 vm_object_t obj; 1513 1514 obj = bp->b_bufobj->bo_object; 1515 1516 /* 1517 * Get the base offset and length of the buffer. Note that 1518 * in the VMIO case if the buffer block size is not 1519 * page-aligned then b_data pointer may not be page-aligned. 1520 * But our b_pages[] array *IS* page aligned. 1521 * 1522 * block sizes less then DEV_BSIZE (usually 512) are not 1523 * supported due to the page granularity bits (m->valid, 1524 * m->dirty, etc...). 1525 * 1526 * See man buf(9) for more information 1527 */ 1528 resid = bp->b_bufsize; 1529 foff = bp->b_offset; 1530 VM_OBJECT_WLOCK(obj); 1531 for (i = 0; i < bp->b_npages; i++) { 1532 int had_bogus = 0; 1533 1534 m = bp->b_pages[i]; 1535 1536 /* 1537 * If we hit a bogus page, fixup *all* the bogus pages 1538 * now. 1539 */ 1540 if (m == bogus_page) { 1541 poff = OFF_TO_IDX(bp->b_offset); 1542 had_bogus = 1; 1543 1544 for (j = i; j < bp->b_npages; j++) { 1545 vm_page_t mtmp; 1546 mtmp = bp->b_pages[j]; 1547 if (mtmp == bogus_page) { 1548 mtmp = vm_page_lookup(obj, poff + j); 1549 if (!mtmp) { 1550 panic("brelse: page missing\n"); 1551 } 1552 bp->b_pages[j] = mtmp; 1553 } 1554 } 1555 1556 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1557 BUF_CHECK_MAPPED(bp); 1558 pmap_qenter( 1559 trunc_page((vm_offset_t)bp->b_data), 1560 bp->b_pages, bp->b_npages); 1561 } 1562 m = bp->b_pages[i]; 1563 } 1564 if ((bp->b_flags & B_NOCACHE) || 1565 (bp->b_ioflags & BIO_ERROR && 1566 bp->b_iocmd == BIO_READ)) { 1567 int poffset = foff & PAGE_MASK; 1568 int presid = resid > (PAGE_SIZE - poffset) ? 1569 (PAGE_SIZE - poffset) : resid; 1570 1571 KASSERT(presid >= 0, ("brelse: extra page")); 1572 vm_page_set_invalid(m, poffset, presid); 1573 if (had_bogus) 1574 printf("avoided corruption bug in bogus_page/brelse code\n"); 1575 } 1576 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1577 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1578 } 1579 VM_OBJECT_WUNLOCK(obj); 1580 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1581 vfs_vmio_release(bp); 1582 1583 } else if (bp->b_flags & B_VMIO) { 1584 1585 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1586 vfs_vmio_release(bp); 1587 } 1588 1589 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1590 if (bp->b_bufsize != 0) 1591 allocbuf(bp, 0); 1592 if (bp->b_vp != NULL) 1593 brelvp(bp); 1594 } 1595 1596 /* enqueue */ 1597 mtx_lock(&bqlock); 1598 /* Handle delayed bremfree() processing. */ 1599 if (bp->b_flags & B_REMFREE) { 1600 struct bufobj *bo; 1601 1602 bo = bp->b_bufobj; 1603 if (bo != NULL) 1604 BO_LOCK(bo); 1605 bremfreel(bp); 1606 if (bo != NULL) 1607 BO_UNLOCK(bo); 1608 } 1609 if (bp->b_qindex != QUEUE_NONE) 1610 panic("brelse: free buffer onto another queue???"); 1611 1612 /* 1613 * If the buffer has junk contents signal it and eventually 1614 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1615 * doesn't find it. 1616 */ 1617 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1618 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1619 bp->b_flags |= B_INVAL; 1620 if (bp->b_flags & B_INVAL) { 1621 if (bp->b_flags & B_DELWRI) 1622 bundirty(bp); 1623 if (bp->b_vp) 1624 brelvp(bp); 1625 } 1626 1627 /* buffers with no memory */ 1628 if (bp->b_bufsize == 0) { 1629 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1630 if (bp->b_vflags & BV_BKGRDINPROG) 1631 panic("losing buffer 1"); 1632 if (bp->b_kvasize) { 1633 bp->b_qindex = QUEUE_EMPTYKVA; 1634 } else { 1635 bp->b_qindex = QUEUE_EMPTY; 1636 } 1637 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1638 /* buffers with junk contents */ 1639 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1640 (bp->b_ioflags & BIO_ERROR)) { 1641 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1642 if (bp->b_vflags & BV_BKGRDINPROG) 1643 panic("losing buffer 2"); 1644 bp->b_qindex = QUEUE_CLEAN; 1645 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1646 /* remaining buffers */ 1647 } else { 1648 if (bp->b_flags & B_DELWRI) 1649 bp->b_qindex = QUEUE_DIRTY; 1650 else 1651 bp->b_qindex = QUEUE_CLEAN; 1652 if (bp->b_flags & B_AGE) { 1653 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, 1654 b_freelist); 1655 } else { 1656 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, 1657 b_freelist); 1658 } 1659 } 1660 #ifdef INVARIANTS 1661 bq_len[bp->b_qindex]++; 1662 #endif 1663 mtx_unlock(&bqlock); 1664 1665 /* 1666 * Fixup numfreebuffers count. The bp is on an appropriate queue 1667 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1668 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1669 * if B_INVAL is set ). 1670 */ 1671 1672 if (!(bp->b_flags & B_DELWRI)) { 1673 struct bufobj *bo; 1674 1675 bo = bp->b_bufobj; 1676 if (bo != NULL) 1677 BO_LOCK(bo); 1678 bufcountwakeup(bp); 1679 if (bo != NULL) 1680 BO_UNLOCK(bo); 1681 } 1682 1683 /* 1684 * Something we can maybe free or reuse 1685 */ 1686 if (bp->b_bufsize || bp->b_kvasize) 1687 bufspacewakeup(); 1688 1689 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1690 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1691 panic("brelse: not dirty"); 1692 /* unlock */ 1693 BUF_UNLOCK(bp); 1694 } 1695 1696 /* 1697 * Release a buffer back to the appropriate queue but do not try to free 1698 * it. The buffer is expected to be used again soon. 1699 * 1700 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1701 * biodone() to requeue an async I/O on completion. It is also used when 1702 * known good buffers need to be requeued but we think we may need the data 1703 * again soon. 1704 * 1705 * XXX we should be able to leave the B_RELBUF hint set on completion. 1706 */ 1707 void 1708 bqrelse(struct buf *bp) 1709 { 1710 struct bufobj *bo; 1711 1712 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1713 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1714 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1715 1716 if (BUF_LOCKRECURSED(bp)) { 1717 /* do not release to free list */ 1718 BUF_UNLOCK(bp); 1719 return; 1720 } 1721 1722 bo = bp->b_bufobj; 1723 if (bp->b_flags & B_MANAGED) { 1724 if (bp->b_flags & B_REMFREE) { 1725 mtx_lock(&bqlock); 1726 if (bo != NULL) 1727 BO_LOCK(bo); 1728 bremfreel(bp); 1729 if (bo != NULL) 1730 BO_UNLOCK(bo); 1731 mtx_unlock(&bqlock); 1732 } 1733 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1734 BUF_UNLOCK(bp); 1735 return; 1736 } 1737 1738 mtx_lock(&bqlock); 1739 /* Handle delayed bremfree() processing. */ 1740 if (bp->b_flags & B_REMFREE) { 1741 if (bo != NULL) 1742 BO_LOCK(bo); 1743 bremfreel(bp); 1744 if (bo != NULL) 1745 BO_UNLOCK(bo); 1746 } 1747 if (bp->b_qindex != QUEUE_NONE) 1748 panic("bqrelse: free buffer onto another queue???"); 1749 /* buffers with stale but valid contents */ 1750 if (bp->b_flags & B_DELWRI) { 1751 bp->b_qindex = QUEUE_DIRTY; 1752 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1753 #ifdef INVARIANTS 1754 bq_len[bp->b_qindex]++; 1755 #endif 1756 } else { 1757 /* 1758 * The locking of the BO_LOCK for checking of the 1759 * BV_BKGRDINPROG is not necessary since the 1760 * BV_BKGRDINPROG cannot be set while we hold the buf 1761 * lock, it can only be cleared if it is already 1762 * pending. 1763 */ 1764 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1765 bp->b_qindex = QUEUE_CLEAN; 1766 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1767 b_freelist); 1768 #ifdef INVARIANTS 1769 bq_len[QUEUE_CLEAN]++; 1770 #endif 1771 } else { 1772 /* 1773 * We are too low on memory, we have to try to free 1774 * the buffer (most importantly: the wired pages 1775 * making up its backing store) *now*. 1776 */ 1777 mtx_unlock(&bqlock); 1778 brelse(bp); 1779 return; 1780 } 1781 } 1782 mtx_unlock(&bqlock); 1783 1784 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) { 1785 if (bo != NULL) 1786 BO_LOCK(bo); 1787 bufcountwakeup(bp); 1788 if (bo != NULL) 1789 BO_UNLOCK(bo); 1790 } 1791 1792 /* 1793 * Something we can maybe free or reuse. 1794 */ 1795 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1796 bufspacewakeup(); 1797 1798 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1799 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1800 panic("bqrelse: not dirty"); 1801 /* unlock */ 1802 BUF_UNLOCK(bp); 1803 } 1804 1805 /* Give pages used by the bp back to the VM system (where possible) */ 1806 static void 1807 vfs_vmio_release(struct buf *bp) 1808 { 1809 int i; 1810 vm_page_t m; 1811 1812 if ((bp->b_flags & B_UNMAPPED) == 0) { 1813 BUF_CHECK_MAPPED(bp); 1814 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1815 } else 1816 BUF_CHECK_UNMAPPED(bp); 1817 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 1818 for (i = 0; i < bp->b_npages; i++) { 1819 m = bp->b_pages[i]; 1820 bp->b_pages[i] = NULL; 1821 /* 1822 * In order to keep page LRU ordering consistent, put 1823 * everything on the inactive queue. 1824 */ 1825 vm_page_lock(m); 1826 vm_page_unwire(m, 0); 1827 /* 1828 * We don't mess with busy pages, it is 1829 * the responsibility of the process that 1830 * busied the pages to deal with them. 1831 */ 1832 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 && 1833 m->wire_count == 0) { 1834 /* 1835 * Might as well free the page if we can and it has 1836 * no valid data. We also free the page if the 1837 * buffer was used for direct I/O 1838 */ 1839 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1840 vm_page_free(m); 1841 } else if (bp->b_flags & B_DIRECT) { 1842 vm_page_try_to_free(m); 1843 } else if (buf_vm_page_count_severe()) { 1844 vm_page_try_to_cache(m); 1845 } 1846 } 1847 vm_page_unlock(m); 1848 } 1849 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 1850 1851 if (bp->b_bufsize) { 1852 bufspacewakeup(); 1853 bp->b_bufsize = 0; 1854 } 1855 bp->b_npages = 0; 1856 bp->b_flags &= ~B_VMIO; 1857 if (bp->b_vp) 1858 brelvp(bp); 1859 } 1860 1861 /* 1862 * Check to see if a block at a particular lbn is available for a clustered 1863 * write. 1864 */ 1865 static int 1866 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1867 { 1868 struct buf *bpa; 1869 int match; 1870 1871 match = 0; 1872 1873 /* If the buf isn't in core skip it */ 1874 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1875 return (0); 1876 1877 /* If the buf is busy we don't want to wait for it */ 1878 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1879 return (0); 1880 1881 /* Only cluster with valid clusterable delayed write buffers */ 1882 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1883 (B_DELWRI | B_CLUSTEROK)) 1884 goto done; 1885 1886 if (bpa->b_bufsize != size) 1887 goto done; 1888 1889 /* 1890 * Check to see if it is in the expected place on disk and that the 1891 * block has been mapped. 1892 */ 1893 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1894 match = 1; 1895 done: 1896 BUF_UNLOCK(bpa); 1897 return (match); 1898 } 1899 1900 /* 1901 * vfs_bio_awrite: 1902 * 1903 * Implement clustered async writes for clearing out B_DELWRI buffers. 1904 * This is much better then the old way of writing only one buffer at 1905 * a time. Note that we may not be presented with the buffers in the 1906 * correct order, so we search for the cluster in both directions. 1907 */ 1908 int 1909 vfs_bio_awrite(struct buf *bp) 1910 { 1911 struct bufobj *bo; 1912 int i; 1913 int j; 1914 daddr_t lblkno = bp->b_lblkno; 1915 struct vnode *vp = bp->b_vp; 1916 int ncl; 1917 int nwritten; 1918 int size; 1919 int maxcl; 1920 int gbflags; 1921 1922 bo = &vp->v_bufobj; 1923 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1924 /* 1925 * right now we support clustered writing only to regular files. If 1926 * we find a clusterable block we could be in the middle of a cluster 1927 * rather then at the beginning. 1928 */ 1929 if ((vp->v_type == VREG) && 1930 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1931 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1932 1933 size = vp->v_mount->mnt_stat.f_iosize; 1934 maxcl = MAXPHYS / size; 1935 1936 BO_LOCK(bo); 1937 for (i = 1; i < maxcl; i++) 1938 if (vfs_bio_clcheck(vp, size, lblkno + i, 1939 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1940 break; 1941 1942 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1943 if (vfs_bio_clcheck(vp, size, lblkno - j, 1944 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1945 break; 1946 BO_UNLOCK(bo); 1947 --j; 1948 ncl = i + j; 1949 /* 1950 * this is a possible cluster write 1951 */ 1952 if (ncl != 1) { 1953 BUF_UNLOCK(bp); 1954 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 1955 gbflags); 1956 return (nwritten); 1957 } 1958 } 1959 bremfree(bp); 1960 bp->b_flags |= B_ASYNC; 1961 /* 1962 * default (old) behavior, writing out only one block 1963 * 1964 * XXX returns b_bufsize instead of b_bcount for nwritten? 1965 */ 1966 nwritten = bp->b_bufsize; 1967 (void) bwrite(bp); 1968 1969 return (nwritten); 1970 } 1971 1972 static void 1973 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 1974 { 1975 1976 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 1977 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 1978 if ((gbflags & GB_UNMAPPED) == 0) { 1979 bp->b_kvabase = (caddr_t)addr; 1980 } else if ((gbflags & GB_KVAALLOC) != 0) { 1981 KASSERT((gbflags & GB_UNMAPPED) != 0, 1982 ("GB_KVAALLOC without GB_UNMAPPED")); 1983 bp->b_kvaalloc = (caddr_t)addr; 1984 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 1985 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 1986 } 1987 bp->b_kvasize = maxsize; 1988 } 1989 1990 /* 1991 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 1992 * needed. 1993 */ 1994 static int 1995 allocbufkva(struct buf *bp, int maxsize, int gbflags) 1996 { 1997 vm_offset_t addr; 1998 int rv; 1999 2000 bfreekva(bp); 2001 addr = 0; 2002 2003 vm_map_lock(buffer_map); 2004 if (vm_map_findspace(buffer_map, vm_map_min(buffer_map), maxsize, 2005 &addr)) { 2006 vm_map_unlock(buffer_map); 2007 /* 2008 * Buffer map is too fragmented. Request the caller 2009 * to defragment the map. 2010 */ 2011 atomic_add_int(&bufdefragcnt, 1); 2012 return (1); 2013 } 2014 rv = vm_map_insert(buffer_map, NULL, 0, addr, addr + maxsize, 2015 VM_PROT_RW, VM_PROT_RW, MAP_NOFAULT); 2016 KASSERT(rv == KERN_SUCCESS, ("vm_map_insert(buffer_map) rv %d", rv)); 2017 vm_map_unlock(buffer_map); 2018 setbufkva(bp, addr, maxsize, gbflags); 2019 atomic_add_long(&bufspace, bp->b_kvasize); 2020 return (0); 2021 } 2022 2023 /* 2024 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2025 * locked vnode is supplied. 2026 */ 2027 static void 2028 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2029 int defrag) 2030 { 2031 struct thread *td; 2032 char *waitmsg; 2033 int fl, flags, norunbuf; 2034 2035 mtx_assert(&bqlock, MA_OWNED); 2036 2037 if (defrag) { 2038 flags = VFS_BIO_NEED_BUFSPACE; 2039 waitmsg = "nbufkv"; 2040 } else if (bufspace >= hibufspace) { 2041 waitmsg = "nbufbs"; 2042 flags = VFS_BIO_NEED_BUFSPACE; 2043 } else { 2044 waitmsg = "newbuf"; 2045 flags = VFS_BIO_NEED_ANY; 2046 } 2047 mtx_lock(&nblock); 2048 needsbuffer |= flags; 2049 mtx_unlock(&nblock); 2050 mtx_unlock(&bqlock); 2051 2052 bd_speedup(); /* heeeelp */ 2053 if ((gbflags & GB_NOWAIT_BD) != 0) 2054 return; 2055 2056 td = curthread; 2057 mtx_lock(&nblock); 2058 while (needsbuffer & flags) { 2059 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2060 mtx_unlock(&nblock); 2061 /* 2062 * getblk() is called with a vnode locked, and 2063 * some majority of the dirty buffers may as 2064 * well belong to the vnode. Flushing the 2065 * buffers there would make a progress that 2066 * cannot be achieved by the buf_daemon, that 2067 * cannot lock the vnode. 2068 */ 2069 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2070 (td->td_pflags & TDP_NORUNNINGBUF); 2071 /* play bufdaemon */ 2072 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2073 fl = buf_do_flush(vp); 2074 td->td_pflags &= norunbuf; 2075 mtx_lock(&nblock); 2076 if (fl != 0) 2077 continue; 2078 if ((needsbuffer & flags) == 0) 2079 break; 2080 } 2081 if (msleep(&needsbuffer, &nblock, (PRIBIO + 4) | slpflag, 2082 waitmsg, slptimeo)) 2083 break; 2084 } 2085 mtx_unlock(&nblock); 2086 } 2087 2088 static void 2089 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2090 { 2091 2092 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2093 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2094 bp->b_kvasize, bp->b_bufsize, qindex); 2095 mtx_assert(&bqlock, MA_NOTOWNED); 2096 2097 /* 2098 * Note: we no longer distinguish between VMIO and non-VMIO 2099 * buffers. 2100 */ 2101 KASSERT((bp->b_flags & B_DELWRI) == 0, 2102 ("delwri buffer %p found in queue %d", bp, qindex)); 2103 2104 if (qindex == QUEUE_CLEAN) { 2105 if (bp->b_flags & B_VMIO) { 2106 bp->b_flags &= ~B_ASYNC; 2107 vfs_vmio_release(bp); 2108 } 2109 if (bp->b_vp != NULL) 2110 brelvp(bp); 2111 } 2112 2113 /* 2114 * Get the rest of the buffer freed up. b_kva* is still valid 2115 * after this operation. 2116 */ 2117 2118 if (bp->b_rcred != NOCRED) { 2119 crfree(bp->b_rcred); 2120 bp->b_rcred = NOCRED; 2121 } 2122 if (bp->b_wcred != NOCRED) { 2123 crfree(bp->b_wcred); 2124 bp->b_wcred = NOCRED; 2125 } 2126 if (!LIST_EMPTY(&bp->b_dep)) 2127 buf_deallocate(bp); 2128 if (bp->b_vflags & BV_BKGRDINPROG) 2129 panic("losing buffer 3"); 2130 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2131 bp, bp->b_vp, qindex)); 2132 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2133 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2134 2135 if (bp->b_bufsize) 2136 allocbuf(bp, 0); 2137 2138 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2139 bp->b_ioflags = 0; 2140 bp->b_xflags = 0; 2141 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 2142 ("buf %p still counted as free?", bp)); 2143 bp->b_vflags = 0; 2144 bp->b_vp = NULL; 2145 bp->b_blkno = bp->b_lblkno = 0; 2146 bp->b_offset = NOOFFSET; 2147 bp->b_iodone = 0; 2148 bp->b_error = 0; 2149 bp->b_resid = 0; 2150 bp->b_bcount = 0; 2151 bp->b_npages = 0; 2152 bp->b_dirtyoff = bp->b_dirtyend = 0; 2153 bp->b_bufobj = NULL; 2154 bp->b_pin_count = 0; 2155 bp->b_fsprivate1 = NULL; 2156 bp->b_fsprivate2 = NULL; 2157 bp->b_fsprivate3 = NULL; 2158 2159 LIST_INIT(&bp->b_dep); 2160 } 2161 2162 static int flushingbufs; 2163 2164 static struct buf * 2165 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2166 { 2167 struct buf *bp, *nbp; 2168 int nqindex, qindex, pass; 2169 2170 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2171 2172 pass = 1; 2173 restart: 2174 atomic_add_int(&getnewbufrestarts, 1); 2175 2176 /* 2177 * Setup for scan. If we do not have enough free buffers, 2178 * we setup a degenerate case that immediately fails. Note 2179 * that if we are specially marked process, we are allowed to 2180 * dip into our reserves. 2181 * 2182 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2183 * for the allocation of the mapped buffer. For unmapped, the 2184 * easiest is to start with EMPTY outright. 2185 * 2186 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2187 * However, there are a number of cases (defragging, reusing, ...) 2188 * where we cannot backup. 2189 */ 2190 nbp = NULL; 2191 mtx_lock(&bqlock); 2192 if (!defrag && unmapped) { 2193 nqindex = QUEUE_EMPTY; 2194 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2195 } 2196 if (nbp == NULL) { 2197 nqindex = QUEUE_EMPTYKVA; 2198 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2199 } 2200 2201 /* 2202 * If no EMPTYKVA buffers and we are either defragging or 2203 * reusing, locate a CLEAN buffer to free or reuse. If 2204 * bufspace useage is low skip this step so we can allocate a 2205 * new buffer. 2206 */ 2207 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2208 nqindex = QUEUE_CLEAN; 2209 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2210 } 2211 2212 /* 2213 * If we could not find or were not allowed to reuse a CLEAN 2214 * buffer, check to see if it is ok to use an EMPTY buffer. 2215 * We can only use an EMPTY buffer if allocating its KVA would 2216 * not otherwise run us out of buffer space. No KVA is needed 2217 * for the unmapped allocation. 2218 */ 2219 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2220 metadata)) { 2221 nqindex = QUEUE_EMPTY; 2222 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2223 } 2224 2225 /* 2226 * All available buffers might be clean, retry ignoring the 2227 * lobufspace as the last resort. 2228 */ 2229 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2230 nqindex = QUEUE_CLEAN; 2231 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2232 } 2233 2234 /* 2235 * Run scan, possibly freeing data and/or kva mappings on the fly 2236 * depending. 2237 */ 2238 while ((bp = nbp) != NULL) { 2239 qindex = nqindex; 2240 2241 /* 2242 * Calculate next bp (we can only use it if we do not 2243 * block or do other fancy things). 2244 */ 2245 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2246 switch (qindex) { 2247 case QUEUE_EMPTY: 2248 nqindex = QUEUE_EMPTYKVA; 2249 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2250 if (nbp != NULL) 2251 break; 2252 /* FALLTHROUGH */ 2253 case QUEUE_EMPTYKVA: 2254 nqindex = QUEUE_CLEAN; 2255 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2256 if (nbp != NULL) 2257 break; 2258 /* FALLTHROUGH */ 2259 case QUEUE_CLEAN: 2260 if (metadata && pass == 1) { 2261 pass = 2; 2262 nqindex = QUEUE_EMPTY; 2263 nbp = TAILQ_FIRST( 2264 &bufqueues[QUEUE_EMPTY]); 2265 } 2266 /* 2267 * nbp is NULL. 2268 */ 2269 break; 2270 } 2271 } 2272 /* 2273 * If we are defragging then we need a buffer with 2274 * b_kvasize != 0. XXX this situation should no longer 2275 * occur, if defrag is non-zero the buffer's b_kvasize 2276 * should also be non-zero at this point. XXX 2277 */ 2278 if (defrag && bp->b_kvasize == 0) { 2279 printf("Warning: defrag empty buffer %p\n", bp); 2280 continue; 2281 } 2282 2283 /* 2284 * Start freeing the bp. This is somewhat involved. nbp 2285 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2286 */ 2287 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2288 continue; 2289 if (bp->b_vp) { 2290 BO_LOCK(bp->b_bufobj); 2291 if (bp->b_vflags & BV_BKGRDINPROG) { 2292 BO_UNLOCK(bp->b_bufobj); 2293 BUF_UNLOCK(bp); 2294 continue; 2295 } 2296 BO_UNLOCK(bp->b_bufobj); 2297 } 2298 2299 KASSERT(bp->b_qindex == qindex, 2300 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2301 2302 if (bp->b_bufobj != NULL) 2303 BO_LOCK(bp->b_bufobj); 2304 bremfreel(bp); 2305 if (bp->b_bufobj != NULL) 2306 BO_UNLOCK(bp->b_bufobj); 2307 mtx_unlock(&bqlock); 2308 /* 2309 * NOTE: nbp is now entirely invalid. We can only restart 2310 * the scan from this point on. 2311 */ 2312 2313 getnewbuf_reuse_bp(bp, qindex); 2314 mtx_assert(&bqlock, MA_NOTOWNED); 2315 2316 /* 2317 * If we are defragging then free the buffer. 2318 */ 2319 if (defrag) { 2320 bp->b_flags |= B_INVAL; 2321 bfreekva(bp); 2322 brelse(bp); 2323 defrag = 0; 2324 goto restart; 2325 } 2326 2327 /* 2328 * Notify any waiters for the buffer lock about 2329 * identity change by freeing the buffer. 2330 */ 2331 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2332 bp->b_flags |= B_INVAL; 2333 bfreekva(bp); 2334 brelse(bp); 2335 goto restart; 2336 } 2337 2338 if (metadata) 2339 break; 2340 2341 /* 2342 * If we are overcomitted then recover the buffer and its 2343 * KVM space. This occurs in rare situations when multiple 2344 * processes are blocked in getnewbuf() or allocbuf(). 2345 */ 2346 if (bufspace >= hibufspace) 2347 flushingbufs = 1; 2348 if (flushingbufs && bp->b_kvasize != 0) { 2349 bp->b_flags |= B_INVAL; 2350 bfreekva(bp); 2351 brelse(bp); 2352 goto restart; 2353 } 2354 if (bufspace < lobufspace) 2355 flushingbufs = 0; 2356 break; 2357 } 2358 return (bp); 2359 } 2360 2361 /* 2362 * getnewbuf: 2363 * 2364 * Find and initialize a new buffer header, freeing up existing buffers 2365 * in the bufqueues as necessary. The new buffer is returned locked. 2366 * 2367 * Important: B_INVAL is not set. If the caller wishes to throw the 2368 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2369 * 2370 * We block if: 2371 * We have insufficient buffer headers 2372 * We have insufficient buffer space 2373 * buffer_map is too fragmented ( space reservation fails ) 2374 * If we have to flush dirty buffers ( but we try to avoid this ) 2375 * 2376 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 2377 * Instead we ask the buf daemon to do it for us. We attempt to 2378 * avoid piecemeal wakeups of the pageout daemon. 2379 */ 2380 static struct buf * 2381 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2382 int gbflags) 2383 { 2384 struct buf *bp; 2385 int defrag, metadata; 2386 2387 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2388 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2389 if (!unmapped_buf_allowed) 2390 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2391 2392 defrag = 0; 2393 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2394 vp->v_type == VCHR) 2395 metadata = 1; 2396 else 2397 metadata = 0; 2398 /* 2399 * We can't afford to block since we might be holding a vnode lock, 2400 * which may prevent system daemons from running. We deal with 2401 * low-memory situations by proactively returning memory and running 2402 * async I/O rather then sync I/O. 2403 */ 2404 atomic_add_int(&getnewbufcalls, 1); 2405 atomic_subtract_int(&getnewbufrestarts, 1); 2406 restart: 2407 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2408 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2409 if (bp != NULL) 2410 defrag = 0; 2411 2412 /* 2413 * If we exhausted our list, sleep as appropriate. We may have to 2414 * wakeup various daemons and write out some dirty buffers. 2415 * 2416 * Generally we are sleeping due to insufficient buffer space. 2417 */ 2418 if (bp == NULL) { 2419 mtx_assert(&bqlock, MA_OWNED); 2420 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2421 mtx_assert(&bqlock, MA_NOTOWNED); 2422 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2423 mtx_assert(&bqlock, MA_NOTOWNED); 2424 2425 bfreekva(bp); 2426 bp->b_flags |= B_UNMAPPED; 2427 bp->b_kvabase = bp->b_data = unmapped_buf; 2428 bp->b_kvasize = maxsize; 2429 atomic_add_long(&bufspace, bp->b_kvasize); 2430 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2431 atomic_add_int(&bufreusecnt, 1); 2432 } else { 2433 mtx_assert(&bqlock, MA_NOTOWNED); 2434 2435 /* 2436 * We finally have a valid bp. We aren't quite out of the 2437 * woods, we still have to reserve kva space. In order 2438 * to keep fragmentation sane we only allocate kva in 2439 * BKVASIZE chunks. 2440 */ 2441 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2442 2443 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2444 B_KVAALLOC)) == B_UNMAPPED) { 2445 if (allocbufkva(bp, maxsize, gbflags)) { 2446 defrag = 1; 2447 bp->b_flags |= B_INVAL; 2448 brelse(bp); 2449 goto restart; 2450 } 2451 atomic_add_int(&bufreusecnt, 1); 2452 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2453 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2454 /* 2455 * If the reused buffer has KVA allocated, 2456 * reassign b_kvaalloc to b_kvabase. 2457 */ 2458 bp->b_kvabase = bp->b_kvaalloc; 2459 bp->b_flags &= ~B_KVAALLOC; 2460 atomic_subtract_long(&unmapped_bufspace, 2461 bp->b_kvasize); 2462 atomic_add_int(&bufreusecnt, 1); 2463 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2464 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2465 GB_KVAALLOC)) { 2466 /* 2467 * The case of reused buffer already have KVA 2468 * mapped, but the request is for unmapped 2469 * buffer with KVA allocated. 2470 */ 2471 bp->b_kvaalloc = bp->b_kvabase; 2472 bp->b_data = bp->b_kvabase = unmapped_buf; 2473 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2474 atomic_add_long(&unmapped_bufspace, 2475 bp->b_kvasize); 2476 atomic_add_int(&bufreusecnt, 1); 2477 } 2478 if ((gbflags & GB_UNMAPPED) == 0) { 2479 bp->b_saveaddr = bp->b_kvabase; 2480 bp->b_data = bp->b_saveaddr; 2481 bp->b_flags &= ~B_UNMAPPED; 2482 BUF_CHECK_MAPPED(bp); 2483 } 2484 } 2485 return (bp); 2486 } 2487 2488 /* 2489 * buf_daemon: 2490 * 2491 * buffer flushing daemon. Buffers are normally flushed by the 2492 * update daemon but if it cannot keep up this process starts to 2493 * take the load in an attempt to prevent getnewbuf() from blocking. 2494 */ 2495 2496 static struct kproc_desc buf_kp = { 2497 "bufdaemon", 2498 buf_daemon, 2499 &bufdaemonproc 2500 }; 2501 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2502 2503 static int 2504 buf_do_flush(struct vnode *vp) 2505 { 2506 int flushed; 2507 2508 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2509 if (flushed == 0) { 2510 /* 2511 * Could not find any buffers without rollback 2512 * dependencies, so just write the first one 2513 * in the hopes of eventually making progress. 2514 */ 2515 flushbufqueues(vp, QUEUE_DIRTY, 1); 2516 } 2517 return (flushed); 2518 } 2519 2520 static void 2521 buf_daemon() 2522 { 2523 int lodirtysave; 2524 2525 /* 2526 * This process needs to be suspended prior to shutdown sync. 2527 */ 2528 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2529 SHUTDOWN_PRI_LAST); 2530 2531 /* 2532 * This process is allowed to take the buffer cache to the limit 2533 */ 2534 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2535 mtx_lock(&bdlock); 2536 for (;;) { 2537 bd_request = 0; 2538 mtx_unlock(&bdlock); 2539 2540 kproc_suspend_check(bufdaemonproc); 2541 lodirtysave = lodirtybuffers; 2542 if (bd_speedupreq) { 2543 lodirtybuffers = numdirtybuffers / 2; 2544 bd_speedupreq = 0; 2545 } 2546 /* 2547 * Do the flush. Limit the amount of in-transit I/O we 2548 * allow to build up, otherwise we would completely saturate 2549 * the I/O system. Wakeup any waiting processes before we 2550 * normally would so they can run in parallel with our drain. 2551 */ 2552 while (numdirtybuffers > lodirtybuffers) { 2553 if (buf_do_flush(NULL) == 0) 2554 break; 2555 kern_yield(PRI_USER); 2556 } 2557 lodirtybuffers = lodirtysave; 2558 2559 /* 2560 * Only clear bd_request if we have reached our low water 2561 * mark. The buf_daemon normally waits 1 second and 2562 * then incrementally flushes any dirty buffers that have 2563 * built up, within reason. 2564 * 2565 * If we were unable to hit our low water mark and couldn't 2566 * find any flushable buffers, we sleep half a second. 2567 * Otherwise we loop immediately. 2568 */ 2569 mtx_lock(&bdlock); 2570 if (numdirtybuffers <= lodirtybuffers) { 2571 /* 2572 * We reached our low water mark, reset the 2573 * request and sleep until we are needed again. 2574 * The sleep is just so the suspend code works. 2575 */ 2576 bd_request = 0; 2577 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2578 } else { 2579 /* 2580 * We couldn't find any flushable dirty buffers but 2581 * still have too many dirty buffers, we 2582 * have to sleep and try again. (rare) 2583 */ 2584 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2585 } 2586 } 2587 } 2588 2589 /* 2590 * flushbufqueues: 2591 * 2592 * Try to flush a buffer in the dirty queue. We must be careful to 2593 * free up B_INVAL buffers instead of write them, which NFS is 2594 * particularly sensitive to. 2595 */ 2596 static int flushwithdeps = 0; 2597 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2598 0, "Number of buffers flushed with dependecies that require rollbacks"); 2599 2600 static int 2601 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2602 { 2603 struct buf *sentinel; 2604 struct vnode *vp; 2605 struct mount *mp; 2606 struct buf *bp; 2607 int hasdeps; 2608 int flushed; 2609 int target; 2610 2611 if (lvp == NULL) { 2612 target = numdirtybuffers - lodirtybuffers; 2613 if (flushdeps && target > 2) 2614 target /= 2; 2615 } else 2616 target = flushbufqtarget; 2617 flushed = 0; 2618 bp = NULL; 2619 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2620 sentinel->b_qindex = QUEUE_SENTINEL; 2621 mtx_lock(&bqlock); 2622 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2623 while (flushed != target) { 2624 bp = TAILQ_NEXT(sentinel, b_freelist); 2625 if (bp != NULL) { 2626 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2627 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2628 b_freelist); 2629 } else 2630 break; 2631 /* 2632 * Skip sentinels inserted by other invocations of the 2633 * flushbufqueues(), taking care to not reorder them. 2634 */ 2635 if (bp->b_qindex == QUEUE_SENTINEL) 2636 continue; 2637 /* 2638 * Only flush the buffers that belong to the 2639 * vnode locked by the curthread. 2640 */ 2641 if (lvp != NULL && bp->b_vp != lvp) 2642 continue; 2643 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2644 continue; 2645 if (bp->b_pin_count > 0) { 2646 BUF_UNLOCK(bp); 2647 continue; 2648 } 2649 BO_LOCK(bp->b_bufobj); 2650 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2651 (bp->b_flags & B_DELWRI) == 0) { 2652 BO_UNLOCK(bp->b_bufobj); 2653 BUF_UNLOCK(bp); 2654 continue; 2655 } 2656 BO_UNLOCK(bp->b_bufobj); 2657 if (bp->b_flags & B_INVAL) { 2658 bremfreel(bp); 2659 mtx_unlock(&bqlock); 2660 brelse(bp); 2661 flushed++; 2662 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2663 mtx_lock(&bqlock); 2664 continue; 2665 } 2666 2667 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2668 if (flushdeps == 0) { 2669 BUF_UNLOCK(bp); 2670 continue; 2671 } 2672 hasdeps = 1; 2673 } else 2674 hasdeps = 0; 2675 /* 2676 * We must hold the lock on a vnode before writing 2677 * one of its buffers. Otherwise we may confuse, or 2678 * in the case of a snapshot vnode, deadlock the 2679 * system. 2680 * 2681 * The lock order here is the reverse of the normal 2682 * of vnode followed by buf lock. This is ok because 2683 * the NOWAIT will prevent deadlock. 2684 */ 2685 vp = bp->b_vp; 2686 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2687 BUF_UNLOCK(bp); 2688 continue; 2689 } 2690 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2691 mtx_unlock(&bqlock); 2692 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2693 bp, bp->b_vp, bp->b_flags); 2694 if (curproc == bufdaemonproc) 2695 vfs_bio_awrite(bp); 2696 else { 2697 bremfree(bp); 2698 bwrite(bp); 2699 notbufdflashes++; 2700 } 2701 vn_finished_write(mp); 2702 VOP_UNLOCK(vp, 0); 2703 flushwithdeps += hasdeps; 2704 flushed++; 2705 2706 /* 2707 * Sleeping on runningbufspace while holding 2708 * vnode lock leads to deadlock. 2709 */ 2710 if (curproc == bufdaemonproc) 2711 waitrunningbufspace(); 2712 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2713 mtx_lock(&bqlock); 2714 continue; 2715 } 2716 vn_finished_write(mp); 2717 BUF_UNLOCK(bp); 2718 } 2719 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2720 mtx_unlock(&bqlock); 2721 free(sentinel, M_TEMP); 2722 return (flushed); 2723 } 2724 2725 /* 2726 * Check to see if a block is currently memory resident. 2727 */ 2728 struct buf * 2729 incore(struct bufobj *bo, daddr_t blkno) 2730 { 2731 struct buf *bp; 2732 2733 BO_LOCK(bo); 2734 bp = gbincore(bo, blkno); 2735 BO_UNLOCK(bo); 2736 return (bp); 2737 } 2738 2739 /* 2740 * Returns true if no I/O is needed to access the 2741 * associated VM object. This is like incore except 2742 * it also hunts around in the VM system for the data. 2743 */ 2744 2745 static int 2746 inmem(struct vnode * vp, daddr_t blkno) 2747 { 2748 vm_object_t obj; 2749 vm_offset_t toff, tinc, size; 2750 vm_page_t m; 2751 vm_ooffset_t off; 2752 2753 ASSERT_VOP_LOCKED(vp, "inmem"); 2754 2755 if (incore(&vp->v_bufobj, blkno)) 2756 return 1; 2757 if (vp->v_mount == NULL) 2758 return 0; 2759 obj = vp->v_object; 2760 if (obj == NULL) 2761 return (0); 2762 2763 size = PAGE_SIZE; 2764 if (size > vp->v_mount->mnt_stat.f_iosize) 2765 size = vp->v_mount->mnt_stat.f_iosize; 2766 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2767 2768 VM_OBJECT_WLOCK(obj); 2769 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2770 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2771 if (!m) 2772 goto notinmem; 2773 tinc = size; 2774 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2775 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2776 if (vm_page_is_valid(m, 2777 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2778 goto notinmem; 2779 } 2780 VM_OBJECT_WUNLOCK(obj); 2781 return 1; 2782 2783 notinmem: 2784 VM_OBJECT_WUNLOCK(obj); 2785 return (0); 2786 } 2787 2788 /* 2789 * Set the dirty range for a buffer based on the status of the dirty 2790 * bits in the pages comprising the buffer. The range is limited 2791 * to the size of the buffer. 2792 * 2793 * Tell the VM system that the pages associated with this buffer 2794 * are clean. This is used for delayed writes where the data is 2795 * going to go to disk eventually without additional VM intevention. 2796 * 2797 * Note that while we only really need to clean through to b_bcount, we 2798 * just go ahead and clean through to b_bufsize. 2799 */ 2800 static void 2801 vfs_clean_pages_dirty_buf(struct buf *bp) 2802 { 2803 vm_ooffset_t foff, noff, eoff; 2804 vm_page_t m; 2805 int i; 2806 2807 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2808 return; 2809 2810 foff = bp->b_offset; 2811 KASSERT(bp->b_offset != NOOFFSET, 2812 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2813 2814 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2815 vfs_drain_busy_pages(bp); 2816 vfs_setdirty_locked_object(bp); 2817 for (i = 0; i < bp->b_npages; i++) { 2818 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2819 eoff = noff; 2820 if (eoff > bp->b_offset + bp->b_bufsize) 2821 eoff = bp->b_offset + bp->b_bufsize; 2822 m = bp->b_pages[i]; 2823 vfs_page_set_validclean(bp, foff, m); 2824 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2825 foff = noff; 2826 } 2827 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2828 } 2829 2830 static void 2831 vfs_setdirty_locked_object(struct buf *bp) 2832 { 2833 vm_object_t object; 2834 int i; 2835 2836 object = bp->b_bufobj->bo_object; 2837 VM_OBJECT_ASSERT_WLOCKED(object); 2838 2839 /* 2840 * We qualify the scan for modified pages on whether the 2841 * object has been flushed yet. 2842 */ 2843 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2844 vm_offset_t boffset; 2845 vm_offset_t eoffset; 2846 2847 /* 2848 * test the pages to see if they have been modified directly 2849 * by users through the VM system. 2850 */ 2851 for (i = 0; i < bp->b_npages; i++) 2852 vm_page_test_dirty(bp->b_pages[i]); 2853 2854 /* 2855 * Calculate the encompassing dirty range, boffset and eoffset, 2856 * (eoffset - boffset) bytes. 2857 */ 2858 2859 for (i = 0; i < bp->b_npages; i++) { 2860 if (bp->b_pages[i]->dirty) 2861 break; 2862 } 2863 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2864 2865 for (i = bp->b_npages - 1; i >= 0; --i) { 2866 if (bp->b_pages[i]->dirty) { 2867 break; 2868 } 2869 } 2870 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2871 2872 /* 2873 * Fit it to the buffer. 2874 */ 2875 2876 if (eoffset > bp->b_bcount) 2877 eoffset = bp->b_bcount; 2878 2879 /* 2880 * If we have a good dirty range, merge with the existing 2881 * dirty range. 2882 */ 2883 2884 if (boffset < eoffset) { 2885 if (bp->b_dirtyoff > boffset) 2886 bp->b_dirtyoff = boffset; 2887 if (bp->b_dirtyend < eoffset) 2888 bp->b_dirtyend = eoffset; 2889 } 2890 } 2891 } 2892 2893 /* 2894 * Allocate the KVA mapping for an existing buffer. It handles the 2895 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2896 * KVA which is not mapped (B_KVAALLOC). 2897 */ 2898 static void 2899 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2900 { 2901 struct buf *scratch_bp; 2902 int bsize, maxsize, need_mapping, need_kva; 2903 off_t offset; 2904 2905 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2906 (gbflags & GB_UNMAPPED) == 0; 2907 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2908 (gbflags & GB_KVAALLOC) != 0; 2909 if (!need_mapping && !need_kva) 2910 return; 2911 2912 BUF_CHECK_UNMAPPED(bp); 2913 2914 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2915 /* 2916 * Buffer is not mapped, but the KVA was already 2917 * reserved at the time of the instantiation. Use the 2918 * allocated space. 2919 */ 2920 bp->b_flags &= ~B_KVAALLOC; 2921 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2922 bp->b_kvabase = bp->b_kvaalloc; 2923 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 2924 goto has_addr; 2925 } 2926 2927 /* 2928 * Calculate the amount of the address space we would reserve 2929 * if the buffer was mapped. 2930 */ 2931 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 2932 offset = blkno * bsize; 2933 maxsize = size + (offset & PAGE_MASK); 2934 maxsize = imax(maxsize, bsize); 2935 2936 mapping_loop: 2937 if (allocbufkva(bp, maxsize, gbflags)) { 2938 /* 2939 * Request defragmentation. getnewbuf() returns us the 2940 * allocated space by the scratch buffer KVA. 2941 */ 2942 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 2943 (GB_UNMAPPED | GB_KVAALLOC)); 2944 if (scratch_bp == NULL) { 2945 if ((gbflags & GB_NOWAIT_BD) != 0) { 2946 /* 2947 * XXXKIB: defragmentation cannot 2948 * succeed, not sure what else to do. 2949 */ 2950 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 2951 } 2952 atomic_add_int(&mappingrestarts, 1); 2953 goto mapping_loop; 2954 } 2955 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 2956 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 2957 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 2958 scratch_bp->b_kvasize, gbflags); 2959 2960 /* Get rid of the scratch buffer. */ 2961 scratch_bp->b_kvasize = 0; 2962 scratch_bp->b_flags |= B_INVAL; 2963 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 2964 brelse(scratch_bp); 2965 } 2966 if (!need_mapping) 2967 return; 2968 2969 has_addr: 2970 bp->b_saveaddr = bp->b_kvabase; 2971 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 2972 bp->b_flags &= ~B_UNMAPPED; 2973 BUF_CHECK_MAPPED(bp); 2974 bpmap_qenter(bp); 2975 } 2976 2977 /* 2978 * getblk: 2979 * 2980 * Get a block given a specified block and offset into a file/device. 2981 * The buffers B_DONE bit will be cleared on return, making it almost 2982 * ready for an I/O initiation. B_INVAL may or may not be set on 2983 * return. The caller should clear B_INVAL prior to initiating a 2984 * READ. 2985 * 2986 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2987 * an existing buffer. 2988 * 2989 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2990 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2991 * and then cleared based on the backing VM. If the previous buffer is 2992 * non-0-sized but invalid, B_CACHE will be cleared. 2993 * 2994 * If getblk() must create a new buffer, the new buffer is returned with 2995 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2996 * case it is returned with B_INVAL clear and B_CACHE set based on the 2997 * backing VM. 2998 * 2999 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3000 * B_CACHE bit is clear. 3001 * 3002 * What this means, basically, is that the caller should use B_CACHE to 3003 * determine whether the buffer is fully valid or not and should clear 3004 * B_INVAL prior to issuing a read. If the caller intends to validate 3005 * the buffer by loading its data area with something, the caller needs 3006 * to clear B_INVAL. If the caller does this without issuing an I/O, 3007 * the caller should set B_CACHE ( as an optimization ), else the caller 3008 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3009 * a write attempt or if it was a successfull read. If the caller 3010 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3011 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3012 */ 3013 struct buf * 3014 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3015 int flags) 3016 { 3017 struct buf *bp; 3018 struct bufobj *bo; 3019 int bsize, error, maxsize, vmio; 3020 off_t offset; 3021 3022 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3023 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3024 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3025 ASSERT_VOP_LOCKED(vp, "getblk"); 3026 if (size > MAXBSIZE) 3027 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 3028 if (!unmapped_buf_allowed) 3029 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3030 3031 bo = &vp->v_bufobj; 3032 loop: 3033 /* 3034 * Block if we are low on buffers. Certain processes are allowed 3035 * to completely exhaust the buffer cache. 3036 * 3037 * If this check ever becomes a bottleneck it may be better to 3038 * move it into the else, when gbincore() fails. At the moment 3039 * it isn't a problem. 3040 */ 3041 if (numfreebuffers == 0) { 3042 if (TD_IS_IDLETHREAD(curthread)) 3043 return NULL; 3044 mtx_lock(&nblock); 3045 needsbuffer |= VFS_BIO_NEED_ANY; 3046 mtx_unlock(&nblock); 3047 } 3048 3049 BO_LOCK(bo); 3050 bp = gbincore(bo, blkno); 3051 if (bp != NULL) { 3052 int lockflags; 3053 /* 3054 * Buffer is in-core. If the buffer is not busy nor managed, 3055 * it must be on a queue. 3056 */ 3057 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3058 3059 if (flags & GB_LOCK_NOWAIT) 3060 lockflags |= LK_NOWAIT; 3061 3062 error = BUF_TIMELOCK(bp, lockflags, 3063 BO_MTX(bo), "getblk", slpflag, slptimeo); 3064 3065 /* 3066 * If we slept and got the lock we have to restart in case 3067 * the buffer changed identities. 3068 */ 3069 if (error == ENOLCK) 3070 goto loop; 3071 /* We timed out or were interrupted. */ 3072 else if (error) 3073 return (NULL); 3074 /* If recursed, assume caller knows the rules. */ 3075 else if (BUF_LOCKRECURSED(bp)) 3076 goto end; 3077 3078 /* 3079 * The buffer is locked. B_CACHE is cleared if the buffer is 3080 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3081 * and for a VMIO buffer B_CACHE is adjusted according to the 3082 * backing VM cache. 3083 */ 3084 if (bp->b_flags & B_INVAL) 3085 bp->b_flags &= ~B_CACHE; 3086 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3087 bp->b_flags |= B_CACHE; 3088 if (bp->b_flags & B_MANAGED) 3089 MPASS(bp->b_qindex == QUEUE_NONE); 3090 else { 3091 BO_LOCK(bo); 3092 bremfree(bp); 3093 BO_UNLOCK(bo); 3094 } 3095 3096 /* 3097 * check for size inconsistencies for non-VMIO case. 3098 */ 3099 if (bp->b_bcount != size) { 3100 if ((bp->b_flags & B_VMIO) == 0 || 3101 (size > bp->b_kvasize)) { 3102 if (bp->b_flags & B_DELWRI) { 3103 /* 3104 * If buffer is pinned and caller does 3105 * not want sleep waiting for it to be 3106 * unpinned, bail out 3107 * */ 3108 if (bp->b_pin_count > 0) { 3109 if (flags & GB_LOCK_NOWAIT) { 3110 bqrelse(bp); 3111 return (NULL); 3112 } else { 3113 bunpin_wait(bp); 3114 } 3115 } 3116 bp->b_flags |= B_NOCACHE; 3117 bwrite(bp); 3118 } else { 3119 if (LIST_EMPTY(&bp->b_dep)) { 3120 bp->b_flags |= B_RELBUF; 3121 brelse(bp); 3122 } else { 3123 bp->b_flags |= B_NOCACHE; 3124 bwrite(bp); 3125 } 3126 } 3127 goto loop; 3128 } 3129 } 3130 3131 /* 3132 * Handle the case of unmapped buffer which should 3133 * become mapped, or the buffer for which KVA 3134 * reservation is requested. 3135 */ 3136 bp_unmapped_get_kva(bp, blkno, size, flags); 3137 3138 /* 3139 * If the size is inconsistant in the VMIO case, we can resize 3140 * the buffer. This might lead to B_CACHE getting set or 3141 * cleared. If the size has not changed, B_CACHE remains 3142 * unchanged from its previous state. 3143 */ 3144 if (bp->b_bcount != size) 3145 allocbuf(bp, size); 3146 3147 KASSERT(bp->b_offset != NOOFFSET, 3148 ("getblk: no buffer offset")); 3149 3150 /* 3151 * A buffer with B_DELWRI set and B_CACHE clear must 3152 * be committed before we can return the buffer in 3153 * order to prevent the caller from issuing a read 3154 * ( due to B_CACHE not being set ) and overwriting 3155 * it. 3156 * 3157 * Most callers, including NFS and FFS, need this to 3158 * operate properly either because they assume they 3159 * can issue a read if B_CACHE is not set, or because 3160 * ( for example ) an uncached B_DELWRI might loop due 3161 * to softupdates re-dirtying the buffer. In the latter 3162 * case, B_CACHE is set after the first write completes, 3163 * preventing further loops. 3164 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3165 * above while extending the buffer, we cannot allow the 3166 * buffer to remain with B_CACHE set after the write 3167 * completes or it will represent a corrupt state. To 3168 * deal with this we set B_NOCACHE to scrap the buffer 3169 * after the write. 3170 * 3171 * We might be able to do something fancy, like setting 3172 * B_CACHE in bwrite() except if B_DELWRI is already set, 3173 * so the below call doesn't set B_CACHE, but that gets real 3174 * confusing. This is much easier. 3175 */ 3176 3177 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3178 bp->b_flags |= B_NOCACHE; 3179 bwrite(bp); 3180 goto loop; 3181 } 3182 bp->b_flags &= ~B_DONE; 3183 } else { 3184 /* 3185 * Buffer is not in-core, create new buffer. The buffer 3186 * returned by getnewbuf() is locked. Note that the returned 3187 * buffer is also considered valid (not marked B_INVAL). 3188 */ 3189 BO_UNLOCK(bo); 3190 /* 3191 * If the user does not want us to create the buffer, bail out 3192 * here. 3193 */ 3194 if (flags & GB_NOCREAT) 3195 return NULL; 3196 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3197 offset = blkno * bsize; 3198 vmio = vp->v_object != NULL; 3199 if (vmio) { 3200 maxsize = size + (offset & PAGE_MASK); 3201 } else { 3202 maxsize = size; 3203 /* Do not allow non-VMIO notmapped buffers. */ 3204 flags &= ~GB_UNMAPPED; 3205 } 3206 maxsize = imax(maxsize, bsize); 3207 3208 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3209 if (bp == NULL) { 3210 if (slpflag || slptimeo) 3211 return NULL; 3212 goto loop; 3213 } 3214 3215 /* 3216 * This code is used to make sure that a buffer is not 3217 * created while the getnewbuf routine is blocked. 3218 * This can be a problem whether the vnode is locked or not. 3219 * If the buffer is created out from under us, we have to 3220 * throw away the one we just created. 3221 * 3222 * Note: this must occur before we associate the buffer 3223 * with the vp especially considering limitations in 3224 * the splay tree implementation when dealing with duplicate 3225 * lblkno's. 3226 */ 3227 BO_LOCK(bo); 3228 if (gbincore(bo, blkno)) { 3229 BO_UNLOCK(bo); 3230 bp->b_flags |= B_INVAL; 3231 brelse(bp); 3232 goto loop; 3233 } 3234 3235 /* 3236 * Insert the buffer into the hash, so that it can 3237 * be found by incore. 3238 */ 3239 bp->b_blkno = bp->b_lblkno = blkno; 3240 bp->b_offset = offset; 3241 bgetvp(vp, bp); 3242 BO_UNLOCK(bo); 3243 3244 /* 3245 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3246 * buffer size starts out as 0, B_CACHE will be set by 3247 * allocbuf() for the VMIO case prior to it testing the 3248 * backing store for validity. 3249 */ 3250 3251 if (vmio) { 3252 bp->b_flags |= B_VMIO; 3253 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3254 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3255 bp, vp->v_object, bp->b_bufobj->bo_object)); 3256 } else { 3257 bp->b_flags &= ~B_VMIO; 3258 KASSERT(bp->b_bufobj->bo_object == NULL, 3259 ("ARGH! has b_bufobj->bo_object %p %p\n", 3260 bp, bp->b_bufobj->bo_object)); 3261 BUF_CHECK_MAPPED(bp); 3262 } 3263 3264 allocbuf(bp, size); 3265 bp->b_flags &= ~B_DONE; 3266 } 3267 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3268 BUF_ASSERT_HELD(bp); 3269 end: 3270 KASSERT(bp->b_bufobj == bo, 3271 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3272 return (bp); 3273 } 3274 3275 /* 3276 * Get an empty, disassociated buffer of given size. The buffer is initially 3277 * set to B_INVAL. 3278 */ 3279 struct buf * 3280 geteblk(int size, int flags) 3281 { 3282 struct buf *bp; 3283 int maxsize; 3284 3285 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3286 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3287 if ((flags & GB_NOWAIT_BD) && 3288 (curthread->td_pflags & TDP_BUFNEED) != 0) 3289 return (NULL); 3290 } 3291 allocbuf(bp, size); 3292 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3293 BUF_ASSERT_HELD(bp); 3294 return (bp); 3295 } 3296 3297 3298 /* 3299 * This code constitutes the buffer memory from either anonymous system 3300 * memory (in the case of non-VMIO operations) or from an associated 3301 * VM object (in the case of VMIO operations). This code is able to 3302 * resize a buffer up or down. 3303 * 3304 * Note that this code is tricky, and has many complications to resolve 3305 * deadlock or inconsistant data situations. Tread lightly!!! 3306 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3307 * the caller. Calling this code willy nilly can result in the loss of data. 3308 * 3309 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3310 * B_CACHE for the non-VMIO case. 3311 */ 3312 3313 int 3314 allocbuf(struct buf *bp, int size) 3315 { 3316 int newbsize, mbsize; 3317 int i; 3318 3319 BUF_ASSERT_HELD(bp); 3320 3321 if (bp->b_kvasize < size) 3322 panic("allocbuf: buffer too small"); 3323 3324 if ((bp->b_flags & B_VMIO) == 0) { 3325 caddr_t origbuf; 3326 int origbufsize; 3327 /* 3328 * Just get anonymous memory from the kernel. Don't 3329 * mess with B_CACHE. 3330 */ 3331 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3332 if (bp->b_flags & B_MALLOC) 3333 newbsize = mbsize; 3334 else 3335 newbsize = round_page(size); 3336 3337 if (newbsize < bp->b_bufsize) { 3338 /* 3339 * malloced buffers are not shrunk 3340 */ 3341 if (bp->b_flags & B_MALLOC) { 3342 if (newbsize) { 3343 bp->b_bcount = size; 3344 } else { 3345 free(bp->b_data, M_BIOBUF); 3346 if (bp->b_bufsize) { 3347 atomic_subtract_long( 3348 &bufmallocspace, 3349 bp->b_bufsize); 3350 bufspacewakeup(); 3351 bp->b_bufsize = 0; 3352 } 3353 bp->b_saveaddr = bp->b_kvabase; 3354 bp->b_data = bp->b_saveaddr; 3355 bp->b_bcount = 0; 3356 bp->b_flags &= ~B_MALLOC; 3357 } 3358 return 1; 3359 } 3360 vm_hold_free_pages(bp, newbsize); 3361 } else if (newbsize > bp->b_bufsize) { 3362 /* 3363 * We only use malloced memory on the first allocation. 3364 * and revert to page-allocated memory when the buffer 3365 * grows. 3366 */ 3367 /* 3368 * There is a potential smp race here that could lead 3369 * to bufmallocspace slightly passing the max. It 3370 * is probably extremely rare and not worth worrying 3371 * over. 3372 */ 3373 if ( (bufmallocspace < maxbufmallocspace) && 3374 (bp->b_bufsize == 0) && 3375 (mbsize <= PAGE_SIZE/2)) { 3376 3377 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3378 bp->b_bufsize = mbsize; 3379 bp->b_bcount = size; 3380 bp->b_flags |= B_MALLOC; 3381 atomic_add_long(&bufmallocspace, mbsize); 3382 return 1; 3383 } 3384 origbuf = NULL; 3385 origbufsize = 0; 3386 /* 3387 * If the buffer is growing on its other-than-first allocation, 3388 * then we revert to the page-allocation scheme. 3389 */ 3390 if (bp->b_flags & B_MALLOC) { 3391 origbuf = bp->b_data; 3392 origbufsize = bp->b_bufsize; 3393 bp->b_data = bp->b_kvabase; 3394 if (bp->b_bufsize) { 3395 atomic_subtract_long(&bufmallocspace, 3396 bp->b_bufsize); 3397 bufspacewakeup(); 3398 bp->b_bufsize = 0; 3399 } 3400 bp->b_flags &= ~B_MALLOC; 3401 newbsize = round_page(newbsize); 3402 } 3403 vm_hold_load_pages( 3404 bp, 3405 (vm_offset_t) bp->b_data + bp->b_bufsize, 3406 (vm_offset_t) bp->b_data + newbsize); 3407 if (origbuf) { 3408 bcopy(origbuf, bp->b_data, origbufsize); 3409 free(origbuf, M_BIOBUF); 3410 } 3411 } 3412 } else { 3413 int desiredpages; 3414 3415 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3416 desiredpages = (size == 0) ? 0 : 3417 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3418 3419 if (bp->b_flags & B_MALLOC) 3420 panic("allocbuf: VMIO buffer can't be malloced"); 3421 /* 3422 * Set B_CACHE initially if buffer is 0 length or will become 3423 * 0-length. 3424 */ 3425 if (size == 0 || bp->b_bufsize == 0) 3426 bp->b_flags |= B_CACHE; 3427 3428 if (newbsize < bp->b_bufsize) { 3429 /* 3430 * DEV_BSIZE aligned new buffer size is less then the 3431 * DEV_BSIZE aligned existing buffer size. Figure out 3432 * if we have to remove any pages. 3433 */ 3434 if (desiredpages < bp->b_npages) { 3435 vm_page_t m; 3436 3437 if ((bp->b_flags & B_UNMAPPED) == 0) { 3438 BUF_CHECK_MAPPED(bp); 3439 pmap_qremove((vm_offset_t)trunc_page( 3440 (vm_offset_t)bp->b_data) + 3441 (desiredpages << PAGE_SHIFT), 3442 (bp->b_npages - desiredpages)); 3443 } else 3444 BUF_CHECK_UNMAPPED(bp); 3445 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3446 for (i = desiredpages; i < bp->b_npages; i++) { 3447 /* 3448 * the page is not freed here -- it 3449 * is the responsibility of 3450 * vnode_pager_setsize 3451 */ 3452 m = bp->b_pages[i]; 3453 KASSERT(m != bogus_page, 3454 ("allocbuf: bogus page found")); 3455 while (vm_page_sleep_if_busy(m, TRUE, 3456 "biodep")) 3457 continue; 3458 3459 bp->b_pages[i] = NULL; 3460 vm_page_lock(m); 3461 vm_page_unwire(m, 0); 3462 vm_page_unlock(m); 3463 } 3464 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3465 bp->b_npages = desiredpages; 3466 } 3467 } else if (size > bp->b_bcount) { 3468 /* 3469 * We are growing the buffer, possibly in a 3470 * byte-granular fashion. 3471 */ 3472 vm_object_t obj; 3473 vm_offset_t toff; 3474 vm_offset_t tinc; 3475 3476 /* 3477 * Step 1, bring in the VM pages from the object, 3478 * allocating them if necessary. We must clear 3479 * B_CACHE if these pages are not valid for the 3480 * range covered by the buffer. 3481 */ 3482 3483 obj = bp->b_bufobj->bo_object; 3484 3485 VM_OBJECT_WLOCK(obj); 3486 while (bp->b_npages < desiredpages) { 3487 vm_page_t m; 3488 3489 /* 3490 * We must allocate system pages since blocking 3491 * here could interfere with paging I/O, no 3492 * matter which process we are. 3493 * 3494 * We can only test VPO_BUSY here. Blocking on 3495 * m->busy might lead to a deadlock: 3496 * vm_fault->getpages->cluster_read->allocbuf 3497 * Thus, we specify VM_ALLOC_IGN_SBUSY. 3498 */ 3499 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3500 bp->b_npages, VM_ALLOC_NOBUSY | 3501 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3502 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY | 3503 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3504 if (m->valid == 0) 3505 bp->b_flags &= ~B_CACHE; 3506 bp->b_pages[bp->b_npages] = m; 3507 ++bp->b_npages; 3508 } 3509 3510 /* 3511 * Step 2. We've loaded the pages into the buffer, 3512 * we have to figure out if we can still have B_CACHE 3513 * set. Note that B_CACHE is set according to the 3514 * byte-granular range ( bcount and size ), new the 3515 * aligned range ( newbsize ). 3516 * 3517 * The VM test is against m->valid, which is DEV_BSIZE 3518 * aligned. Needless to say, the validity of the data 3519 * needs to also be DEV_BSIZE aligned. Note that this 3520 * fails with NFS if the server or some other client 3521 * extends the file's EOF. If our buffer is resized, 3522 * B_CACHE may remain set! XXX 3523 */ 3524 3525 toff = bp->b_bcount; 3526 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3527 3528 while ((bp->b_flags & B_CACHE) && toff < size) { 3529 vm_pindex_t pi; 3530 3531 if (tinc > (size - toff)) 3532 tinc = size - toff; 3533 3534 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3535 PAGE_SHIFT; 3536 3537 vfs_buf_test_cache( 3538 bp, 3539 bp->b_offset, 3540 toff, 3541 tinc, 3542 bp->b_pages[pi] 3543 ); 3544 toff += tinc; 3545 tinc = PAGE_SIZE; 3546 } 3547 VM_OBJECT_WUNLOCK(obj); 3548 3549 /* 3550 * Step 3, fixup the KVM pmap. 3551 */ 3552 if ((bp->b_flags & B_UNMAPPED) == 0) 3553 bpmap_qenter(bp); 3554 else 3555 BUF_CHECK_UNMAPPED(bp); 3556 } 3557 } 3558 if (newbsize < bp->b_bufsize) 3559 bufspacewakeup(); 3560 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3561 bp->b_bcount = size; /* requested buffer size */ 3562 return 1; 3563 } 3564 3565 extern int inflight_transient_maps; 3566 3567 void 3568 biodone(struct bio *bp) 3569 { 3570 struct mtx *mtxp; 3571 void (*done)(struct bio *); 3572 vm_offset_t start, end; 3573 int transient; 3574 3575 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3576 mtx_lock(mtxp); 3577 bp->bio_flags |= BIO_DONE; 3578 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3579 start = trunc_page((vm_offset_t)bp->bio_data); 3580 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3581 transient = 1; 3582 } else { 3583 transient = 0; 3584 start = end = 0; 3585 } 3586 done = bp->bio_done; 3587 if (done == NULL) 3588 wakeup(bp); 3589 mtx_unlock(mtxp); 3590 if (done != NULL) 3591 done(bp); 3592 if (transient) { 3593 pmap_qremove(start, OFF_TO_IDX(end - start)); 3594 vm_map_remove(bio_transient_map, start, end); 3595 atomic_add_int(&inflight_transient_maps, -1); 3596 } 3597 } 3598 3599 /* 3600 * Wait for a BIO to finish. 3601 * 3602 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3603 * case is not yet clear. 3604 */ 3605 int 3606 biowait(struct bio *bp, const char *wchan) 3607 { 3608 struct mtx *mtxp; 3609 3610 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3611 mtx_lock(mtxp); 3612 while ((bp->bio_flags & BIO_DONE) == 0) 3613 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3614 mtx_unlock(mtxp); 3615 if (bp->bio_error != 0) 3616 return (bp->bio_error); 3617 if (!(bp->bio_flags & BIO_ERROR)) 3618 return (0); 3619 return (EIO); 3620 } 3621 3622 void 3623 biofinish(struct bio *bp, struct devstat *stat, int error) 3624 { 3625 3626 if (error) { 3627 bp->bio_error = error; 3628 bp->bio_flags |= BIO_ERROR; 3629 } 3630 if (stat != NULL) 3631 devstat_end_transaction_bio(stat, bp); 3632 biodone(bp); 3633 } 3634 3635 /* 3636 * bufwait: 3637 * 3638 * Wait for buffer I/O completion, returning error status. The buffer 3639 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3640 * error and cleared. 3641 */ 3642 int 3643 bufwait(struct buf *bp) 3644 { 3645 if (bp->b_iocmd == BIO_READ) 3646 bwait(bp, PRIBIO, "biord"); 3647 else 3648 bwait(bp, PRIBIO, "biowr"); 3649 if (bp->b_flags & B_EINTR) { 3650 bp->b_flags &= ~B_EINTR; 3651 return (EINTR); 3652 } 3653 if (bp->b_ioflags & BIO_ERROR) { 3654 return (bp->b_error ? bp->b_error : EIO); 3655 } else { 3656 return (0); 3657 } 3658 } 3659 3660 /* 3661 * Call back function from struct bio back up to struct buf. 3662 */ 3663 static void 3664 bufdonebio(struct bio *bip) 3665 { 3666 struct buf *bp; 3667 3668 bp = bip->bio_caller2; 3669 bp->b_resid = bp->b_bcount - bip->bio_completed; 3670 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3671 bp->b_ioflags = bip->bio_flags; 3672 bp->b_error = bip->bio_error; 3673 if (bp->b_error) 3674 bp->b_ioflags |= BIO_ERROR; 3675 bufdone(bp); 3676 g_destroy_bio(bip); 3677 } 3678 3679 void 3680 dev_strategy(struct cdev *dev, struct buf *bp) 3681 { 3682 struct cdevsw *csw; 3683 struct bio *bip; 3684 int ref; 3685 3686 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3687 panic("b_iocmd botch"); 3688 for (;;) { 3689 bip = g_new_bio(); 3690 if (bip != NULL) 3691 break; 3692 /* Try again later */ 3693 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3694 } 3695 bip->bio_cmd = bp->b_iocmd; 3696 bip->bio_offset = bp->b_iooffset; 3697 bip->bio_length = bp->b_bcount; 3698 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3699 bdata2bio(bp, bip); 3700 bip->bio_done = bufdonebio; 3701 bip->bio_caller2 = bp; 3702 bip->bio_dev = dev; 3703 KASSERT(dev->si_refcount > 0, 3704 ("dev_strategy on un-referenced struct cdev *(%s)", 3705 devtoname(dev))); 3706 csw = dev_refthread(dev, &ref); 3707 if (csw == NULL) { 3708 g_destroy_bio(bip); 3709 bp->b_error = ENXIO; 3710 bp->b_ioflags = BIO_ERROR; 3711 bufdone(bp); 3712 return; 3713 } 3714 (*csw->d_strategy)(bip); 3715 dev_relthread(dev, ref); 3716 } 3717 3718 /* 3719 * bufdone: 3720 * 3721 * Finish I/O on a buffer, optionally calling a completion function. 3722 * This is usually called from an interrupt so process blocking is 3723 * not allowed. 3724 * 3725 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3726 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3727 * assuming B_INVAL is clear. 3728 * 3729 * For the VMIO case, we set B_CACHE if the op was a read and no 3730 * read error occured, or if the op was a write. B_CACHE is never 3731 * set if the buffer is invalid or otherwise uncacheable. 3732 * 3733 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3734 * initiator to leave B_INVAL set to brelse the buffer out of existance 3735 * in the biodone routine. 3736 */ 3737 void 3738 bufdone(struct buf *bp) 3739 { 3740 struct bufobj *dropobj; 3741 void (*biodone)(struct buf *); 3742 3743 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3744 dropobj = NULL; 3745 3746 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3747 BUF_ASSERT_HELD(bp); 3748 3749 runningbufwakeup(bp); 3750 if (bp->b_iocmd == BIO_WRITE) 3751 dropobj = bp->b_bufobj; 3752 /* call optional completion function if requested */ 3753 if (bp->b_iodone != NULL) { 3754 biodone = bp->b_iodone; 3755 bp->b_iodone = NULL; 3756 (*biodone) (bp); 3757 if (dropobj) 3758 bufobj_wdrop(dropobj); 3759 return; 3760 } 3761 3762 bufdone_finish(bp); 3763 3764 if (dropobj) 3765 bufobj_wdrop(dropobj); 3766 } 3767 3768 void 3769 bufdone_finish(struct buf *bp) 3770 { 3771 BUF_ASSERT_HELD(bp); 3772 3773 if (!LIST_EMPTY(&bp->b_dep)) 3774 buf_complete(bp); 3775 3776 if (bp->b_flags & B_VMIO) { 3777 vm_ooffset_t foff; 3778 vm_page_t m; 3779 vm_object_t obj; 3780 struct vnode *vp; 3781 int bogus, i, iosize; 3782 3783 obj = bp->b_bufobj->bo_object; 3784 KASSERT(obj->paging_in_progress >= bp->b_npages, 3785 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3786 obj->paging_in_progress, bp->b_npages)); 3787 3788 vp = bp->b_vp; 3789 KASSERT(vp->v_holdcnt > 0, 3790 ("biodone_finish: vnode %p has zero hold count", vp)); 3791 KASSERT(vp->v_object != NULL, 3792 ("biodone_finish: vnode %p has no vm_object", vp)); 3793 3794 foff = bp->b_offset; 3795 KASSERT(bp->b_offset != NOOFFSET, 3796 ("biodone_finish: bp %p has no buffer offset", bp)); 3797 3798 /* 3799 * Set B_CACHE if the op was a normal read and no error 3800 * occured. B_CACHE is set for writes in the b*write() 3801 * routines. 3802 */ 3803 iosize = bp->b_bcount - bp->b_resid; 3804 if (bp->b_iocmd == BIO_READ && 3805 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3806 !(bp->b_ioflags & BIO_ERROR)) { 3807 bp->b_flags |= B_CACHE; 3808 } 3809 bogus = 0; 3810 VM_OBJECT_WLOCK(obj); 3811 for (i = 0; i < bp->b_npages; i++) { 3812 int bogusflag = 0; 3813 int resid; 3814 3815 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3816 if (resid > iosize) 3817 resid = iosize; 3818 3819 /* 3820 * cleanup bogus pages, restoring the originals 3821 */ 3822 m = bp->b_pages[i]; 3823 if (m == bogus_page) { 3824 bogus = bogusflag = 1; 3825 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3826 if (m == NULL) 3827 panic("biodone: page disappeared!"); 3828 bp->b_pages[i] = m; 3829 } 3830 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3831 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3832 (intmax_t)foff, (uintmax_t)m->pindex)); 3833 3834 /* 3835 * In the write case, the valid and clean bits are 3836 * already changed correctly ( see bdwrite() ), so we 3837 * only need to do this here in the read case. 3838 */ 3839 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3840 KASSERT((m->dirty & vm_page_bits(foff & 3841 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3842 " page %p has unexpected dirty bits", m)); 3843 vfs_page_set_valid(bp, foff, m); 3844 } 3845 3846 vm_page_io_finish(m); 3847 vm_object_pip_subtract(obj, 1); 3848 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3849 iosize -= resid; 3850 } 3851 vm_object_pip_wakeupn(obj, 0); 3852 VM_OBJECT_WUNLOCK(obj); 3853 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3854 BUF_CHECK_MAPPED(bp); 3855 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3856 bp->b_pages, bp->b_npages); 3857 } 3858 } 3859 3860 /* 3861 * For asynchronous completions, release the buffer now. The brelse 3862 * will do a wakeup there if necessary - so no need to do a wakeup 3863 * here in the async case. The sync case always needs to do a wakeup. 3864 */ 3865 3866 if (bp->b_flags & B_ASYNC) { 3867 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3868 brelse(bp); 3869 else 3870 bqrelse(bp); 3871 } else 3872 bdone(bp); 3873 } 3874 3875 /* 3876 * This routine is called in lieu of iodone in the case of 3877 * incomplete I/O. This keeps the busy status for pages 3878 * consistant. 3879 */ 3880 void 3881 vfs_unbusy_pages(struct buf *bp) 3882 { 3883 int i; 3884 vm_object_t obj; 3885 vm_page_t m; 3886 3887 runningbufwakeup(bp); 3888 if (!(bp->b_flags & B_VMIO)) 3889 return; 3890 3891 obj = bp->b_bufobj->bo_object; 3892 VM_OBJECT_WLOCK(obj); 3893 for (i = 0; i < bp->b_npages; i++) { 3894 m = bp->b_pages[i]; 3895 if (m == bogus_page) { 3896 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3897 if (!m) 3898 panic("vfs_unbusy_pages: page missing\n"); 3899 bp->b_pages[i] = m; 3900 if ((bp->b_flags & B_UNMAPPED) == 0) { 3901 BUF_CHECK_MAPPED(bp); 3902 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3903 bp->b_pages, bp->b_npages); 3904 } else 3905 BUF_CHECK_UNMAPPED(bp); 3906 } 3907 vm_object_pip_subtract(obj, 1); 3908 vm_page_io_finish(m); 3909 } 3910 vm_object_pip_wakeupn(obj, 0); 3911 VM_OBJECT_WUNLOCK(obj); 3912 } 3913 3914 /* 3915 * vfs_page_set_valid: 3916 * 3917 * Set the valid bits in a page based on the supplied offset. The 3918 * range is restricted to the buffer's size. 3919 * 3920 * This routine is typically called after a read completes. 3921 */ 3922 static void 3923 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3924 { 3925 vm_ooffset_t eoff; 3926 3927 /* 3928 * Compute the end offset, eoff, such that [off, eoff) does not span a 3929 * page boundary and eoff is not greater than the end of the buffer. 3930 * The end of the buffer, in this case, is our file EOF, not the 3931 * allocation size of the buffer. 3932 */ 3933 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3934 if (eoff > bp->b_offset + bp->b_bcount) 3935 eoff = bp->b_offset + bp->b_bcount; 3936 3937 /* 3938 * Set valid range. This is typically the entire buffer and thus the 3939 * entire page. 3940 */ 3941 if (eoff > off) 3942 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3943 } 3944 3945 /* 3946 * vfs_page_set_validclean: 3947 * 3948 * Set the valid bits and clear the dirty bits in a page based on the 3949 * supplied offset. The range is restricted to the buffer's size. 3950 */ 3951 static void 3952 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3953 { 3954 vm_ooffset_t soff, eoff; 3955 3956 /* 3957 * Start and end offsets in buffer. eoff - soff may not cross a 3958 * page boundry or cross the end of the buffer. The end of the 3959 * buffer, in this case, is our file EOF, not the allocation size 3960 * of the buffer. 3961 */ 3962 soff = off; 3963 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3964 if (eoff > bp->b_offset + bp->b_bcount) 3965 eoff = bp->b_offset + bp->b_bcount; 3966 3967 /* 3968 * Set valid range. This is typically the entire buffer and thus the 3969 * entire page. 3970 */ 3971 if (eoff > soff) { 3972 vm_page_set_validclean( 3973 m, 3974 (vm_offset_t) (soff & PAGE_MASK), 3975 (vm_offset_t) (eoff - soff) 3976 ); 3977 } 3978 } 3979 3980 /* 3981 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If 3982 * any page is busy, drain the flag. 3983 */ 3984 static void 3985 vfs_drain_busy_pages(struct buf *bp) 3986 { 3987 vm_page_t m; 3988 int i, last_busied; 3989 3990 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 3991 last_busied = 0; 3992 for (i = 0; i < bp->b_npages; i++) { 3993 m = bp->b_pages[i]; 3994 if ((m->oflags & VPO_BUSY) != 0) { 3995 for (; last_busied < i; last_busied++) 3996 vm_page_busy(bp->b_pages[last_busied]); 3997 while ((m->oflags & VPO_BUSY) != 0) 3998 vm_page_sleep(m, "vbpage"); 3999 } 4000 } 4001 for (i = 0; i < last_busied; i++) 4002 vm_page_wakeup(bp->b_pages[i]); 4003 } 4004 4005 /* 4006 * This routine is called before a device strategy routine. 4007 * It is used to tell the VM system that paging I/O is in 4008 * progress, and treat the pages associated with the buffer 4009 * almost as being VPO_BUSY. Also the object paging_in_progress 4010 * flag is handled to make sure that the object doesn't become 4011 * inconsistant. 4012 * 4013 * Since I/O has not been initiated yet, certain buffer flags 4014 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4015 * and should be ignored. 4016 */ 4017 void 4018 vfs_busy_pages(struct buf *bp, int clear_modify) 4019 { 4020 int i, bogus; 4021 vm_object_t obj; 4022 vm_ooffset_t foff; 4023 vm_page_t m; 4024 4025 if (!(bp->b_flags & B_VMIO)) 4026 return; 4027 4028 obj = bp->b_bufobj->bo_object; 4029 foff = bp->b_offset; 4030 KASSERT(bp->b_offset != NOOFFSET, 4031 ("vfs_busy_pages: no buffer offset")); 4032 VM_OBJECT_WLOCK(obj); 4033 vfs_drain_busy_pages(bp); 4034 if (bp->b_bufsize != 0) 4035 vfs_setdirty_locked_object(bp); 4036 bogus = 0; 4037 for (i = 0; i < bp->b_npages; i++) { 4038 m = bp->b_pages[i]; 4039 4040 if ((bp->b_flags & B_CLUSTER) == 0) { 4041 vm_object_pip_add(obj, 1); 4042 vm_page_io_start(m); 4043 } 4044 /* 4045 * When readying a buffer for a read ( i.e 4046 * clear_modify == 0 ), it is important to do 4047 * bogus_page replacement for valid pages in 4048 * partially instantiated buffers. Partially 4049 * instantiated buffers can, in turn, occur when 4050 * reconstituting a buffer from its VM backing store 4051 * base. We only have to do this if B_CACHE is 4052 * clear ( which causes the I/O to occur in the 4053 * first place ). The replacement prevents the read 4054 * I/O from overwriting potentially dirty VM-backed 4055 * pages. XXX bogus page replacement is, uh, bogus. 4056 * It may not work properly with small-block devices. 4057 * We need to find a better way. 4058 */ 4059 if (clear_modify) { 4060 pmap_remove_write(m); 4061 vfs_page_set_validclean(bp, foff, m); 4062 } else if (m->valid == VM_PAGE_BITS_ALL && 4063 (bp->b_flags & B_CACHE) == 0) { 4064 bp->b_pages[i] = bogus_page; 4065 bogus++; 4066 } 4067 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4068 } 4069 VM_OBJECT_WUNLOCK(obj); 4070 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4071 BUF_CHECK_MAPPED(bp); 4072 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4073 bp->b_pages, bp->b_npages); 4074 } 4075 } 4076 4077 /* 4078 * vfs_bio_set_valid: 4079 * 4080 * Set the range within the buffer to valid. The range is 4081 * relative to the beginning of the buffer, b_offset. Note that 4082 * b_offset itself may be offset from the beginning of the first 4083 * page. 4084 */ 4085 void 4086 vfs_bio_set_valid(struct buf *bp, int base, int size) 4087 { 4088 int i, n; 4089 vm_page_t m; 4090 4091 if (!(bp->b_flags & B_VMIO)) 4092 return; 4093 4094 /* 4095 * Fixup base to be relative to beginning of first page. 4096 * Set initial n to be the maximum number of bytes in the 4097 * first page that can be validated. 4098 */ 4099 base += (bp->b_offset & PAGE_MASK); 4100 n = PAGE_SIZE - (base & PAGE_MASK); 4101 4102 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4103 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4104 m = bp->b_pages[i]; 4105 if (n > size) 4106 n = size; 4107 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4108 base += n; 4109 size -= n; 4110 n = PAGE_SIZE; 4111 } 4112 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4113 } 4114 4115 /* 4116 * vfs_bio_clrbuf: 4117 * 4118 * If the specified buffer is a non-VMIO buffer, clear the entire 4119 * buffer. If the specified buffer is a VMIO buffer, clear and 4120 * validate only the previously invalid portions of the buffer. 4121 * This routine essentially fakes an I/O, so we need to clear 4122 * BIO_ERROR and B_INVAL. 4123 * 4124 * Note that while we only theoretically need to clear through b_bcount, 4125 * we go ahead and clear through b_bufsize. 4126 */ 4127 void 4128 vfs_bio_clrbuf(struct buf *bp) 4129 { 4130 int i, j, mask, sa, ea, slide; 4131 4132 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4133 clrbuf(bp); 4134 return; 4135 } 4136 bp->b_flags &= ~B_INVAL; 4137 bp->b_ioflags &= ~BIO_ERROR; 4138 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4139 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4140 (bp->b_offset & PAGE_MASK) == 0) { 4141 if (bp->b_pages[0] == bogus_page) 4142 goto unlock; 4143 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4144 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4145 if ((bp->b_pages[0]->valid & mask) == mask) 4146 goto unlock; 4147 if ((bp->b_pages[0]->valid & mask) == 0) { 4148 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4149 bp->b_pages[0]->valid |= mask; 4150 goto unlock; 4151 } 4152 } 4153 sa = bp->b_offset & PAGE_MASK; 4154 slide = 0; 4155 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4156 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4157 ea = slide & PAGE_MASK; 4158 if (ea == 0) 4159 ea = PAGE_SIZE; 4160 if (bp->b_pages[i] == bogus_page) 4161 continue; 4162 j = sa / DEV_BSIZE; 4163 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4164 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4165 if ((bp->b_pages[i]->valid & mask) == mask) 4166 continue; 4167 if ((bp->b_pages[i]->valid & mask) == 0) 4168 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4169 else { 4170 for (; sa < ea; sa += DEV_BSIZE, j++) { 4171 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4172 pmap_zero_page_area(bp->b_pages[i], 4173 sa, DEV_BSIZE); 4174 } 4175 } 4176 } 4177 bp->b_pages[i]->valid |= mask; 4178 } 4179 unlock: 4180 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4181 bp->b_resid = 0; 4182 } 4183 4184 void 4185 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4186 { 4187 vm_page_t m; 4188 int i, n; 4189 4190 if ((bp->b_flags & B_UNMAPPED) == 0) { 4191 BUF_CHECK_MAPPED(bp); 4192 bzero(bp->b_data + base, size); 4193 } else { 4194 BUF_CHECK_UNMAPPED(bp); 4195 n = PAGE_SIZE - (base & PAGE_MASK); 4196 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4197 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4198 m = bp->b_pages[i]; 4199 if (n > size) 4200 n = size; 4201 pmap_zero_page_area(m, base & PAGE_MASK, n); 4202 base += n; 4203 size -= n; 4204 n = PAGE_SIZE; 4205 } 4206 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4207 } 4208 } 4209 4210 /* 4211 * vm_hold_load_pages and vm_hold_free_pages get pages into 4212 * a buffers address space. The pages are anonymous and are 4213 * not associated with a file object. 4214 */ 4215 static void 4216 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4217 { 4218 vm_offset_t pg; 4219 vm_page_t p; 4220 int index; 4221 4222 BUF_CHECK_MAPPED(bp); 4223 4224 to = round_page(to); 4225 from = round_page(from); 4226 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4227 4228 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4229 tryagain: 4230 /* 4231 * note: must allocate system pages since blocking here 4232 * could interfere with paging I/O, no matter which 4233 * process we are. 4234 */ 4235 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4236 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4237 if (p == NULL) { 4238 VM_WAIT; 4239 goto tryagain; 4240 } 4241 pmap_qenter(pg, &p, 1); 4242 bp->b_pages[index] = p; 4243 } 4244 bp->b_npages = index; 4245 } 4246 4247 /* Return pages associated with this buf to the vm system */ 4248 static void 4249 vm_hold_free_pages(struct buf *bp, int newbsize) 4250 { 4251 vm_offset_t from; 4252 vm_page_t p; 4253 int index, newnpages; 4254 4255 BUF_CHECK_MAPPED(bp); 4256 4257 from = round_page((vm_offset_t)bp->b_data + newbsize); 4258 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4259 if (bp->b_npages > newnpages) 4260 pmap_qremove(from, bp->b_npages - newnpages); 4261 for (index = newnpages; index < bp->b_npages; index++) { 4262 p = bp->b_pages[index]; 4263 bp->b_pages[index] = NULL; 4264 if (p->busy != 0) 4265 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4266 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4267 p->wire_count--; 4268 vm_page_free(p); 4269 atomic_subtract_int(&cnt.v_wire_count, 1); 4270 } 4271 bp->b_npages = newnpages; 4272 } 4273 4274 /* 4275 * Map an IO request into kernel virtual address space. 4276 * 4277 * All requests are (re)mapped into kernel VA space. 4278 * Notice that we use b_bufsize for the size of the buffer 4279 * to be mapped. b_bcount might be modified by the driver. 4280 * 4281 * Note that even if the caller determines that the address space should 4282 * be valid, a race or a smaller-file mapped into a larger space may 4283 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4284 * check the return value. 4285 */ 4286 int 4287 vmapbuf(struct buf *bp, int mapbuf) 4288 { 4289 caddr_t kva; 4290 vm_prot_t prot; 4291 int pidx; 4292 4293 if (bp->b_bufsize < 0) 4294 return (-1); 4295 prot = VM_PROT_READ; 4296 if (bp->b_iocmd == BIO_READ) 4297 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4298 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4299 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4300 btoc(MAXPHYS))) < 0) 4301 return (-1); 4302 bp->b_npages = pidx; 4303 if (mapbuf || !unmapped_buf_allowed) { 4304 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4305 kva = bp->b_saveaddr; 4306 bp->b_saveaddr = bp->b_data; 4307 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4308 bp->b_flags &= ~B_UNMAPPED; 4309 } else { 4310 bp->b_flags |= B_UNMAPPED; 4311 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4312 bp->b_saveaddr = bp->b_data; 4313 bp->b_data = unmapped_buf; 4314 } 4315 return(0); 4316 } 4317 4318 /* 4319 * Free the io map PTEs associated with this IO operation. 4320 * We also invalidate the TLB entries and restore the original b_addr. 4321 */ 4322 void 4323 vunmapbuf(struct buf *bp) 4324 { 4325 int npages; 4326 4327 npages = bp->b_npages; 4328 if (bp->b_flags & B_UNMAPPED) 4329 bp->b_flags &= ~B_UNMAPPED; 4330 else 4331 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4332 vm_page_unhold_pages(bp->b_pages, npages); 4333 4334 bp->b_data = bp->b_saveaddr; 4335 } 4336 4337 void 4338 bdone(struct buf *bp) 4339 { 4340 struct mtx *mtxp; 4341 4342 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4343 mtx_lock(mtxp); 4344 bp->b_flags |= B_DONE; 4345 wakeup(bp); 4346 mtx_unlock(mtxp); 4347 } 4348 4349 void 4350 bwait(struct buf *bp, u_char pri, const char *wchan) 4351 { 4352 struct mtx *mtxp; 4353 4354 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4355 mtx_lock(mtxp); 4356 while ((bp->b_flags & B_DONE) == 0) 4357 msleep(bp, mtxp, pri, wchan, 0); 4358 mtx_unlock(mtxp); 4359 } 4360 4361 int 4362 bufsync(struct bufobj *bo, int waitfor) 4363 { 4364 4365 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4366 } 4367 4368 void 4369 bufstrategy(struct bufobj *bo, struct buf *bp) 4370 { 4371 int i = 0; 4372 struct vnode *vp; 4373 4374 vp = bp->b_vp; 4375 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4376 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4377 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4378 i = VOP_STRATEGY(vp, bp); 4379 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4380 } 4381 4382 void 4383 bufobj_wrefl(struct bufobj *bo) 4384 { 4385 4386 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4387 ASSERT_BO_LOCKED(bo); 4388 bo->bo_numoutput++; 4389 } 4390 4391 void 4392 bufobj_wref(struct bufobj *bo) 4393 { 4394 4395 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4396 BO_LOCK(bo); 4397 bo->bo_numoutput++; 4398 BO_UNLOCK(bo); 4399 } 4400 4401 void 4402 bufobj_wdrop(struct bufobj *bo) 4403 { 4404 4405 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4406 BO_LOCK(bo); 4407 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4408 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4409 bo->bo_flag &= ~BO_WWAIT; 4410 wakeup(&bo->bo_numoutput); 4411 } 4412 BO_UNLOCK(bo); 4413 } 4414 4415 int 4416 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4417 { 4418 int error; 4419 4420 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4421 ASSERT_BO_LOCKED(bo); 4422 error = 0; 4423 while (bo->bo_numoutput) { 4424 bo->bo_flag |= BO_WWAIT; 4425 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 4426 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4427 if (error) 4428 break; 4429 } 4430 return (error); 4431 } 4432 4433 void 4434 bpin(struct buf *bp) 4435 { 4436 struct mtx *mtxp; 4437 4438 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4439 mtx_lock(mtxp); 4440 bp->b_pin_count++; 4441 mtx_unlock(mtxp); 4442 } 4443 4444 void 4445 bunpin(struct buf *bp) 4446 { 4447 struct mtx *mtxp; 4448 4449 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4450 mtx_lock(mtxp); 4451 if (--bp->b_pin_count == 0) 4452 wakeup(bp); 4453 mtx_unlock(mtxp); 4454 } 4455 4456 void 4457 bunpin_wait(struct buf *bp) 4458 { 4459 struct mtx *mtxp; 4460 4461 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4462 mtx_lock(mtxp); 4463 while (bp->b_pin_count > 0) 4464 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4465 mtx_unlock(mtxp); 4466 } 4467 4468 /* 4469 * Set bio_data or bio_ma for struct bio from the struct buf. 4470 */ 4471 void 4472 bdata2bio(struct buf *bp, struct bio *bip) 4473 { 4474 4475 if ((bp->b_flags & B_UNMAPPED) != 0) { 4476 KASSERT(unmapped_buf_allowed, ("unmapped")); 4477 bip->bio_ma = bp->b_pages; 4478 bip->bio_ma_n = bp->b_npages; 4479 bip->bio_data = unmapped_buf; 4480 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4481 bip->bio_flags |= BIO_UNMAPPED; 4482 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4483 PAGE_SIZE == bp->b_npages, 4484 ("Buffer %p too short: %d %d %d", bp, bip->bio_ma_offset, 4485 bip->bio_length, bip->bio_ma_n)); 4486 } else { 4487 bip->bio_data = bp->b_data; 4488 bip->bio_ma = NULL; 4489 } 4490 } 4491 4492 #include "opt_ddb.h" 4493 #ifdef DDB 4494 #include <ddb/ddb.h> 4495 4496 /* DDB command to show buffer data */ 4497 DB_SHOW_COMMAND(buffer, db_show_buffer) 4498 { 4499 /* get args */ 4500 struct buf *bp = (struct buf *)addr; 4501 4502 if (!have_addr) { 4503 db_printf("usage: show buffer <addr>\n"); 4504 return; 4505 } 4506 4507 db_printf("buf at %p\n", bp); 4508 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4509 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4510 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4511 db_printf( 4512 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4513 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4514 "b_dep = %p\n", 4515 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4516 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4517 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4518 if (bp->b_npages) { 4519 int i; 4520 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4521 for (i = 0; i < bp->b_npages; i++) { 4522 vm_page_t m; 4523 m = bp->b_pages[i]; 4524 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4525 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4526 if ((i + 1) < bp->b_npages) 4527 db_printf(","); 4528 } 4529 db_printf("\n"); 4530 } 4531 db_printf(" "); 4532 BUF_LOCKPRINTINFO(bp); 4533 } 4534 4535 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4536 { 4537 struct buf *bp; 4538 int i; 4539 4540 for (i = 0; i < nbuf; i++) { 4541 bp = &buf[i]; 4542 if (BUF_ISLOCKED(bp)) { 4543 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4544 db_printf("\n"); 4545 } 4546 } 4547 } 4548 4549 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4550 { 4551 struct vnode *vp; 4552 struct buf *bp; 4553 4554 if (!have_addr) { 4555 db_printf("usage: show vnodebufs <addr>\n"); 4556 return; 4557 } 4558 vp = (struct vnode *)addr; 4559 db_printf("Clean buffers:\n"); 4560 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4561 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4562 db_printf("\n"); 4563 } 4564 db_printf("Dirty buffers:\n"); 4565 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4566 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4567 db_printf("\n"); 4568 } 4569 } 4570 4571 DB_COMMAND(countfreebufs, db_coundfreebufs) 4572 { 4573 struct buf *bp; 4574 int i, used = 0, nfree = 0; 4575 4576 if (have_addr) { 4577 db_printf("usage: countfreebufs\n"); 4578 return; 4579 } 4580 4581 for (i = 0; i < nbuf; i++) { 4582 bp = &buf[i]; 4583 if ((bp->b_vflags & BV_INFREECNT) != 0) 4584 nfree++; 4585 else 4586 used++; 4587 } 4588 4589 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4590 nfree + used); 4591 db_printf("numfreebuffers is %d\n", numfreebuffers); 4592 } 4593 #endif /* DDB */ 4594