1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2004 Poul-Henning Kamp 5 * Copyright (c) 1994,1997 John S. Dyson 6 * Copyright (c) 2013 The FreeBSD Foundation 7 * All rights reserved. 8 * 9 * Portions of this software were developed by Konstantin Belousov 10 * under sponsorship from the FreeBSD Foundation. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 /* 35 * this file contains a new buffer I/O scheme implementing a coherent 36 * VM object and buffer cache scheme. Pains have been taken to make 37 * sure that the performance degradation associated with schemes such 38 * as this is not realized. 39 * 40 * Author: John S. Dyson 41 * Significant help during the development and debugging phases 42 * had been provided by David Greenman, also of the FreeBSD core team. 43 * 44 * see man buf(9) for more info. 45 */ 46 47 #include <sys/cdefs.h> 48 __FBSDID("$FreeBSD$"); 49 50 #include <sys/param.h> 51 #include <sys/systm.h> 52 #include <sys/asan.h> 53 #include <sys/bio.h> 54 #include <sys/bitset.h> 55 #include <sys/conf.h> 56 #include <sys/counter.h> 57 #include <sys/buf.h> 58 #include <sys/devicestat.h> 59 #include <sys/eventhandler.h> 60 #include <sys/fail.h> 61 #include <sys/ktr.h> 62 #include <sys/limits.h> 63 #include <sys/lock.h> 64 #include <sys/malloc.h> 65 #include <sys/mount.h> 66 #include <sys/mutex.h> 67 #include <sys/kernel.h> 68 #include <sys/kthread.h> 69 #include <sys/proc.h> 70 #include <sys/racct.h> 71 #include <sys/refcount.h> 72 #include <sys/resourcevar.h> 73 #include <sys/rwlock.h> 74 #include <sys/smp.h> 75 #include <sys/sysctl.h> 76 #include <sys/syscallsubr.h> 77 #include <sys/vmem.h> 78 #include <sys/vmmeter.h> 79 #include <sys/vnode.h> 80 #include <sys/watchdog.h> 81 #include <geom/geom.h> 82 #include <vm/vm.h> 83 #include <vm/vm_param.h> 84 #include <vm/vm_kern.h> 85 #include <vm/vm_object.h> 86 #include <vm/vm_page.h> 87 #include <vm/vm_pageout.h> 88 #include <vm/vm_pager.h> 89 #include <vm/vm_extern.h> 90 #include <vm/vm_map.h> 91 #include <vm/swap_pager.h> 92 93 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 94 95 struct bio_ops bioops; /* I/O operation notification */ 96 97 struct buf_ops buf_ops_bio = { 98 .bop_name = "buf_ops_bio", 99 .bop_write = bufwrite, 100 .bop_strategy = bufstrategy, 101 .bop_sync = bufsync, 102 .bop_bdflush = bufbdflush, 103 }; 104 105 struct bufqueue { 106 struct mtx_padalign bq_lock; 107 TAILQ_HEAD(, buf) bq_queue; 108 uint8_t bq_index; 109 uint16_t bq_subqueue; 110 int bq_len; 111 } __aligned(CACHE_LINE_SIZE); 112 113 #define BQ_LOCKPTR(bq) (&(bq)->bq_lock) 114 #define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq))) 115 #define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq))) 116 #define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED) 117 118 struct bufdomain { 119 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */ 120 struct bufqueue bd_dirtyq; 121 struct bufqueue *bd_cleanq; 122 struct mtx_padalign bd_run_lock; 123 /* Constants */ 124 long bd_maxbufspace; 125 long bd_hibufspace; 126 long bd_lobufspace; 127 long bd_bufspacethresh; 128 int bd_hifreebuffers; 129 int bd_lofreebuffers; 130 int bd_hidirtybuffers; 131 int bd_lodirtybuffers; 132 int bd_dirtybufthresh; 133 int bd_lim; 134 /* atomics */ 135 int bd_wanted; 136 bool bd_shutdown; 137 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers; 138 int __aligned(CACHE_LINE_SIZE) bd_running; 139 long __aligned(CACHE_LINE_SIZE) bd_bufspace; 140 int __aligned(CACHE_LINE_SIZE) bd_freebuffers; 141 } __aligned(CACHE_LINE_SIZE); 142 143 #define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock) 144 #define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd))) 145 #define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd))) 146 #define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED) 147 #define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock) 148 #define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd))) 149 #define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd))) 150 #define BD_DOMAIN(bd) (bd - bdomain) 151 152 static char *buf; /* buffer header pool */ 153 static struct buf * 154 nbufp(unsigned i) 155 { 156 return ((struct buf *)(buf + (sizeof(struct buf) + 157 sizeof(vm_page_t) * atop(maxbcachebuf)) * i)); 158 } 159 160 caddr_t __read_mostly unmapped_buf; 161 162 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 163 struct proc *bufdaemonproc; 164 165 static void vm_hold_free_pages(struct buf *bp, int newbsize); 166 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 167 vm_offset_t to); 168 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 169 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 170 vm_page_t m); 171 static void vfs_clean_pages_dirty_buf(struct buf *bp); 172 static void vfs_setdirty_range(struct buf *bp); 173 static void vfs_vmio_invalidate(struct buf *bp); 174 static void vfs_vmio_truncate(struct buf *bp, int npages); 175 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 176 static int vfs_bio_clcheck(struct vnode *vp, int size, 177 daddr_t lblkno, daddr_t blkno); 178 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int, 179 void (*)(struct buf *)); 180 static int buf_flush(struct vnode *vp, struct bufdomain *, int); 181 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int); 182 static void buf_daemon(void); 183 static __inline void bd_wakeup(void); 184 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 185 static void bufkva_reclaim(vmem_t *, int); 186 static void bufkva_free(struct buf *); 187 static int buf_import(void *, void **, int, int, int); 188 static void buf_release(void *, void **, int); 189 static void maxbcachebuf_adjust(void); 190 static inline struct bufdomain *bufdomain(struct buf *); 191 static void bq_remove(struct bufqueue *bq, struct buf *bp); 192 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock); 193 static int buf_recycle(struct bufdomain *, bool kva); 194 static void bq_init(struct bufqueue *bq, int qindex, int cpu, 195 const char *lockname); 196 static void bd_init(struct bufdomain *bd); 197 static int bd_flushall(struct bufdomain *bd); 198 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS); 199 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS); 200 201 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 202 int vmiodirenable = TRUE; 203 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 204 "Use the VM system for directory writes"); 205 long runningbufspace; 206 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 207 "Amount of presently outstanding async buffer io"); 208 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 209 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers"); 210 static counter_u64_t bufkvaspace; 211 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 212 "Kernel virtual memory used for buffers"); 213 static long maxbufspace; 214 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace, 215 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace, 216 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L", 217 "Maximum allowed value of bufspace (including metadata)"); 218 static long bufmallocspace; 219 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 220 "Amount of malloced memory for buffers"); 221 static long maxbufmallocspace; 222 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 223 0, "Maximum amount of malloced memory for buffers"); 224 static long lobufspace; 225 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace, 226 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace, 227 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L", 228 "Minimum amount of buffers we want to have"); 229 long hibufspace; 230 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace, 231 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace, 232 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L", 233 "Maximum allowed value of bufspace (excluding metadata)"); 234 long bufspacethresh; 235 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh, 236 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh, 237 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L", 238 "Bufspace consumed before waking the daemon to free some"); 239 static counter_u64_t buffreekvacnt; 240 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 241 "Number of times we have freed the KVA space from some buffer"); 242 static counter_u64_t bufdefragcnt; 243 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 244 "Number of times we have had to repeat buffer allocation to defragment"); 245 static long lorunningspace; 246 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 247 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 248 "Minimum preferred space used for in-progress I/O"); 249 static long hirunningspace; 250 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 251 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 252 "Maximum amount of space to use for in-progress I/O"); 253 int dirtybufferflushes; 254 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 255 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 256 int bdwriteskip; 257 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 258 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 259 int altbufferflushes; 260 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW | CTLFLAG_STATS, 261 &altbufferflushes, 0, "Number of fsync flushes to limit dirty buffers"); 262 static int recursiveflushes; 263 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW | CTLFLAG_STATS, 264 &recursiveflushes, 0, "Number of flushes skipped due to being recursive"); 265 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS); 266 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers, 267 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I", 268 "Number of buffers that are dirty (has unwritten changes) at the moment"); 269 static int lodirtybuffers; 270 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers, 271 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers, 272 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I", 273 "How many buffers we want to have free before bufdaemon can sleep"); 274 static int hidirtybuffers; 275 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers, 276 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers, 277 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I", 278 "When the number of dirty buffers is considered severe"); 279 int dirtybufthresh; 280 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh, 281 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh, 282 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I", 283 "Number of bdwrite to bawrite conversions to clear dirty buffers"); 284 static int numfreebuffers; 285 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 286 "Number of free buffers"); 287 static int lofreebuffers; 288 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers, 289 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers, 290 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I", 291 "Target number of free buffers"); 292 static int hifreebuffers; 293 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers, 294 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers, 295 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I", 296 "Threshold for clean buffer recycling"); 297 static counter_u64_t getnewbufcalls; 298 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, 299 &getnewbufcalls, "Number of calls to getnewbuf"); 300 static counter_u64_t getnewbufrestarts; 301 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, 302 &getnewbufrestarts, 303 "Number of times getnewbuf has had to restart a buffer acquisition"); 304 static counter_u64_t mappingrestarts; 305 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD, 306 &mappingrestarts, 307 "Number of times getblk has had to restart a buffer mapping for " 308 "unmapped buffer"); 309 static counter_u64_t numbufallocfails; 310 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, 311 &numbufallocfails, "Number of times buffer allocations failed"); 312 static int flushbufqtarget = 100; 313 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 314 "Amount of work to do in flushbufqueues when helping bufdaemon"); 315 static counter_u64_t notbufdflushes; 316 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 317 "Number of dirty buffer flushes done by the bufdaemon helpers"); 318 static long barrierwrites; 319 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW | CTLFLAG_STATS, 320 &barrierwrites, 0, "Number of barrier writes"); 321 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 322 &unmapped_buf_allowed, 0, 323 "Permit the use of the unmapped i/o"); 324 int maxbcachebuf = MAXBCACHEBUF; 325 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0, 326 "Maximum size of a buffer cache block"); 327 328 /* 329 * This lock synchronizes access to bd_request. 330 */ 331 static struct mtx_padalign __exclusive_cache_line bdlock; 332 333 /* 334 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 335 * waitrunningbufspace(). 336 */ 337 static struct mtx_padalign __exclusive_cache_line rbreqlock; 338 339 /* 340 * Lock that protects bdirtywait. 341 */ 342 static struct mtx_padalign __exclusive_cache_line bdirtylock; 343 344 /* 345 * bufdaemon shutdown request and sleep channel. 346 */ 347 static bool bd_shutdown; 348 349 /* 350 * Wakeup point for bufdaemon, as well as indicator of whether it is already 351 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 352 * is idling. 353 */ 354 static int bd_request; 355 356 /* 357 * Request for the buf daemon to write more buffers than is indicated by 358 * lodirtybuf. This may be necessary to push out excess dependencies or 359 * defragment the address space where a simple count of the number of dirty 360 * buffers is insufficient to characterize the demand for flushing them. 361 */ 362 static int bd_speedupreq; 363 364 /* 365 * Synchronization (sleep/wakeup) variable for active buffer space requests. 366 * Set when wait starts, cleared prior to wakeup(). 367 * Used in runningbufwakeup() and waitrunningbufspace(). 368 */ 369 static int runningbufreq; 370 371 /* 372 * Synchronization for bwillwrite() waiters. 373 */ 374 static int bdirtywait; 375 376 /* 377 * Definitions for the buffer free lists. 378 */ 379 #define QUEUE_NONE 0 /* on no queue */ 380 #define QUEUE_EMPTY 1 /* empty buffer headers */ 381 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 382 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 383 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */ 384 385 /* Maximum number of buffer domains. */ 386 #define BUF_DOMAINS 8 387 388 struct bufdomainset bdlodirty; /* Domains > lodirty */ 389 struct bufdomainset bdhidirty; /* Domains > hidirty */ 390 391 /* Configured number of clean queues. */ 392 static int __read_mostly buf_domains; 393 394 BITSET_DEFINE(bufdomainset, BUF_DOMAINS); 395 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS]; 396 struct bufqueue __exclusive_cache_line bqempty; 397 398 /* 399 * per-cpu empty buffer cache. 400 */ 401 uma_zone_t buf_zone; 402 403 static int 404 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 405 { 406 long value; 407 int error; 408 409 value = *(long *)arg1; 410 error = sysctl_handle_long(oidp, &value, 0, req); 411 if (error != 0 || req->newptr == NULL) 412 return (error); 413 mtx_lock(&rbreqlock); 414 if (arg1 == &hirunningspace) { 415 if (value < lorunningspace) 416 error = EINVAL; 417 else 418 hirunningspace = value; 419 } else { 420 KASSERT(arg1 == &lorunningspace, 421 ("%s: unknown arg1", __func__)); 422 if (value > hirunningspace) 423 error = EINVAL; 424 else 425 lorunningspace = value; 426 } 427 mtx_unlock(&rbreqlock); 428 return (error); 429 } 430 431 static int 432 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS) 433 { 434 int error; 435 int value; 436 int i; 437 438 value = *(int *)arg1; 439 error = sysctl_handle_int(oidp, &value, 0, req); 440 if (error != 0 || req->newptr == NULL) 441 return (error); 442 *(int *)arg1 = value; 443 for (i = 0; i < buf_domains; i++) 444 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 445 value / buf_domains; 446 447 return (error); 448 } 449 450 static int 451 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS) 452 { 453 long value; 454 int error; 455 int i; 456 457 value = *(long *)arg1; 458 error = sysctl_handle_long(oidp, &value, 0, req); 459 if (error != 0 || req->newptr == NULL) 460 return (error); 461 *(long *)arg1 = value; 462 for (i = 0; i < buf_domains; i++) 463 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 464 value / buf_domains; 465 466 return (error); 467 } 468 469 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 470 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 471 static int 472 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 473 { 474 long lvalue; 475 int ivalue; 476 int i; 477 478 lvalue = 0; 479 for (i = 0; i < buf_domains; i++) 480 lvalue += bdomain[i].bd_bufspace; 481 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 482 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 483 if (lvalue > INT_MAX) 484 /* On overflow, still write out a long to trigger ENOMEM. */ 485 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 486 ivalue = lvalue; 487 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 488 } 489 #else 490 static int 491 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 492 { 493 long lvalue; 494 int i; 495 496 lvalue = 0; 497 for (i = 0; i < buf_domains; i++) 498 lvalue += bdomain[i].bd_bufspace; 499 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 500 } 501 #endif 502 503 static int 504 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS) 505 { 506 int value; 507 int i; 508 509 value = 0; 510 for (i = 0; i < buf_domains; i++) 511 value += bdomain[i].bd_numdirtybuffers; 512 return (sysctl_handle_int(oidp, &value, 0, req)); 513 } 514 515 /* 516 * bdirtywakeup: 517 * 518 * Wakeup any bwillwrite() waiters. 519 */ 520 static void 521 bdirtywakeup(void) 522 { 523 mtx_lock(&bdirtylock); 524 if (bdirtywait) { 525 bdirtywait = 0; 526 wakeup(&bdirtywait); 527 } 528 mtx_unlock(&bdirtylock); 529 } 530 531 /* 532 * bd_clear: 533 * 534 * Clear a domain from the appropriate bitsets when dirtybuffers 535 * is decremented. 536 */ 537 static void 538 bd_clear(struct bufdomain *bd) 539 { 540 541 mtx_lock(&bdirtylock); 542 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers) 543 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 544 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers) 545 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 546 mtx_unlock(&bdirtylock); 547 } 548 549 /* 550 * bd_set: 551 * 552 * Set a domain in the appropriate bitsets when dirtybuffers 553 * is incremented. 554 */ 555 static void 556 bd_set(struct bufdomain *bd) 557 { 558 559 mtx_lock(&bdirtylock); 560 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers) 561 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 562 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers) 563 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 564 mtx_unlock(&bdirtylock); 565 } 566 567 /* 568 * bdirtysub: 569 * 570 * Decrement the numdirtybuffers count by one and wakeup any 571 * threads blocked in bwillwrite(). 572 */ 573 static void 574 bdirtysub(struct buf *bp) 575 { 576 struct bufdomain *bd; 577 int num; 578 579 bd = bufdomain(bp); 580 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1); 581 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 582 bdirtywakeup(); 583 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 584 bd_clear(bd); 585 } 586 587 /* 588 * bdirtyadd: 589 * 590 * Increment the numdirtybuffers count by one and wakeup the buf 591 * daemon if needed. 592 */ 593 static void 594 bdirtyadd(struct buf *bp) 595 { 596 struct bufdomain *bd; 597 int num; 598 599 /* 600 * Only do the wakeup once as we cross the boundary. The 601 * buf daemon will keep running until the condition clears. 602 */ 603 bd = bufdomain(bp); 604 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1); 605 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 606 bd_wakeup(); 607 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 608 bd_set(bd); 609 } 610 611 /* 612 * bufspace_daemon_wakeup: 613 * 614 * Wakeup the daemons responsible for freeing clean bufs. 615 */ 616 static void 617 bufspace_daemon_wakeup(struct bufdomain *bd) 618 { 619 620 /* 621 * avoid the lock if the daemon is running. 622 */ 623 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) { 624 BD_RUN_LOCK(bd); 625 atomic_store_int(&bd->bd_running, 1); 626 wakeup(&bd->bd_running); 627 BD_RUN_UNLOCK(bd); 628 } 629 } 630 631 /* 632 * bufspace_adjust: 633 * 634 * Adjust the reported bufspace for a KVA managed buffer, possibly 635 * waking any waiters. 636 */ 637 static void 638 bufspace_adjust(struct buf *bp, int bufsize) 639 { 640 struct bufdomain *bd; 641 long space; 642 int diff; 643 644 KASSERT((bp->b_flags & B_MALLOC) == 0, 645 ("bufspace_adjust: malloc buf %p", bp)); 646 bd = bufdomain(bp); 647 diff = bufsize - bp->b_bufsize; 648 if (diff < 0) { 649 atomic_subtract_long(&bd->bd_bufspace, -diff); 650 } else if (diff > 0) { 651 space = atomic_fetchadd_long(&bd->bd_bufspace, diff); 652 /* Wake up the daemon on the transition. */ 653 if (space < bd->bd_bufspacethresh && 654 space + diff >= bd->bd_bufspacethresh) 655 bufspace_daemon_wakeup(bd); 656 } 657 bp->b_bufsize = bufsize; 658 } 659 660 /* 661 * bufspace_reserve: 662 * 663 * Reserve bufspace before calling allocbuf(). metadata has a 664 * different space limit than data. 665 */ 666 static int 667 bufspace_reserve(struct bufdomain *bd, int size, bool metadata) 668 { 669 long limit, new; 670 long space; 671 672 if (metadata) 673 limit = bd->bd_maxbufspace; 674 else 675 limit = bd->bd_hibufspace; 676 space = atomic_fetchadd_long(&bd->bd_bufspace, size); 677 new = space + size; 678 if (new > limit) { 679 atomic_subtract_long(&bd->bd_bufspace, size); 680 return (ENOSPC); 681 } 682 683 /* Wake up the daemon on the transition. */ 684 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh) 685 bufspace_daemon_wakeup(bd); 686 687 return (0); 688 } 689 690 /* 691 * bufspace_release: 692 * 693 * Release reserved bufspace after bufspace_adjust() has consumed it. 694 */ 695 static void 696 bufspace_release(struct bufdomain *bd, int size) 697 { 698 699 atomic_subtract_long(&bd->bd_bufspace, size); 700 } 701 702 /* 703 * bufspace_wait: 704 * 705 * Wait for bufspace, acting as the buf daemon if a locked vnode is 706 * supplied. bd_wanted must be set prior to polling for space. The 707 * operation must be re-tried on return. 708 */ 709 static void 710 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags, 711 int slpflag, int slptimeo) 712 { 713 struct thread *td; 714 int error, fl, norunbuf; 715 716 if ((gbflags & GB_NOWAIT_BD) != 0) 717 return; 718 719 td = curthread; 720 BD_LOCK(bd); 721 while (bd->bd_wanted) { 722 if (vp != NULL && vp->v_type != VCHR && 723 (td->td_pflags & TDP_BUFNEED) == 0) { 724 BD_UNLOCK(bd); 725 /* 726 * getblk() is called with a vnode locked, and 727 * some majority of the dirty buffers may as 728 * well belong to the vnode. Flushing the 729 * buffers there would make a progress that 730 * cannot be achieved by the buf_daemon, that 731 * cannot lock the vnode. 732 */ 733 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 734 (td->td_pflags & TDP_NORUNNINGBUF); 735 736 /* 737 * Play bufdaemon. The getnewbuf() function 738 * may be called while the thread owns lock 739 * for another dirty buffer for the same 740 * vnode, which makes it impossible to use 741 * VOP_FSYNC() there, due to the buffer lock 742 * recursion. 743 */ 744 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 745 fl = buf_flush(vp, bd, flushbufqtarget); 746 td->td_pflags &= norunbuf; 747 BD_LOCK(bd); 748 if (fl != 0) 749 continue; 750 if (bd->bd_wanted == 0) 751 break; 752 } 753 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 754 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 755 if (error != 0) 756 break; 757 } 758 BD_UNLOCK(bd); 759 } 760 761 static void 762 bufspace_daemon_shutdown(void *arg, int howto __unused) 763 { 764 struct bufdomain *bd = arg; 765 int error; 766 767 BD_RUN_LOCK(bd); 768 bd->bd_shutdown = true; 769 wakeup(&bd->bd_running); 770 error = msleep(&bd->bd_shutdown, BD_RUN_LOCKPTR(bd), 0, 771 "bufspace_shutdown", 60 * hz); 772 BD_RUN_UNLOCK(bd); 773 if (error != 0) 774 printf("bufspacedaemon wait error: %d\n", error); 775 } 776 777 /* 778 * bufspace_daemon: 779 * 780 * buffer space management daemon. Tries to maintain some marginal 781 * amount of free buffer space so that requesting processes neither 782 * block nor work to reclaim buffers. 783 */ 784 static void 785 bufspace_daemon(void *arg) 786 { 787 struct bufdomain *bd = arg; 788 789 EVENTHANDLER_REGISTER(shutdown_pre_sync, bufspace_daemon_shutdown, bd, 790 SHUTDOWN_PRI_LAST + 100); 791 792 BD_RUN_LOCK(bd); 793 while (!bd->bd_shutdown) { 794 BD_RUN_UNLOCK(bd); 795 796 /* 797 * Free buffers from the clean queue until we meet our 798 * targets. 799 * 800 * Theory of operation: The buffer cache is most efficient 801 * when some free buffer headers and space are always 802 * available to getnewbuf(). This daemon attempts to prevent 803 * the excessive blocking and synchronization associated 804 * with shortfall. It goes through three phases according 805 * demand: 806 * 807 * 1) The daemon wakes up voluntarily once per-second 808 * during idle periods when the counters are below 809 * the wakeup thresholds (bufspacethresh, lofreebuffers). 810 * 811 * 2) The daemon wakes up as we cross the thresholds 812 * ahead of any potential blocking. This may bounce 813 * slightly according to the rate of consumption and 814 * release. 815 * 816 * 3) The daemon and consumers are starved for working 817 * clean buffers. This is the 'bufspace' sleep below 818 * which will inefficiently trade bufs with bqrelse 819 * until we return to condition 2. 820 */ 821 while (bd->bd_bufspace > bd->bd_lobufspace || 822 bd->bd_freebuffers < bd->bd_hifreebuffers) { 823 if (buf_recycle(bd, false) != 0) { 824 if (bd_flushall(bd)) 825 continue; 826 /* 827 * Speedup dirty if we've run out of clean 828 * buffers. This is possible in particular 829 * because softdep may held many bufs locked 830 * pending writes to other bufs which are 831 * marked for delayed write, exhausting 832 * clean space until they are written. 833 */ 834 bd_speedup(); 835 BD_LOCK(bd); 836 if (bd->bd_wanted) { 837 msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 838 PRIBIO|PDROP, "bufspace", hz/10); 839 } else 840 BD_UNLOCK(bd); 841 } 842 maybe_yield(); 843 } 844 845 /* 846 * Re-check our limits and sleep. bd_running must be 847 * cleared prior to checking the limits to avoid missed 848 * wakeups. The waker will adjust one of bufspace or 849 * freebuffers prior to checking bd_running. 850 */ 851 BD_RUN_LOCK(bd); 852 if (bd->bd_shutdown) 853 break; 854 atomic_store_int(&bd->bd_running, 0); 855 if (bd->bd_bufspace < bd->bd_bufspacethresh && 856 bd->bd_freebuffers > bd->bd_lofreebuffers) { 857 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), 858 PRIBIO, "-", hz); 859 } else { 860 /* Avoid spurious wakeups while running. */ 861 atomic_store_int(&bd->bd_running, 1); 862 } 863 } 864 wakeup(&bd->bd_shutdown); 865 BD_RUN_UNLOCK(bd); 866 kthread_exit(); 867 } 868 869 /* 870 * bufmallocadjust: 871 * 872 * Adjust the reported bufspace for a malloc managed buffer, possibly 873 * waking any waiters. 874 */ 875 static void 876 bufmallocadjust(struct buf *bp, int bufsize) 877 { 878 int diff; 879 880 KASSERT((bp->b_flags & B_MALLOC) != 0, 881 ("bufmallocadjust: non-malloc buf %p", bp)); 882 diff = bufsize - bp->b_bufsize; 883 if (diff < 0) 884 atomic_subtract_long(&bufmallocspace, -diff); 885 else 886 atomic_add_long(&bufmallocspace, diff); 887 bp->b_bufsize = bufsize; 888 } 889 890 /* 891 * runningwakeup: 892 * 893 * Wake up processes that are waiting on asynchronous writes to fall 894 * below lorunningspace. 895 */ 896 static void 897 runningwakeup(void) 898 { 899 900 mtx_lock(&rbreqlock); 901 if (runningbufreq) { 902 runningbufreq = 0; 903 wakeup(&runningbufreq); 904 } 905 mtx_unlock(&rbreqlock); 906 } 907 908 /* 909 * runningbufwakeup: 910 * 911 * Decrement the outstanding write count according. 912 */ 913 void 914 runningbufwakeup(struct buf *bp) 915 { 916 long space, bspace; 917 918 bspace = bp->b_runningbufspace; 919 if (bspace == 0) 920 return; 921 space = atomic_fetchadd_long(&runningbufspace, -bspace); 922 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 923 space, bspace)); 924 bp->b_runningbufspace = 0; 925 /* 926 * Only acquire the lock and wakeup on the transition from exceeding 927 * the threshold to falling below it. 928 */ 929 if (space < lorunningspace) 930 return; 931 if (space - bspace > lorunningspace) 932 return; 933 runningwakeup(); 934 } 935 936 /* 937 * waitrunningbufspace() 938 * 939 * runningbufspace is a measure of the amount of I/O currently 940 * running. This routine is used in async-write situations to 941 * prevent creating huge backups of pending writes to a device. 942 * Only asynchronous writes are governed by this function. 943 * 944 * This does NOT turn an async write into a sync write. It waits 945 * for earlier writes to complete and generally returns before the 946 * caller's write has reached the device. 947 */ 948 void 949 waitrunningbufspace(void) 950 { 951 952 mtx_lock(&rbreqlock); 953 while (runningbufspace > hirunningspace) { 954 runningbufreq = 1; 955 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 956 } 957 mtx_unlock(&rbreqlock); 958 } 959 960 /* 961 * vfs_buf_test_cache: 962 * 963 * Called when a buffer is extended. This function clears the B_CACHE 964 * bit if the newly extended portion of the buffer does not contain 965 * valid data. 966 */ 967 static __inline void 968 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 969 vm_offset_t size, vm_page_t m) 970 { 971 972 /* 973 * This function and its results are protected by higher level 974 * synchronization requiring vnode and buf locks to page in and 975 * validate pages. 976 */ 977 if (bp->b_flags & B_CACHE) { 978 int base = (foff + off) & PAGE_MASK; 979 if (vm_page_is_valid(m, base, size) == 0) 980 bp->b_flags &= ~B_CACHE; 981 } 982 } 983 984 /* Wake up the buffer daemon if necessary */ 985 static void 986 bd_wakeup(void) 987 { 988 989 mtx_lock(&bdlock); 990 if (bd_request == 0) { 991 bd_request = 1; 992 wakeup(&bd_request); 993 } 994 mtx_unlock(&bdlock); 995 } 996 997 /* 998 * Adjust the maxbcachbuf tunable. 999 */ 1000 static void 1001 maxbcachebuf_adjust(void) 1002 { 1003 int i; 1004 1005 /* 1006 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 1007 */ 1008 i = 2; 1009 while (i * 2 <= maxbcachebuf) 1010 i *= 2; 1011 maxbcachebuf = i; 1012 if (maxbcachebuf < MAXBSIZE) 1013 maxbcachebuf = MAXBSIZE; 1014 if (maxbcachebuf > maxphys) 1015 maxbcachebuf = maxphys; 1016 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 1017 printf("maxbcachebuf=%d\n", maxbcachebuf); 1018 } 1019 1020 /* 1021 * bd_speedup - speedup the buffer cache flushing code 1022 */ 1023 void 1024 bd_speedup(void) 1025 { 1026 int needwake; 1027 1028 mtx_lock(&bdlock); 1029 needwake = 0; 1030 if (bd_speedupreq == 0 || bd_request == 0) 1031 needwake = 1; 1032 bd_speedupreq = 1; 1033 bd_request = 1; 1034 if (needwake) 1035 wakeup(&bd_request); 1036 mtx_unlock(&bdlock); 1037 } 1038 1039 #ifdef __i386__ 1040 #define TRANSIENT_DENOM 5 1041 #else 1042 #define TRANSIENT_DENOM 10 1043 #endif 1044 1045 /* 1046 * Calculating buffer cache scaling values and reserve space for buffer 1047 * headers. This is called during low level kernel initialization and 1048 * may be called more then once. We CANNOT write to the memory area 1049 * being reserved at this time. 1050 */ 1051 caddr_t 1052 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 1053 { 1054 int tuned_nbuf; 1055 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 1056 1057 /* 1058 * With KASAN or KMSAN enabled, the kernel map is shadowed. Account for 1059 * this when sizing maps based on the amount of physical memory 1060 * available. 1061 */ 1062 #if defined(KASAN) 1063 physmem_est = (physmem_est * KASAN_SHADOW_SCALE) / 1064 (KASAN_SHADOW_SCALE + 1); 1065 #elif defined(KMSAN) 1066 physmem_est /= 3; 1067 1068 /* 1069 * KMSAN cannot reliably determine whether buffer data is initialized 1070 * unless it is updated through a KVA mapping. 1071 */ 1072 unmapped_buf_allowed = 0; 1073 #endif 1074 1075 /* 1076 * physmem_est is in pages. Convert it to kilobytes (assumes 1077 * PAGE_SIZE is >= 1K) 1078 */ 1079 physmem_est = physmem_est * (PAGE_SIZE / 1024); 1080 1081 maxbcachebuf_adjust(); 1082 /* 1083 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 1084 * For the first 64MB of ram nominally allocate sufficient buffers to 1085 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 1086 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 1087 * the buffer cache we limit the eventual kva reservation to 1088 * maxbcache bytes. 1089 * 1090 * factor represents the 1/4 x ram conversion. 1091 */ 1092 if (nbuf == 0) { 1093 int factor = 4 * BKVASIZE / 1024; 1094 1095 nbuf = 50; 1096 if (physmem_est > 4096) 1097 nbuf += min((physmem_est - 4096) / factor, 1098 65536 / factor); 1099 if (physmem_est > 65536) 1100 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 1101 32 * 1024 * 1024 / (factor * 5)); 1102 1103 if (maxbcache && nbuf > maxbcache / BKVASIZE) 1104 nbuf = maxbcache / BKVASIZE; 1105 tuned_nbuf = 1; 1106 } else 1107 tuned_nbuf = 0; 1108 1109 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 1110 maxbuf = (LONG_MAX / 3) / BKVASIZE; 1111 if (nbuf > maxbuf) { 1112 if (!tuned_nbuf) 1113 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 1114 maxbuf); 1115 nbuf = maxbuf; 1116 } 1117 1118 /* 1119 * Ideal allocation size for the transient bio submap is 10% 1120 * of the maximal space buffer map. This roughly corresponds 1121 * to the amount of the buffer mapped for typical UFS load. 1122 * 1123 * Clip the buffer map to reserve space for the transient 1124 * BIOs, if its extent is bigger than 90% (80% on i386) of the 1125 * maximum buffer map extent on the platform. 1126 * 1127 * The fall-back to the maxbuf in case of maxbcache unset, 1128 * allows to not trim the buffer KVA for the architectures 1129 * with ample KVA space. 1130 */ 1131 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 1132 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 1133 buf_sz = (long)nbuf * BKVASIZE; 1134 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 1135 (TRANSIENT_DENOM - 1)) { 1136 /* 1137 * There is more KVA than memory. Do not 1138 * adjust buffer map size, and assign the rest 1139 * of maxbuf to transient map. 1140 */ 1141 biotmap_sz = maxbuf_sz - buf_sz; 1142 } else { 1143 /* 1144 * Buffer map spans all KVA we could afford on 1145 * this platform. Give 10% (20% on i386) of 1146 * the buffer map to the transient bio map. 1147 */ 1148 biotmap_sz = buf_sz / TRANSIENT_DENOM; 1149 buf_sz -= biotmap_sz; 1150 } 1151 if (biotmap_sz / INT_MAX > maxphys) 1152 bio_transient_maxcnt = INT_MAX; 1153 else 1154 bio_transient_maxcnt = biotmap_sz / maxphys; 1155 /* 1156 * Artificially limit to 1024 simultaneous in-flight I/Os 1157 * using the transient mapping. 1158 */ 1159 if (bio_transient_maxcnt > 1024) 1160 bio_transient_maxcnt = 1024; 1161 if (tuned_nbuf) 1162 nbuf = buf_sz / BKVASIZE; 1163 } 1164 1165 if (nswbuf == 0) { 1166 nswbuf = min(nbuf / 4, 256); 1167 if (nswbuf < NSWBUF_MIN) 1168 nswbuf = NSWBUF_MIN; 1169 } 1170 1171 /* 1172 * Reserve space for the buffer cache buffers 1173 */ 1174 buf = (char *)v; 1175 v = (caddr_t)buf + (sizeof(struct buf) + sizeof(vm_page_t) * 1176 atop(maxbcachebuf)) * nbuf; 1177 1178 return (v); 1179 } 1180 1181 /* 1182 * Single global constant for BUF_WMESG, to avoid getting multiple 1183 * references. 1184 */ 1185 static const char buf_wmesg[] = "bufwait"; 1186 1187 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1188 void 1189 bufinit(void) 1190 { 1191 struct buf *bp; 1192 int i; 1193 1194 KASSERT(maxbcachebuf >= MAXBSIZE, 1195 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1196 MAXBSIZE)); 1197 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock"); 1198 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1199 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1200 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1201 1202 unmapped_buf = (caddr_t)kva_alloc(maxphys); 1203 1204 /* finally, initialize each buffer header and stick on empty q */ 1205 for (i = 0; i < nbuf; i++) { 1206 bp = nbufp(i); 1207 bzero(bp, sizeof(*bp) + sizeof(vm_page_t) * atop(maxbcachebuf)); 1208 bp->b_flags = B_INVAL; 1209 bp->b_rcred = NOCRED; 1210 bp->b_wcred = NOCRED; 1211 bp->b_qindex = QUEUE_NONE; 1212 bp->b_domain = -1; 1213 bp->b_subqueue = mp_maxid + 1; 1214 bp->b_xflags = 0; 1215 bp->b_data = bp->b_kvabase = unmapped_buf; 1216 LIST_INIT(&bp->b_dep); 1217 BUF_LOCKINIT(bp, buf_wmesg); 1218 bq_insert(&bqempty, bp, false); 1219 } 1220 1221 /* 1222 * maxbufspace is the absolute maximum amount of buffer space we are 1223 * allowed to reserve in KVM and in real terms. The absolute maximum 1224 * is nominally used by metadata. hibufspace is the nominal maximum 1225 * used by most other requests. The differential is required to 1226 * ensure that metadata deadlocks don't occur. 1227 * 1228 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1229 * this may result in KVM fragmentation which is not handled optimally 1230 * by the system. XXX This is less true with vmem. We could use 1231 * PAGE_SIZE. 1232 */ 1233 maxbufspace = (long)nbuf * BKVASIZE; 1234 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1235 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1236 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1237 1238 /* 1239 * Note: The 16 MiB upper limit for hirunningspace was chosen 1240 * arbitrarily and may need further tuning. It corresponds to 1241 * 128 outstanding write IO requests (if IO size is 128 KiB), 1242 * which fits with many RAID controllers' tagged queuing limits. 1243 * The lower 1 MiB limit is the historical upper limit for 1244 * hirunningspace. 1245 */ 1246 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1247 16 * 1024 * 1024), 1024 * 1024); 1248 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1249 1250 /* 1251 * Limit the amount of malloc memory since it is wired permanently into 1252 * the kernel space. Even though this is accounted for in the buffer 1253 * allocation, we don't want the malloced region to grow uncontrolled. 1254 * The malloc scheme improves memory utilization significantly on 1255 * average (small) directories. 1256 */ 1257 maxbufmallocspace = hibufspace / 20; 1258 1259 /* 1260 * Reduce the chance of a deadlock occurring by limiting the number 1261 * of delayed-write dirty buffers we allow to stack up. 1262 */ 1263 hidirtybuffers = nbuf / 4 + 20; 1264 dirtybufthresh = hidirtybuffers * 9 / 10; 1265 /* 1266 * To support extreme low-memory systems, make sure hidirtybuffers 1267 * cannot eat up all available buffer space. This occurs when our 1268 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1269 * buffer space assuming BKVASIZE'd buffers. 1270 */ 1271 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1272 hidirtybuffers >>= 1; 1273 } 1274 lodirtybuffers = hidirtybuffers / 2; 1275 1276 /* 1277 * lofreebuffers should be sufficient to avoid stalling waiting on 1278 * buf headers under heavy utilization. The bufs in per-cpu caches 1279 * are counted as free but will be unavailable to threads executing 1280 * on other cpus. 1281 * 1282 * hifreebuffers is the free target for the bufspace daemon. This 1283 * should be set appropriately to limit work per-iteration. 1284 */ 1285 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1286 hifreebuffers = (3 * lofreebuffers) / 2; 1287 numfreebuffers = nbuf; 1288 1289 /* Setup the kva and free list allocators. */ 1290 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1291 buf_zone = uma_zcache_create("buf free cache", 1292 sizeof(struct buf) + sizeof(vm_page_t) * atop(maxbcachebuf), 1293 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1294 1295 /* 1296 * Size the clean queue according to the amount of buffer space. 1297 * One queue per-256mb up to the max. More queues gives better 1298 * concurrency but less accurate LRU. 1299 */ 1300 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS); 1301 for (i = 0 ; i < buf_domains; i++) { 1302 struct bufdomain *bd; 1303 1304 bd = &bdomain[i]; 1305 bd_init(bd); 1306 bd->bd_freebuffers = nbuf / buf_domains; 1307 bd->bd_hifreebuffers = hifreebuffers / buf_domains; 1308 bd->bd_lofreebuffers = lofreebuffers / buf_domains; 1309 bd->bd_bufspace = 0; 1310 bd->bd_maxbufspace = maxbufspace / buf_domains; 1311 bd->bd_hibufspace = hibufspace / buf_domains; 1312 bd->bd_lobufspace = lobufspace / buf_domains; 1313 bd->bd_bufspacethresh = bufspacethresh / buf_domains; 1314 bd->bd_numdirtybuffers = 0; 1315 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains; 1316 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains; 1317 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains; 1318 /* Don't allow more than 2% of bufs in the per-cpu caches. */ 1319 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus; 1320 } 1321 getnewbufcalls = counter_u64_alloc(M_WAITOK); 1322 getnewbufrestarts = counter_u64_alloc(M_WAITOK); 1323 mappingrestarts = counter_u64_alloc(M_WAITOK); 1324 numbufallocfails = counter_u64_alloc(M_WAITOK); 1325 notbufdflushes = counter_u64_alloc(M_WAITOK); 1326 buffreekvacnt = counter_u64_alloc(M_WAITOK); 1327 bufdefragcnt = counter_u64_alloc(M_WAITOK); 1328 bufkvaspace = counter_u64_alloc(M_WAITOK); 1329 } 1330 1331 #ifdef INVARIANTS 1332 static inline void 1333 vfs_buf_check_mapped(struct buf *bp) 1334 { 1335 1336 KASSERT(bp->b_kvabase != unmapped_buf, 1337 ("mapped buf: b_kvabase was not updated %p", bp)); 1338 KASSERT(bp->b_data != unmapped_buf, 1339 ("mapped buf: b_data was not updated %p", bp)); 1340 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1341 maxphys, ("b_data + b_offset unmapped %p", bp)); 1342 } 1343 1344 static inline void 1345 vfs_buf_check_unmapped(struct buf *bp) 1346 { 1347 1348 KASSERT(bp->b_data == unmapped_buf, 1349 ("unmapped buf: corrupted b_data %p", bp)); 1350 } 1351 1352 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1353 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1354 #else 1355 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1356 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1357 #endif 1358 1359 static int 1360 isbufbusy(struct buf *bp) 1361 { 1362 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1363 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1364 return (1); 1365 return (0); 1366 } 1367 1368 /* 1369 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1370 */ 1371 void 1372 bufshutdown(int show_busybufs) 1373 { 1374 static int first_buf_printf = 1; 1375 struct buf *bp; 1376 int i, iter, nbusy, pbusy; 1377 #ifndef PREEMPTION 1378 int subiter; 1379 #endif 1380 1381 /* 1382 * Sync filesystems for shutdown 1383 */ 1384 wdog_kern_pat(WD_LASTVAL); 1385 kern_sync(curthread); 1386 1387 /* 1388 * With soft updates, some buffers that are 1389 * written will be remarked as dirty until other 1390 * buffers are written. 1391 */ 1392 for (iter = pbusy = 0; iter < 20; iter++) { 1393 nbusy = 0; 1394 for (i = nbuf - 1; i >= 0; i--) { 1395 bp = nbufp(i); 1396 if (isbufbusy(bp)) 1397 nbusy++; 1398 } 1399 if (nbusy == 0) { 1400 if (first_buf_printf) 1401 printf("All buffers synced."); 1402 break; 1403 } 1404 if (first_buf_printf) { 1405 printf("Syncing disks, buffers remaining... "); 1406 first_buf_printf = 0; 1407 } 1408 printf("%d ", nbusy); 1409 if (nbusy < pbusy) 1410 iter = 0; 1411 pbusy = nbusy; 1412 1413 wdog_kern_pat(WD_LASTVAL); 1414 kern_sync(curthread); 1415 1416 #ifdef PREEMPTION 1417 /* 1418 * Spin for a while to allow interrupt threads to run. 1419 */ 1420 DELAY(50000 * iter); 1421 #else 1422 /* 1423 * Context switch several times to allow interrupt 1424 * threads to run. 1425 */ 1426 for (subiter = 0; subiter < 50 * iter; subiter++) { 1427 thread_lock(curthread); 1428 mi_switch(SW_VOL); 1429 DELAY(1000); 1430 } 1431 #endif 1432 } 1433 printf("\n"); 1434 /* 1435 * Count only busy local buffers to prevent forcing 1436 * a fsck if we're just a client of a wedged NFS server 1437 */ 1438 nbusy = 0; 1439 for (i = nbuf - 1; i >= 0; i--) { 1440 bp = nbufp(i); 1441 if (isbufbusy(bp)) { 1442 #if 0 1443 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1444 if (bp->b_dev == NULL) { 1445 TAILQ_REMOVE(&mountlist, 1446 bp->b_vp->v_mount, mnt_list); 1447 continue; 1448 } 1449 #endif 1450 nbusy++; 1451 if (show_busybufs > 0) { 1452 printf( 1453 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1454 nbusy, bp, bp->b_vp, bp->b_flags, 1455 (intmax_t)bp->b_blkno, 1456 (intmax_t)bp->b_lblkno); 1457 BUF_LOCKPRINTINFO(bp); 1458 if (show_busybufs > 1) 1459 vn_printf(bp->b_vp, 1460 "vnode content: "); 1461 } 1462 } 1463 } 1464 if (nbusy) { 1465 /* 1466 * Failed to sync all blocks. Indicate this and don't 1467 * unmount filesystems (thus forcing an fsck on reboot). 1468 */ 1469 printf("Giving up on %d buffers\n", nbusy); 1470 DELAY(5000000); /* 5 seconds */ 1471 swapoff_all(); 1472 } else { 1473 if (!first_buf_printf) 1474 printf("Final sync complete\n"); 1475 1476 /* 1477 * Unmount filesystems and perform swapoff, to quiesce 1478 * the system as much as possible. In particular, no 1479 * I/O should be initiated from top levels since it 1480 * might be abruptly terminated by reset, or otherwise 1481 * erronously handled because other parts of the 1482 * system are disabled. 1483 * 1484 * Swapoff before unmount, because file-backed swap is 1485 * non-operational after unmount of the underlying 1486 * filesystem. 1487 */ 1488 if (!KERNEL_PANICKED()) { 1489 swapoff_all(); 1490 vfs_unmountall(); 1491 } 1492 } 1493 DELAY(100000); /* wait for console output to finish */ 1494 } 1495 1496 static void 1497 bpmap_qenter(struct buf *bp) 1498 { 1499 1500 BUF_CHECK_MAPPED(bp); 1501 1502 /* 1503 * bp->b_data is relative to bp->b_offset, but 1504 * bp->b_offset may be offset into the first page. 1505 */ 1506 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1507 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1508 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1509 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1510 } 1511 1512 static inline struct bufdomain * 1513 bufdomain(struct buf *bp) 1514 { 1515 1516 return (&bdomain[bp->b_domain]); 1517 } 1518 1519 static struct bufqueue * 1520 bufqueue(struct buf *bp) 1521 { 1522 1523 switch (bp->b_qindex) { 1524 case QUEUE_NONE: 1525 /* FALLTHROUGH */ 1526 case QUEUE_SENTINEL: 1527 return (NULL); 1528 case QUEUE_EMPTY: 1529 return (&bqempty); 1530 case QUEUE_DIRTY: 1531 return (&bufdomain(bp)->bd_dirtyq); 1532 case QUEUE_CLEAN: 1533 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]); 1534 default: 1535 break; 1536 } 1537 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex); 1538 } 1539 1540 /* 1541 * Return the locked bufqueue that bp is a member of. 1542 */ 1543 static struct bufqueue * 1544 bufqueue_acquire(struct buf *bp) 1545 { 1546 struct bufqueue *bq, *nbq; 1547 1548 /* 1549 * bp can be pushed from a per-cpu queue to the 1550 * cleanq while we're waiting on the lock. Retry 1551 * if the queues don't match. 1552 */ 1553 bq = bufqueue(bp); 1554 BQ_LOCK(bq); 1555 for (;;) { 1556 nbq = bufqueue(bp); 1557 if (bq == nbq) 1558 break; 1559 BQ_UNLOCK(bq); 1560 BQ_LOCK(nbq); 1561 bq = nbq; 1562 } 1563 return (bq); 1564 } 1565 1566 /* 1567 * binsfree: 1568 * 1569 * Insert the buffer into the appropriate free list. Requires a 1570 * locked buffer on entry and buffer is unlocked before return. 1571 */ 1572 static void 1573 binsfree(struct buf *bp, int qindex) 1574 { 1575 struct bufdomain *bd; 1576 struct bufqueue *bq; 1577 1578 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY, 1579 ("binsfree: Invalid qindex %d", qindex)); 1580 BUF_ASSERT_XLOCKED(bp); 1581 1582 /* 1583 * Handle delayed bremfree() processing. 1584 */ 1585 if (bp->b_flags & B_REMFREE) { 1586 if (bp->b_qindex == qindex) { 1587 bp->b_flags |= B_REUSE; 1588 bp->b_flags &= ~B_REMFREE; 1589 BUF_UNLOCK(bp); 1590 return; 1591 } 1592 bq = bufqueue_acquire(bp); 1593 bq_remove(bq, bp); 1594 BQ_UNLOCK(bq); 1595 } 1596 bd = bufdomain(bp); 1597 if (qindex == QUEUE_CLEAN) { 1598 if (bd->bd_lim != 0) 1599 bq = &bd->bd_subq[PCPU_GET(cpuid)]; 1600 else 1601 bq = bd->bd_cleanq; 1602 } else 1603 bq = &bd->bd_dirtyq; 1604 bq_insert(bq, bp, true); 1605 } 1606 1607 /* 1608 * buf_free: 1609 * 1610 * Free a buffer to the buf zone once it no longer has valid contents. 1611 */ 1612 static void 1613 buf_free(struct buf *bp) 1614 { 1615 1616 if (bp->b_flags & B_REMFREE) 1617 bremfreef(bp); 1618 if (bp->b_vflags & BV_BKGRDINPROG) 1619 panic("losing buffer 1"); 1620 if (bp->b_rcred != NOCRED) { 1621 crfree(bp->b_rcred); 1622 bp->b_rcred = NOCRED; 1623 } 1624 if (bp->b_wcred != NOCRED) { 1625 crfree(bp->b_wcred); 1626 bp->b_wcred = NOCRED; 1627 } 1628 if (!LIST_EMPTY(&bp->b_dep)) 1629 buf_deallocate(bp); 1630 bufkva_free(bp); 1631 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1); 1632 MPASS((bp->b_flags & B_MAXPHYS) == 0); 1633 BUF_UNLOCK(bp); 1634 uma_zfree(buf_zone, bp); 1635 } 1636 1637 /* 1638 * buf_import: 1639 * 1640 * Import bufs into the uma cache from the buf list. The system still 1641 * expects a static array of bufs and much of the synchronization 1642 * around bufs assumes type stable storage. As a result, UMA is used 1643 * only as a per-cpu cache of bufs still maintained on a global list. 1644 */ 1645 static int 1646 buf_import(void *arg, void **store, int cnt, int domain, int flags) 1647 { 1648 struct buf *bp; 1649 int i; 1650 1651 BQ_LOCK(&bqempty); 1652 for (i = 0; i < cnt; i++) { 1653 bp = TAILQ_FIRST(&bqempty.bq_queue); 1654 if (bp == NULL) 1655 break; 1656 bq_remove(&bqempty, bp); 1657 store[i] = bp; 1658 } 1659 BQ_UNLOCK(&bqempty); 1660 1661 return (i); 1662 } 1663 1664 /* 1665 * buf_release: 1666 * 1667 * Release bufs from the uma cache back to the buffer queues. 1668 */ 1669 static void 1670 buf_release(void *arg, void **store, int cnt) 1671 { 1672 struct bufqueue *bq; 1673 struct buf *bp; 1674 int i; 1675 1676 bq = &bqempty; 1677 BQ_LOCK(bq); 1678 for (i = 0; i < cnt; i++) { 1679 bp = store[i]; 1680 /* Inline bq_insert() to batch locking. */ 1681 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1682 bp->b_flags &= ~(B_AGE | B_REUSE); 1683 bq->bq_len++; 1684 bp->b_qindex = bq->bq_index; 1685 } 1686 BQ_UNLOCK(bq); 1687 } 1688 1689 /* 1690 * buf_alloc: 1691 * 1692 * Allocate an empty buffer header. 1693 */ 1694 static struct buf * 1695 buf_alloc(struct bufdomain *bd) 1696 { 1697 struct buf *bp; 1698 int freebufs, error; 1699 1700 /* 1701 * We can only run out of bufs in the buf zone if the average buf 1702 * is less than BKVASIZE. In this case the actual wait/block will 1703 * come from buf_reycle() failing to flush one of these small bufs. 1704 */ 1705 bp = NULL; 1706 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1); 1707 if (freebufs > 0) 1708 bp = uma_zalloc(buf_zone, M_NOWAIT); 1709 if (bp == NULL) { 1710 atomic_add_int(&bd->bd_freebuffers, 1); 1711 bufspace_daemon_wakeup(bd); 1712 counter_u64_add(numbufallocfails, 1); 1713 return (NULL); 1714 } 1715 /* 1716 * Wake-up the bufspace daemon on transition below threshold. 1717 */ 1718 if (freebufs == bd->bd_lofreebuffers) 1719 bufspace_daemon_wakeup(bd); 1720 1721 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 1722 KASSERT(error == 0, ("%s: BUF_LOCK on free buf %p: %d.", __func__, bp, 1723 error)); 1724 (void)error; 1725 1726 KASSERT(bp->b_vp == NULL, 1727 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1728 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1729 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1730 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1731 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1732 KASSERT(bp->b_npages == 0, 1733 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1734 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1735 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1736 MPASS((bp->b_flags & B_MAXPHYS) == 0); 1737 1738 bp->b_domain = BD_DOMAIN(bd); 1739 bp->b_flags = 0; 1740 bp->b_ioflags = 0; 1741 bp->b_xflags = 0; 1742 bp->b_vflags = 0; 1743 bp->b_vp = NULL; 1744 bp->b_blkno = bp->b_lblkno = 0; 1745 bp->b_offset = NOOFFSET; 1746 bp->b_iodone = 0; 1747 bp->b_error = 0; 1748 bp->b_resid = 0; 1749 bp->b_bcount = 0; 1750 bp->b_npages = 0; 1751 bp->b_dirtyoff = bp->b_dirtyend = 0; 1752 bp->b_bufobj = NULL; 1753 bp->b_data = bp->b_kvabase = unmapped_buf; 1754 bp->b_fsprivate1 = NULL; 1755 bp->b_fsprivate2 = NULL; 1756 bp->b_fsprivate3 = NULL; 1757 LIST_INIT(&bp->b_dep); 1758 1759 return (bp); 1760 } 1761 1762 /* 1763 * buf_recycle: 1764 * 1765 * Free a buffer from the given bufqueue. kva controls whether the 1766 * freed buf must own some kva resources. This is used for 1767 * defragmenting. 1768 */ 1769 static int 1770 buf_recycle(struct bufdomain *bd, bool kva) 1771 { 1772 struct bufqueue *bq; 1773 struct buf *bp, *nbp; 1774 1775 if (kva) 1776 counter_u64_add(bufdefragcnt, 1); 1777 nbp = NULL; 1778 bq = bd->bd_cleanq; 1779 BQ_LOCK(bq); 1780 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd), 1781 ("buf_recycle: Locks don't match")); 1782 nbp = TAILQ_FIRST(&bq->bq_queue); 1783 1784 /* 1785 * Run scan, possibly freeing data and/or kva mappings on the fly 1786 * depending. 1787 */ 1788 while ((bp = nbp) != NULL) { 1789 /* 1790 * Calculate next bp (we can only use it if we do not 1791 * release the bqlock). 1792 */ 1793 nbp = TAILQ_NEXT(bp, b_freelist); 1794 1795 /* 1796 * If we are defragging then we need a buffer with 1797 * some kva to reclaim. 1798 */ 1799 if (kva && bp->b_kvasize == 0) 1800 continue; 1801 1802 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1803 continue; 1804 1805 /* 1806 * Implement a second chance algorithm for frequently 1807 * accessed buffers. 1808 */ 1809 if ((bp->b_flags & B_REUSE) != 0) { 1810 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1811 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1812 bp->b_flags &= ~B_REUSE; 1813 BUF_UNLOCK(bp); 1814 continue; 1815 } 1816 1817 /* 1818 * Skip buffers with background writes in progress. 1819 */ 1820 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1821 BUF_UNLOCK(bp); 1822 continue; 1823 } 1824 1825 KASSERT(bp->b_qindex == QUEUE_CLEAN, 1826 ("buf_recycle: inconsistent queue %d bp %p", 1827 bp->b_qindex, bp)); 1828 KASSERT(bp->b_domain == BD_DOMAIN(bd), 1829 ("getnewbuf: queue domain %d doesn't match request %d", 1830 bp->b_domain, (int)BD_DOMAIN(bd))); 1831 /* 1832 * NOTE: nbp is now entirely invalid. We can only restart 1833 * the scan from this point on. 1834 */ 1835 bq_remove(bq, bp); 1836 BQ_UNLOCK(bq); 1837 1838 /* 1839 * Requeue the background write buffer with error and 1840 * restart the scan. 1841 */ 1842 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1843 bqrelse(bp); 1844 BQ_LOCK(bq); 1845 nbp = TAILQ_FIRST(&bq->bq_queue); 1846 continue; 1847 } 1848 bp->b_flags |= B_INVAL; 1849 brelse(bp); 1850 return (0); 1851 } 1852 bd->bd_wanted = 1; 1853 BQ_UNLOCK(bq); 1854 1855 return (ENOBUFS); 1856 } 1857 1858 /* 1859 * bremfree: 1860 * 1861 * Mark the buffer for removal from the appropriate free list. 1862 * 1863 */ 1864 void 1865 bremfree(struct buf *bp) 1866 { 1867 1868 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1869 KASSERT((bp->b_flags & B_REMFREE) == 0, 1870 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1871 KASSERT(bp->b_qindex != QUEUE_NONE, 1872 ("bremfree: buffer %p not on a queue.", bp)); 1873 BUF_ASSERT_XLOCKED(bp); 1874 1875 bp->b_flags |= B_REMFREE; 1876 } 1877 1878 /* 1879 * bremfreef: 1880 * 1881 * Force an immediate removal from a free list. Used only in nfs when 1882 * it abuses the b_freelist pointer. 1883 */ 1884 void 1885 bremfreef(struct buf *bp) 1886 { 1887 struct bufqueue *bq; 1888 1889 bq = bufqueue_acquire(bp); 1890 bq_remove(bq, bp); 1891 BQ_UNLOCK(bq); 1892 } 1893 1894 static void 1895 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname) 1896 { 1897 1898 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF); 1899 TAILQ_INIT(&bq->bq_queue); 1900 bq->bq_len = 0; 1901 bq->bq_index = qindex; 1902 bq->bq_subqueue = subqueue; 1903 } 1904 1905 static void 1906 bd_init(struct bufdomain *bd) 1907 { 1908 int i; 1909 1910 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1]; 1911 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock"); 1912 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock"); 1913 for (i = 0; i <= mp_maxid; i++) 1914 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i, 1915 "bufq clean subqueue lock"); 1916 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF); 1917 } 1918 1919 /* 1920 * bq_remove: 1921 * 1922 * Removes a buffer from the free list, must be called with the 1923 * correct qlock held. 1924 */ 1925 static void 1926 bq_remove(struct bufqueue *bq, struct buf *bp) 1927 { 1928 1929 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X", 1930 bp, bp->b_vp, bp->b_flags); 1931 KASSERT(bp->b_qindex != QUEUE_NONE, 1932 ("bq_remove: buffer %p not on a queue.", bp)); 1933 KASSERT(bufqueue(bp) == bq, 1934 ("bq_remove: Remove buffer %p from wrong queue.", bp)); 1935 1936 BQ_ASSERT_LOCKED(bq); 1937 if (bp->b_qindex != QUEUE_EMPTY) { 1938 BUF_ASSERT_XLOCKED(bp); 1939 } 1940 KASSERT(bq->bq_len >= 1, 1941 ("queue %d underflow", bp->b_qindex)); 1942 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1943 bq->bq_len--; 1944 bp->b_qindex = QUEUE_NONE; 1945 bp->b_flags &= ~(B_REMFREE | B_REUSE); 1946 } 1947 1948 static void 1949 bd_flush(struct bufdomain *bd, struct bufqueue *bq) 1950 { 1951 struct buf *bp; 1952 1953 BQ_ASSERT_LOCKED(bq); 1954 if (bq != bd->bd_cleanq) { 1955 BD_LOCK(bd); 1956 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) { 1957 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1958 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp, 1959 b_freelist); 1960 bp->b_subqueue = bd->bd_cleanq->bq_subqueue; 1961 } 1962 bd->bd_cleanq->bq_len += bq->bq_len; 1963 bq->bq_len = 0; 1964 } 1965 if (bd->bd_wanted) { 1966 bd->bd_wanted = 0; 1967 wakeup(&bd->bd_wanted); 1968 } 1969 if (bq != bd->bd_cleanq) 1970 BD_UNLOCK(bd); 1971 } 1972 1973 static int 1974 bd_flushall(struct bufdomain *bd) 1975 { 1976 struct bufqueue *bq; 1977 int flushed; 1978 int i; 1979 1980 if (bd->bd_lim == 0) 1981 return (0); 1982 flushed = 0; 1983 for (i = 0; i <= mp_maxid; i++) { 1984 bq = &bd->bd_subq[i]; 1985 if (bq->bq_len == 0) 1986 continue; 1987 BQ_LOCK(bq); 1988 bd_flush(bd, bq); 1989 BQ_UNLOCK(bq); 1990 flushed++; 1991 } 1992 1993 return (flushed); 1994 } 1995 1996 static void 1997 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock) 1998 { 1999 struct bufdomain *bd; 2000 2001 if (bp->b_qindex != QUEUE_NONE) 2002 panic("bq_insert: free buffer %p onto another queue?", bp); 2003 2004 bd = bufdomain(bp); 2005 if (bp->b_flags & B_AGE) { 2006 /* Place this buf directly on the real queue. */ 2007 if (bq->bq_index == QUEUE_CLEAN) 2008 bq = bd->bd_cleanq; 2009 BQ_LOCK(bq); 2010 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist); 2011 } else { 2012 BQ_LOCK(bq); 2013 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 2014 } 2015 bp->b_flags &= ~(B_AGE | B_REUSE); 2016 bq->bq_len++; 2017 bp->b_qindex = bq->bq_index; 2018 bp->b_subqueue = bq->bq_subqueue; 2019 2020 /* 2021 * Unlock before we notify so that we don't wakeup a waiter that 2022 * fails a trylock on the buf and sleeps again. 2023 */ 2024 if (unlock) 2025 BUF_UNLOCK(bp); 2026 2027 if (bp->b_qindex == QUEUE_CLEAN) { 2028 /* 2029 * Flush the per-cpu queue and notify any waiters. 2030 */ 2031 if (bd->bd_wanted || (bq != bd->bd_cleanq && 2032 bq->bq_len >= bd->bd_lim)) 2033 bd_flush(bd, bq); 2034 } 2035 BQ_UNLOCK(bq); 2036 } 2037 2038 /* 2039 * bufkva_free: 2040 * 2041 * Free the kva allocation for a buffer. 2042 * 2043 */ 2044 static void 2045 bufkva_free(struct buf *bp) 2046 { 2047 2048 #ifdef INVARIANTS 2049 if (bp->b_kvasize == 0) { 2050 KASSERT(bp->b_kvabase == unmapped_buf && 2051 bp->b_data == unmapped_buf, 2052 ("Leaked KVA space on %p", bp)); 2053 } else if (buf_mapped(bp)) 2054 BUF_CHECK_MAPPED(bp); 2055 else 2056 BUF_CHECK_UNMAPPED(bp); 2057 #endif 2058 if (bp->b_kvasize == 0) 2059 return; 2060 2061 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 2062 counter_u64_add(bufkvaspace, -bp->b_kvasize); 2063 counter_u64_add(buffreekvacnt, 1); 2064 bp->b_data = bp->b_kvabase = unmapped_buf; 2065 bp->b_kvasize = 0; 2066 } 2067 2068 /* 2069 * bufkva_alloc: 2070 * 2071 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 2072 */ 2073 static int 2074 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 2075 { 2076 vm_offset_t addr; 2077 int error; 2078 2079 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 2080 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 2081 MPASS((bp->b_flags & B_MAXPHYS) == 0); 2082 KASSERT(maxsize <= maxbcachebuf, 2083 ("bufkva_alloc kva too large %d %u", maxsize, maxbcachebuf)); 2084 2085 bufkva_free(bp); 2086 2087 addr = 0; 2088 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 2089 if (error != 0) { 2090 /* 2091 * Buffer map is too fragmented. Request the caller 2092 * to defragment the map. 2093 */ 2094 return (error); 2095 } 2096 bp->b_kvabase = (caddr_t)addr; 2097 bp->b_kvasize = maxsize; 2098 counter_u64_add(bufkvaspace, bp->b_kvasize); 2099 if ((gbflags & GB_UNMAPPED) != 0) { 2100 bp->b_data = unmapped_buf; 2101 BUF_CHECK_UNMAPPED(bp); 2102 } else { 2103 bp->b_data = bp->b_kvabase; 2104 BUF_CHECK_MAPPED(bp); 2105 } 2106 return (0); 2107 } 2108 2109 /* 2110 * bufkva_reclaim: 2111 * 2112 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 2113 * callback that fires to avoid returning failure. 2114 */ 2115 static void 2116 bufkva_reclaim(vmem_t *vmem, int flags) 2117 { 2118 bool done; 2119 int q; 2120 int i; 2121 2122 done = false; 2123 for (i = 0; i < 5; i++) { 2124 for (q = 0; q < buf_domains; q++) 2125 if (buf_recycle(&bdomain[q], true) != 0) 2126 done = true; 2127 if (done) 2128 break; 2129 } 2130 return; 2131 } 2132 2133 /* 2134 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 2135 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 2136 * the buffer is valid and we do not have to do anything. 2137 */ 2138 static void 2139 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt, 2140 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *)) 2141 { 2142 struct buf *rabp; 2143 struct thread *td; 2144 int i; 2145 2146 td = curthread; 2147 2148 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 2149 if (inmem(vp, *rablkno)) 2150 continue; 2151 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 2152 if ((rabp->b_flags & B_CACHE) != 0) { 2153 brelse(rabp); 2154 continue; 2155 } 2156 #ifdef RACCT 2157 if (racct_enable) { 2158 PROC_LOCK(curproc); 2159 racct_add_buf(curproc, rabp, 0); 2160 PROC_UNLOCK(curproc); 2161 } 2162 #endif /* RACCT */ 2163 td->td_ru.ru_inblock++; 2164 rabp->b_flags |= B_ASYNC; 2165 rabp->b_flags &= ~B_INVAL; 2166 if ((flags & GB_CKHASH) != 0) { 2167 rabp->b_flags |= B_CKHASH; 2168 rabp->b_ckhashcalc = ckhashfunc; 2169 } 2170 rabp->b_ioflags &= ~BIO_ERROR; 2171 rabp->b_iocmd = BIO_READ; 2172 if (rabp->b_rcred == NOCRED && cred != NOCRED) 2173 rabp->b_rcred = crhold(cred); 2174 vfs_busy_pages(rabp, 0); 2175 BUF_KERNPROC(rabp); 2176 rabp->b_iooffset = dbtob(rabp->b_blkno); 2177 bstrategy(rabp); 2178 } 2179 } 2180 2181 /* 2182 * Entry point for bread() and breadn() via #defines in sys/buf.h. 2183 * 2184 * Get a buffer with the specified data. Look in the cache first. We 2185 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 2186 * is set, the buffer is valid and we do not have to do anything, see 2187 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 2188 * 2189 * Always return a NULL buffer pointer (in bpp) when returning an error. 2190 * 2191 * The blkno parameter is the logical block being requested. Normally 2192 * the mapping of logical block number to disk block address is done 2193 * by calling VOP_BMAP(). However, if the mapping is already known, the 2194 * disk block address can be passed using the dblkno parameter. If the 2195 * disk block address is not known, then the same value should be passed 2196 * for blkno and dblkno. 2197 */ 2198 int 2199 breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, 2200 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags, 2201 void (*ckhashfunc)(struct buf *), struct buf **bpp) 2202 { 2203 struct buf *bp; 2204 struct thread *td; 2205 int error, readwait, rv; 2206 2207 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 2208 td = curthread; 2209 /* 2210 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags 2211 * are specified. 2212 */ 2213 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp); 2214 if (error != 0) { 2215 *bpp = NULL; 2216 return (error); 2217 } 2218 KASSERT(blkno == bp->b_lblkno, 2219 ("getblkx returned buffer for blkno %jd instead of blkno %jd", 2220 (intmax_t)bp->b_lblkno, (intmax_t)blkno)); 2221 flags &= ~GB_NOSPARSE; 2222 *bpp = bp; 2223 2224 /* 2225 * If not found in cache, do some I/O 2226 */ 2227 readwait = 0; 2228 if ((bp->b_flags & B_CACHE) == 0) { 2229 #ifdef RACCT 2230 if (racct_enable) { 2231 PROC_LOCK(td->td_proc); 2232 racct_add_buf(td->td_proc, bp, 0); 2233 PROC_UNLOCK(td->td_proc); 2234 } 2235 #endif /* RACCT */ 2236 td->td_ru.ru_inblock++; 2237 bp->b_iocmd = BIO_READ; 2238 bp->b_flags &= ~B_INVAL; 2239 if ((flags & GB_CKHASH) != 0) { 2240 bp->b_flags |= B_CKHASH; 2241 bp->b_ckhashcalc = ckhashfunc; 2242 } 2243 if ((flags & GB_CVTENXIO) != 0) 2244 bp->b_xflags |= BX_CVTENXIO; 2245 bp->b_ioflags &= ~BIO_ERROR; 2246 if (bp->b_rcred == NOCRED && cred != NOCRED) 2247 bp->b_rcred = crhold(cred); 2248 vfs_busy_pages(bp, 0); 2249 bp->b_iooffset = dbtob(bp->b_blkno); 2250 bstrategy(bp); 2251 ++readwait; 2252 } 2253 2254 /* 2255 * Attempt to initiate asynchronous I/O on read-ahead blocks. 2256 */ 2257 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 2258 2259 rv = 0; 2260 if (readwait) { 2261 rv = bufwait(bp); 2262 if (rv != 0) { 2263 brelse(bp); 2264 *bpp = NULL; 2265 } 2266 } 2267 return (rv); 2268 } 2269 2270 /* 2271 * Write, release buffer on completion. (Done by iodone 2272 * if async). Do not bother writing anything if the buffer 2273 * is invalid. 2274 * 2275 * Note that we set B_CACHE here, indicating that buffer is 2276 * fully valid and thus cacheable. This is true even of NFS 2277 * now so we set it generally. This could be set either here 2278 * or in biodone() since the I/O is synchronous. We put it 2279 * here. 2280 */ 2281 int 2282 bufwrite(struct buf *bp) 2283 { 2284 int oldflags; 2285 struct vnode *vp; 2286 long space; 2287 int vp_md; 2288 2289 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2290 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 2291 bp->b_flags |= B_INVAL | B_RELBUF; 2292 bp->b_flags &= ~B_CACHE; 2293 brelse(bp); 2294 return (ENXIO); 2295 } 2296 if (bp->b_flags & B_INVAL) { 2297 brelse(bp); 2298 return (0); 2299 } 2300 2301 if (bp->b_flags & B_BARRIER) 2302 atomic_add_long(&barrierwrites, 1); 2303 2304 oldflags = bp->b_flags; 2305 2306 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 2307 ("FFS background buffer should not get here %p", bp)); 2308 2309 vp = bp->b_vp; 2310 if (vp) 2311 vp_md = vp->v_vflag & VV_MD; 2312 else 2313 vp_md = 0; 2314 2315 /* 2316 * Mark the buffer clean. Increment the bufobj write count 2317 * before bundirty() call, to prevent other thread from seeing 2318 * empty dirty list and zero counter for writes in progress, 2319 * falsely indicating that the bufobj is clean. 2320 */ 2321 bufobj_wref(bp->b_bufobj); 2322 bundirty(bp); 2323 2324 bp->b_flags &= ~B_DONE; 2325 bp->b_ioflags &= ~BIO_ERROR; 2326 bp->b_flags |= B_CACHE; 2327 bp->b_iocmd = BIO_WRITE; 2328 2329 vfs_busy_pages(bp, 1); 2330 2331 /* 2332 * Normal bwrites pipeline writes 2333 */ 2334 bp->b_runningbufspace = bp->b_bufsize; 2335 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 2336 2337 #ifdef RACCT 2338 if (racct_enable) { 2339 PROC_LOCK(curproc); 2340 racct_add_buf(curproc, bp, 1); 2341 PROC_UNLOCK(curproc); 2342 } 2343 #endif /* RACCT */ 2344 curthread->td_ru.ru_oublock++; 2345 if (oldflags & B_ASYNC) 2346 BUF_KERNPROC(bp); 2347 bp->b_iooffset = dbtob(bp->b_blkno); 2348 buf_track(bp, __func__); 2349 bstrategy(bp); 2350 2351 if ((oldflags & B_ASYNC) == 0) { 2352 int rtval = bufwait(bp); 2353 brelse(bp); 2354 return (rtval); 2355 } else if (space > hirunningspace) { 2356 /* 2357 * don't allow the async write to saturate the I/O 2358 * system. We will not deadlock here because 2359 * we are blocking waiting for I/O that is already in-progress 2360 * to complete. We do not block here if it is the update 2361 * or syncer daemon trying to clean up as that can lead 2362 * to deadlock. 2363 */ 2364 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2365 waitrunningbufspace(); 2366 } 2367 2368 return (0); 2369 } 2370 2371 void 2372 bufbdflush(struct bufobj *bo, struct buf *bp) 2373 { 2374 struct buf *nbp; 2375 struct bufdomain *bd; 2376 2377 bd = &bdomain[bo->bo_domain]; 2378 if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh + 10) { 2379 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2380 altbufferflushes++; 2381 } else if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh) { 2382 BO_LOCK(bo); 2383 /* 2384 * Try to find a buffer to flush. 2385 */ 2386 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2387 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2388 BUF_LOCK(nbp, 2389 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2390 continue; 2391 if (bp == nbp) 2392 panic("bdwrite: found ourselves"); 2393 BO_UNLOCK(bo); 2394 /* Don't countdeps with the bo lock held. */ 2395 if (buf_countdeps(nbp, 0)) { 2396 BO_LOCK(bo); 2397 BUF_UNLOCK(nbp); 2398 continue; 2399 } 2400 if (nbp->b_flags & B_CLUSTEROK) { 2401 vfs_bio_awrite(nbp); 2402 } else { 2403 bremfree(nbp); 2404 bawrite(nbp); 2405 } 2406 dirtybufferflushes++; 2407 break; 2408 } 2409 if (nbp == NULL) 2410 BO_UNLOCK(bo); 2411 } 2412 } 2413 2414 /* 2415 * Delayed write. (Buffer is marked dirty). Do not bother writing 2416 * anything if the buffer is marked invalid. 2417 * 2418 * Note that since the buffer must be completely valid, we can safely 2419 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2420 * biodone() in order to prevent getblk from writing the buffer 2421 * out synchronously. 2422 */ 2423 void 2424 bdwrite(struct buf *bp) 2425 { 2426 struct thread *td = curthread; 2427 struct vnode *vp; 2428 struct bufobj *bo; 2429 2430 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2431 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2432 KASSERT((bp->b_flags & B_BARRIER) == 0, 2433 ("Barrier request in delayed write %p", bp)); 2434 2435 if (bp->b_flags & B_INVAL) { 2436 brelse(bp); 2437 return; 2438 } 2439 2440 /* 2441 * If we have too many dirty buffers, don't create any more. 2442 * If we are wildly over our limit, then force a complete 2443 * cleanup. Otherwise, just keep the situation from getting 2444 * out of control. Note that we have to avoid a recursive 2445 * disaster and not try to clean up after our own cleanup! 2446 */ 2447 vp = bp->b_vp; 2448 bo = bp->b_bufobj; 2449 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2450 td->td_pflags |= TDP_INBDFLUSH; 2451 BO_BDFLUSH(bo, bp); 2452 td->td_pflags &= ~TDP_INBDFLUSH; 2453 } else 2454 recursiveflushes++; 2455 2456 bdirty(bp); 2457 /* 2458 * Set B_CACHE, indicating that the buffer is fully valid. This is 2459 * true even of NFS now. 2460 */ 2461 bp->b_flags |= B_CACHE; 2462 2463 /* 2464 * This bmap keeps the system from needing to do the bmap later, 2465 * perhaps when the system is attempting to do a sync. Since it 2466 * is likely that the indirect block -- or whatever other datastructure 2467 * that the filesystem needs is still in memory now, it is a good 2468 * thing to do this. Note also, that if the pageout daemon is 2469 * requesting a sync -- there might not be enough memory to do 2470 * the bmap then... So, this is important to do. 2471 */ 2472 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2473 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2474 } 2475 2476 buf_track(bp, __func__); 2477 2478 /* 2479 * Set the *dirty* buffer range based upon the VM system dirty 2480 * pages. 2481 * 2482 * Mark the buffer pages as clean. We need to do this here to 2483 * satisfy the vnode_pager and the pageout daemon, so that it 2484 * thinks that the pages have been "cleaned". Note that since 2485 * the pages are in a delayed write buffer -- the VFS layer 2486 * "will" see that the pages get written out on the next sync, 2487 * or perhaps the cluster will be completed. 2488 */ 2489 vfs_clean_pages_dirty_buf(bp); 2490 bqrelse(bp); 2491 2492 /* 2493 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2494 * due to the softdep code. 2495 */ 2496 } 2497 2498 /* 2499 * bdirty: 2500 * 2501 * Turn buffer into delayed write request. We must clear BIO_READ and 2502 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2503 * itself to properly update it in the dirty/clean lists. We mark it 2504 * B_DONE to ensure that any asynchronization of the buffer properly 2505 * clears B_DONE ( else a panic will occur later ). 2506 * 2507 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2508 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2509 * should only be called if the buffer is known-good. 2510 * 2511 * Since the buffer is not on a queue, we do not update the numfreebuffers 2512 * count. 2513 * 2514 * The buffer must be on QUEUE_NONE. 2515 */ 2516 void 2517 bdirty(struct buf *bp) 2518 { 2519 2520 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2521 bp, bp->b_vp, bp->b_flags); 2522 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2523 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2524 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2525 bp->b_flags &= ~(B_RELBUF); 2526 bp->b_iocmd = BIO_WRITE; 2527 2528 if ((bp->b_flags & B_DELWRI) == 0) { 2529 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2530 reassignbuf(bp); 2531 bdirtyadd(bp); 2532 } 2533 } 2534 2535 /* 2536 * bundirty: 2537 * 2538 * Clear B_DELWRI for buffer. 2539 * 2540 * Since the buffer is not on a queue, we do not update the numfreebuffers 2541 * count. 2542 * 2543 * The buffer must be on QUEUE_NONE. 2544 */ 2545 2546 void 2547 bundirty(struct buf *bp) 2548 { 2549 2550 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2551 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2552 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2553 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2554 2555 if (bp->b_flags & B_DELWRI) { 2556 bp->b_flags &= ~B_DELWRI; 2557 reassignbuf(bp); 2558 bdirtysub(bp); 2559 } 2560 /* 2561 * Since it is now being written, we can clear its deferred write flag. 2562 */ 2563 bp->b_flags &= ~B_DEFERRED; 2564 } 2565 2566 /* 2567 * bawrite: 2568 * 2569 * Asynchronous write. Start output on a buffer, but do not wait for 2570 * it to complete. The buffer is released when the output completes. 2571 * 2572 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2573 * B_INVAL buffers. Not us. 2574 */ 2575 void 2576 bawrite(struct buf *bp) 2577 { 2578 2579 bp->b_flags |= B_ASYNC; 2580 (void) bwrite(bp); 2581 } 2582 2583 /* 2584 * babarrierwrite: 2585 * 2586 * Asynchronous barrier write. Start output on a buffer, but do not 2587 * wait for it to complete. Place a write barrier after this write so 2588 * that this buffer and all buffers written before it are committed to 2589 * the disk before any buffers written after this write are committed 2590 * to the disk. The buffer is released when the output completes. 2591 */ 2592 void 2593 babarrierwrite(struct buf *bp) 2594 { 2595 2596 bp->b_flags |= B_ASYNC | B_BARRIER; 2597 (void) bwrite(bp); 2598 } 2599 2600 /* 2601 * bbarrierwrite: 2602 * 2603 * Synchronous barrier write. Start output on a buffer and wait for 2604 * it to complete. Place a write barrier after this write so that 2605 * this buffer and all buffers written before it are committed to 2606 * the disk before any buffers written after this write are committed 2607 * to the disk. The buffer is released when the output completes. 2608 */ 2609 int 2610 bbarrierwrite(struct buf *bp) 2611 { 2612 2613 bp->b_flags |= B_BARRIER; 2614 return (bwrite(bp)); 2615 } 2616 2617 /* 2618 * bwillwrite: 2619 * 2620 * Called prior to the locking of any vnodes when we are expecting to 2621 * write. We do not want to starve the buffer cache with too many 2622 * dirty buffers so we block here. By blocking prior to the locking 2623 * of any vnodes we attempt to avoid the situation where a locked vnode 2624 * prevents the various system daemons from flushing related buffers. 2625 */ 2626 void 2627 bwillwrite(void) 2628 { 2629 2630 if (buf_dirty_count_severe()) { 2631 mtx_lock(&bdirtylock); 2632 while (buf_dirty_count_severe()) { 2633 bdirtywait = 1; 2634 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2635 "flswai", 0); 2636 } 2637 mtx_unlock(&bdirtylock); 2638 } 2639 } 2640 2641 /* 2642 * Return true if we have too many dirty buffers. 2643 */ 2644 int 2645 buf_dirty_count_severe(void) 2646 { 2647 2648 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty)); 2649 } 2650 2651 /* 2652 * brelse: 2653 * 2654 * Release a busy buffer and, if requested, free its resources. The 2655 * buffer will be stashed in the appropriate bufqueue[] allowing it 2656 * to be accessed later as a cache entity or reused for other purposes. 2657 */ 2658 void 2659 brelse(struct buf *bp) 2660 { 2661 struct mount *v_mnt; 2662 int qindex; 2663 2664 /* 2665 * Many functions erroneously call brelse with a NULL bp under rare 2666 * error conditions. Simply return when called with a NULL bp. 2667 */ 2668 if (bp == NULL) 2669 return; 2670 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2671 bp, bp->b_vp, bp->b_flags); 2672 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2673 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2674 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2675 ("brelse: non-VMIO buffer marked NOREUSE")); 2676 2677 if (BUF_LOCKRECURSED(bp)) { 2678 /* 2679 * Do not process, in particular, do not handle the 2680 * B_INVAL/B_RELBUF and do not release to free list. 2681 */ 2682 BUF_UNLOCK(bp); 2683 return; 2684 } 2685 2686 if (bp->b_flags & B_MANAGED) { 2687 bqrelse(bp); 2688 return; 2689 } 2690 2691 if (LIST_EMPTY(&bp->b_dep)) { 2692 bp->b_flags &= ~B_IOSTARTED; 2693 } else { 2694 KASSERT((bp->b_flags & B_IOSTARTED) == 0, 2695 ("brelse: SU io not finished bp %p", bp)); 2696 } 2697 2698 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2699 BO_LOCK(bp->b_bufobj); 2700 bp->b_vflags &= ~BV_BKGRDERR; 2701 BO_UNLOCK(bp->b_bufobj); 2702 bdirty(bp); 2703 } 2704 2705 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2706 (bp->b_flags & B_INVALONERR)) { 2707 /* 2708 * Forced invalidation of dirty buffer contents, to be used 2709 * after a failed write in the rare case that the loss of the 2710 * contents is acceptable. The buffer is invalidated and 2711 * freed. 2712 */ 2713 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE; 2714 bp->b_flags &= ~(B_ASYNC | B_CACHE); 2715 } 2716 2717 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2718 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2719 !(bp->b_flags & B_INVAL)) { 2720 /* 2721 * Failed write, redirty. All errors except ENXIO (which 2722 * means the device is gone) are treated as being 2723 * transient. 2724 * 2725 * XXX Treating EIO as transient is not correct; the 2726 * contract with the local storage device drivers is that 2727 * they will only return EIO once the I/O is no longer 2728 * retriable. Network I/O also respects this through the 2729 * guarantees of TCP and/or the internal retries of NFS. 2730 * ENOMEM might be transient, but we also have no way of 2731 * knowing when its ok to retry/reschedule. In general, 2732 * this entire case should be made obsolete through better 2733 * error handling/recovery and resource scheduling. 2734 * 2735 * Do this also for buffers that failed with ENXIO, but have 2736 * non-empty dependencies - the soft updates code might need 2737 * to access the buffer to untangle them. 2738 * 2739 * Must clear BIO_ERROR to prevent pages from being scrapped. 2740 */ 2741 bp->b_ioflags &= ~BIO_ERROR; 2742 bdirty(bp); 2743 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2744 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2745 /* 2746 * Either a failed read I/O, or we were asked to free or not 2747 * cache the buffer, or we failed to write to a device that's 2748 * no longer present. 2749 */ 2750 bp->b_flags |= B_INVAL; 2751 if (!LIST_EMPTY(&bp->b_dep)) 2752 buf_deallocate(bp); 2753 if (bp->b_flags & B_DELWRI) 2754 bdirtysub(bp); 2755 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2756 if ((bp->b_flags & B_VMIO) == 0) { 2757 allocbuf(bp, 0); 2758 if (bp->b_vp) 2759 brelvp(bp); 2760 } 2761 } 2762 2763 /* 2764 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2765 * is called with B_DELWRI set, the underlying pages may wind up 2766 * getting freed causing a previous write (bdwrite()) to get 'lost' 2767 * because pages associated with a B_DELWRI bp are marked clean. 2768 * 2769 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2770 * if B_DELWRI is set. 2771 */ 2772 if (bp->b_flags & B_DELWRI) 2773 bp->b_flags &= ~B_RELBUF; 2774 2775 /* 2776 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2777 * constituted, not even NFS buffers now. Two flags effect this. If 2778 * B_INVAL, the struct buf is invalidated but the VM object is kept 2779 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2780 * 2781 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2782 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2783 * buffer is also B_INVAL because it hits the re-dirtying code above. 2784 * 2785 * Normally we can do this whether a buffer is B_DELWRI or not. If 2786 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2787 * the commit state and we cannot afford to lose the buffer. If the 2788 * buffer has a background write in progress, we need to keep it 2789 * around to prevent it from being reconstituted and starting a second 2790 * background write. 2791 */ 2792 2793 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL; 2794 2795 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2796 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2797 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 || 2798 vn_isdisk(bp->b_vp) || (bp->b_flags & B_DELWRI) == 0)) { 2799 vfs_vmio_invalidate(bp); 2800 allocbuf(bp, 0); 2801 } 2802 2803 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2804 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2805 allocbuf(bp, 0); 2806 bp->b_flags &= ~B_NOREUSE; 2807 if (bp->b_vp != NULL) 2808 brelvp(bp); 2809 } 2810 2811 /* 2812 * If the buffer has junk contents signal it and eventually 2813 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2814 * doesn't find it. 2815 */ 2816 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2817 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2818 bp->b_flags |= B_INVAL; 2819 if (bp->b_flags & B_INVAL) { 2820 if (bp->b_flags & B_DELWRI) 2821 bundirty(bp); 2822 if (bp->b_vp) 2823 brelvp(bp); 2824 } 2825 2826 buf_track(bp, __func__); 2827 2828 /* buffers with no memory */ 2829 if (bp->b_bufsize == 0) { 2830 buf_free(bp); 2831 return; 2832 } 2833 /* buffers with junk contents */ 2834 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2835 (bp->b_ioflags & BIO_ERROR)) { 2836 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2837 if (bp->b_vflags & BV_BKGRDINPROG) 2838 panic("losing buffer 2"); 2839 qindex = QUEUE_CLEAN; 2840 bp->b_flags |= B_AGE; 2841 /* remaining buffers */ 2842 } else if (bp->b_flags & B_DELWRI) 2843 qindex = QUEUE_DIRTY; 2844 else 2845 qindex = QUEUE_CLEAN; 2846 2847 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2848 panic("brelse: not dirty"); 2849 2850 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT); 2851 bp->b_xflags &= ~(BX_CVTENXIO); 2852 /* binsfree unlocks bp. */ 2853 binsfree(bp, qindex); 2854 } 2855 2856 /* 2857 * Release a buffer back to the appropriate queue but do not try to free 2858 * it. The buffer is expected to be used again soon. 2859 * 2860 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2861 * biodone() to requeue an async I/O on completion. It is also used when 2862 * known good buffers need to be requeued but we think we may need the data 2863 * again soon. 2864 * 2865 * XXX we should be able to leave the B_RELBUF hint set on completion. 2866 */ 2867 void 2868 bqrelse(struct buf *bp) 2869 { 2870 int qindex; 2871 2872 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2873 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2874 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2875 2876 qindex = QUEUE_NONE; 2877 if (BUF_LOCKRECURSED(bp)) { 2878 /* do not release to free list */ 2879 BUF_UNLOCK(bp); 2880 return; 2881 } 2882 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2883 bp->b_xflags &= ~(BX_CVTENXIO); 2884 2885 if (LIST_EMPTY(&bp->b_dep)) { 2886 bp->b_flags &= ~B_IOSTARTED; 2887 } else { 2888 KASSERT((bp->b_flags & B_IOSTARTED) == 0, 2889 ("bqrelse: SU io not finished bp %p", bp)); 2890 } 2891 2892 if (bp->b_flags & B_MANAGED) { 2893 if (bp->b_flags & B_REMFREE) 2894 bremfreef(bp); 2895 goto out; 2896 } 2897 2898 /* buffers with stale but valid contents */ 2899 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2900 BV_BKGRDERR)) == BV_BKGRDERR) { 2901 BO_LOCK(bp->b_bufobj); 2902 bp->b_vflags &= ~BV_BKGRDERR; 2903 BO_UNLOCK(bp->b_bufobj); 2904 qindex = QUEUE_DIRTY; 2905 } else { 2906 if ((bp->b_flags & B_DELWRI) == 0 && 2907 (bp->b_xflags & BX_VNDIRTY)) 2908 panic("bqrelse: not dirty"); 2909 if ((bp->b_flags & B_NOREUSE) != 0) { 2910 brelse(bp); 2911 return; 2912 } 2913 qindex = QUEUE_CLEAN; 2914 } 2915 buf_track(bp, __func__); 2916 /* binsfree unlocks bp. */ 2917 binsfree(bp, qindex); 2918 return; 2919 2920 out: 2921 buf_track(bp, __func__); 2922 /* unlock */ 2923 BUF_UNLOCK(bp); 2924 } 2925 2926 /* 2927 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2928 * restore bogus pages. 2929 */ 2930 static void 2931 vfs_vmio_iodone(struct buf *bp) 2932 { 2933 vm_ooffset_t foff; 2934 vm_page_t m; 2935 vm_object_t obj; 2936 struct vnode *vp __unused; 2937 int i, iosize, resid; 2938 bool bogus; 2939 2940 obj = bp->b_bufobj->bo_object; 2941 KASSERT(blockcount_read(&obj->paging_in_progress) >= bp->b_npages, 2942 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2943 blockcount_read(&obj->paging_in_progress), bp->b_npages)); 2944 2945 vp = bp->b_vp; 2946 VNPASS(vp->v_holdcnt > 0, vp); 2947 VNPASS(vp->v_object != NULL, vp); 2948 2949 foff = bp->b_offset; 2950 KASSERT(bp->b_offset != NOOFFSET, 2951 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2952 2953 bogus = false; 2954 iosize = bp->b_bcount - bp->b_resid; 2955 for (i = 0; i < bp->b_npages; i++) { 2956 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2957 if (resid > iosize) 2958 resid = iosize; 2959 2960 /* 2961 * cleanup bogus pages, restoring the originals 2962 */ 2963 m = bp->b_pages[i]; 2964 if (m == bogus_page) { 2965 bogus = true; 2966 m = vm_page_relookup(obj, OFF_TO_IDX(foff)); 2967 if (m == NULL) 2968 panic("biodone: page disappeared!"); 2969 bp->b_pages[i] = m; 2970 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2971 /* 2972 * In the write case, the valid and clean bits are 2973 * already changed correctly ( see bdwrite() ), so we 2974 * only need to do this here in the read case. 2975 */ 2976 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2977 resid)) == 0, ("vfs_vmio_iodone: page %p " 2978 "has unexpected dirty bits", m)); 2979 vfs_page_set_valid(bp, foff, m); 2980 } 2981 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2982 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2983 (intmax_t)foff, (uintmax_t)m->pindex)); 2984 2985 vm_page_sunbusy(m); 2986 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2987 iosize -= resid; 2988 } 2989 vm_object_pip_wakeupn(obj, bp->b_npages); 2990 if (bogus && buf_mapped(bp)) { 2991 BUF_CHECK_MAPPED(bp); 2992 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2993 bp->b_pages, bp->b_npages); 2994 } 2995 } 2996 2997 /* 2998 * Perform page invalidation when a buffer is released. The fully invalid 2999 * pages will be reclaimed later in vfs_vmio_truncate(). 3000 */ 3001 static void 3002 vfs_vmio_invalidate(struct buf *bp) 3003 { 3004 vm_object_t obj; 3005 vm_page_t m; 3006 int flags, i, resid, poffset, presid; 3007 3008 if (buf_mapped(bp)) { 3009 BUF_CHECK_MAPPED(bp); 3010 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 3011 } else 3012 BUF_CHECK_UNMAPPED(bp); 3013 /* 3014 * Get the base offset and length of the buffer. Note that 3015 * in the VMIO case if the buffer block size is not 3016 * page-aligned then b_data pointer may not be page-aligned. 3017 * But our b_pages[] array *IS* page aligned. 3018 * 3019 * block sizes less then DEV_BSIZE (usually 512) are not 3020 * supported due to the page granularity bits (m->valid, 3021 * m->dirty, etc...). 3022 * 3023 * See man buf(9) for more information 3024 */ 3025 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 3026 obj = bp->b_bufobj->bo_object; 3027 resid = bp->b_bufsize; 3028 poffset = bp->b_offset & PAGE_MASK; 3029 VM_OBJECT_WLOCK(obj); 3030 for (i = 0; i < bp->b_npages; i++) { 3031 m = bp->b_pages[i]; 3032 if (m == bogus_page) 3033 panic("vfs_vmio_invalidate: Unexpected bogus page."); 3034 bp->b_pages[i] = NULL; 3035 3036 presid = resid > (PAGE_SIZE - poffset) ? 3037 (PAGE_SIZE - poffset) : resid; 3038 KASSERT(presid >= 0, ("brelse: extra page")); 3039 vm_page_busy_acquire(m, VM_ALLOC_SBUSY); 3040 if (pmap_page_wired_mappings(m) == 0) 3041 vm_page_set_invalid(m, poffset, presid); 3042 vm_page_sunbusy(m); 3043 vm_page_release_locked(m, flags); 3044 resid -= presid; 3045 poffset = 0; 3046 } 3047 VM_OBJECT_WUNLOCK(obj); 3048 bp->b_npages = 0; 3049 } 3050 3051 /* 3052 * Page-granular truncation of an existing VMIO buffer. 3053 */ 3054 static void 3055 vfs_vmio_truncate(struct buf *bp, int desiredpages) 3056 { 3057 vm_object_t obj; 3058 vm_page_t m; 3059 int flags, i; 3060 3061 if (bp->b_npages == desiredpages) 3062 return; 3063 3064 if (buf_mapped(bp)) { 3065 BUF_CHECK_MAPPED(bp); 3066 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 3067 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 3068 } else 3069 BUF_CHECK_UNMAPPED(bp); 3070 3071 /* 3072 * The object lock is needed only if we will attempt to free pages. 3073 */ 3074 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 3075 if ((bp->b_flags & B_DIRECT) != 0) { 3076 flags |= VPR_TRYFREE; 3077 obj = bp->b_bufobj->bo_object; 3078 VM_OBJECT_WLOCK(obj); 3079 } else { 3080 obj = NULL; 3081 } 3082 for (i = desiredpages; i < bp->b_npages; i++) { 3083 m = bp->b_pages[i]; 3084 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3085 bp->b_pages[i] = NULL; 3086 if (obj != NULL) 3087 vm_page_release_locked(m, flags); 3088 else 3089 vm_page_release(m, flags); 3090 } 3091 if (obj != NULL) 3092 VM_OBJECT_WUNLOCK(obj); 3093 bp->b_npages = desiredpages; 3094 } 3095 3096 /* 3097 * Byte granular extension of VMIO buffers. 3098 */ 3099 static void 3100 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3101 { 3102 /* 3103 * We are growing the buffer, possibly in a 3104 * byte-granular fashion. 3105 */ 3106 vm_object_t obj; 3107 vm_offset_t toff; 3108 vm_offset_t tinc; 3109 vm_page_t m; 3110 3111 /* 3112 * Step 1, bring in the VM pages from the object, allocating 3113 * them if necessary. We must clear B_CACHE if these pages 3114 * are not valid for the range covered by the buffer. 3115 */ 3116 obj = bp->b_bufobj->bo_object; 3117 if (bp->b_npages < desiredpages) { 3118 KASSERT(desiredpages <= atop(maxbcachebuf), 3119 ("vfs_vmio_extend past maxbcachebuf %p %d %u", 3120 bp, desiredpages, maxbcachebuf)); 3121 3122 /* 3123 * We must allocate system pages since blocking 3124 * here could interfere with paging I/O, no 3125 * matter which process we are. 3126 * 3127 * Only exclusive busy can be tested here. 3128 * Blocking on shared busy might lead to 3129 * deadlocks once allocbuf() is called after 3130 * pages are vfs_busy_pages(). 3131 */ 3132 (void)vm_page_grab_pages_unlocked(obj, 3133 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3134 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3135 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3136 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3137 bp->b_npages = desiredpages; 3138 } 3139 3140 /* 3141 * Step 2. We've loaded the pages into the buffer, 3142 * we have to figure out if we can still have B_CACHE 3143 * set. Note that B_CACHE is set according to the 3144 * byte-granular range ( bcount and size ), not the 3145 * aligned range ( newbsize ). 3146 * 3147 * The VM test is against m->valid, which is DEV_BSIZE 3148 * aligned. Needless to say, the validity of the data 3149 * needs to also be DEV_BSIZE aligned. Note that this 3150 * fails with NFS if the server or some other client 3151 * extends the file's EOF. If our buffer is resized, 3152 * B_CACHE may remain set! XXX 3153 */ 3154 toff = bp->b_bcount; 3155 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3156 while ((bp->b_flags & B_CACHE) && toff < size) { 3157 vm_pindex_t pi; 3158 3159 if (tinc > (size - toff)) 3160 tinc = size - toff; 3161 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3162 m = bp->b_pages[pi]; 3163 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3164 toff += tinc; 3165 tinc = PAGE_SIZE; 3166 } 3167 3168 /* 3169 * Step 3, fixup the KVA pmap. 3170 */ 3171 if (buf_mapped(bp)) 3172 bpmap_qenter(bp); 3173 else 3174 BUF_CHECK_UNMAPPED(bp); 3175 } 3176 3177 /* 3178 * Check to see if a block at a particular lbn is available for a clustered 3179 * write. 3180 */ 3181 static int 3182 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3183 { 3184 struct buf *bpa; 3185 int match; 3186 3187 match = 0; 3188 3189 /* If the buf isn't in core skip it */ 3190 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3191 return (0); 3192 3193 /* If the buf is busy we don't want to wait for it */ 3194 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3195 return (0); 3196 3197 /* Only cluster with valid clusterable delayed write buffers */ 3198 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3199 (B_DELWRI | B_CLUSTEROK)) 3200 goto done; 3201 3202 if (bpa->b_bufsize != size) 3203 goto done; 3204 3205 /* 3206 * Check to see if it is in the expected place on disk and that the 3207 * block has been mapped. 3208 */ 3209 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3210 match = 1; 3211 done: 3212 BUF_UNLOCK(bpa); 3213 return (match); 3214 } 3215 3216 /* 3217 * vfs_bio_awrite: 3218 * 3219 * Implement clustered async writes for clearing out B_DELWRI buffers. 3220 * This is much better then the old way of writing only one buffer at 3221 * a time. Note that we may not be presented with the buffers in the 3222 * correct order, so we search for the cluster in both directions. 3223 */ 3224 int 3225 vfs_bio_awrite(struct buf *bp) 3226 { 3227 struct bufobj *bo; 3228 int i; 3229 int j; 3230 daddr_t lblkno = bp->b_lblkno; 3231 struct vnode *vp = bp->b_vp; 3232 int ncl; 3233 int nwritten; 3234 int size; 3235 int maxcl; 3236 int gbflags; 3237 3238 bo = &vp->v_bufobj; 3239 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3240 /* 3241 * right now we support clustered writing only to regular files. If 3242 * we find a clusterable block we could be in the middle of a cluster 3243 * rather then at the beginning. 3244 */ 3245 if ((vp->v_type == VREG) && 3246 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3247 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3248 size = vp->v_mount->mnt_stat.f_iosize; 3249 maxcl = maxphys / size; 3250 3251 BO_RLOCK(bo); 3252 for (i = 1; i < maxcl; i++) 3253 if (vfs_bio_clcheck(vp, size, lblkno + i, 3254 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3255 break; 3256 3257 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3258 if (vfs_bio_clcheck(vp, size, lblkno - j, 3259 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3260 break; 3261 BO_RUNLOCK(bo); 3262 --j; 3263 ncl = i + j; 3264 /* 3265 * this is a possible cluster write 3266 */ 3267 if (ncl != 1) { 3268 BUF_UNLOCK(bp); 3269 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3270 gbflags); 3271 return (nwritten); 3272 } 3273 } 3274 bremfree(bp); 3275 bp->b_flags |= B_ASYNC; 3276 /* 3277 * default (old) behavior, writing out only one block 3278 * 3279 * XXX returns b_bufsize instead of b_bcount for nwritten? 3280 */ 3281 nwritten = bp->b_bufsize; 3282 (void) bwrite(bp); 3283 3284 return (nwritten); 3285 } 3286 3287 /* 3288 * getnewbuf_kva: 3289 * 3290 * Allocate KVA for an empty buf header according to gbflags. 3291 */ 3292 static int 3293 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3294 { 3295 3296 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3297 /* 3298 * In order to keep fragmentation sane we only allocate kva 3299 * in BKVASIZE chunks. XXX with vmem we can do page size. 3300 */ 3301 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3302 3303 if (maxsize != bp->b_kvasize && 3304 bufkva_alloc(bp, maxsize, gbflags)) 3305 return (ENOSPC); 3306 } 3307 return (0); 3308 } 3309 3310 /* 3311 * getnewbuf: 3312 * 3313 * Find and initialize a new buffer header, freeing up existing buffers 3314 * in the bufqueues as necessary. The new buffer is returned locked. 3315 * 3316 * We block if: 3317 * We have insufficient buffer headers 3318 * We have insufficient buffer space 3319 * buffer_arena is too fragmented ( space reservation fails ) 3320 * If we have to flush dirty buffers ( but we try to avoid this ) 3321 * 3322 * The caller is responsible for releasing the reserved bufspace after 3323 * allocbuf() is called. 3324 */ 3325 static struct buf * 3326 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3327 { 3328 struct bufdomain *bd; 3329 struct buf *bp; 3330 bool metadata, reserved; 3331 3332 bp = NULL; 3333 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3334 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3335 if (!unmapped_buf_allowed) 3336 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3337 3338 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3339 vp->v_type == VCHR) 3340 metadata = true; 3341 else 3342 metadata = false; 3343 if (vp == NULL) 3344 bd = &bdomain[0]; 3345 else 3346 bd = &bdomain[vp->v_bufobj.bo_domain]; 3347 3348 counter_u64_add(getnewbufcalls, 1); 3349 reserved = false; 3350 do { 3351 if (reserved == false && 3352 bufspace_reserve(bd, maxsize, metadata) != 0) { 3353 counter_u64_add(getnewbufrestarts, 1); 3354 continue; 3355 } 3356 reserved = true; 3357 if ((bp = buf_alloc(bd)) == NULL) { 3358 counter_u64_add(getnewbufrestarts, 1); 3359 continue; 3360 } 3361 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3362 return (bp); 3363 break; 3364 } while (buf_recycle(bd, false) == 0); 3365 3366 if (reserved) 3367 bufspace_release(bd, maxsize); 3368 if (bp != NULL) { 3369 bp->b_flags |= B_INVAL; 3370 brelse(bp); 3371 } 3372 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3373 3374 return (NULL); 3375 } 3376 3377 /* 3378 * buf_daemon: 3379 * 3380 * buffer flushing daemon. Buffers are normally flushed by the 3381 * update daemon but if it cannot keep up this process starts to 3382 * take the load in an attempt to prevent getnewbuf() from blocking. 3383 */ 3384 static struct kproc_desc buf_kp = { 3385 "bufdaemon", 3386 buf_daemon, 3387 &bufdaemonproc 3388 }; 3389 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3390 3391 static int 3392 buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3393 { 3394 int flushed; 3395 3396 flushed = flushbufqueues(vp, bd, target, 0); 3397 if (flushed == 0) { 3398 /* 3399 * Could not find any buffers without rollback 3400 * dependencies, so just write the first one 3401 * in the hopes of eventually making progress. 3402 */ 3403 if (vp != NULL && target > 2) 3404 target /= 2; 3405 flushbufqueues(vp, bd, target, 1); 3406 } 3407 return (flushed); 3408 } 3409 3410 static void 3411 buf_daemon_shutdown(void *arg __unused, int howto __unused) 3412 { 3413 int error; 3414 3415 mtx_lock(&bdlock); 3416 bd_shutdown = true; 3417 wakeup(&bd_request); 3418 error = msleep(&bd_shutdown, &bdlock, 0, "buf_daemon_shutdown", 3419 60 * hz); 3420 mtx_unlock(&bdlock); 3421 if (error != 0) 3422 printf("bufdaemon wait error: %d\n", error); 3423 } 3424 3425 static void 3426 buf_daemon() 3427 { 3428 struct bufdomain *bd; 3429 int speedupreq; 3430 int lodirty; 3431 int i; 3432 3433 /* 3434 * This process needs to be suspended prior to shutdown sync. 3435 */ 3436 EVENTHANDLER_REGISTER(shutdown_pre_sync, buf_daemon_shutdown, NULL, 3437 SHUTDOWN_PRI_LAST + 100); 3438 3439 /* 3440 * Start the buf clean daemons as children threads. 3441 */ 3442 for (i = 0 ; i < buf_domains; i++) { 3443 int error; 3444 3445 error = kthread_add((void (*)(void *))bufspace_daemon, 3446 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3447 if (error) 3448 panic("error %d spawning bufspace daemon", error); 3449 } 3450 3451 /* 3452 * This process is allowed to take the buffer cache to the limit 3453 */ 3454 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3455 mtx_lock(&bdlock); 3456 while (!bd_shutdown) { 3457 bd_request = 0; 3458 mtx_unlock(&bdlock); 3459 3460 /* 3461 * Save speedupreq for this pass and reset to capture new 3462 * requests. 3463 */ 3464 speedupreq = bd_speedupreq; 3465 bd_speedupreq = 0; 3466 3467 /* 3468 * Flush each domain sequentially according to its level and 3469 * the speedup request. 3470 */ 3471 for (i = 0; i < buf_domains; i++) { 3472 bd = &bdomain[i]; 3473 if (speedupreq) 3474 lodirty = bd->bd_numdirtybuffers / 2; 3475 else 3476 lodirty = bd->bd_lodirtybuffers; 3477 while (bd->bd_numdirtybuffers > lodirty) { 3478 if (buf_flush(NULL, bd, 3479 bd->bd_numdirtybuffers - lodirty) == 0) 3480 break; 3481 kern_yield(PRI_USER); 3482 } 3483 } 3484 3485 /* 3486 * Only clear bd_request if we have reached our low water 3487 * mark. The buf_daemon normally waits 1 second and 3488 * then incrementally flushes any dirty buffers that have 3489 * built up, within reason. 3490 * 3491 * If we were unable to hit our low water mark and couldn't 3492 * find any flushable buffers, we sleep for a short period 3493 * to avoid endless loops on unlockable buffers. 3494 */ 3495 mtx_lock(&bdlock); 3496 if (bd_shutdown) 3497 break; 3498 if (BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3499 /* 3500 * We reached our low water mark, reset the 3501 * request and sleep until we are needed again. 3502 * The sleep is just so the suspend code works. 3503 */ 3504 bd_request = 0; 3505 /* 3506 * Do an extra wakeup in case dirty threshold 3507 * changed via sysctl and the explicit transition 3508 * out of shortfall was missed. 3509 */ 3510 bdirtywakeup(); 3511 if (runningbufspace <= lorunningspace) 3512 runningwakeup(); 3513 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3514 } else { 3515 /* 3516 * We couldn't find any flushable dirty buffers but 3517 * still have too many dirty buffers, we 3518 * have to sleep and try again. (rare) 3519 */ 3520 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3521 } 3522 } 3523 wakeup(&bd_shutdown); 3524 mtx_unlock(&bdlock); 3525 kthread_exit(); 3526 } 3527 3528 /* 3529 * flushbufqueues: 3530 * 3531 * Try to flush a buffer in the dirty queue. We must be careful to 3532 * free up B_INVAL buffers instead of write them, which NFS is 3533 * particularly sensitive to. 3534 */ 3535 static int flushwithdeps = 0; 3536 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS, 3537 &flushwithdeps, 0, 3538 "Number of buffers flushed with dependencies that require rollbacks"); 3539 3540 static int 3541 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3542 int flushdeps) 3543 { 3544 struct bufqueue *bq; 3545 struct buf *sentinel; 3546 struct vnode *vp; 3547 struct mount *mp; 3548 struct buf *bp; 3549 int hasdeps; 3550 int flushed; 3551 int error; 3552 bool unlock; 3553 3554 flushed = 0; 3555 bq = &bd->bd_dirtyq; 3556 bp = NULL; 3557 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3558 sentinel->b_qindex = QUEUE_SENTINEL; 3559 BQ_LOCK(bq); 3560 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3561 BQ_UNLOCK(bq); 3562 while (flushed != target) { 3563 maybe_yield(); 3564 BQ_LOCK(bq); 3565 bp = TAILQ_NEXT(sentinel, b_freelist); 3566 if (bp != NULL) { 3567 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3568 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3569 b_freelist); 3570 } else { 3571 BQ_UNLOCK(bq); 3572 break; 3573 } 3574 /* 3575 * Skip sentinels inserted by other invocations of the 3576 * flushbufqueues(), taking care to not reorder them. 3577 * 3578 * Only flush the buffers that belong to the 3579 * vnode locked by the curthread. 3580 */ 3581 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3582 bp->b_vp != lvp)) { 3583 BQ_UNLOCK(bq); 3584 continue; 3585 } 3586 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3587 BQ_UNLOCK(bq); 3588 if (error != 0) 3589 continue; 3590 3591 /* 3592 * BKGRDINPROG can only be set with the buf and bufobj 3593 * locks both held. We tolerate a race to clear it here. 3594 */ 3595 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3596 (bp->b_flags & B_DELWRI) == 0) { 3597 BUF_UNLOCK(bp); 3598 continue; 3599 } 3600 if (bp->b_flags & B_INVAL) { 3601 bremfreef(bp); 3602 brelse(bp); 3603 flushed++; 3604 continue; 3605 } 3606 3607 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3608 if (flushdeps == 0) { 3609 BUF_UNLOCK(bp); 3610 continue; 3611 } 3612 hasdeps = 1; 3613 } else 3614 hasdeps = 0; 3615 /* 3616 * We must hold the lock on a vnode before writing 3617 * one of its buffers. Otherwise we may confuse, or 3618 * in the case of a snapshot vnode, deadlock the 3619 * system. 3620 * 3621 * The lock order here is the reverse of the normal 3622 * of vnode followed by buf lock. This is ok because 3623 * the NOWAIT will prevent deadlock. 3624 */ 3625 vp = bp->b_vp; 3626 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3627 BUF_UNLOCK(bp); 3628 continue; 3629 } 3630 if (lvp == NULL) { 3631 unlock = true; 3632 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3633 } else { 3634 ASSERT_VOP_LOCKED(vp, "getbuf"); 3635 unlock = false; 3636 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3637 vn_lock(vp, LK_TRYUPGRADE); 3638 } 3639 if (error == 0) { 3640 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3641 bp, bp->b_vp, bp->b_flags); 3642 if (curproc == bufdaemonproc) { 3643 vfs_bio_awrite(bp); 3644 } else { 3645 bremfree(bp); 3646 bwrite(bp); 3647 counter_u64_add(notbufdflushes, 1); 3648 } 3649 vn_finished_write(mp); 3650 if (unlock) 3651 VOP_UNLOCK(vp); 3652 flushwithdeps += hasdeps; 3653 flushed++; 3654 3655 /* 3656 * Sleeping on runningbufspace while holding 3657 * vnode lock leads to deadlock. 3658 */ 3659 if (curproc == bufdaemonproc && 3660 runningbufspace > hirunningspace) 3661 waitrunningbufspace(); 3662 continue; 3663 } 3664 vn_finished_write(mp); 3665 BUF_UNLOCK(bp); 3666 } 3667 BQ_LOCK(bq); 3668 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3669 BQ_UNLOCK(bq); 3670 free(sentinel, M_TEMP); 3671 return (flushed); 3672 } 3673 3674 /* 3675 * Check to see if a block is currently memory resident. 3676 */ 3677 struct buf * 3678 incore(struct bufobj *bo, daddr_t blkno) 3679 { 3680 return (gbincore_unlocked(bo, blkno)); 3681 } 3682 3683 /* 3684 * Returns true if no I/O is needed to access the 3685 * associated VM object. This is like incore except 3686 * it also hunts around in the VM system for the data. 3687 */ 3688 bool 3689 inmem(struct vnode * vp, daddr_t blkno) 3690 { 3691 vm_object_t obj; 3692 vm_offset_t toff, tinc, size; 3693 vm_page_t m, n; 3694 vm_ooffset_t off; 3695 int valid; 3696 3697 ASSERT_VOP_LOCKED(vp, "inmem"); 3698 3699 if (incore(&vp->v_bufobj, blkno)) 3700 return (true); 3701 if (vp->v_mount == NULL) 3702 return (false); 3703 obj = vp->v_object; 3704 if (obj == NULL) 3705 return (false); 3706 3707 size = PAGE_SIZE; 3708 if (size > vp->v_mount->mnt_stat.f_iosize) 3709 size = vp->v_mount->mnt_stat.f_iosize; 3710 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3711 3712 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3713 m = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff)); 3714 recheck: 3715 if (m == NULL) 3716 return (false); 3717 3718 tinc = size; 3719 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3720 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3721 /* 3722 * Consider page validity only if page mapping didn't change 3723 * during the check. 3724 */ 3725 valid = vm_page_is_valid(m, 3726 (vm_offset_t)((toff + off) & PAGE_MASK), tinc); 3727 n = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff)); 3728 if (m != n) { 3729 m = n; 3730 goto recheck; 3731 } 3732 if (!valid) 3733 return (false); 3734 } 3735 return (true); 3736 } 3737 3738 /* 3739 * Set the dirty range for a buffer based on the status of the dirty 3740 * bits in the pages comprising the buffer. The range is limited 3741 * to the size of the buffer. 3742 * 3743 * Tell the VM system that the pages associated with this buffer 3744 * are clean. This is used for delayed writes where the data is 3745 * going to go to disk eventually without additional VM intevention. 3746 * 3747 * Note that while we only really need to clean through to b_bcount, we 3748 * just go ahead and clean through to b_bufsize. 3749 */ 3750 static void 3751 vfs_clean_pages_dirty_buf(struct buf *bp) 3752 { 3753 vm_ooffset_t foff, noff, eoff; 3754 vm_page_t m; 3755 int i; 3756 3757 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3758 return; 3759 3760 foff = bp->b_offset; 3761 KASSERT(bp->b_offset != NOOFFSET, 3762 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3763 3764 vfs_busy_pages_acquire(bp); 3765 vfs_setdirty_range(bp); 3766 for (i = 0; i < bp->b_npages; i++) { 3767 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3768 eoff = noff; 3769 if (eoff > bp->b_offset + bp->b_bufsize) 3770 eoff = bp->b_offset + bp->b_bufsize; 3771 m = bp->b_pages[i]; 3772 vfs_page_set_validclean(bp, foff, m); 3773 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3774 foff = noff; 3775 } 3776 vfs_busy_pages_release(bp); 3777 } 3778 3779 static void 3780 vfs_setdirty_range(struct buf *bp) 3781 { 3782 vm_offset_t boffset; 3783 vm_offset_t eoffset; 3784 int i; 3785 3786 /* 3787 * test the pages to see if they have been modified directly 3788 * by users through the VM system. 3789 */ 3790 for (i = 0; i < bp->b_npages; i++) 3791 vm_page_test_dirty(bp->b_pages[i]); 3792 3793 /* 3794 * Calculate the encompassing dirty range, boffset and eoffset, 3795 * (eoffset - boffset) bytes. 3796 */ 3797 3798 for (i = 0; i < bp->b_npages; i++) { 3799 if (bp->b_pages[i]->dirty) 3800 break; 3801 } 3802 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3803 3804 for (i = bp->b_npages - 1; i >= 0; --i) { 3805 if (bp->b_pages[i]->dirty) { 3806 break; 3807 } 3808 } 3809 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3810 3811 /* 3812 * Fit it to the buffer. 3813 */ 3814 3815 if (eoffset > bp->b_bcount) 3816 eoffset = bp->b_bcount; 3817 3818 /* 3819 * If we have a good dirty range, merge with the existing 3820 * dirty range. 3821 */ 3822 3823 if (boffset < eoffset) { 3824 if (bp->b_dirtyoff > boffset) 3825 bp->b_dirtyoff = boffset; 3826 if (bp->b_dirtyend < eoffset) 3827 bp->b_dirtyend = eoffset; 3828 } 3829 } 3830 3831 /* 3832 * Allocate the KVA mapping for an existing buffer. 3833 * If an unmapped buffer is provided but a mapped buffer is requested, take 3834 * also care to properly setup mappings between pages and KVA. 3835 */ 3836 static void 3837 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3838 { 3839 int bsize, maxsize, need_mapping, need_kva; 3840 off_t offset; 3841 3842 need_mapping = bp->b_data == unmapped_buf && 3843 (gbflags & GB_UNMAPPED) == 0; 3844 need_kva = bp->b_kvabase == unmapped_buf && 3845 bp->b_data == unmapped_buf && 3846 (gbflags & GB_KVAALLOC) != 0; 3847 if (!need_mapping && !need_kva) 3848 return; 3849 3850 BUF_CHECK_UNMAPPED(bp); 3851 3852 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3853 /* 3854 * Buffer is not mapped, but the KVA was already 3855 * reserved at the time of the instantiation. Use the 3856 * allocated space. 3857 */ 3858 goto has_addr; 3859 } 3860 3861 /* 3862 * Calculate the amount of the address space we would reserve 3863 * if the buffer was mapped. 3864 */ 3865 bsize = vn_isdisk(bp->b_vp) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3866 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3867 offset = blkno * bsize; 3868 maxsize = size + (offset & PAGE_MASK); 3869 maxsize = imax(maxsize, bsize); 3870 3871 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3872 if ((gbflags & GB_NOWAIT_BD) != 0) { 3873 /* 3874 * XXXKIB: defragmentation cannot 3875 * succeed, not sure what else to do. 3876 */ 3877 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3878 } 3879 counter_u64_add(mappingrestarts, 1); 3880 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3881 } 3882 has_addr: 3883 if (need_mapping) { 3884 /* b_offset is handled by bpmap_qenter. */ 3885 bp->b_data = bp->b_kvabase; 3886 BUF_CHECK_MAPPED(bp); 3887 bpmap_qenter(bp); 3888 } 3889 } 3890 3891 struct buf * 3892 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3893 int flags) 3894 { 3895 struct buf *bp; 3896 int error; 3897 3898 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp); 3899 if (error != 0) 3900 return (NULL); 3901 return (bp); 3902 } 3903 3904 /* 3905 * getblkx: 3906 * 3907 * Get a block given a specified block and offset into a file/device. 3908 * The buffers B_DONE bit will be cleared on return, making it almost 3909 * ready for an I/O initiation. B_INVAL may or may not be set on 3910 * return. The caller should clear B_INVAL prior to initiating a 3911 * READ. 3912 * 3913 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3914 * an existing buffer. 3915 * 3916 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3917 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3918 * and then cleared based on the backing VM. If the previous buffer is 3919 * non-0-sized but invalid, B_CACHE will be cleared. 3920 * 3921 * If getblk() must create a new buffer, the new buffer is returned with 3922 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3923 * case it is returned with B_INVAL clear and B_CACHE set based on the 3924 * backing VM. 3925 * 3926 * getblk() also forces a bwrite() for any B_DELWRI buffer whose 3927 * B_CACHE bit is clear. 3928 * 3929 * What this means, basically, is that the caller should use B_CACHE to 3930 * determine whether the buffer is fully valid or not and should clear 3931 * B_INVAL prior to issuing a read. If the caller intends to validate 3932 * the buffer by loading its data area with something, the caller needs 3933 * to clear B_INVAL. If the caller does this without issuing an I/O, 3934 * the caller should set B_CACHE ( as an optimization ), else the caller 3935 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3936 * a write attempt or if it was a successful read. If the caller 3937 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3938 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3939 * 3940 * The blkno parameter is the logical block being requested. Normally 3941 * the mapping of logical block number to disk block address is done 3942 * by calling VOP_BMAP(). However, if the mapping is already known, the 3943 * disk block address can be passed using the dblkno parameter. If the 3944 * disk block address is not known, then the same value should be passed 3945 * for blkno and dblkno. 3946 */ 3947 int 3948 getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag, 3949 int slptimeo, int flags, struct buf **bpp) 3950 { 3951 struct buf *bp; 3952 struct bufobj *bo; 3953 daddr_t d_blkno; 3954 int bsize, error, maxsize, vmio; 3955 off_t offset; 3956 3957 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3958 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3959 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3960 if (vp->v_type != VCHR) 3961 ASSERT_VOP_LOCKED(vp, "getblk"); 3962 if (size > maxbcachebuf) 3963 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3964 maxbcachebuf); 3965 if (!unmapped_buf_allowed) 3966 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3967 3968 bo = &vp->v_bufobj; 3969 d_blkno = dblkno; 3970 3971 /* Attempt lockless lookup first. */ 3972 bp = gbincore_unlocked(bo, blkno); 3973 if (bp == NULL) { 3974 /* 3975 * With GB_NOCREAT we must be sure about not finding the buffer 3976 * as it may have been reassigned during unlocked lookup. 3977 */ 3978 if ((flags & GB_NOCREAT) != 0) 3979 goto loop; 3980 goto newbuf_unlocked; 3981 } 3982 3983 error = BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL, "getblku", 0, 3984 0); 3985 if (error != 0) 3986 goto loop; 3987 3988 /* Verify buf identify has not changed since lookup. */ 3989 if (bp->b_bufobj == bo && bp->b_lblkno == blkno) 3990 goto foundbuf_fastpath; 3991 3992 /* It changed, fallback to locked lookup. */ 3993 BUF_UNLOCK_RAW(bp); 3994 3995 loop: 3996 BO_RLOCK(bo); 3997 bp = gbincore(bo, blkno); 3998 if (bp != NULL) { 3999 int lockflags; 4000 4001 /* 4002 * Buffer is in-core. If the buffer is not busy nor managed, 4003 * it must be on a queue. 4004 */ 4005 lockflags = LK_EXCLUSIVE | LK_INTERLOCK | 4006 ((flags & GB_LOCK_NOWAIT) ? LK_NOWAIT : LK_SLEEPFAIL); 4007 4008 error = BUF_TIMELOCK(bp, lockflags, 4009 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 4010 4011 /* 4012 * If we slept and got the lock we have to restart in case 4013 * the buffer changed identities. 4014 */ 4015 if (error == ENOLCK) 4016 goto loop; 4017 /* We timed out or were interrupted. */ 4018 else if (error != 0) 4019 return (error); 4020 4021 foundbuf_fastpath: 4022 /* If recursed, assume caller knows the rules. */ 4023 if (BUF_LOCKRECURSED(bp)) 4024 goto end; 4025 4026 /* 4027 * The buffer is locked. B_CACHE is cleared if the buffer is 4028 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 4029 * and for a VMIO buffer B_CACHE is adjusted according to the 4030 * backing VM cache. 4031 */ 4032 if (bp->b_flags & B_INVAL) 4033 bp->b_flags &= ~B_CACHE; 4034 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 4035 bp->b_flags |= B_CACHE; 4036 if (bp->b_flags & B_MANAGED) 4037 MPASS(bp->b_qindex == QUEUE_NONE); 4038 else 4039 bremfree(bp); 4040 4041 /* 4042 * check for size inconsistencies for non-VMIO case. 4043 */ 4044 if (bp->b_bcount != size) { 4045 if ((bp->b_flags & B_VMIO) == 0 || 4046 (size > bp->b_kvasize)) { 4047 if (bp->b_flags & B_DELWRI) { 4048 bp->b_flags |= B_NOCACHE; 4049 bwrite(bp); 4050 } else { 4051 if (LIST_EMPTY(&bp->b_dep)) { 4052 bp->b_flags |= B_RELBUF; 4053 brelse(bp); 4054 } else { 4055 bp->b_flags |= B_NOCACHE; 4056 bwrite(bp); 4057 } 4058 } 4059 goto loop; 4060 } 4061 } 4062 4063 /* 4064 * Handle the case of unmapped buffer which should 4065 * become mapped, or the buffer for which KVA 4066 * reservation is requested. 4067 */ 4068 bp_unmapped_get_kva(bp, blkno, size, flags); 4069 4070 /* 4071 * If the size is inconsistent in the VMIO case, we can resize 4072 * the buffer. This might lead to B_CACHE getting set or 4073 * cleared. If the size has not changed, B_CACHE remains 4074 * unchanged from its previous state. 4075 */ 4076 allocbuf(bp, size); 4077 4078 KASSERT(bp->b_offset != NOOFFSET, 4079 ("getblk: no buffer offset")); 4080 4081 /* 4082 * A buffer with B_DELWRI set and B_CACHE clear must 4083 * be committed before we can return the buffer in 4084 * order to prevent the caller from issuing a read 4085 * ( due to B_CACHE not being set ) and overwriting 4086 * it. 4087 * 4088 * Most callers, including NFS and FFS, need this to 4089 * operate properly either because they assume they 4090 * can issue a read if B_CACHE is not set, or because 4091 * ( for example ) an uncached B_DELWRI might loop due 4092 * to softupdates re-dirtying the buffer. In the latter 4093 * case, B_CACHE is set after the first write completes, 4094 * preventing further loops. 4095 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 4096 * above while extending the buffer, we cannot allow the 4097 * buffer to remain with B_CACHE set after the write 4098 * completes or it will represent a corrupt state. To 4099 * deal with this we set B_NOCACHE to scrap the buffer 4100 * after the write. 4101 * 4102 * We might be able to do something fancy, like setting 4103 * B_CACHE in bwrite() except if B_DELWRI is already set, 4104 * so the below call doesn't set B_CACHE, but that gets real 4105 * confusing. This is much easier. 4106 */ 4107 4108 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 4109 bp->b_flags |= B_NOCACHE; 4110 bwrite(bp); 4111 goto loop; 4112 } 4113 bp->b_flags &= ~B_DONE; 4114 } else { 4115 /* 4116 * Buffer is not in-core, create new buffer. The buffer 4117 * returned by getnewbuf() is locked. Note that the returned 4118 * buffer is also considered valid (not marked B_INVAL). 4119 */ 4120 BO_RUNLOCK(bo); 4121 newbuf_unlocked: 4122 /* 4123 * If the user does not want us to create the buffer, bail out 4124 * here. 4125 */ 4126 if (flags & GB_NOCREAT) 4127 return (EEXIST); 4128 4129 bsize = vn_isdisk(vp) ? DEV_BSIZE : bo->bo_bsize; 4130 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4131 offset = blkno * bsize; 4132 vmio = vp->v_object != NULL; 4133 if (vmio) { 4134 maxsize = size + (offset & PAGE_MASK); 4135 } else { 4136 maxsize = size; 4137 /* Do not allow non-VMIO notmapped buffers. */ 4138 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4139 } 4140 maxsize = imax(maxsize, bsize); 4141 if ((flags & GB_NOSPARSE) != 0 && vmio && 4142 !vn_isdisk(vp)) { 4143 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4144 KASSERT(error != EOPNOTSUPP, 4145 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4146 vp)); 4147 if (error != 0) 4148 return (error); 4149 if (d_blkno == -1) 4150 return (EJUSTRETURN); 4151 } 4152 4153 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4154 if (bp == NULL) { 4155 if (slpflag || slptimeo) 4156 return (ETIMEDOUT); 4157 /* 4158 * XXX This is here until the sleep path is diagnosed 4159 * enough to work under very low memory conditions. 4160 * 4161 * There's an issue on low memory, 4BSD+non-preempt 4162 * systems (eg MIPS routers with 32MB RAM) where buffer 4163 * exhaustion occurs without sleeping for buffer 4164 * reclaimation. This just sticks in a loop and 4165 * constantly attempts to allocate a buffer, which 4166 * hits exhaustion and tries to wakeup bufdaemon. 4167 * This never happens because we never yield. 4168 * 4169 * The real solution is to identify and fix these cases 4170 * so we aren't effectively busy-waiting in a loop 4171 * until the reclaimation path has cycles to run. 4172 */ 4173 kern_yield(PRI_USER); 4174 goto loop; 4175 } 4176 4177 /* 4178 * This code is used to make sure that a buffer is not 4179 * created while the getnewbuf routine is blocked. 4180 * This can be a problem whether the vnode is locked or not. 4181 * If the buffer is created out from under us, we have to 4182 * throw away the one we just created. 4183 * 4184 * Note: this must occur before we associate the buffer 4185 * with the vp especially considering limitations in 4186 * the splay tree implementation when dealing with duplicate 4187 * lblkno's. 4188 */ 4189 BO_LOCK(bo); 4190 if (gbincore(bo, blkno)) { 4191 BO_UNLOCK(bo); 4192 bp->b_flags |= B_INVAL; 4193 bufspace_release(bufdomain(bp), maxsize); 4194 brelse(bp); 4195 goto loop; 4196 } 4197 4198 /* 4199 * Insert the buffer into the hash, so that it can 4200 * be found by incore. 4201 */ 4202 bp->b_lblkno = blkno; 4203 bp->b_blkno = d_blkno; 4204 bp->b_offset = offset; 4205 bgetvp(vp, bp); 4206 BO_UNLOCK(bo); 4207 4208 /* 4209 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4210 * buffer size starts out as 0, B_CACHE will be set by 4211 * allocbuf() for the VMIO case prior to it testing the 4212 * backing store for validity. 4213 */ 4214 4215 if (vmio) { 4216 bp->b_flags |= B_VMIO; 4217 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4218 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4219 bp, vp->v_object, bp->b_bufobj->bo_object)); 4220 } else { 4221 bp->b_flags &= ~B_VMIO; 4222 KASSERT(bp->b_bufobj->bo_object == NULL, 4223 ("ARGH! has b_bufobj->bo_object %p %p\n", 4224 bp, bp->b_bufobj->bo_object)); 4225 BUF_CHECK_MAPPED(bp); 4226 } 4227 4228 allocbuf(bp, size); 4229 bufspace_release(bufdomain(bp), maxsize); 4230 bp->b_flags &= ~B_DONE; 4231 } 4232 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4233 end: 4234 buf_track(bp, __func__); 4235 KASSERT(bp->b_bufobj == bo, 4236 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4237 *bpp = bp; 4238 return (0); 4239 } 4240 4241 /* 4242 * Get an empty, disassociated buffer of given size. The buffer is initially 4243 * set to B_INVAL. 4244 */ 4245 struct buf * 4246 geteblk(int size, int flags) 4247 { 4248 struct buf *bp; 4249 int maxsize; 4250 4251 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4252 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4253 if ((flags & GB_NOWAIT_BD) && 4254 (curthread->td_pflags & TDP_BUFNEED) != 0) 4255 return (NULL); 4256 } 4257 allocbuf(bp, size); 4258 bufspace_release(bufdomain(bp), maxsize); 4259 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4260 return (bp); 4261 } 4262 4263 /* 4264 * Truncate the backing store for a non-vmio buffer. 4265 */ 4266 static void 4267 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4268 { 4269 4270 if (bp->b_flags & B_MALLOC) { 4271 /* 4272 * malloced buffers are not shrunk 4273 */ 4274 if (newbsize == 0) { 4275 bufmallocadjust(bp, 0); 4276 free(bp->b_data, M_BIOBUF); 4277 bp->b_data = bp->b_kvabase; 4278 bp->b_flags &= ~B_MALLOC; 4279 } 4280 return; 4281 } 4282 vm_hold_free_pages(bp, newbsize); 4283 bufspace_adjust(bp, newbsize); 4284 } 4285 4286 /* 4287 * Extend the backing for a non-VMIO buffer. 4288 */ 4289 static void 4290 vfs_nonvmio_extend(struct buf *bp, int newbsize) 4291 { 4292 caddr_t origbuf; 4293 int origbufsize; 4294 4295 /* 4296 * We only use malloced memory on the first allocation. 4297 * and revert to page-allocated memory when the buffer 4298 * grows. 4299 * 4300 * There is a potential smp race here that could lead 4301 * to bufmallocspace slightly passing the max. It 4302 * is probably extremely rare and not worth worrying 4303 * over. 4304 */ 4305 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4306 bufmallocspace < maxbufmallocspace) { 4307 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4308 bp->b_flags |= B_MALLOC; 4309 bufmallocadjust(bp, newbsize); 4310 return; 4311 } 4312 4313 /* 4314 * If the buffer is growing on its other-than-first 4315 * allocation then we revert to the page-allocation 4316 * scheme. 4317 */ 4318 origbuf = NULL; 4319 origbufsize = 0; 4320 if (bp->b_flags & B_MALLOC) { 4321 origbuf = bp->b_data; 4322 origbufsize = bp->b_bufsize; 4323 bp->b_data = bp->b_kvabase; 4324 bufmallocadjust(bp, 0); 4325 bp->b_flags &= ~B_MALLOC; 4326 newbsize = round_page(newbsize); 4327 } 4328 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4329 (vm_offset_t) bp->b_data + newbsize); 4330 if (origbuf != NULL) { 4331 bcopy(origbuf, bp->b_data, origbufsize); 4332 free(origbuf, M_BIOBUF); 4333 } 4334 bufspace_adjust(bp, newbsize); 4335 } 4336 4337 /* 4338 * This code constitutes the buffer memory from either anonymous system 4339 * memory (in the case of non-VMIO operations) or from an associated 4340 * VM object (in the case of VMIO operations). This code is able to 4341 * resize a buffer up or down. 4342 * 4343 * Note that this code is tricky, and has many complications to resolve 4344 * deadlock or inconsistent data situations. Tread lightly!!! 4345 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4346 * the caller. Calling this code willy nilly can result in the loss of data. 4347 * 4348 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4349 * B_CACHE for the non-VMIO case. 4350 */ 4351 int 4352 allocbuf(struct buf *bp, int size) 4353 { 4354 int newbsize; 4355 4356 if (bp->b_bcount == size) 4357 return (1); 4358 4359 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 4360 panic("allocbuf: buffer too small"); 4361 4362 newbsize = roundup2(size, DEV_BSIZE); 4363 if ((bp->b_flags & B_VMIO) == 0) { 4364 if ((bp->b_flags & B_MALLOC) == 0) 4365 newbsize = round_page(newbsize); 4366 /* 4367 * Just get anonymous memory from the kernel. Don't 4368 * mess with B_CACHE. 4369 */ 4370 if (newbsize < bp->b_bufsize) 4371 vfs_nonvmio_truncate(bp, newbsize); 4372 else if (newbsize > bp->b_bufsize) 4373 vfs_nonvmio_extend(bp, newbsize); 4374 } else { 4375 int desiredpages; 4376 4377 desiredpages = (size == 0) ? 0 : 4378 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4379 4380 if (bp->b_flags & B_MALLOC) 4381 panic("allocbuf: VMIO buffer can't be malloced"); 4382 /* 4383 * Set B_CACHE initially if buffer is 0 length or will become 4384 * 0-length. 4385 */ 4386 if (size == 0 || bp->b_bufsize == 0) 4387 bp->b_flags |= B_CACHE; 4388 4389 if (newbsize < bp->b_bufsize) 4390 vfs_vmio_truncate(bp, desiredpages); 4391 /* XXX This looks as if it should be newbsize > b_bufsize */ 4392 else if (size > bp->b_bcount) 4393 vfs_vmio_extend(bp, desiredpages, size); 4394 bufspace_adjust(bp, newbsize); 4395 } 4396 bp->b_bcount = size; /* requested buffer size. */ 4397 return (1); 4398 } 4399 4400 extern int inflight_transient_maps; 4401 4402 static struct bio_queue nondump_bios; 4403 4404 void 4405 biodone(struct bio *bp) 4406 { 4407 struct mtx *mtxp; 4408 void (*done)(struct bio *); 4409 vm_offset_t start, end; 4410 4411 biotrack(bp, __func__); 4412 4413 /* 4414 * Avoid completing I/O when dumping after a panic since that may 4415 * result in a deadlock in the filesystem or pager code. Note that 4416 * this doesn't affect dumps that were started manually since we aim 4417 * to keep the system usable after it has been resumed. 4418 */ 4419 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4420 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4421 return; 4422 } 4423 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4424 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4425 bp->bio_flags |= BIO_UNMAPPED; 4426 start = trunc_page((vm_offset_t)bp->bio_data); 4427 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4428 bp->bio_data = unmapped_buf; 4429 pmap_qremove(start, atop(end - start)); 4430 vmem_free(transient_arena, start, end - start); 4431 atomic_add_int(&inflight_transient_maps, -1); 4432 } 4433 done = bp->bio_done; 4434 /* 4435 * The check for done == biodone is to allow biodone to be 4436 * used as a bio_done routine. 4437 */ 4438 if (done == NULL || done == biodone) { 4439 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4440 mtx_lock(mtxp); 4441 bp->bio_flags |= BIO_DONE; 4442 wakeup(bp); 4443 mtx_unlock(mtxp); 4444 } else 4445 done(bp); 4446 } 4447 4448 /* 4449 * Wait for a BIO to finish. 4450 */ 4451 int 4452 biowait(struct bio *bp, const char *wmesg) 4453 { 4454 struct mtx *mtxp; 4455 4456 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4457 mtx_lock(mtxp); 4458 while ((bp->bio_flags & BIO_DONE) == 0) 4459 msleep(bp, mtxp, PRIBIO, wmesg, 0); 4460 mtx_unlock(mtxp); 4461 if (bp->bio_error != 0) 4462 return (bp->bio_error); 4463 if (!(bp->bio_flags & BIO_ERROR)) 4464 return (0); 4465 return (EIO); 4466 } 4467 4468 void 4469 biofinish(struct bio *bp, struct devstat *stat, int error) 4470 { 4471 4472 if (error) { 4473 bp->bio_error = error; 4474 bp->bio_flags |= BIO_ERROR; 4475 } 4476 if (stat != NULL) 4477 devstat_end_transaction_bio(stat, bp); 4478 biodone(bp); 4479 } 4480 4481 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4482 void 4483 biotrack_buf(struct bio *bp, const char *location) 4484 { 4485 4486 buf_track(bp->bio_track_bp, location); 4487 } 4488 #endif 4489 4490 /* 4491 * bufwait: 4492 * 4493 * Wait for buffer I/O completion, returning error status. The buffer 4494 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4495 * error and cleared. 4496 */ 4497 int 4498 bufwait(struct buf *bp) 4499 { 4500 if (bp->b_iocmd == BIO_READ) 4501 bwait(bp, PRIBIO, "biord"); 4502 else 4503 bwait(bp, PRIBIO, "biowr"); 4504 if (bp->b_flags & B_EINTR) { 4505 bp->b_flags &= ~B_EINTR; 4506 return (EINTR); 4507 } 4508 if (bp->b_ioflags & BIO_ERROR) { 4509 return (bp->b_error ? bp->b_error : EIO); 4510 } else { 4511 return (0); 4512 } 4513 } 4514 4515 /* 4516 * bufdone: 4517 * 4518 * Finish I/O on a buffer, optionally calling a completion function. 4519 * This is usually called from an interrupt so process blocking is 4520 * not allowed. 4521 * 4522 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4523 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4524 * assuming B_INVAL is clear. 4525 * 4526 * For the VMIO case, we set B_CACHE if the op was a read and no 4527 * read error occurred, or if the op was a write. B_CACHE is never 4528 * set if the buffer is invalid or otherwise uncacheable. 4529 * 4530 * bufdone does not mess with B_INVAL, allowing the I/O routine or the 4531 * initiator to leave B_INVAL set to brelse the buffer out of existence 4532 * in the biodone routine. 4533 */ 4534 void 4535 bufdone(struct buf *bp) 4536 { 4537 struct bufobj *dropobj; 4538 void (*biodone)(struct buf *); 4539 4540 buf_track(bp, __func__); 4541 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4542 dropobj = NULL; 4543 4544 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4545 4546 runningbufwakeup(bp); 4547 if (bp->b_iocmd == BIO_WRITE) 4548 dropobj = bp->b_bufobj; 4549 /* call optional completion function if requested */ 4550 if (bp->b_iodone != NULL) { 4551 biodone = bp->b_iodone; 4552 bp->b_iodone = NULL; 4553 (*biodone) (bp); 4554 if (dropobj) 4555 bufobj_wdrop(dropobj); 4556 return; 4557 } 4558 if (bp->b_flags & B_VMIO) { 4559 /* 4560 * Set B_CACHE if the op was a normal read and no error 4561 * occurred. B_CACHE is set for writes in the b*write() 4562 * routines. 4563 */ 4564 if (bp->b_iocmd == BIO_READ && 4565 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4566 !(bp->b_ioflags & BIO_ERROR)) 4567 bp->b_flags |= B_CACHE; 4568 vfs_vmio_iodone(bp); 4569 } 4570 if (!LIST_EMPTY(&bp->b_dep)) 4571 buf_complete(bp); 4572 if ((bp->b_flags & B_CKHASH) != 0) { 4573 KASSERT(bp->b_iocmd == BIO_READ, 4574 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4575 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4576 (*bp->b_ckhashcalc)(bp); 4577 } 4578 /* 4579 * For asynchronous completions, release the buffer now. The brelse 4580 * will do a wakeup there if necessary - so no need to do a wakeup 4581 * here in the async case. The sync case always needs to do a wakeup. 4582 */ 4583 if (bp->b_flags & B_ASYNC) { 4584 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4585 (bp->b_ioflags & BIO_ERROR)) 4586 brelse(bp); 4587 else 4588 bqrelse(bp); 4589 } else 4590 bdone(bp); 4591 if (dropobj) 4592 bufobj_wdrop(dropobj); 4593 } 4594 4595 /* 4596 * This routine is called in lieu of iodone in the case of 4597 * incomplete I/O. This keeps the busy status for pages 4598 * consistent. 4599 */ 4600 void 4601 vfs_unbusy_pages(struct buf *bp) 4602 { 4603 int i; 4604 vm_object_t obj; 4605 vm_page_t m; 4606 4607 runningbufwakeup(bp); 4608 if (!(bp->b_flags & B_VMIO)) 4609 return; 4610 4611 obj = bp->b_bufobj->bo_object; 4612 for (i = 0; i < bp->b_npages; i++) { 4613 m = bp->b_pages[i]; 4614 if (m == bogus_page) { 4615 m = vm_page_relookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4616 if (!m) 4617 panic("vfs_unbusy_pages: page missing\n"); 4618 bp->b_pages[i] = m; 4619 if (buf_mapped(bp)) { 4620 BUF_CHECK_MAPPED(bp); 4621 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4622 bp->b_pages, bp->b_npages); 4623 } else 4624 BUF_CHECK_UNMAPPED(bp); 4625 } 4626 vm_page_sunbusy(m); 4627 } 4628 vm_object_pip_wakeupn(obj, bp->b_npages); 4629 } 4630 4631 /* 4632 * vfs_page_set_valid: 4633 * 4634 * Set the valid bits in a page based on the supplied offset. The 4635 * range is restricted to the buffer's size. 4636 * 4637 * This routine is typically called after a read completes. 4638 */ 4639 static void 4640 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4641 { 4642 vm_ooffset_t eoff; 4643 4644 /* 4645 * Compute the end offset, eoff, such that [off, eoff) does not span a 4646 * page boundary and eoff is not greater than the end of the buffer. 4647 * The end of the buffer, in this case, is our file EOF, not the 4648 * allocation size of the buffer. 4649 */ 4650 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4651 if (eoff > bp->b_offset + bp->b_bcount) 4652 eoff = bp->b_offset + bp->b_bcount; 4653 4654 /* 4655 * Set valid range. This is typically the entire buffer and thus the 4656 * entire page. 4657 */ 4658 if (eoff > off) 4659 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4660 } 4661 4662 /* 4663 * vfs_page_set_validclean: 4664 * 4665 * Set the valid bits and clear the dirty bits in a page based on the 4666 * supplied offset. The range is restricted to the buffer's size. 4667 */ 4668 static void 4669 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4670 { 4671 vm_ooffset_t soff, eoff; 4672 4673 /* 4674 * Start and end offsets in buffer. eoff - soff may not cross a 4675 * page boundary or cross the end of the buffer. The end of the 4676 * buffer, in this case, is our file EOF, not the allocation size 4677 * of the buffer. 4678 */ 4679 soff = off; 4680 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4681 if (eoff > bp->b_offset + bp->b_bcount) 4682 eoff = bp->b_offset + bp->b_bcount; 4683 4684 /* 4685 * Set valid range. This is typically the entire buffer and thus the 4686 * entire page. 4687 */ 4688 if (eoff > soff) { 4689 vm_page_set_validclean( 4690 m, 4691 (vm_offset_t) (soff & PAGE_MASK), 4692 (vm_offset_t) (eoff - soff) 4693 ); 4694 } 4695 } 4696 4697 /* 4698 * Acquire a shared busy on all pages in the buf. 4699 */ 4700 void 4701 vfs_busy_pages_acquire(struct buf *bp) 4702 { 4703 int i; 4704 4705 for (i = 0; i < bp->b_npages; i++) 4706 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY); 4707 } 4708 4709 void 4710 vfs_busy_pages_release(struct buf *bp) 4711 { 4712 int i; 4713 4714 for (i = 0; i < bp->b_npages; i++) 4715 vm_page_sunbusy(bp->b_pages[i]); 4716 } 4717 4718 /* 4719 * This routine is called before a device strategy routine. 4720 * It is used to tell the VM system that paging I/O is in 4721 * progress, and treat the pages associated with the buffer 4722 * almost as being exclusive busy. Also the object paging_in_progress 4723 * flag is handled to make sure that the object doesn't become 4724 * inconsistent. 4725 * 4726 * Since I/O has not been initiated yet, certain buffer flags 4727 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4728 * and should be ignored. 4729 */ 4730 void 4731 vfs_busy_pages(struct buf *bp, int clear_modify) 4732 { 4733 vm_object_t obj; 4734 vm_ooffset_t foff; 4735 vm_page_t m; 4736 int i; 4737 bool bogus; 4738 4739 if (!(bp->b_flags & B_VMIO)) 4740 return; 4741 4742 obj = bp->b_bufobj->bo_object; 4743 foff = bp->b_offset; 4744 KASSERT(bp->b_offset != NOOFFSET, 4745 ("vfs_busy_pages: no buffer offset")); 4746 if ((bp->b_flags & B_CLUSTER) == 0) { 4747 vm_object_pip_add(obj, bp->b_npages); 4748 vfs_busy_pages_acquire(bp); 4749 } 4750 if (bp->b_bufsize != 0) 4751 vfs_setdirty_range(bp); 4752 bogus = false; 4753 for (i = 0; i < bp->b_npages; i++) { 4754 m = bp->b_pages[i]; 4755 vm_page_assert_sbusied(m); 4756 4757 /* 4758 * When readying a buffer for a read ( i.e 4759 * clear_modify == 0 ), it is important to do 4760 * bogus_page replacement for valid pages in 4761 * partially instantiated buffers. Partially 4762 * instantiated buffers can, in turn, occur when 4763 * reconstituting a buffer from its VM backing store 4764 * base. We only have to do this if B_CACHE is 4765 * clear ( which causes the I/O to occur in the 4766 * first place ). The replacement prevents the read 4767 * I/O from overwriting potentially dirty VM-backed 4768 * pages. XXX bogus page replacement is, uh, bogus. 4769 * It may not work properly with small-block devices. 4770 * We need to find a better way. 4771 */ 4772 if (clear_modify) { 4773 pmap_remove_write(m); 4774 vfs_page_set_validclean(bp, foff, m); 4775 } else if (vm_page_all_valid(m) && 4776 (bp->b_flags & B_CACHE) == 0) { 4777 bp->b_pages[i] = bogus_page; 4778 bogus = true; 4779 } 4780 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4781 } 4782 if (bogus && buf_mapped(bp)) { 4783 BUF_CHECK_MAPPED(bp); 4784 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4785 bp->b_pages, bp->b_npages); 4786 } 4787 } 4788 4789 /* 4790 * vfs_bio_set_valid: 4791 * 4792 * Set the range within the buffer to valid. The range is 4793 * relative to the beginning of the buffer, b_offset. Note that 4794 * b_offset itself may be offset from the beginning of the first 4795 * page. 4796 */ 4797 void 4798 vfs_bio_set_valid(struct buf *bp, int base, int size) 4799 { 4800 int i, n; 4801 vm_page_t m; 4802 4803 if (!(bp->b_flags & B_VMIO)) 4804 return; 4805 4806 /* 4807 * Fixup base to be relative to beginning of first page. 4808 * Set initial n to be the maximum number of bytes in the 4809 * first page that can be validated. 4810 */ 4811 base += (bp->b_offset & PAGE_MASK); 4812 n = PAGE_SIZE - (base & PAGE_MASK); 4813 4814 /* 4815 * Busy may not be strictly necessary here because the pages are 4816 * unlikely to be fully valid and the vnode lock will synchronize 4817 * their access via getpages. It is grabbed for consistency with 4818 * other page validation. 4819 */ 4820 vfs_busy_pages_acquire(bp); 4821 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4822 m = bp->b_pages[i]; 4823 if (n > size) 4824 n = size; 4825 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4826 base += n; 4827 size -= n; 4828 n = PAGE_SIZE; 4829 } 4830 vfs_busy_pages_release(bp); 4831 } 4832 4833 /* 4834 * vfs_bio_clrbuf: 4835 * 4836 * If the specified buffer is a non-VMIO buffer, clear the entire 4837 * buffer. If the specified buffer is a VMIO buffer, clear and 4838 * validate only the previously invalid portions of the buffer. 4839 * This routine essentially fakes an I/O, so we need to clear 4840 * BIO_ERROR and B_INVAL. 4841 * 4842 * Note that while we only theoretically need to clear through b_bcount, 4843 * we go ahead and clear through b_bufsize. 4844 */ 4845 void 4846 vfs_bio_clrbuf(struct buf *bp) 4847 { 4848 int i, j, mask, sa, ea, slide; 4849 4850 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4851 clrbuf(bp); 4852 return; 4853 } 4854 bp->b_flags &= ~B_INVAL; 4855 bp->b_ioflags &= ~BIO_ERROR; 4856 vfs_busy_pages_acquire(bp); 4857 sa = bp->b_offset & PAGE_MASK; 4858 slide = 0; 4859 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4860 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4861 ea = slide & PAGE_MASK; 4862 if (ea == 0) 4863 ea = PAGE_SIZE; 4864 if (bp->b_pages[i] == bogus_page) 4865 continue; 4866 j = sa / DEV_BSIZE; 4867 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4868 if ((bp->b_pages[i]->valid & mask) == mask) 4869 continue; 4870 if ((bp->b_pages[i]->valid & mask) == 0) 4871 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4872 else { 4873 for (; sa < ea; sa += DEV_BSIZE, j++) { 4874 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4875 pmap_zero_page_area(bp->b_pages[i], 4876 sa, DEV_BSIZE); 4877 } 4878 } 4879 } 4880 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE, 4881 roundup2(ea - sa, DEV_BSIZE)); 4882 } 4883 vfs_busy_pages_release(bp); 4884 bp->b_resid = 0; 4885 } 4886 4887 void 4888 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4889 { 4890 vm_page_t m; 4891 int i, n; 4892 4893 if (buf_mapped(bp)) { 4894 BUF_CHECK_MAPPED(bp); 4895 bzero(bp->b_data + base, size); 4896 } else { 4897 BUF_CHECK_UNMAPPED(bp); 4898 n = PAGE_SIZE - (base & PAGE_MASK); 4899 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4900 m = bp->b_pages[i]; 4901 if (n > size) 4902 n = size; 4903 pmap_zero_page_area(m, base & PAGE_MASK, n); 4904 base += n; 4905 size -= n; 4906 n = PAGE_SIZE; 4907 } 4908 } 4909 } 4910 4911 /* 4912 * Update buffer flags based on I/O request parameters, optionally releasing the 4913 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4914 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4915 * I/O). Otherwise the buffer is released to the cache. 4916 */ 4917 static void 4918 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4919 { 4920 4921 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4922 ("buf %p non-VMIO noreuse", bp)); 4923 4924 if ((ioflag & IO_DIRECT) != 0) 4925 bp->b_flags |= B_DIRECT; 4926 if ((ioflag & IO_EXT) != 0) 4927 bp->b_xflags |= BX_ALTDATA; 4928 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4929 bp->b_flags |= B_RELBUF; 4930 if ((ioflag & IO_NOREUSE) != 0) 4931 bp->b_flags |= B_NOREUSE; 4932 if (release) 4933 brelse(bp); 4934 } else if (release) 4935 bqrelse(bp); 4936 } 4937 4938 void 4939 vfs_bio_brelse(struct buf *bp, int ioflag) 4940 { 4941 4942 b_io_dismiss(bp, ioflag, true); 4943 } 4944 4945 void 4946 vfs_bio_set_flags(struct buf *bp, int ioflag) 4947 { 4948 4949 b_io_dismiss(bp, ioflag, false); 4950 } 4951 4952 /* 4953 * vm_hold_load_pages and vm_hold_free_pages get pages into 4954 * a buffers address space. The pages are anonymous and are 4955 * not associated with a file object. 4956 */ 4957 static void 4958 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4959 { 4960 vm_offset_t pg; 4961 vm_page_t p; 4962 int index; 4963 4964 BUF_CHECK_MAPPED(bp); 4965 4966 to = round_page(to); 4967 from = round_page(from); 4968 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4969 MPASS((bp->b_flags & B_MAXPHYS) == 0); 4970 KASSERT(to - from <= maxbcachebuf, 4971 ("vm_hold_load_pages too large %p %#jx %#jx %u", 4972 bp, (uintmax_t)from, (uintmax_t)to, maxbcachebuf)); 4973 4974 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4975 /* 4976 * note: must allocate system pages since blocking here 4977 * could interfere with paging I/O, no matter which 4978 * process we are. 4979 */ 4980 p = vm_page_alloc_noobj(VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 4981 VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | VM_ALLOC_WAITOK); 4982 pmap_qenter(pg, &p, 1); 4983 bp->b_pages[index] = p; 4984 } 4985 bp->b_npages = index; 4986 } 4987 4988 /* Return pages associated with this buf to the vm system */ 4989 static void 4990 vm_hold_free_pages(struct buf *bp, int newbsize) 4991 { 4992 vm_offset_t from; 4993 vm_page_t p; 4994 int index, newnpages; 4995 4996 BUF_CHECK_MAPPED(bp); 4997 4998 from = round_page((vm_offset_t)bp->b_data + newbsize); 4999 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 5000 if (bp->b_npages > newnpages) 5001 pmap_qremove(from, bp->b_npages - newnpages); 5002 for (index = newnpages; index < bp->b_npages; index++) { 5003 p = bp->b_pages[index]; 5004 bp->b_pages[index] = NULL; 5005 vm_page_unwire_noq(p); 5006 vm_page_free(p); 5007 } 5008 bp->b_npages = newnpages; 5009 } 5010 5011 /* 5012 * Map an IO request into kernel virtual address space. 5013 * 5014 * All requests are (re)mapped into kernel VA space. 5015 * Notice that we use b_bufsize for the size of the buffer 5016 * to be mapped. b_bcount might be modified by the driver. 5017 * 5018 * Note that even if the caller determines that the address space should 5019 * be valid, a race or a smaller-file mapped into a larger space may 5020 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 5021 * check the return value. 5022 * 5023 * This function only works with pager buffers. 5024 */ 5025 int 5026 vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf) 5027 { 5028 vm_prot_t prot; 5029 int pidx; 5030 5031 MPASS((bp->b_flags & B_MAXPHYS) != 0); 5032 prot = VM_PROT_READ; 5033 if (bp->b_iocmd == BIO_READ) 5034 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 5035 pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 5036 (vm_offset_t)uaddr, len, prot, bp->b_pages, PBUF_PAGES); 5037 if (pidx < 0) 5038 return (-1); 5039 bp->b_bufsize = len; 5040 bp->b_npages = pidx; 5041 bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK; 5042 if (mapbuf || !unmapped_buf_allowed) { 5043 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 5044 bp->b_data = bp->b_kvabase + bp->b_offset; 5045 } else 5046 bp->b_data = unmapped_buf; 5047 return (0); 5048 } 5049 5050 /* 5051 * Free the io map PTEs associated with this IO operation. 5052 * We also invalidate the TLB entries and restore the original b_addr. 5053 * 5054 * This function only works with pager buffers. 5055 */ 5056 void 5057 vunmapbuf(struct buf *bp) 5058 { 5059 int npages; 5060 5061 npages = bp->b_npages; 5062 if (buf_mapped(bp)) 5063 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 5064 vm_page_unhold_pages(bp->b_pages, npages); 5065 5066 bp->b_data = unmapped_buf; 5067 } 5068 5069 void 5070 bdone(struct buf *bp) 5071 { 5072 struct mtx *mtxp; 5073 5074 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5075 mtx_lock(mtxp); 5076 bp->b_flags |= B_DONE; 5077 wakeup(bp); 5078 mtx_unlock(mtxp); 5079 } 5080 5081 void 5082 bwait(struct buf *bp, u_char pri, const char *wchan) 5083 { 5084 struct mtx *mtxp; 5085 5086 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5087 mtx_lock(mtxp); 5088 while ((bp->b_flags & B_DONE) == 0) 5089 msleep(bp, mtxp, pri, wchan, 0); 5090 mtx_unlock(mtxp); 5091 } 5092 5093 int 5094 bufsync(struct bufobj *bo, int waitfor) 5095 { 5096 5097 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 5098 } 5099 5100 void 5101 bufstrategy(struct bufobj *bo, struct buf *bp) 5102 { 5103 int i __unused; 5104 struct vnode *vp; 5105 5106 vp = bp->b_vp; 5107 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5108 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5109 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5110 i = VOP_STRATEGY(vp, bp); 5111 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5112 } 5113 5114 /* 5115 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5116 */ 5117 void 5118 bufobj_init(struct bufobj *bo, void *private) 5119 { 5120 static volatile int bufobj_cleanq; 5121 5122 bo->bo_domain = 5123 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5124 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5125 bo->bo_private = private; 5126 TAILQ_INIT(&bo->bo_clean.bv_hd); 5127 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5128 } 5129 5130 void 5131 bufobj_wrefl(struct bufobj *bo) 5132 { 5133 5134 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5135 ASSERT_BO_WLOCKED(bo); 5136 bo->bo_numoutput++; 5137 } 5138 5139 void 5140 bufobj_wref(struct bufobj *bo) 5141 { 5142 5143 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5144 BO_LOCK(bo); 5145 bo->bo_numoutput++; 5146 BO_UNLOCK(bo); 5147 } 5148 5149 void 5150 bufobj_wdrop(struct bufobj *bo) 5151 { 5152 5153 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5154 BO_LOCK(bo); 5155 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5156 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5157 bo->bo_flag &= ~BO_WWAIT; 5158 wakeup(&bo->bo_numoutput); 5159 } 5160 BO_UNLOCK(bo); 5161 } 5162 5163 int 5164 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5165 { 5166 int error; 5167 5168 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5169 ASSERT_BO_WLOCKED(bo); 5170 error = 0; 5171 while (bo->bo_numoutput) { 5172 bo->bo_flag |= BO_WWAIT; 5173 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5174 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5175 if (error) 5176 break; 5177 } 5178 return (error); 5179 } 5180 5181 /* 5182 * Set bio_data or bio_ma for struct bio from the struct buf. 5183 */ 5184 void 5185 bdata2bio(struct buf *bp, struct bio *bip) 5186 { 5187 5188 if (!buf_mapped(bp)) { 5189 KASSERT(unmapped_buf_allowed, ("unmapped")); 5190 bip->bio_ma = bp->b_pages; 5191 bip->bio_ma_n = bp->b_npages; 5192 bip->bio_data = unmapped_buf; 5193 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5194 bip->bio_flags |= BIO_UNMAPPED; 5195 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5196 PAGE_SIZE == bp->b_npages, 5197 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5198 (long long)bip->bio_length, bip->bio_ma_n)); 5199 } else { 5200 bip->bio_data = bp->b_data; 5201 bip->bio_ma = NULL; 5202 } 5203 } 5204 5205 /* 5206 * The MIPS pmap code currently doesn't handle aliased pages. 5207 * The VIPT caches may not handle page aliasing themselves, leading 5208 * to data corruption. 5209 * 5210 * As such, this code makes a system extremely unhappy if said 5211 * system doesn't support unaliasing the above situation in hardware. 5212 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 5213 * this feature at build time, so it has to be handled in software. 5214 * 5215 * Once the MIPS pmap/cache code grows to support this function on 5216 * earlier chips, it should be flipped back off. 5217 */ 5218 #ifdef __mips__ 5219 static int buf_pager_relbuf = 1; 5220 #else 5221 static int buf_pager_relbuf = 0; 5222 #endif 5223 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5224 &buf_pager_relbuf, 0, 5225 "Make buffer pager release buffers after reading"); 5226 5227 /* 5228 * The buffer pager. It uses buffer reads to validate pages. 5229 * 5230 * In contrast to the generic local pager from vm/vnode_pager.c, this 5231 * pager correctly and easily handles volumes where the underlying 5232 * device block size is greater than the machine page size. The 5233 * buffer cache transparently extends the requested page run to be 5234 * aligned at the block boundary, and does the necessary bogus page 5235 * replacements in the addends to avoid obliterating already valid 5236 * pages. 5237 * 5238 * The only non-trivial issue is that the exclusive busy state for 5239 * pages, which is assumed by the vm_pager_getpages() interface, is 5240 * incompatible with the VMIO buffer cache's desire to share-busy the 5241 * pages. This function performs a trivial downgrade of the pages' 5242 * state before reading buffers, and a less trivial upgrade from the 5243 * shared-busy to excl-busy state after the read. 5244 */ 5245 int 5246 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5247 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5248 vbg_get_blksize_t get_blksize) 5249 { 5250 vm_page_t m; 5251 vm_object_t object; 5252 struct buf *bp; 5253 struct mount *mp; 5254 daddr_t lbn, lbnp; 5255 vm_ooffset_t la, lb, poff, poffe; 5256 long bo_bs, bsize; 5257 int br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5258 bool redo, lpart; 5259 5260 object = vp->v_object; 5261 mp = vp->v_mount; 5262 error = 0; 5263 la = IDX_TO_OFF(ma[count - 1]->pindex); 5264 if (la >= object->un_pager.vnp.vnp_size) 5265 return (VM_PAGER_BAD); 5266 5267 /* 5268 * Change the meaning of la from where the last requested page starts 5269 * to where it ends, because that's the end of the requested region 5270 * and the start of the potential read-ahead region. 5271 */ 5272 la += PAGE_SIZE; 5273 lpart = la > object->un_pager.vnp.vnp_size; 5274 error = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)), 5275 &bo_bs); 5276 if (error != 0) 5277 return (VM_PAGER_ERROR); 5278 5279 /* 5280 * Calculate read-ahead, behind and total pages. 5281 */ 5282 pgsin = count; 5283 lb = IDX_TO_OFF(ma[0]->pindex); 5284 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5285 pgsin += pgsin_b; 5286 if (rbehind != NULL) 5287 *rbehind = pgsin_b; 5288 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5289 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5290 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5291 PAGE_SIZE) - la); 5292 pgsin += pgsin_a; 5293 if (rahead != NULL) 5294 *rahead = pgsin_a; 5295 VM_CNT_INC(v_vnodein); 5296 VM_CNT_ADD(v_vnodepgsin, pgsin); 5297 5298 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5299 != 0) ? GB_UNMAPPED : 0; 5300 again: 5301 for (i = 0; i < count; i++) { 5302 if (ma[i] != bogus_page) 5303 vm_page_busy_downgrade(ma[i]); 5304 } 5305 5306 lbnp = -1; 5307 for (i = 0; i < count; i++) { 5308 m = ma[i]; 5309 if (m == bogus_page) 5310 continue; 5311 5312 /* 5313 * Pages are shared busy and the object lock is not 5314 * owned, which together allow for the pages' 5315 * invalidation. The racy test for validity avoids 5316 * useless creation of the buffer for the most typical 5317 * case when invalidation is not used in redo or for 5318 * parallel read. The shared->excl upgrade loop at 5319 * the end of the function catches the race in a 5320 * reliable way (protected by the object lock). 5321 */ 5322 if (vm_page_all_valid(m)) 5323 continue; 5324 5325 poff = IDX_TO_OFF(m->pindex); 5326 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5327 for (; poff < poffe; poff += bsize) { 5328 lbn = get_lblkno(vp, poff); 5329 if (lbn == lbnp) 5330 goto next_page; 5331 lbnp = lbn; 5332 5333 error = get_blksize(vp, lbn, &bsize); 5334 if (error == 0) 5335 error = bread_gb(vp, lbn, bsize, 5336 curthread->td_ucred, br_flags, &bp); 5337 if (error != 0) 5338 goto end_pages; 5339 if (bp->b_rcred == curthread->td_ucred) { 5340 crfree(bp->b_rcred); 5341 bp->b_rcred = NOCRED; 5342 } 5343 if (LIST_EMPTY(&bp->b_dep)) { 5344 /* 5345 * Invalidation clears m->valid, but 5346 * may leave B_CACHE flag if the 5347 * buffer existed at the invalidation 5348 * time. In this case, recycle the 5349 * buffer to do real read on next 5350 * bread() after redo. 5351 * 5352 * Otherwise B_RELBUF is not strictly 5353 * necessary, enable to reduce buf 5354 * cache pressure. 5355 */ 5356 if (buf_pager_relbuf || 5357 !vm_page_all_valid(m)) 5358 bp->b_flags |= B_RELBUF; 5359 5360 bp->b_flags &= ~B_NOCACHE; 5361 brelse(bp); 5362 } else { 5363 bqrelse(bp); 5364 } 5365 } 5366 KASSERT(1 /* racy, enable for debugging */ || 5367 vm_page_all_valid(m) || i == count - 1, 5368 ("buf %d %p invalid", i, m)); 5369 if (i == count - 1 && lpart) { 5370 if (!vm_page_none_valid(m) && 5371 !vm_page_all_valid(m)) 5372 vm_page_zero_invalid(m, TRUE); 5373 } 5374 next_page:; 5375 } 5376 end_pages: 5377 5378 redo = false; 5379 for (i = 0; i < count; i++) { 5380 if (ma[i] == bogus_page) 5381 continue; 5382 if (vm_page_busy_tryupgrade(ma[i]) == 0) { 5383 vm_page_sunbusy(ma[i]); 5384 ma[i] = vm_page_grab_unlocked(object, ma[i]->pindex, 5385 VM_ALLOC_NORMAL); 5386 } 5387 5388 /* 5389 * Since the pages were only sbusy while neither the 5390 * buffer nor the object lock was held by us, or 5391 * reallocated while vm_page_grab() slept for busy 5392 * relinguish, they could have been invalidated. 5393 * Recheck the valid bits and re-read as needed. 5394 * 5395 * Note that the last page is made fully valid in the 5396 * read loop, and partial validity for the page at 5397 * index count - 1 could mean that the page was 5398 * invalidated or removed, so we must restart for 5399 * safety as well. 5400 */ 5401 if (!vm_page_all_valid(ma[i])) 5402 redo = true; 5403 } 5404 if (redo && error == 0) 5405 goto again; 5406 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5407 } 5408 5409 #include "opt_ddb.h" 5410 #ifdef DDB 5411 #include <ddb/ddb.h> 5412 5413 /* DDB command to show buffer data */ 5414 DB_SHOW_COMMAND(buffer, db_show_buffer) 5415 { 5416 /* get args */ 5417 struct buf *bp = (struct buf *)addr; 5418 #ifdef FULL_BUF_TRACKING 5419 uint32_t i, j; 5420 #endif 5421 5422 if (!have_addr) { 5423 db_printf("usage: show buffer <addr>\n"); 5424 return; 5425 } 5426 5427 db_printf("buf at %p\n", bp); 5428 db_printf("b_flags = 0x%b, b_xflags=0x%b\n", 5429 (u_int)bp->b_flags, PRINT_BUF_FLAGS, 5430 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS); 5431 db_printf("b_vflags=0x%b b_ioflags0x%b\n", 5432 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS, 5433 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS); 5434 db_printf( 5435 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5436 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, " 5437 "b_vp = %p, b_dep = %p\n", 5438 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5439 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5440 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first); 5441 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5442 bp->b_kvabase, bp->b_kvasize); 5443 if (bp->b_npages) { 5444 int i; 5445 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5446 for (i = 0; i < bp->b_npages; i++) { 5447 vm_page_t m; 5448 m = bp->b_pages[i]; 5449 if (m != NULL) 5450 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5451 (u_long)m->pindex, 5452 (u_long)VM_PAGE_TO_PHYS(m)); 5453 else 5454 db_printf("( ??? )"); 5455 if ((i + 1) < bp->b_npages) 5456 db_printf(","); 5457 } 5458 db_printf("\n"); 5459 } 5460 BUF_LOCKPRINTINFO(bp); 5461 #if defined(FULL_BUF_TRACKING) 5462 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5463 5464 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5465 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5466 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5467 continue; 5468 db_printf(" %2u: %s\n", j, 5469 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5470 } 5471 #elif defined(BUF_TRACKING) 5472 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5473 #endif 5474 db_printf(" "); 5475 } 5476 5477 DB_SHOW_COMMAND(bufqueues, bufqueues) 5478 { 5479 struct bufdomain *bd; 5480 struct buf *bp; 5481 long total; 5482 int i, j, cnt; 5483 5484 db_printf("bqempty: %d\n", bqempty.bq_len); 5485 5486 for (i = 0; i < buf_domains; i++) { 5487 bd = &bdomain[i]; 5488 db_printf("Buf domain %d\n", i); 5489 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5490 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5491 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5492 db_printf("\n"); 5493 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5494 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5495 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5496 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5497 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5498 db_printf("\n"); 5499 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5500 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5501 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5502 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5503 db_printf("\n"); 5504 total = 0; 5505 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5506 total += bp->b_bufsize; 5507 db_printf("\tcleanq count\t%d (%ld)\n", 5508 bd->bd_cleanq->bq_len, total); 5509 total = 0; 5510 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5511 total += bp->b_bufsize; 5512 db_printf("\tdirtyq count\t%d (%ld)\n", 5513 bd->bd_dirtyq.bq_len, total); 5514 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5515 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5516 db_printf("\tCPU "); 5517 for (j = 0; j <= mp_maxid; j++) 5518 db_printf("%d, ", bd->bd_subq[j].bq_len); 5519 db_printf("\n"); 5520 cnt = 0; 5521 total = 0; 5522 for (j = 0; j < nbuf; j++) { 5523 bp = nbufp(j); 5524 if (bp->b_domain == i && BUF_ISLOCKED(bp)) { 5525 cnt++; 5526 total += bp->b_bufsize; 5527 } 5528 } 5529 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5530 cnt = 0; 5531 total = 0; 5532 for (j = 0; j < nbuf; j++) { 5533 bp = nbufp(j); 5534 if (bp->b_domain == i) { 5535 cnt++; 5536 total += bp->b_bufsize; 5537 } 5538 } 5539 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5540 } 5541 } 5542 5543 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 5544 { 5545 struct buf *bp; 5546 int i; 5547 5548 for (i = 0; i < nbuf; i++) { 5549 bp = nbufp(i); 5550 if (BUF_ISLOCKED(bp)) { 5551 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5552 db_printf("\n"); 5553 if (db_pager_quit) 5554 break; 5555 } 5556 } 5557 } 5558 5559 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5560 { 5561 struct vnode *vp; 5562 struct buf *bp; 5563 5564 if (!have_addr) { 5565 db_printf("usage: show vnodebufs <addr>\n"); 5566 return; 5567 } 5568 vp = (struct vnode *)addr; 5569 db_printf("Clean buffers:\n"); 5570 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5571 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5572 db_printf("\n"); 5573 } 5574 db_printf("Dirty buffers:\n"); 5575 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5576 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5577 db_printf("\n"); 5578 } 5579 } 5580 5581 DB_COMMAND(countfreebufs, db_coundfreebufs) 5582 { 5583 struct buf *bp; 5584 int i, used = 0, nfree = 0; 5585 5586 if (have_addr) { 5587 db_printf("usage: countfreebufs\n"); 5588 return; 5589 } 5590 5591 for (i = 0; i < nbuf; i++) { 5592 bp = nbufp(i); 5593 if (bp->b_qindex == QUEUE_EMPTY) 5594 nfree++; 5595 else 5596 used++; 5597 } 5598 5599 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5600 nfree + used); 5601 db_printf("numfreebuffers is %d\n", numfreebuffers); 5602 } 5603 #endif /* DDB */ 5604