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