1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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; 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 if (KERNEL_PANICKED()) 770 return; 771 772 BD_RUN_LOCK(bd); 773 bd->bd_shutdown = true; 774 wakeup(&bd->bd_running); 775 error = msleep(&bd->bd_shutdown, BD_RUN_LOCKPTR(bd), 0, 776 "bufspace_shutdown", 60 * hz); 777 BD_RUN_UNLOCK(bd); 778 if (error != 0) 779 printf("bufspacedaemon wait error: %d\n", error); 780 } 781 782 /* 783 * bufspace_daemon: 784 * 785 * buffer space management daemon. Tries to maintain some marginal 786 * amount of free buffer space so that requesting processes neither 787 * block nor work to reclaim buffers. 788 */ 789 static void 790 bufspace_daemon(void *arg) 791 { 792 struct bufdomain *bd = arg; 793 794 EVENTHANDLER_REGISTER(shutdown_pre_sync, bufspace_daemon_shutdown, bd, 795 SHUTDOWN_PRI_LAST + 100); 796 797 BD_RUN_LOCK(bd); 798 while (!bd->bd_shutdown) { 799 BD_RUN_UNLOCK(bd); 800 801 /* 802 * Free buffers from the clean queue until we meet our 803 * targets. 804 * 805 * Theory of operation: The buffer cache is most efficient 806 * when some free buffer headers and space are always 807 * available to getnewbuf(). This daemon attempts to prevent 808 * the excessive blocking and synchronization associated 809 * with shortfall. It goes through three phases according 810 * demand: 811 * 812 * 1) The daemon wakes up voluntarily once per-second 813 * during idle periods when the counters are below 814 * the wakeup thresholds (bufspacethresh, lofreebuffers). 815 * 816 * 2) The daemon wakes up as we cross the thresholds 817 * ahead of any potential blocking. This may bounce 818 * slightly according to the rate of consumption and 819 * release. 820 * 821 * 3) The daemon and consumers are starved for working 822 * clean buffers. This is the 'bufspace' sleep below 823 * which will inefficiently trade bufs with bqrelse 824 * until we return to condition 2. 825 */ 826 while (bd->bd_bufspace > bd->bd_lobufspace || 827 bd->bd_freebuffers < bd->bd_hifreebuffers) { 828 if (buf_recycle(bd, false) != 0) { 829 if (bd_flushall(bd)) 830 continue; 831 /* 832 * Speedup dirty if we've run out of clean 833 * buffers. This is possible in particular 834 * because softdep may held many bufs locked 835 * pending writes to other bufs which are 836 * marked for delayed write, exhausting 837 * clean space until they are written. 838 */ 839 bd_speedup(); 840 BD_LOCK(bd); 841 if (bd->bd_wanted) { 842 msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 843 PRIBIO|PDROP, "bufspace", hz/10); 844 } else 845 BD_UNLOCK(bd); 846 } 847 maybe_yield(); 848 } 849 850 /* 851 * Re-check our limits and sleep. bd_running must be 852 * cleared prior to checking the limits to avoid missed 853 * wakeups. The waker will adjust one of bufspace or 854 * freebuffers prior to checking bd_running. 855 */ 856 BD_RUN_LOCK(bd); 857 if (bd->bd_shutdown) 858 break; 859 atomic_store_int(&bd->bd_running, 0); 860 if (bd->bd_bufspace < bd->bd_bufspacethresh && 861 bd->bd_freebuffers > bd->bd_lofreebuffers) { 862 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), 863 PRIBIO, "-", hz); 864 } else { 865 /* Avoid spurious wakeups while running. */ 866 atomic_store_int(&bd->bd_running, 1); 867 } 868 } 869 wakeup(&bd->bd_shutdown); 870 BD_RUN_UNLOCK(bd); 871 kthread_exit(); 872 } 873 874 /* 875 * bufmallocadjust: 876 * 877 * Adjust the reported bufspace for a malloc managed buffer, possibly 878 * waking any waiters. 879 */ 880 static void 881 bufmallocadjust(struct buf *bp, int bufsize) 882 { 883 int diff; 884 885 KASSERT((bp->b_flags & B_MALLOC) != 0, 886 ("bufmallocadjust: non-malloc buf %p", bp)); 887 diff = bufsize - bp->b_bufsize; 888 if (diff < 0) 889 atomic_subtract_long(&bufmallocspace, -diff); 890 else 891 atomic_add_long(&bufmallocspace, diff); 892 bp->b_bufsize = bufsize; 893 } 894 895 /* 896 * runningwakeup: 897 * 898 * Wake up processes that are waiting on asynchronous writes to fall 899 * below lorunningspace. 900 */ 901 static void 902 runningwakeup(void) 903 { 904 905 mtx_lock(&rbreqlock); 906 if (runningbufreq) { 907 runningbufreq = 0; 908 wakeup(&runningbufreq); 909 } 910 mtx_unlock(&rbreqlock); 911 } 912 913 /* 914 * runningbufwakeup: 915 * 916 * Decrement the outstanding write count according. 917 */ 918 void 919 runningbufwakeup(struct buf *bp) 920 { 921 long space, bspace; 922 923 bspace = bp->b_runningbufspace; 924 if (bspace == 0) 925 return; 926 space = atomic_fetchadd_long(&runningbufspace, -bspace); 927 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 928 space, bspace)); 929 bp->b_runningbufspace = 0; 930 /* 931 * Only acquire the lock and wakeup on the transition from exceeding 932 * the threshold to falling below it. 933 */ 934 if (space < lorunningspace) 935 return; 936 if (space - bspace > lorunningspace) 937 return; 938 runningwakeup(); 939 } 940 941 /* 942 * waitrunningbufspace() 943 * 944 * runningbufspace is a measure of the amount of I/O currently 945 * running. This routine is used in async-write situations to 946 * prevent creating huge backups of pending writes to a device. 947 * Only asynchronous writes are governed by this function. 948 * 949 * This does NOT turn an async write into a sync write. It waits 950 * for earlier writes to complete and generally returns before the 951 * caller's write has reached the device. 952 */ 953 void 954 waitrunningbufspace(void) 955 { 956 957 mtx_lock(&rbreqlock); 958 while (runningbufspace > hirunningspace) { 959 runningbufreq = 1; 960 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 961 } 962 mtx_unlock(&rbreqlock); 963 } 964 965 /* 966 * vfs_buf_test_cache: 967 * 968 * Called when a buffer is extended. This function clears the B_CACHE 969 * bit if the newly extended portion of the buffer does not contain 970 * valid data. 971 */ 972 static __inline void 973 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 974 vm_offset_t size, vm_page_t m) 975 { 976 977 /* 978 * This function and its results are protected by higher level 979 * synchronization requiring vnode and buf locks to page in and 980 * validate pages. 981 */ 982 if (bp->b_flags & B_CACHE) { 983 int base = (foff + off) & PAGE_MASK; 984 if (vm_page_is_valid(m, base, size) == 0) 985 bp->b_flags &= ~B_CACHE; 986 } 987 } 988 989 /* Wake up the buffer daemon if necessary */ 990 static void 991 bd_wakeup(void) 992 { 993 994 mtx_lock(&bdlock); 995 if (bd_request == 0) { 996 bd_request = 1; 997 wakeup(&bd_request); 998 } 999 mtx_unlock(&bdlock); 1000 } 1001 1002 /* 1003 * Adjust the maxbcachbuf tunable. 1004 */ 1005 static void 1006 maxbcachebuf_adjust(void) 1007 { 1008 int i; 1009 1010 /* 1011 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 1012 */ 1013 i = 2; 1014 while (i * 2 <= maxbcachebuf) 1015 i *= 2; 1016 maxbcachebuf = i; 1017 if (maxbcachebuf < MAXBSIZE) 1018 maxbcachebuf = MAXBSIZE; 1019 if (maxbcachebuf > maxphys) 1020 maxbcachebuf = maxphys; 1021 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 1022 printf("maxbcachebuf=%d\n", maxbcachebuf); 1023 } 1024 1025 /* 1026 * bd_speedup - speedup the buffer cache flushing code 1027 */ 1028 void 1029 bd_speedup(void) 1030 { 1031 int needwake; 1032 1033 mtx_lock(&bdlock); 1034 needwake = 0; 1035 if (bd_speedupreq == 0 || bd_request == 0) 1036 needwake = 1; 1037 bd_speedupreq = 1; 1038 bd_request = 1; 1039 if (needwake) 1040 wakeup(&bd_request); 1041 mtx_unlock(&bdlock); 1042 } 1043 1044 #ifdef __i386__ 1045 #define TRANSIENT_DENOM 5 1046 #else 1047 #define TRANSIENT_DENOM 10 1048 #endif 1049 1050 /* 1051 * Calculating buffer cache scaling values and reserve space for buffer 1052 * headers. This is called during low level kernel initialization and 1053 * may be called more then once. We CANNOT write to the memory area 1054 * being reserved at this time. 1055 */ 1056 caddr_t 1057 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 1058 { 1059 int tuned_nbuf; 1060 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 1061 1062 /* 1063 * With KASAN or KMSAN enabled, the kernel map is shadowed. Account for 1064 * this when sizing maps based on the amount of physical memory 1065 * available. 1066 */ 1067 #if defined(KASAN) 1068 physmem_est = (physmem_est * KASAN_SHADOW_SCALE) / 1069 (KASAN_SHADOW_SCALE + 1); 1070 #elif defined(KMSAN) 1071 physmem_est /= 3; 1072 1073 /* 1074 * KMSAN cannot reliably determine whether buffer data is initialized 1075 * unless it is updated through a KVA mapping. 1076 */ 1077 unmapped_buf_allowed = 0; 1078 #endif 1079 1080 /* 1081 * physmem_est is in pages. Convert it to kilobytes (assumes 1082 * PAGE_SIZE is >= 1K) 1083 */ 1084 physmem_est = physmem_est * (PAGE_SIZE / 1024); 1085 1086 maxbcachebuf_adjust(); 1087 /* 1088 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 1089 * For the first 64MB of ram nominally allocate sufficient buffers to 1090 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 1091 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 1092 * the buffer cache we limit the eventual kva reservation to 1093 * maxbcache bytes. 1094 * 1095 * factor represents the 1/4 x ram conversion. 1096 */ 1097 if (nbuf == 0) { 1098 int factor = 4 * BKVASIZE / 1024; 1099 1100 nbuf = 50; 1101 if (physmem_est > 4096) 1102 nbuf += min((physmem_est - 4096) / factor, 1103 65536 / factor); 1104 if (physmem_est > 65536) 1105 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 1106 32 * 1024 * 1024 / (factor * 5)); 1107 1108 if (maxbcache && nbuf > maxbcache / BKVASIZE) 1109 nbuf = maxbcache / BKVASIZE; 1110 tuned_nbuf = 1; 1111 } else 1112 tuned_nbuf = 0; 1113 1114 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 1115 maxbuf = (LONG_MAX / 3) / BKVASIZE; 1116 if (nbuf > maxbuf) { 1117 if (!tuned_nbuf) 1118 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 1119 maxbuf); 1120 nbuf = maxbuf; 1121 } 1122 1123 /* 1124 * Ideal allocation size for the transient bio submap is 10% 1125 * of the maximal space buffer map. This roughly corresponds 1126 * to the amount of the buffer mapped for typical UFS load. 1127 * 1128 * Clip the buffer map to reserve space for the transient 1129 * BIOs, if its extent is bigger than 90% (80% on i386) of the 1130 * maximum buffer map extent on the platform. 1131 * 1132 * The fall-back to the maxbuf in case of maxbcache unset, 1133 * allows to not trim the buffer KVA for the architectures 1134 * with ample KVA space. 1135 */ 1136 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 1137 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 1138 buf_sz = (long)nbuf * BKVASIZE; 1139 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 1140 (TRANSIENT_DENOM - 1)) { 1141 /* 1142 * There is more KVA than memory. Do not 1143 * adjust buffer map size, and assign the rest 1144 * of maxbuf to transient map. 1145 */ 1146 biotmap_sz = maxbuf_sz - buf_sz; 1147 } else { 1148 /* 1149 * Buffer map spans all KVA we could afford on 1150 * this platform. Give 10% (20% on i386) of 1151 * the buffer map to the transient bio map. 1152 */ 1153 biotmap_sz = buf_sz / TRANSIENT_DENOM; 1154 buf_sz -= biotmap_sz; 1155 } 1156 if (biotmap_sz / INT_MAX > maxphys) 1157 bio_transient_maxcnt = INT_MAX; 1158 else 1159 bio_transient_maxcnt = biotmap_sz / maxphys; 1160 /* 1161 * Artificially limit to 1024 simultaneous in-flight I/Os 1162 * using the transient mapping. 1163 */ 1164 if (bio_transient_maxcnt > 1024) 1165 bio_transient_maxcnt = 1024; 1166 if (tuned_nbuf) 1167 nbuf = buf_sz / BKVASIZE; 1168 } 1169 1170 if (nswbuf == 0) { 1171 nswbuf = min(nbuf / 4, 256); 1172 if (nswbuf < NSWBUF_MIN) 1173 nswbuf = NSWBUF_MIN; 1174 } 1175 1176 /* 1177 * Reserve space for the buffer cache buffers 1178 */ 1179 buf = (char *)v; 1180 v = (caddr_t)buf + (sizeof(struct buf) + sizeof(vm_page_t) * 1181 atop(maxbcachebuf)) * nbuf; 1182 1183 return (v); 1184 } 1185 1186 /* 1187 * Single global constant for BUF_WMESG, to avoid getting multiple 1188 * references. 1189 */ 1190 static const char buf_wmesg[] = "bufwait"; 1191 1192 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1193 void 1194 bufinit(void) 1195 { 1196 struct buf *bp; 1197 int i; 1198 1199 KASSERT(maxbcachebuf >= MAXBSIZE, 1200 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1201 MAXBSIZE)); 1202 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock"); 1203 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1204 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1205 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1206 1207 unmapped_buf = (caddr_t)kva_alloc(maxphys); 1208 1209 /* finally, initialize each buffer header and stick on empty q */ 1210 for (i = 0; i < nbuf; i++) { 1211 bp = nbufp(i); 1212 bzero(bp, sizeof(*bp) + sizeof(vm_page_t) * atop(maxbcachebuf)); 1213 bp->b_flags = B_INVAL; 1214 bp->b_rcred = NOCRED; 1215 bp->b_wcred = NOCRED; 1216 bp->b_qindex = QUEUE_NONE; 1217 bp->b_domain = -1; 1218 bp->b_subqueue = mp_maxid + 1; 1219 bp->b_xflags = 0; 1220 bp->b_data = bp->b_kvabase = unmapped_buf; 1221 LIST_INIT(&bp->b_dep); 1222 BUF_LOCKINIT(bp, buf_wmesg); 1223 bq_insert(&bqempty, bp, false); 1224 } 1225 1226 /* 1227 * maxbufspace is the absolute maximum amount of buffer space we are 1228 * allowed to reserve in KVM and in real terms. The absolute maximum 1229 * is nominally used by metadata. hibufspace is the nominal maximum 1230 * used by most other requests. The differential is required to 1231 * ensure that metadata deadlocks don't occur. 1232 * 1233 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1234 * this may result in KVM fragmentation which is not handled optimally 1235 * by the system. XXX This is less true with vmem. We could use 1236 * PAGE_SIZE. 1237 */ 1238 maxbufspace = (long)nbuf * BKVASIZE; 1239 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1240 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1241 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1242 1243 /* 1244 * Note: The 16 MiB upper limit for hirunningspace was chosen 1245 * arbitrarily and may need further tuning. It corresponds to 1246 * 128 outstanding write IO requests (if IO size is 128 KiB), 1247 * which fits with many RAID controllers' tagged queuing limits. 1248 * The lower 1 MiB limit is the historical upper limit for 1249 * hirunningspace. 1250 */ 1251 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1252 16 * 1024 * 1024), 1024 * 1024); 1253 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1254 1255 /* 1256 * Limit the amount of malloc memory since it is wired permanently into 1257 * the kernel space. Even though this is accounted for in the buffer 1258 * allocation, we don't want the malloced region to grow uncontrolled. 1259 * The malloc scheme improves memory utilization significantly on 1260 * average (small) directories. 1261 */ 1262 maxbufmallocspace = hibufspace / 20; 1263 1264 /* 1265 * Reduce the chance of a deadlock occurring by limiting the number 1266 * of delayed-write dirty buffers we allow to stack up. 1267 */ 1268 hidirtybuffers = nbuf / 4 + 20; 1269 dirtybufthresh = hidirtybuffers * 9 / 10; 1270 /* 1271 * To support extreme low-memory systems, make sure hidirtybuffers 1272 * cannot eat up all available buffer space. This occurs when our 1273 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1274 * buffer space assuming BKVASIZE'd buffers. 1275 */ 1276 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1277 hidirtybuffers >>= 1; 1278 } 1279 lodirtybuffers = hidirtybuffers / 2; 1280 1281 /* 1282 * lofreebuffers should be sufficient to avoid stalling waiting on 1283 * buf headers under heavy utilization. The bufs in per-cpu caches 1284 * are counted as free but will be unavailable to threads executing 1285 * on other cpus. 1286 * 1287 * hifreebuffers is the free target for the bufspace daemon. This 1288 * should be set appropriately to limit work per-iteration. 1289 */ 1290 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1291 hifreebuffers = (3 * lofreebuffers) / 2; 1292 numfreebuffers = nbuf; 1293 1294 /* Setup the kva and free list allocators. */ 1295 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1296 buf_zone = uma_zcache_create("buf free cache", 1297 sizeof(struct buf) + sizeof(vm_page_t) * atop(maxbcachebuf), 1298 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1299 1300 /* 1301 * Size the clean queue according to the amount of buffer space. 1302 * One queue per-256mb up to the max. More queues gives better 1303 * concurrency but less accurate LRU. 1304 */ 1305 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS); 1306 for (i = 0 ; i < buf_domains; i++) { 1307 struct bufdomain *bd; 1308 1309 bd = &bdomain[i]; 1310 bd_init(bd); 1311 bd->bd_freebuffers = nbuf / buf_domains; 1312 bd->bd_hifreebuffers = hifreebuffers / buf_domains; 1313 bd->bd_lofreebuffers = lofreebuffers / buf_domains; 1314 bd->bd_bufspace = 0; 1315 bd->bd_maxbufspace = maxbufspace / buf_domains; 1316 bd->bd_hibufspace = hibufspace / buf_domains; 1317 bd->bd_lobufspace = lobufspace / buf_domains; 1318 bd->bd_bufspacethresh = bufspacethresh / buf_domains; 1319 bd->bd_numdirtybuffers = 0; 1320 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains; 1321 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains; 1322 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains; 1323 /* Don't allow more than 2% of bufs in the per-cpu caches. */ 1324 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus; 1325 } 1326 getnewbufcalls = counter_u64_alloc(M_WAITOK); 1327 getnewbufrestarts = counter_u64_alloc(M_WAITOK); 1328 mappingrestarts = counter_u64_alloc(M_WAITOK); 1329 numbufallocfails = counter_u64_alloc(M_WAITOK); 1330 notbufdflushes = counter_u64_alloc(M_WAITOK); 1331 buffreekvacnt = counter_u64_alloc(M_WAITOK); 1332 bufdefragcnt = counter_u64_alloc(M_WAITOK); 1333 bufkvaspace = counter_u64_alloc(M_WAITOK); 1334 } 1335 1336 #ifdef INVARIANTS 1337 static inline void 1338 vfs_buf_check_mapped(struct buf *bp) 1339 { 1340 1341 KASSERT(bp->b_kvabase != unmapped_buf, 1342 ("mapped buf: b_kvabase was not updated %p", bp)); 1343 KASSERT(bp->b_data != unmapped_buf, 1344 ("mapped buf: b_data was not updated %p", bp)); 1345 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1346 maxphys, ("b_data + b_offset unmapped %p", bp)); 1347 } 1348 1349 static inline void 1350 vfs_buf_check_unmapped(struct buf *bp) 1351 { 1352 1353 KASSERT(bp->b_data == unmapped_buf, 1354 ("unmapped buf: corrupted b_data %p", bp)); 1355 } 1356 1357 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1358 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1359 #else 1360 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1361 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1362 #endif 1363 1364 static int 1365 isbufbusy(struct buf *bp) 1366 { 1367 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1368 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1369 return (1); 1370 return (0); 1371 } 1372 1373 /* 1374 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1375 */ 1376 void 1377 bufshutdown(int show_busybufs) 1378 { 1379 static int first_buf_printf = 1; 1380 struct buf *bp; 1381 int i, iter, nbusy, pbusy; 1382 #ifndef PREEMPTION 1383 int subiter; 1384 #endif 1385 1386 /* 1387 * Sync filesystems for shutdown 1388 */ 1389 wdog_kern_pat(WD_LASTVAL); 1390 kern_sync(curthread); 1391 1392 /* 1393 * With soft updates, some buffers that are 1394 * written will be remarked as dirty until other 1395 * buffers are written. 1396 */ 1397 for (iter = pbusy = 0; iter < 20; iter++) { 1398 nbusy = 0; 1399 for (i = nbuf - 1; i >= 0; i--) { 1400 bp = nbufp(i); 1401 if (isbufbusy(bp)) 1402 nbusy++; 1403 } 1404 if (nbusy == 0) { 1405 if (first_buf_printf) 1406 printf("All buffers synced."); 1407 break; 1408 } 1409 if (first_buf_printf) { 1410 printf("Syncing disks, buffers remaining... "); 1411 first_buf_printf = 0; 1412 } 1413 printf("%d ", nbusy); 1414 if (nbusy < pbusy) 1415 iter = 0; 1416 pbusy = nbusy; 1417 1418 wdog_kern_pat(WD_LASTVAL); 1419 kern_sync(curthread); 1420 1421 #ifdef PREEMPTION 1422 /* 1423 * Spin for a while to allow interrupt threads to run. 1424 */ 1425 DELAY(50000 * iter); 1426 #else 1427 /* 1428 * Context switch several times to allow interrupt 1429 * threads to run. 1430 */ 1431 for (subiter = 0; subiter < 50 * iter; subiter++) { 1432 sched_relinquish(curthread); 1433 DELAY(1000); 1434 } 1435 #endif 1436 } 1437 printf("\n"); 1438 /* 1439 * Count only busy local buffers to prevent forcing 1440 * a fsck if we're just a client of a wedged NFS server 1441 */ 1442 nbusy = 0; 1443 for (i = nbuf - 1; i >= 0; i--) { 1444 bp = nbufp(i); 1445 if (isbufbusy(bp)) { 1446 #if 0 1447 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1448 if (bp->b_dev == NULL) { 1449 TAILQ_REMOVE(&mountlist, 1450 bp->b_vp->v_mount, mnt_list); 1451 continue; 1452 } 1453 #endif 1454 nbusy++; 1455 if (show_busybufs > 0) { 1456 printf( 1457 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1458 nbusy, bp, bp->b_vp, bp->b_flags, 1459 (intmax_t)bp->b_blkno, 1460 (intmax_t)bp->b_lblkno); 1461 BUF_LOCKPRINTINFO(bp); 1462 if (show_busybufs > 1) 1463 vn_printf(bp->b_vp, 1464 "vnode content: "); 1465 } 1466 } 1467 } 1468 if (nbusy) { 1469 /* 1470 * Failed to sync all blocks. Indicate this and don't 1471 * unmount filesystems (thus forcing an fsck on reboot). 1472 */ 1473 BOOTTRACE("shutdown failed to sync buffers"); 1474 printf("Giving up on %d buffers\n", nbusy); 1475 DELAY(5000000); /* 5 seconds */ 1476 swapoff_all(); 1477 } else { 1478 BOOTTRACE("shutdown sync complete"); 1479 if (!first_buf_printf) 1480 printf("Final sync complete\n"); 1481 1482 /* 1483 * Unmount filesystems and perform swapoff, to quiesce 1484 * the system as much as possible. In particular, no 1485 * I/O should be initiated from top levels since it 1486 * might be abruptly terminated by reset, or otherwise 1487 * erronously handled because other parts of the 1488 * system are disabled. 1489 * 1490 * Swapoff before unmount, because file-backed swap is 1491 * non-operational after unmount of the underlying 1492 * filesystem. 1493 */ 1494 if (!KERNEL_PANICKED()) { 1495 swapoff_all(); 1496 vfs_unmountall(); 1497 } 1498 BOOTTRACE("shutdown unmounted all filesystems"); 1499 } 1500 DELAY(100000); /* wait for console output to finish */ 1501 } 1502 1503 static void 1504 bpmap_qenter(struct buf *bp) 1505 { 1506 1507 BUF_CHECK_MAPPED(bp); 1508 1509 /* 1510 * bp->b_data is relative to bp->b_offset, but 1511 * bp->b_offset may be offset into the first page. 1512 */ 1513 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1514 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1515 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1516 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1517 } 1518 1519 static inline struct bufdomain * 1520 bufdomain(struct buf *bp) 1521 { 1522 1523 return (&bdomain[bp->b_domain]); 1524 } 1525 1526 static struct bufqueue * 1527 bufqueue(struct buf *bp) 1528 { 1529 1530 switch (bp->b_qindex) { 1531 case QUEUE_NONE: 1532 /* FALLTHROUGH */ 1533 case QUEUE_SENTINEL: 1534 return (NULL); 1535 case QUEUE_EMPTY: 1536 return (&bqempty); 1537 case QUEUE_DIRTY: 1538 return (&bufdomain(bp)->bd_dirtyq); 1539 case QUEUE_CLEAN: 1540 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]); 1541 default: 1542 break; 1543 } 1544 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex); 1545 } 1546 1547 /* 1548 * Return the locked bufqueue that bp is a member of. 1549 */ 1550 static struct bufqueue * 1551 bufqueue_acquire(struct buf *bp) 1552 { 1553 struct bufqueue *bq, *nbq; 1554 1555 /* 1556 * bp can be pushed from a per-cpu queue to the 1557 * cleanq while we're waiting on the lock. Retry 1558 * if the queues don't match. 1559 */ 1560 bq = bufqueue(bp); 1561 BQ_LOCK(bq); 1562 for (;;) { 1563 nbq = bufqueue(bp); 1564 if (bq == nbq) 1565 break; 1566 BQ_UNLOCK(bq); 1567 BQ_LOCK(nbq); 1568 bq = nbq; 1569 } 1570 return (bq); 1571 } 1572 1573 /* 1574 * binsfree: 1575 * 1576 * Insert the buffer into the appropriate free list. Requires a 1577 * locked buffer on entry and buffer is unlocked before return. 1578 */ 1579 static void 1580 binsfree(struct buf *bp, int qindex) 1581 { 1582 struct bufdomain *bd; 1583 struct bufqueue *bq; 1584 1585 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY, 1586 ("binsfree: Invalid qindex %d", qindex)); 1587 BUF_ASSERT_XLOCKED(bp); 1588 1589 /* 1590 * Handle delayed bremfree() processing. 1591 */ 1592 if (bp->b_flags & B_REMFREE) { 1593 if (bp->b_qindex == qindex) { 1594 bp->b_flags |= B_REUSE; 1595 bp->b_flags &= ~B_REMFREE; 1596 BUF_UNLOCK(bp); 1597 return; 1598 } 1599 bq = bufqueue_acquire(bp); 1600 bq_remove(bq, bp); 1601 BQ_UNLOCK(bq); 1602 } 1603 bd = bufdomain(bp); 1604 if (qindex == QUEUE_CLEAN) { 1605 if (bd->bd_lim != 0) 1606 bq = &bd->bd_subq[PCPU_GET(cpuid)]; 1607 else 1608 bq = bd->bd_cleanq; 1609 } else 1610 bq = &bd->bd_dirtyq; 1611 bq_insert(bq, bp, true); 1612 } 1613 1614 /* 1615 * buf_free: 1616 * 1617 * Free a buffer to the buf zone once it no longer has valid contents. 1618 */ 1619 static void 1620 buf_free(struct buf *bp) 1621 { 1622 1623 if (bp->b_flags & B_REMFREE) 1624 bremfreef(bp); 1625 if (bp->b_vflags & BV_BKGRDINPROG) 1626 panic("losing buffer 1"); 1627 if (bp->b_rcred != NOCRED) { 1628 crfree(bp->b_rcred); 1629 bp->b_rcred = NOCRED; 1630 } 1631 if (bp->b_wcred != NOCRED) { 1632 crfree(bp->b_wcred); 1633 bp->b_wcred = NOCRED; 1634 } 1635 if (!LIST_EMPTY(&bp->b_dep)) 1636 buf_deallocate(bp); 1637 bufkva_free(bp); 1638 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1); 1639 MPASS((bp->b_flags & B_MAXPHYS) == 0); 1640 BUF_UNLOCK(bp); 1641 uma_zfree(buf_zone, bp); 1642 } 1643 1644 /* 1645 * buf_import: 1646 * 1647 * Import bufs into the uma cache from the buf list. The system still 1648 * expects a static array of bufs and much of the synchronization 1649 * around bufs assumes type stable storage. As a result, UMA is used 1650 * only as a per-cpu cache of bufs still maintained on a global list. 1651 */ 1652 static int 1653 buf_import(void *arg, void **store, int cnt, int domain, int flags) 1654 { 1655 struct buf *bp; 1656 int i; 1657 1658 BQ_LOCK(&bqempty); 1659 for (i = 0; i < cnt; i++) { 1660 bp = TAILQ_FIRST(&bqempty.bq_queue); 1661 if (bp == NULL) 1662 break; 1663 bq_remove(&bqempty, bp); 1664 store[i] = bp; 1665 } 1666 BQ_UNLOCK(&bqempty); 1667 1668 return (i); 1669 } 1670 1671 /* 1672 * buf_release: 1673 * 1674 * Release bufs from the uma cache back to the buffer queues. 1675 */ 1676 static void 1677 buf_release(void *arg, void **store, int cnt) 1678 { 1679 struct bufqueue *bq; 1680 struct buf *bp; 1681 int i; 1682 1683 bq = &bqempty; 1684 BQ_LOCK(bq); 1685 for (i = 0; i < cnt; i++) { 1686 bp = store[i]; 1687 /* Inline bq_insert() to batch locking. */ 1688 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1689 bp->b_flags &= ~(B_AGE | B_REUSE); 1690 bq->bq_len++; 1691 bp->b_qindex = bq->bq_index; 1692 } 1693 BQ_UNLOCK(bq); 1694 } 1695 1696 /* 1697 * buf_alloc: 1698 * 1699 * Allocate an empty buffer header. 1700 */ 1701 static struct buf * 1702 buf_alloc(struct bufdomain *bd) 1703 { 1704 struct buf *bp; 1705 int freebufs, error; 1706 1707 /* 1708 * We can only run out of bufs in the buf zone if the average buf 1709 * is less than BKVASIZE. In this case the actual wait/block will 1710 * come from buf_reycle() failing to flush one of these small bufs. 1711 */ 1712 bp = NULL; 1713 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1); 1714 if (freebufs > 0) 1715 bp = uma_zalloc(buf_zone, M_NOWAIT); 1716 if (bp == NULL) { 1717 atomic_add_int(&bd->bd_freebuffers, 1); 1718 bufspace_daemon_wakeup(bd); 1719 counter_u64_add(numbufallocfails, 1); 1720 return (NULL); 1721 } 1722 /* 1723 * Wake-up the bufspace daemon on transition below threshold. 1724 */ 1725 if (freebufs == bd->bd_lofreebuffers) 1726 bufspace_daemon_wakeup(bd); 1727 1728 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWITNESS, NULL); 1729 KASSERT(error == 0, ("%s: BUF_LOCK on free buf %p: %d.", __func__, bp, 1730 error)); 1731 (void)error; 1732 1733 KASSERT(bp->b_vp == NULL, 1734 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1735 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1736 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1737 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1738 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1739 KASSERT(bp->b_npages == 0, 1740 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1741 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1742 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1743 MPASS((bp->b_flags & B_MAXPHYS) == 0); 1744 1745 bp->b_domain = BD_DOMAIN(bd); 1746 bp->b_flags = 0; 1747 bp->b_ioflags = 0; 1748 bp->b_xflags = 0; 1749 bp->b_vflags = 0; 1750 bp->b_vp = NULL; 1751 bp->b_blkno = bp->b_lblkno = 0; 1752 bp->b_offset = NOOFFSET; 1753 bp->b_iodone = 0; 1754 bp->b_error = 0; 1755 bp->b_resid = 0; 1756 bp->b_bcount = 0; 1757 bp->b_npages = 0; 1758 bp->b_dirtyoff = bp->b_dirtyend = 0; 1759 bp->b_bufobj = NULL; 1760 bp->b_data = bp->b_kvabase = unmapped_buf; 1761 bp->b_fsprivate1 = NULL; 1762 bp->b_fsprivate2 = NULL; 1763 bp->b_fsprivate3 = NULL; 1764 LIST_INIT(&bp->b_dep); 1765 1766 return (bp); 1767 } 1768 1769 /* 1770 * buf_recycle: 1771 * 1772 * Free a buffer from the given bufqueue. kva controls whether the 1773 * freed buf must own some kva resources. This is used for 1774 * defragmenting. 1775 */ 1776 static int 1777 buf_recycle(struct bufdomain *bd, bool kva) 1778 { 1779 struct bufqueue *bq; 1780 struct buf *bp, *nbp; 1781 1782 if (kva) 1783 counter_u64_add(bufdefragcnt, 1); 1784 nbp = NULL; 1785 bq = bd->bd_cleanq; 1786 BQ_LOCK(bq); 1787 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd), 1788 ("buf_recycle: Locks don't match")); 1789 nbp = TAILQ_FIRST(&bq->bq_queue); 1790 1791 /* 1792 * Run scan, possibly freeing data and/or kva mappings on the fly 1793 * depending. 1794 */ 1795 while ((bp = nbp) != NULL) { 1796 /* 1797 * Calculate next bp (we can only use it if we do not 1798 * release the bqlock). 1799 */ 1800 nbp = TAILQ_NEXT(bp, b_freelist); 1801 1802 /* 1803 * If we are defragging then we need a buffer with 1804 * some kva to reclaim. 1805 */ 1806 if (kva && bp->b_kvasize == 0) 1807 continue; 1808 1809 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1810 continue; 1811 1812 /* 1813 * Implement a second chance algorithm for frequently 1814 * accessed buffers. 1815 */ 1816 if ((bp->b_flags & B_REUSE) != 0) { 1817 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1818 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1819 bp->b_flags &= ~B_REUSE; 1820 BUF_UNLOCK(bp); 1821 continue; 1822 } 1823 1824 /* 1825 * Skip buffers with background writes in progress. 1826 */ 1827 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1828 BUF_UNLOCK(bp); 1829 continue; 1830 } 1831 1832 KASSERT(bp->b_qindex == QUEUE_CLEAN, 1833 ("buf_recycle: inconsistent queue %d bp %p", 1834 bp->b_qindex, bp)); 1835 KASSERT(bp->b_domain == BD_DOMAIN(bd), 1836 ("getnewbuf: queue domain %d doesn't match request %d", 1837 bp->b_domain, (int)BD_DOMAIN(bd))); 1838 /* 1839 * NOTE: nbp is now entirely invalid. We can only restart 1840 * the scan from this point on. 1841 */ 1842 bq_remove(bq, bp); 1843 BQ_UNLOCK(bq); 1844 1845 /* 1846 * Requeue the background write buffer with error and 1847 * restart the scan. 1848 */ 1849 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1850 bqrelse(bp); 1851 BQ_LOCK(bq); 1852 nbp = TAILQ_FIRST(&bq->bq_queue); 1853 continue; 1854 } 1855 bp->b_flags |= B_INVAL; 1856 brelse(bp); 1857 return (0); 1858 } 1859 bd->bd_wanted = 1; 1860 BQ_UNLOCK(bq); 1861 1862 return (ENOBUFS); 1863 } 1864 1865 /* 1866 * bremfree: 1867 * 1868 * Mark the buffer for removal from the appropriate free list. 1869 * 1870 */ 1871 void 1872 bremfree(struct buf *bp) 1873 { 1874 1875 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1876 KASSERT((bp->b_flags & B_REMFREE) == 0, 1877 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1878 KASSERT(bp->b_qindex != QUEUE_NONE, 1879 ("bremfree: buffer %p not on a queue.", bp)); 1880 BUF_ASSERT_XLOCKED(bp); 1881 1882 bp->b_flags |= B_REMFREE; 1883 } 1884 1885 /* 1886 * bremfreef: 1887 * 1888 * Force an immediate removal from a free list. Used only in nfs when 1889 * it abuses the b_freelist pointer. 1890 */ 1891 void 1892 bremfreef(struct buf *bp) 1893 { 1894 struct bufqueue *bq; 1895 1896 bq = bufqueue_acquire(bp); 1897 bq_remove(bq, bp); 1898 BQ_UNLOCK(bq); 1899 } 1900 1901 static void 1902 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname) 1903 { 1904 1905 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF); 1906 TAILQ_INIT(&bq->bq_queue); 1907 bq->bq_len = 0; 1908 bq->bq_index = qindex; 1909 bq->bq_subqueue = subqueue; 1910 } 1911 1912 static void 1913 bd_init(struct bufdomain *bd) 1914 { 1915 int i; 1916 1917 /* Per-CPU clean buf queues, plus one global queue. */ 1918 bd->bd_subq = mallocarray(mp_maxid + 2, sizeof(struct bufqueue), 1919 M_BIOBUF, M_WAITOK | M_ZERO); 1920 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1]; 1921 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock"); 1922 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock"); 1923 for (i = 0; i <= mp_maxid; i++) 1924 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i, 1925 "bufq clean subqueue lock"); 1926 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF); 1927 } 1928 1929 /* 1930 * bq_remove: 1931 * 1932 * Removes a buffer from the free list, must be called with the 1933 * correct qlock held. 1934 */ 1935 static void 1936 bq_remove(struct bufqueue *bq, struct buf *bp) 1937 { 1938 1939 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X", 1940 bp, bp->b_vp, bp->b_flags); 1941 KASSERT(bp->b_qindex != QUEUE_NONE, 1942 ("bq_remove: buffer %p not on a queue.", bp)); 1943 KASSERT(bufqueue(bp) == bq, 1944 ("bq_remove: Remove buffer %p from wrong queue.", bp)); 1945 1946 BQ_ASSERT_LOCKED(bq); 1947 if (bp->b_qindex != QUEUE_EMPTY) { 1948 BUF_ASSERT_XLOCKED(bp); 1949 } 1950 KASSERT(bq->bq_len >= 1, 1951 ("queue %d underflow", bp->b_qindex)); 1952 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1953 bq->bq_len--; 1954 bp->b_qindex = QUEUE_NONE; 1955 bp->b_flags &= ~(B_REMFREE | B_REUSE); 1956 } 1957 1958 static void 1959 bd_flush(struct bufdomain *bd, struct bufqueue *bq) 1960 { 1961 struct buf *bp; 1962 1963 BQ_ASSERT_LOCKED(bq); 1964 if (bq != bd->bd_cleanq) { 1965 BD_LOCK(bd); 1966 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) { 1967 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1968 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp, 1969 b_freelist); 1970 bp->b_subqueue = bd->bd_cleanq->bq_subqueue; 1971 } 1972 bd->bd_cleanq->bq_len += bq->bq_len; 1973 bq->bq_len = 0; 1974 } 1975 if (bd->bd_wanted) { 1976 bd->bd_wanted = 0; 1977 wakeup(&bd->bd_wanted); 1978 } 1979 if (bq != bd->bd_cleanq) 1980 BD_UNLOCK(bd); 1981 } 1982 1983 static int 1984 bd_flushall(struct bufdomain *bd) 1985 { 1986 struct bufqueue *bq; 1987 int flushed; 1988 int i; 1989 1990 if (bd->bd_lim == 0) 1991 return (0); 1992 flushed = 0; 1993 for (i = 0; i <= mp_maxid; i++) { 1994 bq = &bd->bd_subq[i]; 1995 if (bq->bq_len == 0) 1996 continue; 1997 BQ_LOCK(bq); 1998 bd_flush(bd, bq); 1999 BQ_UNLOCK(bq); 2000 flushed++; 2001 } 2002 2003 return (flushed); 2004 } 2005 2006 static void 2007 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock) 2008 { 2009 struct bufdomain *bd; 2010 2011 if (bp->b_qindex != QUEUE_NONE) 2012 panic("bq_insert: free buffer %p onto another queue?", bp); 2013 2014 bd = bufdomain(bp); 2015 if (bp->b_flags & B_AGE) { 2016 /* Place this buf directly on the real queue. */ 2017 if (bq->bq_index == QUEUE_CLEAN) 2018 bq = bd->bd_cleanq; 2019 BQ_LOCK(bq); 2020 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist); 2021 } else { 2022 BQ_LOCK(bq); 2023 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 2024 } 2025 bp->b_flags &= ~(B_AGE | B_REUSE); 2026 bq->bq_len++; 2027 bp->b_qindex = bq->bq_index; 2028 bp->b_subqueue = bq->bq_subqueue; 2029 2030 /* 2031 * Unlock before we notify so that we don't wakeup a waiter that 2032 * fails a trylock on the buf and sleeps again. 2033 */ 2034 if (unlock) 2035 BUF_UNLOCK(bp); 2036 2037 if (bp->b_qindex == QUEUE_CLEAN) { 2038 /* 2039 * Flush the per-cpu queue and notify any waiters. 2040 */ 2041 if (bd->bd_wanted || (bq != bd->bd_cleanq && 2042 bq->bq_len >= bd->bd_lim)) 2043 bd_flush(bd, bq); 2044 } 2045 BQ_UNLOCK(bq); 2046 } 2047 2048 /* 2049 * bufkva_free: 2050 * 2051 * Free the kva allocation for a buffer. 2052 * 2053 */ 2054 static void 2055 bufkva_free(struct buf *bp) 2056 { 2057 2058 #ifdef INVARIANTS 2059 if (bp->b_kvasize == 0) { 2060 KASSERT(bp->b_kvabase == unmapped_buf && 2061 bp->b_data == unmapped_buf, 2062 ("Leaked KVA space on %p", bp)); 2063 } else if (buf_mapped(bp)) 2064 BUF_CHECK_MAPPED(bp); 2065 else 2066 BUF_CHECK_UNMAPPED(bp); 2067 #endif 2068 if (bp->b_kvasize == 0) 2069 return; 2070 2071 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 2072 counter_u64_add(bufkvaspace, -bp->b_kvasize); 2073 counter_u64_add(buffreekvacnt, 1); 2074 bp->b_data = bp->b_kvabase = unmapped_buf; 2075 bp->b_kvasize = 0; 2076 } 2077 2078 /* 2079 * bufkva_alloc: 2080 * 2081 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 2082 */ 2083 static int 2084 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 2085 { 2086 vm_offset_t addr; 2087 int error; 2088 2089 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 2090 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 2091 MPASS((bp->b_flags & B_MAXPHYS) == 0); 2092 KASSERT(maxsize <= maxbcachebuf, 2093 ("bufkva_alloc kva too large %d %u", maxsize, maxbcachebuf)); 2094 2095 bufkva_free(bp); 2096 2097 addr = 0; 2098 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 2099 if (error != 0) { 2100 /* 2101 * Buffer map is too fragmented. Request the caller 2102 * to defragment the map. 2103 */ 2104 return (error); 2105 } 2106 bp->b_kvabase = (caddr_t)addr; 2107 bp->b_kvasize = maxsize; 2108 counter_u64_add(bufkvaspace, bp->b_kvasize); 2109 if ((gbflags & GB_UNMAPPED) != 0) { 2110 bp->b_data = unmapped_buf; 2111 BUF_CHECK_UNMAPPED(bp); 2112 } else { 2113 bp->b_data = bp->b_kvabase; 2114 BUF_CHECK_MAPPED(bp); 2115 } 2116 return (0); 2117 } 2118 2119 /* 2120 * bufkva_reclaim: 2121 * 2122 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 2123 * callback that fires to avoid returning failure. 2124 */ 2125 static void 2126 bufkva_reclaim(vmem_t *vmem, int flags) 2127 { 2128 bool done; 2129 int q; 2130 int i; 2131 2132 done = false; 2133 for (i = 0; i < 5; i++) { 2134 for (q = 0; q < buf_domains; q++) 2135 if (buf_recycle(&bdomain[q], true) != 0) 2136 done = true; 2137 if (done) 2138 break; 2139 } 2140 return; 2141 } 2142 2143 /* 2144 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 2145 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 2146 * the buffer is valid and we do not have to do anything. 2147 */ 2148 static void 2149 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt, 2150 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *)) 2151 { 2152 struct buf *rabp; 2153 struct thread *td; 2154 int i; 2155 2156 td = curthread; 2157 2158 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 2159 if (inmem(vp, *rablkno)) 2160 continue; 2161 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 2162 if ((rabp->b_flags & B_CACHE) != 0) { 2163 brelse(rabp); 2164 continue; 2165 } 2166 #ifdef RACCT 2167 if (racct_enable) { 2168 PROC_LOCK(curproc); 2169 racct_add_buf(curproc, rabp, 0); 2170 PROC_UNLOCK(curproc); 2171 } 2172 #endif /* RACCT */ 2173 td->td_ru.ru_inblock++; 2174 rabp->b_flags |= B_ASYNC; 2175 rabp->b_flags &= ~B_INVAL; 2176 if ((flags & GB_CKHASH) != 0) { 2177 rabp->b_flags |= B_CKHASH; 2178 rabp->b_ckhashcalc = ckhashfunc; 2179 } 2180 rabp->b_ioflags &= ~BIO_ERROR; 2181 rabp->b_iocmd = BIO_READ; 2182 if (rabp->b_rcred == NOCRED && cred != NOCRED) 2183 rabp->b_rcred = crhold(cred); 2184 vfs_busy_pages(rabp, 0); 2185 BUF_KERNPROC(rabp); 2186 rabp->b_iooffset = dbtob(rabp->b_blkno); 2187 bstrategy(rabp); 2188 } 2189 } 2190 2191 /* 2192 * Entry point for bread() and breadn() via #defines in sys/buf.h. 2193 * 2194 * Get a buffer with the specified data. Look in the cache first. We 2195 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 2196 * is set, the buffer is valid and we do not have to do anything, see 2197 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 2198 * 2199 * Always return a NULL buffer pointer (in bpp) when returning an error. 2200 * 2201 * The blkno parameter is the logical block being requested. Normally 2202 * the mapping of logical block number to disk block address is done 2203 * by calling VOP_BMAP(). However, if the mapping is already known, the 2204 * disk block address can be passed using the dblkno parameter. If the 2205 * disk block address is not known, then the same value should be passed 2206 * for blkno and dblkno. 2207 */ 2208 int 2209 breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, 2210 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags, 2211 void (*ckhashfunc)(struct buf *), struct buf **bpp) 2212 { 2213 struct buf *bp; 2214 struct thread *td; 2215 int error, readwait, rv; 2216 2217 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 2218 td = curthread; 2219 /* 2220 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags 2221 * are specified. 2222 */ 2223 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp); 2224 if (error != 0) { 2225 *bpp = NULL; 2226 return (error); 2227 } 2228 KASSERT(blkno == bp->b_lblkno, 2229 ("getblkx returned buffer for blkno %jd instead of blkno %jd", 2230 (intmax_t)bp->b_lblkno, (intmax_t)blkno)); 2231 flags &= ~GB_NOSPARSE; 2232 *bpp = bp; 2233 2234 /* 2235 * If not found in cache, do some I/O 2236 */ 2237 readwait = 0; 2238 if ((bp->b_flags & B_CACHE) == 0) { 2239 #ifdef RACCT 2240 if (racct_enable) { 2241 PROC_LOCK(td->td_proc); 2242 racct_add_buf(td->td_proc, bp, 0); 2243 PROC_UNLOCK(td->td_proc); 2244 } 2245 #endif /* RACCT */ 2246 td->td_ru.ru_inblock++; 2247 bp->b_iocmd = BIO_READ; 2248 bp->b_flags &= ~B_INVAL; 2249 if ((flags & GB_CKHASH) != 0) { 2250 bp->b_flags |= B_CKHASH; 2251 bp->b_ckhashcalc = ckhashfunc; 2252 } 2253 if ((flags & GB_CVTENXIO) != 0) 2254 bp->b_xflags |= BX_CVTENXIO; 2255 bp->b_ioflags &= ~BIO_ERROR; 2256 if (bp->b_rcred == NOCRED && cred != NOCRED) 2257 bp->b_rcred = crhold(cred); 2258 vfs_busy_pages(bp, 0); 2259 bp->b_iooffset = dbtob(bp->b_blkno); 2260 bstrategy(bp); 2261 ++readwait; 2262 } 2263 2264 /* 2265 * Attempt to initiate asynchronous I/O on read-ahead blocks. 2266 */ 2267 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 2268 2269 rv = 0; 2270 if (readwait) { 2271 rv = bufwait(bp); 2272 if (rv != 0) { 2273 brelse(bp); 2274 *bpp = NULL; 2275 } 2276 } 2277 return (rv); 2278 } 2279 2280 /* 2281 * Write, release buffer on completion. (Done by iodone 2282 * if async). Do not bother writing anything if the buffer 2283 * is invalid. 2284 * 2285 * Note that we set B_CACHE here, indicating that buffer is 2286 * fully valid and thus cacheable. This is true even of NFS 2287 * now so we set it generally. This could be set either here 2288 * or in biodone() since the I/O is synchronous. We put it 2289 * here. 2290 */ 2291 int 2292 bufwrite(struct buf *bp) 2293 { 2294 int oldflags; 2295 struct vnode *vp; 2296 long space; 2297 int vp_md; 2298 2299 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2300 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 2301 bp->b_flags |= B_INVAL | B_RELBUF; 2302 bp->b_flags &= ~B_CACHE; 2303 brelse(bp); 2304 return (ENXIO); 2305 } 2306 if (bp->b_flags & B_INVAL) { 2307 brelse(bp); 2308 return (0); 2309 } 2310 2311 if (bp->b_flags & B_BARRIER) 2312 atomic_add_long(&barrierwrites, 1); 2313 2314 oldflags = bp->b_flags; 2315 2316 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 2317 ("FFS background buffer should not get here %p", bp)); 2318 2319 vp = bp->b_vp; 2320 if (vp) 2321 vp_md = vp->v_vflag & VV_MD; 2322 else 2323 vp_md = 0; 2324 2325 /* 2326 * Mark the buffer clean. Increment the bufobj write count 2327 * before bundirty() call, to prevent other thread from seeing 2328 * empty dirty list and zero counter for writes in progress, 2329 * falsely indicating that the bufobj is clean. 2330 */ 2331 bufobj_wref(bp->b_bufobj); 2332 bundirty(bp); 2333 2334 bp->b_flags &= ~B_DONE; 2335 bp->b_ioflags &= ~BIO_ERROR; 2336 bp->b_flags |= B_CACHE; 2337 bp->b_iocmd = BIO_WRITE; 2338 2339 vfs_busy_pages(bp, 1); 2340 2341 /* 2342 * Normal bwrites pipeline writes 2343 */ 2344 bp->b_runningbufspace = bp->b_bufsize; 2345 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 2346 2347 #ifdef RACCT 2348 if (racct_enable) { 2349 PROC_LOCK(curproc); 2350 racct_add_buf(curproc, bp, 1); 2351 PROC_UNLOCK(curproc); 2352 } 2353 #endif /* RACCT */ 2354 curthread->td_ru.ru_oublock++; 2355 if (oldflags & B_ASYNC) 2356 BUF_KERNPROC(bp); 2357 bp->b_iooffset = dbtob(bp->b_blkno); 2358 buf_track(bp, __func__); 2359 bstrategy(bp); 2360 2361 if ((oldflags & B_ASYNC) == 0) { 2362 int rtval = bufwait(bp); 2363 brelse(bp); 2364 return (rtval); 2365 } else if (space > hirunningspace) { 2366 /* 2367 * don't allow the async write to saturate the I/O 2368 * system. We will not deadlock here because 2369 * we are blocking waiting for I/O that is already in-progress 2370 * to complete. We do not block here if it is the update 2371 * or syncer daemon trying to clean up as that can lead 2372 * to deadlock. 2373 */ 2374 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2375 waitrunningbufspace(); 2376 } 2377 2378 return (0); 2379 } 2380 2381 void 2382 bufbdflush(struct bufobj *bo, struct buf *bp) 2383 { 2384 struct buf *nbp; 2385 struct bufdomain *bd; 2386 2387 bd = &bdomain[bo->bo_domain]; 2388 if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh + 10) { 2389 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2390 altbufferflushes++; 2391 } else if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh) { 2392 BO_LOCK(bo); 2393 /* 2394 * Try to find a buffer to flush. 2395 */ 2396 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2397 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2398 BUF_LOCK(nbp, 2399 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2400 continue; 2401 if (bp == nbp) 2402 panic("bdwrite: found ourselves"); 2403 BO_UNLOCK(bo); 2404 /* Don't countdeps with the bo lock held. */ 2405 if (buf_countdeps(nbp, 0)) { 2406 BO_LOCK(bo); 2407 BUF_UNLOCK(nbp); 2408 continue; 2409 } 2410 if (nbp->b_flags & B_CLUSTEROK) { 2411 vfs_bio_awrite(nbp); 2412 } else { 2413 bremfree(nbp); 2414 bawrite(nbp); 2415 } 2416 dirtybufferflushes++; 2417 break; 2418 } 2419 if (nbp == NULL) 2420 BO_UNLOCK(bo); 2421 } 2422 } 2423 2424 /* 2425 * Delayed write. (Buffer is marked dirty). Do not bother writing 2426 * anything if the buffer is marked invalid. 2427 * 2428 * Note that since the buffer must be completely valid, we can safely 2429 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2430 * biodone() in order to prevent getblk from writing the buffer 2431 * out synchronously. 2432 */ 2433 void 2434 bdwrite(struct buf *bp) 2435 { 2436 struct thread *td = curthread; 2437 struct vnode *vp; 2438 struct bufobj *bo; 2439 2440 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2441 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2442 KASSERT((bp->b_flags & B_BARRIER) == 0, 2443 ("Barrier request in delayed write %p", bp)); 2444 2445 if (bp->b_flags & B_INVAL) { 2446 brelse(bp); 2447 return; 2448 } 2449 2450 /* 2451 * If we have too many dirty buffers, don't create any more. 2452 * If we are wildly over our limit, then force a complete 2453 * cleanup. Otherwise, just keep the situation from getting 2454 * out of control. Note that we have to avoid a recursive 2455 * disaster and not try to clean up after our own cleanup! 2456 */ 2457 vp = bp->b_vp; 2458 bo = bp->b_bufobj; 2459 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2460 td->td_pflags |= TDP_INBDFLUSH; 2461 BO_BDFLUSH(bo, bp); 2462 td->td_pflags &= ~TDP_INBDFLUSH; 2463 } else 2464 recursiveflushes++; 2465 2466 bdirty(bp); 2467 /* 2468 * Set B_CACHE, indicating that the buffer is fully valid. This is 2469 * true even of NFS now. 2470 */ 2471 bp->b_flags |= B_CACHE; 2472 2473 /* 2474 * This bmap keeps the system from needing to do the bmap later, 2475 * perhaps when the system is attempting to do a sync. Since it 2476 * is likely that the indirect block -- or whatever other datastructure 2477 * that the filesystem needs is still in memory now, it is a good 2478 * thing to do this. Note also, that if the pageout daemon is 2479 * requesting a sync -- there might not be enough memory to do 2480 * the bmap then... So, this is important to do. 2481 */ 2482 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2483 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2484 } 2485 2486 buf_track(bp, __func__); 2487 2488 /* 2489 * Set the *dirty* buffer range based upon the VM system dirty 2490 * pages. 2491 * 2492 * Mark the buffer pages as clean. We need to do this here to 2493 * satisfy the vnode_pager and the pageout daemon, so that it 2494 * thinks that the pages have been "cleaned". Note that since 2495 * the pages are in a delayed write buffer -- the VFS layer 2496 * "will" see that the pages get written out on the next sync, 2497 * or perhaps the cluster will be completed. 2498 */ 2499 vfs_clean_pages_dirty_buf(bp); 2500 bqrelse(bp); 2501 2502 /* 2503 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2504 * due to the softdep code. 2505 */ 2506 } 2507 2508 /* 2509 * bdirty: 2510 * 2511 * Turn buffer into delayed write request. We must clear BIO_READ and 2512 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2513 * itself to properly update it in the dirty/clean lists. We mark it 2514 * B_DONE to ensure that any asynchronization of the buffer properly 2515 * clears B_DONE ( else a panic will occur later ). 2516 * 2517 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2518 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2519 * should only be called if the buffer is known-good. 2520 * 2521 * Since the buffer is not on a queue, we do not update the numfreebuffers 2522 * count. 2523 * 2524 * The buffer must be on QUEUE_NONE. 2525 */ 2526 void 2527 bdirty(struct buf *bp) 2528 { 2529 2530 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2531 bp, bp->b_vp, bp->b_flags); 2532 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2533 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2534 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2535 bp->b_flags &= ~(B_RELBUF); 2536 bp->b_iocmd = BIO_WRITE; 2537 2538 if ((bp->b_flags & B_DELWRI) == 0) { 2539 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2540 reassignbuf(bp); 2541 bdirtyadd(bp); 2542 } 2543 } 2544 2545 /* 2546 * bundirty: 2547 * 2548 * Clear B_DELWRI for buffer. 2549 * 2550 * Since the buffer is not on a queue, we do not update the numfreebuffers 2551 * count. 2552 * 2553 * The buffer must be on QUEUE_NONE. 2554 */ 2555 2556 void 2557 bundirty(struct buf *bp) 2558 { 2559 2560 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2561 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2562 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2563 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2564 2565 if (bp->b_flags & B_DELWRI) { 2566 bp->b_flags &= ~B_DELWRI; 2567 reassignbuf(bp); 2568 bdirtysub(bp); 2569 } 2570 /* 2571 * Since it is now being written, we can clear its deferred write flag. 2572 */ 2573 bp->b_flags &= ~B_DEFERRED; 2574 } 2575 2576 /* 2577 * bawrite: 2578 * 2579 * Asynchronous write. Start output on a buffer, but do not wait for 2580 * it to complete. The buffer is released when the output completes. 2581 * 2582 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2583 * B_INVAL buffers. Not us. 2584 */ 2585 void 2586 bawrite(struct buf *bp) 2587 { 2588 2589 bp->b_flags |= B_ASYNC; 2590 (void) bwrite(bp); 2591 } 2592 2593 /* 2594 * babarrierwrite: 2595 * 2596 * Asynchronous barrier write. Start output on a buffer, but do not 2597 * wait for it to complete. Place a write barrier after this write so 2598 * that this buffer and all buffers written before it are committed to 2599 * the disk before any buffers written after this write are committed 2600 * to the disk. The buffer is released when the output completes. 2601 */ 2602 void 2603 babarrierwrite(struct buf *bp) 2604 { 2605 2606 bp->b_flags |= B_ASYNC | B_BARRIER; 2607 (void) bwrite(bp); 2608 } 2609 2610 /* 2611 * bbarrierwrite: 2612 * 2613 * Synchronous barrier write. Start output on a buffer and wait for 2614 * it to complete. Place a write barrier after this write so that 2615 * this buffer and all buffers written before it are committed to 2616 * the disk before any buffers written after this write are committed 2617 * to the disk. The buffer is released when the output completes. 2618 */ 2619 int 2620 bbarrierwrite(struct buf *bp) 2621 { 2622 2623 bp->b_flags |= B_BARRIER; 2624 return (bwrite(bp)); 2625 } 2626 2627 /* 2628 * bwillwrite: 2629 * 2630 * Called prior to the locking of any vnodes when we are expecting to 2631 * write. We do not want to starve the buffer cache with too many 2632 * dirty buffers so we block here. By blocking prior to the locking 2633 * of any vnodes we attempt to avoid the situation where a locked vnode 2634 * prevents the various system daemons from flushing related buffers. 2635 */ 2636 void 2637 bwillwrite(void) 2638 { 2639 2640 if (buf_dirty_count_severe()) { 2641 mtx_lock(&bdirtylock); 2642 while (buf_dirty_count_severe()) { 2643 bdirtywait = 1; 2644 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2645 "flswai", 0); 2646 } 2647 mtx_unlock(&bdirtylock); 2648 } 2649 } 2650 2651 /* 2652 * Return true if we have too many dirty buffers. 2653 */ 2654 int 2655 buf_dirty_count_severe(void) 2656 { 2657 2658 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty)); 2659 } 2660 2661 /* 2662 * brelse: 2663 * 2664 * Release a busy buffer and, if requested, free its resources. The 2665 * buffer will be stashed in the appropriate bufqueue[] allowing it 2666 * to be accessed later as a cache entity or reused for other purposes. 2667 */ 2668 void 2669 brelse(struct buf *bp) 2670 { 2671 struct mount *v_mnt; 2672 int qindex; 2673 2674 /* 2675 * Many functions erroneously call brelse with a NULL bp under rare 2676 * error conditions. Simply return when called with a NULL bp. 2677 */ 2678 if (bp == NULL) 2679 return; 2680 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2681 bp, bp->b_vp, bp->b_flags); 2682 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2683 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2684 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2685 ("brelse: non-VMIO buffer marked NOREUSE")); 2686 2687 if (BUF_LOCKRECURSED(bp)) { 2688 /* 2689 * Do not process, in particular, do not handle the 2690 * B_INVAL/B_RELBUF and do not release to free list. 2691 */ 2692 BUF_UNLOCK(bp); 2693 return; 2694 } 2695 2696 if (bp->b_flags & B_MANAGED) { 2697 bqrelse(bp); 2698 return; 2699 } 2700 2701 if (LIST_EMPTY(&bp->b_dep)) { 2702 bp->b_flags &= ~B_IOSTARTED; 2703 } else { 2704 KASSERT((bp->b_flags & B_IOSTARTED) == 0, 2705 ("brelse: SU io not finished bp %p", bp)); 2706 } 2707 2708 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2709 BO_LOCK(bp->b_bufobj); 2710 bp->b_vflags &= ~BV_BKGRDERR; 2711 BO_UNLOCK(bp->b_bufobj); 2712 bdirty(bp); 2713 } 2714 2715 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2716 (bp->b_flags & B_INVALONERR)) { 2717 /* 2718 * Forced invalidation of dirty buffer contents, to be used 2719 * after a failed write in the rare case that the loss of the 2720 * contents is acceptable. The buffer is invalidated and 2721 * freed. 2722 */ 2723 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE; 2724 bp->b_flags &= ~(B_ASYNC | B_CACHE); 2725 } 2726 2727 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2728 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2729 !(bp->b_flags & B_INVAL)) { 2730 /* 2731 * Failed write, redirty. All errors except ENXIO (which 2732 * means the device is gone) are treated as being 2733 * transient. 2734 * 2735 * XXX Treating EIO as transient is not correct; the 2736 * contract with the local storage device drivers is that 2737 * they will only return EIO once the I/O is no longer 2738 * retriable. Network I/O also respects this through the 2739 * guarantees of TCP and/or the internal retries of NFS. 2740 * ENOMEM might be transient, but we also have no way of 2741 * knowing when its ok to retry/reschedule. In general, 2742 * this entire case should be made obsolete through better 2743 * error handling/recovery and resource scheduling. 2744 * 2745 * Do this also for buffers that failed with ENXIO, but have 2746 * non-empty dependencies - the soft updates code might need 2747 * to access the buffer to untangle them. 2748 * 2749 * Must clear BIO_ERROR to prevent pages from being scrapped. 2750 */ 2751 bp->b_ioflags &= ~BIO_ERROR; 2752 bdirty(bp); 2753 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2754 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2755 /* 2756 * Either a failed read I/O, or we were asked to free or not 2757 * cache the buffer, or we failed to write to a device that's 2758 * no longer present. 2759 */ 2760 bp->b_flags |= B_INVAL; 2761 if (!LIST_EMPTY(&bp->b_dep)) 2762 buf_deallocate(bp); 2763 if (bp->b_flags & B_DELWRI) 2764 bdirtysub(bp); 2765 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2766 if ((bp->b_flags & B_VMIO) == 0) { 2767 allocbuf(bp, 0); 2768 if (bp->b_vp) 2769 brelvp(bp); 2770 } 2771 } 2772 2773 /* 2774 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2775 * is called with B_DELWRI set, the underlying pages may wind up 2776 * getting freed causing a previous write (bdwrite()) to get 'lost' 2777 * because pages associated with a B_DELWRI bp are marked clean. 2778 * 2779 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2780 * if B_DELWRI is set. 2781 */ 2782 if (bp->b_flags & B_DELWRI) 2783 bp->b_flags &= ~B_RELBUF; 2784 2785 /* 2786 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2787 * constituted, not even NFS buffers now. Two flags effect this. If 2788 * B_INVAL, the struct buf is invalidated but the VM object is kept 2789 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2790 * 2791 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2792 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2793 * buffer is also B_INVAL because it hits the re-dirtying code above. 2794 * 2795 * Normally we can do this whether a buffer is B_DELWRI or not. If 2796 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2797 * the commit state and we cannot afford to lose the buffer. If the 2798 * buffer has a background write in progress, we need to keep it 2799 * around to prevent it from being reconstituted and starting a second 2800 * background write. 2801 */ 2802 2803 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL; 2804 2805 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2806 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2807 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 || 2808 vn_isdisk(bp->b_vp) || (bp->b_flags & B_DELWRI) == 0)) { 2809 vfs_vmio_invalidate(bp); 2810 allocbuf(bp, 0); 2811 } 2812 2813 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2814 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2815 allocbuf(bp, 0); 2816 bp->b_flags &= ~B_NOREUSE; 2817 if (bp->b_vp != NULL) 2818 brelvp(bp); 2819 } 2820 2821 /* 2822 * If the buffer has junk contents signal it and eventually 2823 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2824 * doesn't find it. 2825 */ 2826 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2827 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2828 bp->b_flags |= B_INVAL; 2829 if (bp->b_flags & B_INVAL) { 2830 if (bp->b_flags & B_DELWRI) 2831 bundirty(bp); 2832 if (bp->b_vp) 2833 brelvp(bp); 2834 } 2835 2836 buf_track(bp, __func__); 2837 2838 /* buffers with no memory */ 2839 if (bp->b_bufsize == 0) { 2840 buf_free(bp); 2841 return; 2842 } 2843 /* buffers with junk contents */ 2844 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2845 (bp->b_ioflags & BIO_ERROR)) { 2846 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2847 if (bp->b_vflags & BV_BKGRDINPROG) 2848 panic("losing buffer 2"); 2849 qindex = QUEUE_CLEAN; 2850 bp->b_flags |= B_AGE; 2851 /* remaining buffers */ 2852 } else if (bp->b_flags & B_DELWRI) 2853 qindex = QUEUE_DIRTY; 2854 else 2855 qindex = QUEUE_CLEAN; 2856 2857 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2858 panic("brelse: not dirty"); 2859 2860 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT); 2861 bp->b_xflags &= ~(BX_CVTENXIO); 2862 /* binsfree unlocks bp. */ 2863 binsfree(bp, qindex); 2864 } 2865 2866 /* 2867 * Release a buffer back to the appropriate queue but do not try to free 2868 * it. The buffer is expected to be used again soon. 2869 * 2870 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2871 * biodone() to requeue an async I/O on completion. It is also used when 2872 * known good buffers need to be requeued but we think we may need the data 2873 * again soon. 2874 * 2875 * XXX we should be able to leave the B_RELBUF hint set on completion. 2876 */ 2877 void 2878 bqrelse(struct buf *bp) 2879 { 2880 int qindex; 2881 2882 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2883 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2884 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2885 2886 qindex = QUEUE_NONE; 2887 if (BUF_LOCKRECURSED(bp)) { 2888 /* do not release to free list */ 2889 BUF_UNLOCK(bp); 2890 return; 2891 } 2892 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2893 bp->b_xflags &= ~(BX_CVTENXIO); 2894 2895 if (LIST_EMPTY(&bp->b_dep)) { 2896 bp->b_flags &= ~B_IOSTARTED; 2897 } else { 2898 KASSERT((bp->b_flags & B_IOSTARTED) == 0, 2899 ("bqrelse: SU io not finished bp %p", bp)); 2900 } 2901 2902 if (bp->b_flags & B_MANAGED) { 2903 if (bp->b_flags & B_REMFREE) 2904 bremfreef(bp); 2905 goto out; 2906 } 2907 2908 /* buffers with stale but valid contents */ 2909 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2910 BV_BKGRDERR)) == BV_BKGRDERR) { 2911 BO_LOCK(bp->b_bufobj); 2912 bp->b_vflags &= ~BV_BKGRDERR; 2913 BO_UNLOCK(bp->b_bufobj); 2914 qindex = QUEUE_DIRTY; 2915 } else { 2916 if ((bp->b_flags & B_DELWRI) == 0 && 2917 (bp->b_xflags & BX_VNDIRTY)) 2918 panic("bqrelse: not dirty"); 2919 if ((bp->b_flags & B_NOREUSE) != 0) { 2920 brelse(bp); 2921 return; 2922 } 2923 qindex = QUEUE_CLEAN; 2924 } 2925 buf_track(bp, __func__); 2926 /* binsfree unlocks bp. */ 2927 binsfree(bp, qindex); 2928 return; 2929 2930 out: 2931 buf_track(bp, __func__); 2932 /* unlock */ 2933 BUF_UNLOCK(bp); 2934 } 2935 2936 /* 2937 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2938 * restore bogus pages. 2939 */ 2940 static void 2941 vfs_vmio_iodone(struct buf *bp) 2942 { 2943 vm_ooffset_t foff; 2944 vm_page_t m; 2945 vm_object_t obj; 2946 struct vnode *vp __unused; 2947 int i, iosize, resid; 2948 bool bogus; 2949 2950 obj = bp->b_bufobj->bo_object; 2951 KASSERT(blockcount_read(&obj->paging_in_progress) >= bp->b_npages, 2952 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2953 blockcount_read(&obj->paging_in_progress), bp->b_npages)); 2954 2955 vp = bp->b_vp; 2956 VNPASS(vp->v_holdcnt > 0, vp); 2957 VNPASS(vp->v_object != NULL, vp); 2958 2959 foff = bp->b_offset; 2960 KASSERT(bp->b_offset != NOOFFSET, 2961 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2962 2963 bogus = false; 2964 iosize = bp->b_bcount - bp->b_resid; 2965 for (i = 0; i < bp->b_npages; i++) { 2966 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2967 if (resid > iosize) 2968 resid = iosize; 2969 2970 /* 2971 * cleanup bogus pages, restoring the originals 2972 */ 2973 m = bp->b_pages[i]; 2974 if (m == bogus_page) { 2975 bogus = true; 2976 m = vm_page_relookup(obj, OFF_TO_IDX(foff)); 2977 if (m == NULL) 2978 panic("biodone: page disappeared!"); 2979 bp->b_pages[i] = m; 2980 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2981 /* 2982 * In the write case, the valid and clean bits are 2983 * already changed correctly ( see bdwrite() ), so we 2984 * only need to do this here in the read case. 2985 */ 2986 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2987 resid)) == 0, ("vfs_vmio_iodone: page %p " 2988 "has unexpected dirty bits", m)); 2989 vfs_page_set_valid(bp, foff, m); 2990 } 2991 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2992 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2993 (intmax_t)foff, (uintmax_t)m->pindex)); 2994 2995 vm_page_sunbusy(m); 2996 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2997 iosize -= resid; 2998 } 2999 vm_object_pip_wakeupn(obj, bp->b_npages); 3000 if (bogus && buf_mapped(bp)) { 3001 BUF_CHECK_MAPPED(bp); 3002 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3003 bp->b_pages, bp->b_npages); 3004 } 3005 } 3006 3007 /* 3008 * Perform page invalidation when a buffer is released. The fully invalid 3009 * pages will be reclaimed later in vfs_vmio_truncate(). 3010 */ 3011 static void 3012 vfs_vmio_invalidate(struct buf *bp) 3013 { 3014 vm_object_t obj; 3015 vm_page_t m; 3016 int flags, i, resid, poffset, presid; 3017 3018 if (buf_mapped(bp)) { 3019 BUF_CHECK_MAPPED(bp); 3020 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 3021 } else 3022 BUF_CHECK_UNMAPPED(bp); 3023 /* 3024 * Get the base offset and length of the buffer. Note that 3025 * in the VMIO case if the buffer block size is not 3026 * page-aligned then b_data pointer may not be page-aligned. 3027 * But our b_pages[] array *IS* page aligned. 3028 * 3029 * block sizes less then DEV_BSIZE (usually 512) are not 3030 * supported due to the page granularity bits (m->valid, 3031 * m->dirty, etc...). 3032 * 3033 * See man buf(9) for more information 3034 */ 3035 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 3036 obj = bp->b_bufobj->bo_object; 3037 resid = bp->b_bufsize; 3038 poffset = bp->b_offset & PAGE_MASK; 3039 VM_OBJECT_WLOCK(obj); 3040 for (i = 0; i < bp->b_npages; i++) { 3041 m = bp->b_pages[i]; 3042 if (m == bogus_page) 3043 panic("vfs_vmio_invalidate: Unexpected bogus page."); 3044 bp->b_pages[i] = NULL; 3045 3046 presid = resid > (PAGE_SIZE - poffset) ? 3047 (PAGE_SIZE - poffset) : resid; 3048 KASSERT(presid >= 0, ("brelse: extra page")); 3049 vm_page_busy_acquire(m, VM_ALLOC_SBUSY); 3050 if (pmap_page_wired_mappings(m) == 0) 3051 vm_page_set_invalid(m, poffset, presid); 3052 vm_page_sunbusy(m); 3053 vm_page_release_locked(m, flags); 3054 resid -= presid; 3055 poffset = 0; 3056 } 3057 VM_OBJECT_WUNLOCK(obj); 3058 bp->b_npages = 0; 3059 } 3060 3061 /* 3062 * Page-granular truncation of an existing VMIO buffer. 3063 */ 3064 static void 3065 vfs_vmio_truncate(struct buf *bp, int desiredpages) 3066 { 3067 vm_object_t obj; 3068 vm_page_t m; 3069 int flags, i; 3070 3071 if (bp->b_npages == desiredpages) 3072 return; 3073 3074 if (buf_mapped(bp)) { 3075 BUF_CHECK_MAPPED(bp); 3076 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 3077 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 3078 } else 3079 BUF_CHECK_UNMAPPED(bp); 3080 3081 /* 3082 * The object lock is needed only if we will attempt to free pages. 3083 */ 3084 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 3085 if ((bp->b_flags & B_DIRECT) != 0) { 3086 flags |= VPR_TRYFREE; 3087 obj = bp->b_bufobj->bo_object; 3088 VM_OBJECT_WLOCK(obj); 3089 } else { 3090 obj = NULL; 3091 } 3092 for (i = desiredpages; i < bp->b_npages; i++) { 3093 m = bp->b_pages[i]; 3094 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3095 bp->b_pages[i] = NULL; 3096 if (obj != NULL) 3097 vm_page_release_locked(m, flags); 3098 else 3099 vm_page_release(m, flags); 3100 } 3101 if (obj != NULL) 3102 VM_OBJECT_WUNLOCK(obj); 3103 bp->b_npages = desiredpages; 3104 } 3105 3106 /* 3107 * Byte granular extension of VMIO buffers. 3108 */ 3109 static void 3110 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3111 { 3112 /* 3113 * We are growing the buffer, possibly in a 3114 * byte-granular fashion. 3115 */ 3116 vm_object_t obj; 3117 vm_offset_t toff; 3118 vm_offset_t tinc; 3119 vm_page_t m; 3120 3121 /* 3122 * Step 1, bring in the VM pages from the object, allocating 3123 * them if necessary. We must clear B_CACHE if these pages 3124 * are not valid for the range covered by the buffer. 3125 */ 3126 obj = bp->b_bufobj->bo_object; 3127 if (bp->b_npages < desiredpages) { 3128 KASSERT(desiredpages <= atop(maxbcachebuf), 3129 ("vfs_vmio_extend past maxbcachebuf %p %d %u", 3130 bp, desiredpages, maxbcachebuf)); 3131 3132 /* 3133 * We must allocate system pages since blocking 3134 * here could interfere with paging I/O, no 3135 * matter which process we are. 3136 * 3137 * Only exclusive busy can be tested here. 3138 * Blocking on shared busy might lead to 3139 * deadlocks once allocbuf() is called after 3140 * pages are vfs_busy_pages(). 3141 */ 3142 (void)vm_page_grab_pages_unlocked(obj, 3143 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3144 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3145 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3146 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3147 bp->b_npages = desiredpages; 3148 } 3149 3150 /* 3151 * Step 2. We've loaded the pages into the buffer, 3152 * we have to figure out if we can still have B_CACHE 3153 * set. Note that B_CACHE is set according to the 3154 * byte-granular range ( bcount and size ), not the 3155 * aligned range ( newbsize ). 3156 * 3157 * The VM test is against m->valid, which is DEV_BSIZE 3158 * aligned. Needless to say, the validity of the data 3159 * needs to also be DEV_BSIZE aligned. Note that this 3160 * fails with NFS if the server or some other client 3161 * extends the file's EOF. If our buffer is resized, 3162 * B_CACHE may remain set! XXX 3163 */ 3164 toff = bp->b_bcount; 3165 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3166 while ((bp->b_flags & B_CACHE) && toff < size) { 3167 vm_pindex_t pi; 3168 3169 if (tinc > (size - toff)) 3170 tinc = size - toff; 3171 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3172 m = bp->b_pages[pi]; 3173 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3174 toff += tinc; 3175 tinc = PAGE_SIZE; 3176 } 3177 3178 /* 3179 * Step 3, fixup the KVA pmap. 3180 */ 3181 if (buf_mapped(bp)) 3182 bpmap_qenter(bp); 3183 else 3184 BUF_CHECK_UNMAPPED(bp); 3185 } 3186 3187 /* 3188 * Check to see if a block at a particular lbn is available for a clustered 3189 * write. 3190 */ 3191 static int 3192 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3193 { 3194 struct buf *bpa; 3195 int match; 3196 3197 match = 0; 3198 3199 /* If the buf isn't in core skip it */ 3200 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3201 return (0); 3202 3203 /* If the buf is busy we don't want to wait for it */ 3204 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3205 return (0); 3206 3207 /* Only cluster with valid clusterable delayed write buffers */ 3208 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3209 (B_DELWRI | B_CLUSTEROK)) 3210 goto done; 3211 3212 if (bpa->b_bufsize != size) 3213 goto done; 3214 3215 /* 3216 * Check to see if it is in the expected place on disk and that the 3217 * block has been mapped. 3218 */ 3219 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3220 match = 1; 3221 done: 3222 BUF_UNLOCK(bpa); 3223 return (match); 3224 } 3225 3226 /* 3227 * vfs_bio_awrite: 3228 * 3229 * Implement clustered async writes for clearing out B_DELWRI buffers. 3230 * This is much better then the old way of writing only one buffer at 3231 * a time. Note that we may not be presented with the buffers in the 3232 * correct order, so we search for the cluster in both directions. 3233 */ 3234 int 3235 vfs_bio_awrite(struct buf *bp) 3236 { 3237 struct bufobj *bo; 3238 int i; 3239 int j; 3240 daddr_t lblkno = bp->b_lblkno; 3241 struct vnode *vp = bp->b_vp; 3242 int ncl; 3243 int nwritten; 3244 int size; 3245 int maxcl; 3246 int gbflags; 3247 3248 bo = &vp->v_bufobj; 3249 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3250 /* 3251 * right now we support clustered writing only to regular files. If 3252 * we find a clusterable block we could be in the middle of a cluster 3253 * rather then at the beginning. 3254 */ 3255 if ((vp->v_type == VREG) && 3256 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3257 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3258 size = vp->v_mount->mnt_stat.f_iosize; 3259 maxcl = maxphys / size; 3260 3261 BO_RLOCK(bo); 3262 for (i = 1; i < maxcl; i++) 3263 if (vfs_bio_clcheck(vp, size, lblkno + i, 3264 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3265 break; 3266 3267 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3268 if (vfs_bio_clcheck(vp, size, lblkno - j, 3269 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3270 break; 3271 BO_RUNLOCK(bo); 3272 --j; 3273 ncl = i + j; 3274 /* 3275 * this is a possible cluster write 3276 */ 3277 if (ncl != 1) { 3278 BUF_UNLOCK(bp); 3279 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3280 gbflags); 3281 return (nwritten); 3282 } 3283 } 3284 bremfree(bp); 3285 bp->b_flags |= B_ASYNC; 3286 /* 3287 * default (old) behavior, writing out only one block 3288 * 3289 * XXX returns b_bufsize instead of b_bcount for nwritten? 3290 */ 3291 nwritten = bp->b_bufsize; 3292 (void) bwrite(bp); 3293 3294 return (nwritten); 3295 } 3296 3297 /* 3298 * getnewbuf_kva: 3299 * 3300 * Allocate KVA for an empty buf header according to gbflags. 3301 */ 3302 static int 3303 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3304 { 3305 3306 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3307 /* 3308 * In order to keep fragmentation sane we only allocate kva 3309 * in BKVASIZE chunks. XXX with vmem we can do page size. 3310 */ 3311 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3312 3313 if (maxsize != bp->b_kvasize && 3314 bufkva_alloc(bp, maxsize, gbflags)) 3315 return (ENOSPC); 3316 } 3317 return (0); 3318 } 3319 3320 /* 3321 * getnewbuf: 3322 * 3323 * Find and initialize a new buffer header, freeing up existing buffers 3324 * in the bufqueues as necessary. The new buffer is returned locked. 3325 * 3326 * We block if: 3327 * We have insufficient buffer headers 3328 * We have insufficient buffer space 3329 * buffer_arena is too fragmented ( space reservation fails ) 3330 * If we have to flush dirty buffers ( but we try to avoid this ) 3331 * 3332 * The caller is responsible for releasing the reserved bufspace after 3333 * allocbuf() is called. 3334 */ 3335 static struct buf * 3336 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3337 { 3338 struct bufdomain *bd; 3339 struct buf *bp; 3340 bool metadata, reserved; 3341 3342 bp = NULL; 3343 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3344 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3345 if (!unmapped_buf_allowed) 3346 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3347 3348 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3349 vp->v_type == VCHR) 3350 metadata = true; 3351 else 3352 metadata = false; 3353 if (vp == NULL) 3354 bd = &bdomain[0]; 3355 else 3356 bd = &bdomain[vp->v_bufobj.bo_domain]; 3357 3358 counter_u64_add(getnewbufcalls, 1); 3359 reserved = false; 3360 do { 3361 if (reserved == false && 3362 bufspace_reserve(bd, maxsize, metadata) != 0) { 3363 counter_u64_add(getnewbufrestarts, 1); 3364 continue; 3365 } 3366 reserved = true; 3367 if ((bp = buf_alloc(bd)) == NULL) { 3368 counter_u64_add(getnewbufrestarts, 1); 3369 continue; 3370 } 3371 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3372 return (bp); 3373 break; 3374 } while (buf_recycle(bd, false) == 0); 3375 3376 if (reserved) 3377 bufspace_release(bd, maxsize); 3378 if (bp != NULL) { 3379 bp->b_flags |= B_INVAL; 3380 brelse(bp); 3381 } 3382 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3383 3384 return (NULL); 3385 } 3386 3387 /* 3388 * buf_daemon: 3389 * 3390 * buffer flushing daemon. Buffers are normally flushed by the 3391 * update daemon but if it cannot keep up this process starts to 3392 * take the load in an attempt to prevent getnewbuf() from blocking. 3393 */ 3394 static struct kproc_desc buf_kp = { 3395 "bufdaemon", 3396 buf_daemon, 3397 &bufdaemonproc 3398 }; 3399 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3400 3401 static int 3402 buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3403 { 3404 int flushed; 3405 3406 flushed = flushbufqueues(vp, bd, target, 0); 3407 if (flushed == 0) { 3408 /* 3409 * Could not find any buffers without rollback 3410 * dependencies, so just write the first one 3411 * in the hopes of eventually making progress. 3412 */ 3413 if (vp != NULL && target > 2) 3414 target /= 2; 3415 flushbufqueues(vp, bd, target, 1); 3416 } 3417 return (flushed); 3418 } 3419 3420 static void 3421 buf_daemon_shutdown(void *arg __unused, int howto __unused) 3422 { 3423 int error; 3424 3425 if (KERNEL_PANICKED()) 3426 return; 3427 3428 mtx_lock(&bdlock); 3429 bd_shutdown = true; 3430 wakeup(&bd_request); 3431 error = msleep(&bd_shutdown, &bdlock, 0, "buf_daemon_shutdown", 3432 60 * hz); 3433 mtx_unlock(&bdlock); 3434 if (error != 0) 3435 printf("bufdaemon wait error: %d\n", error); 3436 } 3437 3438 static void 3439 buf_daemon(void) 3440 { 3441 struct bufdomain *bd; 3442 int speedupreq; 3443 int lodirty; 3444 int i; 3445 3446 /* 3447 * This process needs to be suspended prior to shutdown sync. 3448 */ 3449 EVENTHANDLER_REGISTER(shutdown_pre_sync, buf_daemon_shutdown, NULL, 3450 SHUTDOWN_PRI_LAST + 100); 3451 3452 /* 3453 * Start the buf clean daemons as children threads. 3454 */ 3455 for (i = 0 ; i < buf_domains; i++) { 3456 int error; 3457 3458 error = kthread_add((void (*)(void *))bufspace_daemon, 3459 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3460 if (error) 3461 panic("error %d spawning bufspace daemon", error); 3462 } 3463 3464 /* 3465 * This process is allowed to take the buffer cache to the limit 3466 */ 3467 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3468 mtx_lock(&bdlock); 3469 while (!bd_shutdown) { 3470 bd_request = 0; 3471 mtx_unlock(&bdlock); 3472 3473 /* 3474 * Save speedupreq for this pass and reset to capture new 3475 * requests. 3476 */ 3477 speedupreq = bd_speedupreq; 3478 bd_speedupreq = 0; 3479 3480 /* 3481 * Flush each domain sequentially according to its level and 3482 * the speedup request. 3483 */ 3484 for (i = 0; i < buf_domains; i++) { 3485 bd = &bdomain[i]; 3486 if (speedupreq) 3487 lodirty = bd->bd_numdirtybuffers / 2; 3488 else 3489 lodirty = bd->bd_lodirtybuffers; 3490 while (bd->bd_numdirtybuffers > lodirty) { 3491 if (buf_flush(NULL, bd, 3492 bd->bd_numdirtybuffers - lodirty) == 0) 3493 break; 3494 kern_yield(PRI_USER); 3495 } 3496 } 3497 3498 /* 3499 * Only clear bd_request if we have reached our low water 3500 * mark. The buf_daemon normally waits 1 second and 3501 * then incrementally flushes any dirty buffers that have 3502 * built up, within reason. 3503 * 3504 * If we were unable to hit our low water mark and couldn't 3505 * find any flushable buffers, we sleep for a short period 3506 * to avoid endless loops on unlockable buffers. 3507 */ 3508 mtx_lock(&bdlock); 3509 if (bd_shutdown) 3510 break; 3511 if (BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3512 /* 3513 * We reached our low water mark, reset the 3514 * request and sleep until we are needed again. 3515 * The sleep is just so the suspend code works. 3516 */ 3517 bd_request = 0; 3518 /* 3519 * Do an extra wakeup in case dirty threshold 3520 * changed via sysctl and the explicit transition 3521 * out of shortfall was missed. 3522 */ 3523 bdirtywakeup(); 3524 if (runningbufspace <= lorunningspace) 3525 runningwakeup(); 3526 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3527 } else { 3528 /* 3529 * We couldn't find any flushable dirty buffers but 3530 * still have too many dirty buffers, we 3531 * have to sleep and try again. (rare) 3532 */ 3533 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3534 } 3535 } 3536 wakeup(&bd_shutdown); 3537 mtx_unlock(&bdlock); 3538 kthread_exit(); 3539 } 3540 3541 /* 3542 * flushbufqueues: 3543 * 3544 * Try to flush a buffer in the dirty queue. We must be careful to 3545 * free up B_INVAL buffers instead of write them, which NFS is 3546 * particularly sensitive to. 3547 */ 3548 static int flushwithdeps = 0; 3549 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS, 3550 &flushwithdeps, 0, 3551 "Number of buffers flushed with dependencies that require rollbacks"); 3552 3553 static int 3554 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3555 int flushdeps) 3556 { 3557 struct bufqueue *bq; 3558 struct buf *sentinel; 3559 struct vnode *vp; 3560 struct mount *mp; 3561 struct buf *bp; 3562 int hasdeps; 3563 int flushed; 3564 int error; 3565 bool unlock; 3566 3567 flushed = 0; 3568 bq = &bd->bd_dirtyq; 3569 bp = NULL; 3570 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3571 sentinel->b_qindex = QUEUE_SENTINEL; 3572 BQ_LOCK(bq); 3573 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3574 BQ_UNLOCK(bq); 3575 while (flushed != target) { 3576 maybe_yield(); 3577 BQ_LOCK(bq); 3578 bp = TAILQ_NEXT(sentinel, b_freelist); 3579 if (bp != NULL) { 3580 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3581 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3582 b_freelist); 3583 } else { 3584 BQ_UNLOCK(bq); 3585 break; 3586 } 3587 /* 3588 * Skip sentinels inserted by other invocations of the 3589 * flushbufqueues(), taking care to not reorder them. 3590 * 3591 * Only flush the buffers that belong to the 3592 * vnode locked by the curthread. 3593 */ 3594 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3595 bp->b_vp != lvp)) { 3596 BQ_UNLOCK(bq); 3597 continue; 3598 } 3599 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3600 BQ_UNLOCK(bq); 3601 if (error != 0) 3602 continue; 3603 3604 /* 3605 * BKGRDINPROG can only be set with the buf and bufobj 3606 * locks both held. We tolerate a race to clear it here. 3607 */ 3608 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3609 (bp->b_flags & B_DELWRI) == 0) { 3610 BUF_UNLOCK(bp); 3611 continue; 3612 } 3613 if (bp->b_flags & B_INVAL) { 3614 bremfreef(bp); 3615 brelse(bp); 3616 flushed++; 3617 continue; 3618 } 3619 3620 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3621 if (flushdeps == 0) { 3622 BUF_UNLOCK(bp); 3623 continue; 3624 } 3625 hasdeps = 1; 3626 } else 3627 hasdeps = 0; 3628 /* 3629 * We must hold the lock on a vnode before writing 3630 * one of its buffers. Otherwise we may confuse, or 3631 * in the case of a snapshot vnode, deadlock the 3632 * system. 3633 * 3634 * The lock order here is the reverse of the normal 3635 * of vnode followed by buf lock. This is ok because 3636 * the NOWAIT will prevent deadlock. 3637 */ 3638 vp = bp->b_vp; 3639 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3640 BUF_UNLOCK(bp); 3641 continue; 3642 } 3643 if (lvp == NULL) { 3644 unlock = true; 3645 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3646 } else { 3647 ASSERT_VOP_LOCKED(vp, "getbuf"); 3648 unlock = false; 3649 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3650 vn_lock(vp, LK_TRYUPGRADE); 3651 } 3652 if (error == 0) { 3653 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3654 bp, bp->b_vp, bp->b_flags); 3655 if (curproc == bufdaemonproc) { 3656 vfs_bio_awrite(bp); 3657 } else { 3658 bremfree(bp); 3659 bwrite(bp); 3660 counter_u64_add(notbufdflushes, 1); 3661 } 3662 vn_finished_write(mp); 3663 if (unlock) 3664 VOP_UNLOCK(vp); 3665 flushwithdeps += hasdeps; 3666 flushed++; 3667 3668 /* 3669 * Sleeping on runningbufspace while holding 3670 * vnode lock leads to deadlock. 3671 */ 3672 if (curproc == bufdaemonproc && 3673 runningbufspace > hirunningspace) 3674 waitrunningbufspace(); 3675 continue; 3676 } 3677 vn_finished_write(mp); 3678 BUF_UNLOCK(bp); 3679 } 3680 BQ_LOCK(bq); 3681 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3682 BQ_UNLOCK(bq); 3683 free(sentinel, M_TEMP); 3684 return (flushed); 3685 } 3686 3687 /* 3688 * Check to see if a block is currently memory resident. 3689 */ 3690 struct buf * 3691 incore(struct bufobj *bo, daddr_t blkno) 3692 { 3693 return (gbincore_unlocked(bo, blkno)); 3694 } 3695 3696 /* 3697 * Returns true if no I/O is needed to access the 3698 * associated VM object. This is like incore except 3699 * it also hunts around in the VM system for the data. 3700 */ 3701 bool 3702 inmem(struct vnode * vp, daddr_t blkno) 3703 { 3704 vm_object_t obj; 3705 vm_offset_t toff, tinc, size; 3706 vm_page_t m, n; 3707 vm_ooffset_t off; 3708 int valid; 3709 3710 ASSERT_VOP_LOCKED(vp, "inmem"); 3711 3712 if (incore(&vp->v_bufobj, blkno)) 3713 return (true); 3714 if (vp->v_mount == NULL) 3715 return (false); 3716 obj = vp->v_object; 3717 if (obj == NULL) 3718 return (false); 3719 3720 size = PAGE_SIZE; 3721 if (size > vp->v_mount->mnt_stat.f_iosize) 3722 size = vp->v_mount->mnt_stat.f_iosize; 3723 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3724 3725 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3726 m = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff)); 3727 recheck: 3728 if (m == NULL) 3729 return (false); 3730 3731 tinc = size; 3732 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3733 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3734 /* 3735 * Consider page validity only if page mapping didn't change 3736 * during the check. 3737 */ 3738 valid = vm_page_is_valid(m, 3739 (vm_offset_t)((toff + off) & PAGE_MASK), tinc); 3740 n = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff)); 3741 if (m != n) { 3742 m = n; 3743 goto recheck; 3744 } 3745 if (!valid) 3746 return (false); 3747 } 3748 return (true); 3749 } 3750 3751 /* 3752 * Set the dirty range for a buffer based on the status of the dirty 3753 * bits in the pages comprising the buffer. The range is limited 3754 * to the size of the buffer. 3755 * 3756 * Tell the VM system that the pages associated with this buffer 3757 * are clean. This is used for delayed writes where the data is 3758 * going to go to disk eventually without additional VM intevention. 3759 * 3760 * Note that while we only really need to clean through to b_bcount, we 3761 * just go ahead and clean through to b_bufsize. 3762 */ 3763 static void 3764 vfs_clean_pages_dirty_buf(struct buf *bp) 3765 { 3766 vm_ooffset_t foff, noff, eoff; 3767 vm_page_t m; 3768 int i; 3769 3770 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3771 return; 3772 3773 foff = bp->b_offset; 3774 KASSERT(bp->b_offset != NOOFFSET, 3775 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3776 3777 vfs_busy_pages_acquire(bp); 3778 vfs_setdirty_range(bp); 3779 for (i = 0; i < bp->b_npages; i++) { 3780 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3781 eoff = noff; 3782 if (eoff > bp->b_offset + bp->b_bufsize) 3783 eoff = bp->b_offset + bp->b_bufsize; 3784 m = bp->b_pages[i]; 3785 vfs_page_set_validclean(bp, foff, m); 3786 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3787 foff = noff; 3788 } 3789 vfs_busy_pages_release(bp); 3790 } 3791 3792 static void 3793 vfs_setdirty_range(struct buf *bp) 3794 { 3795 vm_offset_t boffset; 3796 vm_offset_t eoffset; 3797 int i; 3798 3799 /* 3800 * test the pages to see if they have been modified directly 3801 * by users through the VM system. 3802 */ 3803 for (i = 0; i < bp->b_npages; i++) 3804 vm_page_test_dirty(bp->b_pages[i]); 3805 3806 /* 3807 * Calculate the encompassing dirty range, boffset and eoffset, 3808 * (eoffset - boffset) bytes. 3809 */ 3810 3811 for (i = 0; i < bp->b_npages; i++) { 3812 if (bp->b_pages[i]->dirty) 3813 break; 3814 } 3815 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3816 3817 for (i = bp->b_npages - 1; i >= 0; --i) { 3818 if (bp->b_pages[i]->dirty) { 3819 break; 3820 } 3821 } 3822 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3823 3824 /* 3825 * Fit it to the buffer. 3826 */ 3827 3828 if (eoffset > bp->b_bcount) 3829 eoffset = bp->b_bcount; 3830 3831 /* 3832 * If we have a good dirty range, merge with the existing 3833 * dirty range. 3834 */ 3835 3836 if (boffset < eoffset) { 3837 if (bp->b_dirtyoff > boffset) 3838 bp->b_dirtyoff = boffset; 3839 if (bp->b_dirtyend < eoffset) 3840 bp->b_dirtyend = eoffset; 3841 } 3842 } 3843 3844 /* 3845 * Allocate the KVA mapping for an existing buffer. 3846 * If an unmapped buffer is provided but a mapped buffer is requested, take 3847 * also care to properly setup mappings between pages and KVA. 3848 */ 3849 static void 3850 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3851 { 3852 int bsize, maxsize, need_mapping, need_kva; 3853 off_t offset; 3854 3855 need_mapping = bp->b_data == unmapped_buf && 3856 (gbflags & GB_UNMAPPED) == 0; 3857 need_kva = bp->b_kvabase == unmapped_buf && 3858 bp->b_data == unmapped_buf && 3859 (gbflags & GB_KVAALLOC) != 0; 3860 if (!need_mapping && !need_kva) 3861 return; 3862 3863 BUF_CHECK_UNMAPPED(bp); 3864 3865 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3866 /* 3867 * Buffer is not mapped, but the KVA was already 3868 * reserved at the time of the instantiation. Use the 3869 * allocated space. 3870 */ 3871 goto has_addr; 3872 } 3873 3874 /* 3875 * Calculate the amount of the address space we would reserve 3876 * if the buffer was mapped. 3877 */ 3878 bsize = vn_isdisk(bp->b_vp) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3879 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3880 offset = blkno * bsize; 3881 maxsize = size + (offset & PAGE_MASK); 3882 maxsize = imax(maxsize, bsize); 3883 3884 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3885 if ((gbflags & GB_NOWAIT_BD) != 0) { 3886 /* 3887 * XXXKIB: defragmentation cannot 3888 * succeed, not sure what else to do. 3889 */ 3890 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3891 } 3892 counter_u64_add(mappingrestarts, 1); 3893 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3894 } 3895 has_addr: 3896 if (need_mapping) { 3897 /* b_offset is handled by bpmap_qenter. */ 3898 bp->b_data = bp->b_kvabase; 3899 BUF_CHECK_MAPPED(bp); 3900 bpmap_qenter(bp); 3901 } 3902 } 3903 3904 struct buf * 3905 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3906 int flags) 3907 { 3908 struct buf *bp; 3909 int error; 3910 3911 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp); 3912 if (error != 0) 3913 return (NULL); 3914 return (bp); 3915 } 3916 3917 /* 3918 * getblkx: 3919 * 3920 * Get a block given a specified block and offset into a file/device. 3921 * The buffers B_DONE bit will be cleared on return, making it almost 3922 * ready for an I/O initiation. B_INVAL may or may not be set on 3923 * return. The caller should clear B_INVAL prior to initiating a 3924 * READ. 3925 * 3926 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3927 * an existing buffer. 3928 * 3929 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3930 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3931 * and then cleared based on the backing VM. If the previous buffer is 3932 * non-0-sized but invalid, B_CACHE will be cleared. 3933 * 3934 * If getblk() must create a new buffer, the new buffer is returned with 3935 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3936 * case it is returned with B_INVAL clear and B_CACHE set based on the 3937 * backing VM. 3938 * 3939 * getblk() also forces a bwrite() for any B_DELWRI buffer whose 3940 * B_CACHE bit is clear. 3941 * 3942 * What this means, basically, is that the caller should use B_CACHE to 3943 * determine whether the buffer is fully valid or not and should clear 3944 * B_INVAL prior to issuing a read. If the caller intends to validate 3945 * the buffer by loading its data area with something, the caller needs 3946 * to clear B_INVAL. If the caller does this without issuing an I/O, 3947 * the caller should set B_CACHE ( as an optimization ), else the caller 3948 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3949 * a write attempt or if it was a successful read. If the caller 3950 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3951 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3952 * 3953 * The blkno parameter is the logical block being requested. Normally 3954 * the mapping of logical block number to disk block address is done 3955 * by calling VOP_BMAP(). However, if the mapping is already known, the 3956 * disk block address can be passed using the dblkno parameter. If the 3957 * disk block address is not known, then the same value should be passed 3958 * for blkno and dblkno. 3959 */ 3960 int 3961 getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag, 3962 int slptimeo, int flags, struct buf **bpp) 3963 { 3964 struct buf *bp; 3965 struct bufobj *bo; 3966 daddr_t d_blkno; 3967 int bsize, error, maxsize, vmio; 3968 off_t offset; 3969 3970 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3971 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3972 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3973 if (vp->v_type != VCHR) 3974 ASSERT_VOP_LOCKED(vp, "getblk"); 3975 if (size > maxbcachebuf) 3976 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3977 maxbcachebuf); 3978 if (!unmapped_buf_allowed) 3979 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3980 3981 bo = &vp->v_bufobj; 3982 d_blkno = dblkno; 3983 3984 /* Attempt lockless lookup first. */ 3985 bp = gbincore_unlocked(bo, blkno); 3986 if (bp == NULL) { 3987 /* 3988 * With GB_NOCREAT we must be sure about not finding the buffer 3989 * as it may have been reassigned during unlocked lookup. 3990 */ 3991 if ((flags & GB_NOCREAT) != 0) 3992 goto loop; 3993 goto newbuf_unlocked; 3994 } 3995 3996 error = BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL, "getblku", 0, 3997 0); 3998 if (error != 0) 3999 goto loop; 4000 4001 /* Verify buf identify has not changed since lookup. */ 4002 if (bp->b_bufobj == bo && bp->b_lblkno == blkno) 4003 goto foundbuf_fastpath; 4004 4005 /* It changed, fallback to locked lookup. */ 4006 BUF_UNLOCK_RAW(bp); 4007 4008 loop: 4009 BO_RLOCK(bo); 4010 bp = gbincore(bo, blkno); 4011 if (bp != NULL) { 4012 int lockflags; 4013 4014 /* 4015 * Buffer is in-core. If the buffer is not busy nor managed, 4016 * it must be on a queue. 4017 */ 4018 lockflags = LK_EXCLUSIVE | LK_INTERLOCK | 4019 ((flags & GB_LOCK_NOWAIT) != 0 ? LK_NOWAIT : LK_SLEEPFAIL); 4020 #ifdef WITNESS 4021 lockflags |= (flags & GB_NOWITNESS) != 0 ? LK_NOWITNESS : 0; 4022 #endif 4023 4024 error = BUF_TIMELOCK(bp, lockflags, 4025 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 4026 4027 /* 4028 * If we slept and got the lock we have to restart in case 4029 * the buffer changed identities. 4030 */ 4031 if (error == ENOLCK) 4032 goto loop; 4033 /* We timed out or were interrupted. */ 4034 else if (error != 0) 4035 return (error); 4036 4037 foundbuf_fastpath: 4038 /* If recursed, assume caller knows the rules. */ 4039 if (BUF_LOCKRECURSED(bp)) 4040 goto end; 4041 4042 /* 4043 * The buffer is locked. B_CACHE is cleared if the buffer is 4044 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 4045 * and for a VMIO buffer B_CACHE is adjusted according to the 4046 * backing VM cache. 4047 */ 4048 if (bp->b_flags & B_INVAL) 4049 bp->b_flags &= ~B_CACHE; 4050 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 4051 bp->b_flags |= B_CACHE; 4052 if (bp->b_flags & B_MANAGED) 4053 MPASS(bp->b_qindex == QUEUE_NONE); 4054 else 4055 bremfree(bp); 4056 4057 /* 4058 * check for size inconsistencies for non-VMIO case. 4059 */ 4060 if (bp->b_bcount != size) { 4061 if ((bp->b_flags & B_VMIO) == 0 || 4062 (size > bp->b_kvasize)) { 4063 if (bp->b_flags & B_DELWRI) { 4064 bp->b_flags |= B_NOCACHE; 4065 bwrite(bp); 4066 } else { 4067 if (LIST_EMPTY(&bp->b_dep)) { 4068 bp->b_flags |= B_RELBUF; 4069 brelse(bp); 4070 } else { 4071 bp->b_flags |= B_NOCACHE; 4072 bwrite(bp); 4073 } 4074 } 4075 goto loop; 4076 } 4077 } 4078 4079 /* 4080 * Handle the case of unmapped buffer which should 4081 * become mapped, or the buffer for which KVA 4082 * reservation is requested. 4083 */ 4084 bp_unmapped_get_kva(bp, blkno, size, flags); 4085 4086 /* 4087 * If the size is inconsistent in the VMIO case, we can resize 4088 * the buffer. This might lead to B_CACHE getting set or 4089 * cleared. If the size has not changed, B_CACHE remains 4090 * unchanged from its previous state. 4091 */ 4092 allocbuf(bp, size); 4093 4094 KASSERT(bp->b_offset != NOOFFSET, 4095 ("getblk: no buffer offset")); 4096 4097 /* 4098 * A buffer with B_DELWRI set and B_CACHE clear must 4099 * be committed before we can return the buffer in 4100 * order to prevent the caller from issuing a read 4101 * ( due to B_CACHE not being set ) and overwriting 4102 * it. 4103 * 4104 * Most callers, including NFS and FFS, need this to 4105 * operate properly either because they assume they 4106 * can issue a read if B_CACHE is not set, or because 4107 * ( for example ) an uncached B_DELWRI might loop due 4108 * to softupdates re-dirtying the buffer. In the latter 4109 * case, B_CACHE is set after the first write completes, 4110 * preventing further loops. 4111 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 4112 * above while extending the buffer, we cannot allow the 4113 * buffer to remain with B_CACHE set after the write 4114 * completes or it will represent a corrupt state. To 4115 * deal with this we set B_NOCACHE to scrap the buffer 4116 * after the write. 4117 * 4118 * We might be able to do something fancy, like setting 4119 * B_CACHE in bwrite() except if B_DELWRI is already set, 4120 * so the below call doesn't set B_CACHE, but that gets real 4121 * confusing. This is much easier. 4122 */ 4123 4124 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 4125 bp->b_flags |= B_NOCACHE; 4126 bwrite(bp); 4127 goto loop; 4128 } 4129 bp->b_flags &= ~B_DONE; 4130 } else { 4131 /* 4132 * Buffer is not in-core, create new buffer. The buffer 4133 * returned by getnewbuf() is locked. Note that the returned 4134 * buffer is also considered valid (not marked B_INVAL). 4135 */ 4136 BO_RUNLOCK(bo); 4137 newbuf_unlocked: 4138 /* 4139 * If the user does not want us to create the buffer, bail out 4140 * here. 4141 */ 4142 if (flags & GB_NOCREAT) 4143 return (EEXIST); 4144 4145 bsize = vn_isdisk(vp) ? DEV_BSIZE : bo->bo_bsize; 4146 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4147 offset = blkno * bsize; 4148 vmio = vp->v_object != NULL; 4149 if (vmio) { 4150 maxsize = size + (offset & PAGE_MASK); 4151 } else { 4152 maxsize = size; 4153 /* Do not allow non-VMIO notmapped buffers. */ 4154 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4155 } 4156 maxsize = imax(maxsize, bsize); 4157 if ((flags & GB_NOSPARSE) != 0 && vmio && 4158 !vn_isdisk(vp)) { 4159 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4160 KASSERT(error != EOPNOTSUPP, 4161 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4162 vp)); 4163 if (error != 0) 4164 return (error); 4165 if (d_blkno == -1) 4166 return (EJUSTRETURN); 4167 } 4168 4169 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4170 if (bp == NULL) { 4171 if (slpflag || slptimeo) 4172 return (ETIMEDOUT); 4173 /* 4174 * XXX This is here until the sleep path is diagnosed 4175 * enough to work under very low memory conditions. 4176 * 4177 * There's an issue on low memory, 4BSD+non-preempt 4178 * systems (eg MIPS routers with 32MB RAM) where buffer 4179 * exhaustion occurs without sleeping for buffer 4180 * reclaimation. This just sticks in a loop and 4181 * constantly attempts to allocate a buffer, which 4182 * hits exhaustion and tries to wakeup bufdaemon. 4183 * This never happens because we never yield. 4184 * 4185 * The real solution is to identify and fix these cases 4186 * so we aren't effectively busy-waiting in a loop 4187 * until the reclaimation path has cycles to run. 4188 */ 4189 kern_yield(PRI_USER); 4190 goto loop; 4191 } 4192 4193 /* 4194 * This code is used to make sure that a buffer is not 4195 * created while the getnewbuf routine is blocked. 4196 * This can be a problem whether the vnode is locked or not. 4197 * If the buffer is created out from under us, we have to 4198 * throw away the one we just created. 4199 * 4200 * Note: this must occur before we associate the buffer 4201 * with the vp especially considering limitations in 4202 * the splay tree implementation when dealing with duplicate 4203 * lblkno's. 4204 */ 4205 BO_LOCK(bo); 4206 if (gbincore(bo, blkno)) { 4207 BO_UNLOCK(bo); 4208 bp->b_flags |= B_INVAL; 4209 bufspace_release(bufdomain(bp), maxsize); 4210 brelse(bp); 4211 goto loop; 4212 } 4213 4214 /* 4215 * Insert the buffer into the hash, so that it can 4216 * be found by incore. 4217 */ 4218 bp->b_lblkno = blkno; 4219 bp->b_blkno = d_blkno; 4220 bp->b_offset = offset; 4221 bgetvp(vp, bp); 4222 BO_UNLOCK(bo); 4223 4224 /* 4225 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4226 * buffer size starts out as 0, B_CACHE will be set by 4227 * allocbuf() for the VMIO case prior to it testing the 4228 * backing store for validity. 4229 */ 4230 4231 if (vmio) { 4232 bp->b_flags |= B_VMIO; 4233 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4234 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4235 bp, vp->v_object, bp->b_bufobj->bo_object)); 4236 } else { 4237 bp->b_flags &= ~B_VMIO; 4238 KASSERT(bp->b_bufobj->bo_object == NULL, 4239 ("ARGH! has b_bufobj->bo_object %p %p\n", 4240 bp, bp->b_bufobj->bo_object)); 4241 BUF_CHECK_MAPPED(bp); 4242 } 4243 4244 allocbuf(bp, size); 4245 bufspace_release(bufdomain(bp), maxsize); 4246 bp->b_flags &= ~B_DONE; 4247 } 4248 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4249 end: 4250 buf_track(bp, __func__); 4251 KASSERT(bp->b_bufobj == bo, 4252 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4253 *bpp = bp; 4254 return (0); 4255 } 4256 4257 /* 4258 * Get an empty, disassociated buffer of given size. The buffer is initially 4259 * set to B_INVAL. 4260 */ 4261 struct buf * 4262 geteblk(int size, int flags) 4263 { 4264 struct buf *bp; 4265 int maxsize; 4266 4267 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4268 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4269 if ((flags & GB_NOWAIT_BD) && 4270 (curthread->td_pflags & TDP_BUFNEED) != 0) 4271 return (NULL); 4272 } 4273 allocbuf(bp, size); 4274 bufspace_release(bufdomain(bp), maxsize); 4275 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4276 return (bp); 4277 } 4278 4279 /* 4280 * Truncate the backing store for a non-vmio buffer. 4281 */ 4282 static void 4283 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4284 { 4285 4286 if (bp->b_flags & B_MALLOC) { 4287 /* 4288 * malloced buffers are not shrunk 4289 */ 4290 if (newbsize == 0) { 4291 bufmallocadjust(bp, 0); 4292 free(bp->b_data, M_BIOBUF); 4293 bp->b_data = bp->b_kvabase; 4294 bp->b_flags &= ~B_MALLOC; 4295 } 4296 return; 4297 } 4298 vm_hold_free_pages(bp, newbsize); 4299 bufspace_adjust(bp, newbsize); 4300 } 4301 4302 /* 4303 * Extend the backing for a non-VMIO buffer. 4304 */ 4305 static void 4306 vfs_nonvmio_extend(struct buf *bp, int newbsize) 4307 { 4308 caddr_t origbuf; 4309 int origbufsize; 4310 4311 /* 4312 * We only use malloced memory on the first allocation. 4313 * and revert to page-allocated memory when the buffer 4314 * grows. 4315 * 4316 * There is a potential smp race here that could lead 4317 * to bufmallocspace slightly passing the max. It 4318 * is probably extremely rare and not worth worrying 4319 * over. 4320 */ 4321 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4322 bufmallocspace < maxbufmallocspace) { 4323 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4324 bp->b_flags |= B_MALLOC; 4325 bufmallocadjust(bp, newbsize); 4326 return; 4327 } 4328 4329 /* 4330 * If the buffer is growing on its other-than-first 4331 * allocation then we revert to the page-allocation 4332 * scheme. 4333 */ 4334 origbuf = NULL; 4335 origbufsize = 0; 4336 if (bp->b_flags & B_MALLOC) { 4337 origbuf = bp->b_data; 4338 origbufsize = bp->b_bufsize; 4339 bp->b_data = bp->b_kvabase; 4340 bufmallocadjust(bp, 0); 4341 bp->b_flags &= ~B_MALLOC; 4342 newbsize = round_page(newbsize); 4343 } 4344 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4345 (vm_offset_t) bp->b_data + newbsize); 4346 if (origbuf != NULL) { 4347 bcopy(origbuf, bp->b_data, origbufsize); 4348 free(origbuf, M_BIOBUF); 4349 } 4350 bufspace_adjust(bp, newbsize); 4351 } 4352 4353 /* 4354 * This code constitutes the buffer memory from either anonymous system 4355 * memory (in the case of non-VMIO operations) or from an associated 4356 * VM object (in the case of VMIO operations). This code is able to 4357 * resize a buffer up or down. 4358 * 4359 * Note that this code is tricky, and has many complications to resolve 4360 * deadlock or inconsistent data situations. Tread lightly!!! 4361 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4362 * the caller. Calling this code willy nilly can result in the loss of data. 4363 * 4364 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4365 * B_CACHE for the non-VMIO case. 4366 */ 4367 int 4368 allocbuf(struct buf *bp, int size) 4369 { 4370 int newbsize; 4371 4372 if (bp->b_bcount == size) 4373 return (1); 4374 4375 KASSERT(bp->b_kvasize == 0 || bp->b_kvasize >= size, 4376 ("allocbuf: buffer too small %p %#x %#x", 4377 bp, bp->b_kvasize, size)); 4378 4379 newbsize = roundup2(size, DEV_BSIZE); 4380 if ((bp->b_flags & B_VMIO) == 0) { 4381 if ((bp->b_flags & B_MALLOC) == 0) 4382 newbsize = round_page(newbsize); 4383 /* 4384 * Just get anonymous memory from the kernel. Don't 4385 * mess with B_CACHE. 4386 */ 4387 if (newbsize < bp->b_bufsize) 4388 vfs_nonvmio_truncate(bp, newbsize); 4389 else if (newbsize > bp->b_bufsize) 4390 vfs_nonvmio_extend(bp, newbsize); 4391 } else { 4392 int desiredpages; 4393 4394 desiredpages = size == 0 ? 0 : 4395 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4396 4397 KASSERT((bp->b_flags & B_MALLOC) == 0, 4398 ("allocbuf: VMIO buffer can't be malloced %p", bp)); 4399 4400 /* 4401 * Set B_CACHE initially if buffer is 0 length or will become 4402 * 0-length. 4403 */ 4404 if (size == 0 || bp->b_bufsize == 0) 4405 bp->b_flags |= B_CACHE; 4406 4407 if (newbsize < bp->b_bufsize) 4408 vfs_vmio_truncate(bp, desiredpages); 4409 /* XXX This looks as if it should be newbsize > b_bufsize */ 4410 else if (size > bp->b_bcount) 4411 vfs_vmio_extend(bp, desiredpages, size); 4412 bufspace_adjust(bp, newbsize); 4413 } 4414 bp->b_bcount = size; /* requested buffer size. */ 4415 return (1); 4416 } 4417 4418 extern int inflight_transient_maps; 4419 4420 static struct bio_queue nondump_bios; 4421 4422 void 4423 biodone(struct bio *bp) 4424 { 4425 struct mtx *mtxp; 4426 void (*done)(struct bio *); 4427 vm_offset_t start, end; 4428 4429 biotrack(bp, __func__); 4430 4431 /* 4432 * Avoid completing I/O when dumping after a panic since that may 4433 * result in a deadlock in the filesystem or pager code. Note that 4434 * this doesn't affect dumps that were started manually since we aim 4435 * to keep the system usable after it has been resumed. 4436 */ 4437 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4438 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4439 return; 4440 } 4441 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4442 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4443 bp->bio_flags |= BIO_UNMAPPED; 4444 start = trunc_page((vm_offset_t)bp->bio_data); 4445 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4446 bp->bio_data = unmapped_buf; 4447 pmap_qremove(start, atop(end - start)); 4448 vmem_free(transient_arena, start, end - start); 4449 atomic_add_int(&inflight_transient_maps, -1); 4450 } 4451 done = bp->bio_done; 4452 /* 4453 * The check for done == biodone is to allow biodone to be 4454 * used as a bio_done routine. 4455 */ 4456 if (done == NULL || done == biodone) { 4457 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4458 mtx_lock(mtxp); 4459 bp->bio_flags |= BIO_DONE; 4460 wakeup(bp); 4461 mtx_unlock(mtxp); 4462 } else 4463 done(bp); 4464 } 4465 4466 /* 4467 * Wait for a BIO to finish. 4468 */ 4469 int 4470 biowait(struct bio *bp, const char *wmesg) 4471 { 4472 struct mtx *mtxp; 4473 4474 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4475 mtx_lock(mtxp); 4476 while ((bp->bio_flags & BIO_DONE) == 0) 4477 msleep(bp, mtxp, PRIBIO, wmesg, 0); 4478 mtx_unlock(mtxp); 4479 if (bp->bio_error != 0) 4480 return (bp->bio_error); 4481 if (!(bp->bio_flags & BIO_ERROR)) 4482 return (0); 4483 return (EIO); 4484 } 4485 4486 void 4487 biofinish(struct bio *bp, struct devstat *stat, int error) 4488 { 4489 4490 if (error) { 4491 bp->bio_error = error; 4492 bp->bio_flags |= BIO_ERROR; 4493 } 4494 if (stat != NULL) 4495 devstat_end_transaction_bio(stat, bp); 4496 biodone(bp); 4497 } 4498 4499 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4500 void 4501 biotrack_buf(struct bio *bp, const char *location) 4502 { 4503 4504 buf_track(bp->bio_track_bp, location); 4505 } 4506 #endif 4507 4508 /* 4509 * bufwait: 4510 * 4511 * Wait for buffer I/O completion, returning error status. The buffer 4512 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4513 * error and cleared. 4514 */ 4515 int 4516 bufwait(struct buf *bp) 4517 { 4518 if (bp->b_iocmd == BIO_READ) 4519 bwait(bp, PRIBIO, "biord"); 4520 else 4521 bwait(bp, PRIBIO, "biowr"); 4522 if (bp->b_flags & B_EINTR) { 4523 bp->b_flags &= ~B_EINTR; 4524 return (EINTR); 4525 } 4526 if (bp->b_ioflags & BIO_ERROR) { 4527 return (bp->b_error ? bp->b_error : EIO); 4528 } else { 4529 return (0); 4530 } 4531 } 4532 4533 /* 4534 * bufdone: 4535 * 4536 * Finish I/O on a buffer, optionally calling a completion function. 4537 * This is usually called from an interrupt so process blocking is 4538 * not allowed. 4539 * 4540 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4541 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4542 * assuming B_INVAL is clear. 4543 * 4544 * For the VMIO case, we set B_CACHE if the op was a read and no 4545 * read error occurred, or if the op was a write. B_CACHE is never 4546 * set if the buffer is invalid or otherwise uncacheable. 4547 * 4548 * bufdone does not mess with B_INVAL, allowing the I/O routine or the 4549 * initiator to leave B_INVAL set to brelse the buffer out of existence 4550 * in the biodone routine. 4551 */ 4552 void 4553 bufdone(struct buf *bp) 4554 { 4555 struct bufobj *dropobj; 4556 void (*biodone)(struct buf *); 4557 4558 buf_track(bp, __func__); 4559 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4560 dropobj = NULL; 4561 4562 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4563 4564 runningbufwakeup(bp); 4565 if (bp->b_iocmd == BIO_WRITE) 4566 dropobj = bp->b_bufobj; 4567 /* call optional completion function if requested */ 4568 if (bp->b_iodone != NULL) { 4569 biodone = bp->b_iodone; 4570 bp->b_iodone = NULL; 4571 (*biodone) (bp); 4572 if (dropobj) 4573 bufobj_wdrop(dropobj); 4574 return; 4575 } 4576 if (bp->b_flags & B_VMIO) { 4577 /* 4578 * Set B_CACHE if the op was a normal read and no error 4579 * occurred. B_CACHE is set for writes in the b*write() 4580 * routines. 4581 */ 4582 if (bp->b_iocmd == BIO_READ && 4583 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4584 !(bp->b_ioflags & BIO_ERROR)) 4585 bp->b_flags |= B_CACHE; 4586 vfs_vmio_iodone(bp); 4587 } 4588 if (!LIST_EMPTY(&bp->b_dep)) 4589 buf_complete(bp); 4590 if ((bp->b_flags & B_CKHASH) != 0) { 4591 KASSERT(bp->b_iocmd == BIO_READ, 4592 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4593 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4594 (*bp->b_ckhashcalc)(bp); 4595 } 4596 /* 4597 * For asynchronous completions, release the buffer now. The brelse 4598 * will do a wakeup there if necessary - so no need to do a wakeup 4599 * here in the async case. The sync case always needs to do a wakeup. 4600 */ 4601 if (bp->b_flags & B_ASYNC) { 4602 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4603 (bp->b_ioflags & BIO_ERROR)) 4604 brelse(bp); 4605 else 4606 bqrelse(bp); 4607 } else 4608 bdone(bp); 4609 if (dropobj) 4610 bufobj_wdrop(dropobj); 4611 } 4612 4613 /* 4614 * This routine is called in lieu of iodone in the case of 4615 * incomplete I/O. This keeps the busy status for pages 4616 * consistent. 4617 */ 4618 void 4619 vfs_unbusy_pages(struct buf *bp) 4620 { 4621 int i; 4622 vm_object_t obj; 4623 vm_page_t m; 4624 4625 runningbufwakeup(bp); 4626 if (!(bp->b_flags & B_VMIO)) 4627 return; 4628 4629 obj = bp->b_bufobj->bo_object; 4630 for (i = 0; i < bp->b_npages; i++) { 4631 m = bp->b_pages[i]; 4632 if (m == bogus_page) { 4633 m = vm_page_relookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4634 if (!m) 4635 panic("vfs_unbusy_pages: page missing\n"); 4636 bp->b_pages[i] = m; 4637 if (buf_mapped(bp)) { 4638 BUF_CHECK_MAPPED(bp); 4639 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4640 bp->b_pages, bp->b_npages); 4641 } else 4642 BUF_CHECK_UNMAPPED(bp); 4643 } 4644 vm_page_sunbusy(m); 4645 } 4646 vm_object_pip_wakeupn(obj, bp->b_npages); 4647 } 4648 4649 /* 4650 * vfs_page_set_valid: 4651 * 4652 * Set the valid bits in a page based on the supplied offset. The 4653 * range is restricted to the buffer's size. 4654 * 4655 * This routine is typically called after a read completes. 4656 */ 4657 static void 4658 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4659 { 4660 vm_ooffset_t eoff; 4661 4662 /* 4663 * Compute the end offset, eoff, such that [off, eoff) does not span a 4664 * page boundary and eoff is not greater than the end of the buffer. 4665 * The end of the buffer, in this case, is our file EOF, not the 4666 * allocation size of the buffer. 4667 */ 4668 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4669 if (eoff > bp->b_offset + bp->b_bcount) 4670 eoff = bp->b_offset + bp->b_bcount; 4671 4672 /* 4673 * Set valid range. This is typically the entire buffer and thus the 4674 * entire page. 4675 */ 4676 if (eoff > off) 4677 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4678 } 4679 4680 /* 4681 * vfs_page_set_validclean: 4682 * 4683 * Set the valid bits and clear the dirty bits in a page based on the 4684 * supplied offset. The range is restricted to the buffer's size. 4685 */ 4686 static void 4687 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4688 { 4689 vm_ooffset_t soff, eoff; 4690 4691 /* 4692 * Start and end offsets in buffer. eoff - soff may not cross a 4693 * page boundary or cross the end of the buffer. The end of the 4694 * buffer, in this case, is our file EOF, not the allocation size 4695 * of the buffer. 4696 */ 4697 soff = off; 4698 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4699 if (eoff > bp->b_offset + bp->b_bcount) 4700 eoff = bp->b_offset + bp->b_bcount; 4701 4702 /* 4703 * Set valid range. This is typically the entire buffer and thus the 4704 * entire page. 4705 */ 4706 if (eoff > soff) { 4707 vm_page_set_validclean( 4708 m, 4709 (vm_offset_t) (soff & PAGE_MASK), 4710 (vm_offset_t) (eoff - soff) 4711 ); 4712 } 4713 } 4714 4715 /* 4716 * Acquire a shared busy on all pages in the buf. 4717 */ 4718 void 4719 vfs_busy_pages_acquire(struct buf *bp) 4720 { 4721 int i; 4722 4723 for (i = 0; i < bp->b_npages; i++) 4724 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY); 4725 } 4726 4727 void 4728 vfs_busy_pages_release(struct buf *bp) 4729 { 4730 int i; 4731 4732 for (i = 0; i < bp->b_npages; i++) 4733 vm_page_sunbusy(bp->b_pages[i]); 4734 } 4735 4736 /* 4737 * This routine is called before a device strategy routine. 4738 * It is used to tell the VM system that paging I/O is in 4739 * progress, and treat the pages associated with the buffer 4740 * almost as being exclusive busy. Also the object paging_in_progress 4741 * flag is handled to make sure that the object doesn't become 4742 * inconsistent. 4743 * 4744 * Since I/O has not been initiated yet, certain buffer flags 4745 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4746 * and should be ignored. 4747 */ 4748 void 4749 vfs_busy_pages(struct buf *bp, int clear_modify) 4750 { 4751 vm_object_t obj; 4752 vm_ooffset_t foff; 4753 vm_page_t m; 4754 int i; 4755 bool bogus; 4756 4757 if (!(bp->b_flags & B_VMIO)) 4758 return; 4759 4760 obj = bp->b_bufobj->bo_object; 4761 foff = bp->b_offset; 4762 KASSERT(bp->b_offset != NOOFFSET, 4763 ("vfs_busy_pages: no buffer offset")); 4764 if ((bp->b_flags & B_CLUSTER) == 0) { 4765 vm_object_pip_add(obj, bp->b_npages); 4766 vfs_busy_pages_acquire(bp); 4767 } 4768 if (bp->b_bufsize != 0) 4769 vfs_setdirty_range(bp); 4770 bogus = false; 4771 for (i = 0; i < bp->b_npages; i++) { 4772 m = bp->b_pages[i]; 4773 vm_page_assert_sbusied(m); 4774 4775 /* 4776 * When readying a buffer for a read ( i.e 4777 * clear_modify == 0 ), it is important to do 4778 * bogus_page replacement for valid pages in 4779 * partially instantiated buffers. Partially 4780 * instantiated buffers can, in turn, occur when 4781 * reconstituting a buffer from its VM backing store 4782 * base. We only have to do this if B_CACHE is 4783 * clear ( which causes the I/O to occur in the 4784 * first place ). The replacement prevents the read 4785 * I/O from overwriting potentially dirty VM-backed 4786 * pages. XXX bogus page replacement is, uh, bogus. 4787 * It may not work properly with small-block devices. 4788 * We need to find a better way. 4789 */ 4790 if (clear_modify) { 4791 pmap_remove_write(m); 4792 vfs_page_set_validclean(bp, foff, m); 4793 } else if (vm_page_all_valid(m) && 4794 (bp->b_flags & B_CACHE) == 0) { 4795 bp->b_pages[i] = bogus_page; 4796 bogus = true; 4797 } 4798 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4799 } 4800 if (bogus && buf_mapped(bp)) { 4801 BUF_CHECK_MAPPED(bp); 4802 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4803 bp->b_pages, bp->b_npages); 4804 } 4805 } 4806 4807 /* 4808 * vfs_bio_set_valid: 4809 * 4810 * Set the range within the buffer to valid. The range is 4811 * relative to the beginning of the buffer, b_offset. Note that 4812 * b_offset itself may be offset from the beginning of the first 4813 * page. 4814 */ 4815 void 4816 vfs_bio_set_valid(struct buf *bp, int base, int size) 4817 { 4818 int i, n; 4819 vm_page_t m; 4820 4821 if (!(bp->b_flags & B_VMIO)) 4822 return; 4823 4824 /* 4825 * Fixup base to be relative to beginning of first page. 4826 * Set initial n to be the maximum number of bytes in the 4827 * first page that can be validated. 4828 */ 4829 base += (bp->b_offset & PAGE_MASK); 4830 n = PAGE_SIZE - (base & PAGE_MASK); 4831 4832 /* 4833 * Busy may not be strictly necessary here because the pages are 4834 * unlikely to be fully valid and the vnode lock will synchronize 4835 * their access via getpages. It is grabbed for consistency with 4836 * other page validation. 4837 */ 4838 vfs_busy_pages_acquire(bp); 4839 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4840 m = bp->b_pages[i]; 4841 if (n > size) 4842 n = size; 4843 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4844 base += n; 4845 size -= n; 4846 n = PAGE_SIZE; 4847 } 4848 vfs_busy_pages_release(bp); 4849 } 4850 4851 /* 4852 * vfs_bio_clrbuf: 4853 * 4854 * If the specified buffer is a non-VMIO buffer, clear the entire 4855 * buffer. If the specified buffer is a VMIO buffer, clear and 4856 * validate only the previously invalid portions of the buffer. 4857 * This routine essentially fakes an I/O, so we need to clear 4858 * BIO_ERROR and B_INVAL. 4859 * 4860 * Note that while we only theoretically need to clear through b_bcount, 4861 * we go ahead and clear through b_bufsize. 4862 */ 4863 void 4864 vfs_bio_clrbuf(struct buf *bp) 4865 { 4866 int i, j, sa, ea, slide, zbits; 4867 vm_page_bits_t mask; 4868 4869 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4870 clrbuf(bp); 4871 return; 4872 } 4873 bp->b_flags &= ~B_INVAL; 4874 bp->b_ioflags &= ~BIO_ERROR; 4875 vfs_busy_pages_acquire(bp); 4876 sa = bp->b_offset & PAGE_MASK; 4877 slide = 0; 4878 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4879 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4880 ea = slide & PAGE_MASK; 4881 if (ea == 0) 4882 ea = PAGE_SIZE; 4883 if (bp->b_pages[i] == bogus_page) 4884 continue; 4885 j = sa / DEV_BSIZE; 4886 zbits = (sizeof(vm_page_bits_t) * NBBY) - 4887 (ea - sa) / DEV_BSIZE; 4888 mask = (VM_PAGE_BITS_ALL >> zbits) << j; 4889 if ((bp->b_pages[i]->valid & mask) == mask) 4890 continue; 4891 if ((bp->b_pages[i]->valid & mask) == 0) 4892 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4893 else { 4894 for (; sa < ea; sa += DEV_BSIZE, j++) { 4895 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4896 pmap_zero_page_area(bp->b_pages[i], 4897 sa, DEV_BSIZE); 4898 } 4899 } 4900 } 4901 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE, 4902 roundup2(ea - sa, DEV_BSIZE)); 4903 } 4904 vfs_busy_pages_release(bp); 4905 bp->b_resid = 0; 4906 } 4907 4908 void 4909 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4910 { 4911 vm_page_t m; 4912 int i, n; 4913 4914 if (buf_mapped(bp)) { 4915 BUF_CHECK_MAPPED(bp); 4916 bzero(bp->b_data + base, size); 4917 } else { 4918 BUF_CHECK_UNMAPPED(bp); 4919 n = PAGE_SIZE - (base & PAGE_MASK); 4920 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4921 m = bp->b_pages[i]; 4922 if (n > size) 4923 n = size; 4924 pmap_zero_page_area(m, base & PAGE_MASK, n); 4925 base += n; 4926 size -= n; 4927 n = PAGE_SIZE; 4928 } 4929 } 4930 } 4931 4932 /* 4933 * Update buffer flags based on I/O request parameters, optionally releasing the 4934 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4935 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4936 * I/O). Otherwise the buffer is released to the cache. 4937 */ 4938 static void 4939 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4940 { 4941 4942 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4943 ("buf %p non-VMIO noreuse", bp)); 4944 4945 if ((ioflag & IO_DIRECT) != 0) 4946 bp->b_flags |= B_DIRECT; 4947 if ((ioflag & IO_EXT) != 0) 4948 bp->b_xflags |= BX_ALTDATA; 4949 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4950 bp->b_flags |= B_RELBUF; 4951 if ((ioflag & IO_NOREUSE) != 0) 4952 bp->b_flags |= B_NOREUSE; 4953 if (release) 4954 brelse(bp); 4955 } else if (release) 4956 bqrelse(bp); 4957 } 4958 4959 void 4960 vfs_bio_brelse(struct buf *bp, int ioflag) 4961 { 4962 4963 b_io_dismiss(bp, ioflag, true); 4964 } 4965 4966 void 4967 vfs_bio_set_flags(struct buf *bp, int ioflag) 4968 { 4969 4970 b_io_dismiss(bp, ioflag, false); 4971 } 4972 4973 /* 4974 * vm_hold_load_pages and vm_hold_free_pages get pages into 4975 * a buffers address space. The pages are anonymous and are 4976 * not associated with a file object. 4977 */ 4978 static void 4979 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4980 { 4981 vm_offset_t pg; 4982 vm_page_t p; 4983 int index; 4984 4985 BUF_CHECK_MAPPED(bp); 4986 4987 to = round_page(to); 4988 from = round_page(from); 4989 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4990 MPASS((bp->b_flags & B_MAXPHYS) == 0); 4991 KASSERT(to - from <= maxbcachebuf, 4992 ("vm_hold_load_pages too large %p %#jx %#jx %u", 4993 bp, (uintmax_t)from, (uintmax_t)to, maxbcachebuf)); 4994 4995 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4996 /* 4997 * note: must allocate system pages since blocking here 4998 * could interfere with paging I/O, no matter which 4999 * process we are. 5000 */ 5001 p = vm_page_alloc_noobj(VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 5002 VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | VM_ALLOC_WAITOK); 5003 pmap_qenter(pg, &p, 1); 5004 bp->b_pages[index] = p; 5005 } 5006 bp->b_npages = index; 5007 } 5008 5009 /* Return pages associated with this buf to the vm system */ 5010 static void 5011 vm_hold_free_pages(struct buf *bp, int newbsize) 5012 { 5013 vm_offset_t from; 5014 vm_page_t p; 5015 int index, newnpages; 5016 5017 BUF_CHECK_MAPPED(bp); 5018 5019 from = round_page((vm_offset_t)bp->b_data + newbsize); 5020 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 5021 if (bp->b_npages > newnpages) 5022 pmap_qremove(from, bp->b_npages - newnpages); 5023 for (index = newnpages; index < bp->b_npages; index++) { 5024 p = bp->b_pages[index]; 5025 bp->b_pages[index] = NULL; 5026 vm_page_unwire_noq(p); 5027 vm_page_free(p); 5028 } 5029 bp->b_npages = newnpages; 5030 } 5031 5032 /* 5033 * Map an IO request into kernel virtual address space. 5034 * 5035 * All requests are (re)mapped into kernel VA space. 5036 * Notice that we use b_bufsize for the size of the buffer 5037 * to be mapped. b_bcount might be modified by the driver. 5038 * 5039 * Note that even if the caller determines that the address space should 5040 * be valid, a race or a smaller-file mapped into a larger space may 5041 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 5042 * check the return value. 5043 * 5044 * This function only works with pager buffers. 5045 */ 5046 int 5047 vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf) 5048 { 5049 vm_prot_t prot; 5050 int pidx; 5051 5052 MPASS((bp->b_flags & B_MAXPHYS) != 0); 5053 prot = VM_PROT_READ; 5054 if (bp->b_iocmd == BIO_READ) 5055 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 5056 pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 5057 (vm_offset_t)uaddr, len, prot, bp->b_pages, PBUF_PAGES); 5058 if (pidx < 0) 5059 return (-1); 5060 bp->b_bufsize = len; 5061 bp->b_npages = pidx; 5062 bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK; 5063 if (mapbuf || !unmapped_buf_allowed) { 5064 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 5065 bp->b_data = bp->b_kvabase + bp->b_offset; 5066 } else 5067 bp->b_data = unmapped_buf; 5068 return (0); 5069 } 5070 5071 /* 5072 * Free the io map PTEs associated with this IO operation. 5073 * We also invalidate the TLB entries and restore the original b_addr. 5074 * 5075 * This function only works with pager buffers. 5076 */ 5077 void 5078 vunmapbuf(struct buf *bp) 5079 { 5080 int npages; 5081 5082 npages = bp->b_npages; 5083 if (buf_mapped(bp)) 5084 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 5085 vm_page_unhold_pages(bp->b_pages, npages); 5086 5087 bp->b_data = unmapped_buf; 5088 } 5089 5090 void 5091 bdone(struct buf *bp) 5092 { 5093 struct mtx *mtxp; 5094 5095 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5096 mtx_lock(mtxp); 5097 bp->b_flags |= B_DONE; 5098 wakeup(bp); 5099 mtx_unlock(mtxp); 5100 } 5101 5102 void 5103 bwait(struct buf *bp, u_char pri, const char *wchan) 5104 { 5105 struct mtx *mtxp; 5106 5107 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5108 mtx_lock(mtxp); 5109 while ((bp->b_flags & B_DONE) == 0) 5110 msleep(bp, mtxp, pri, wchan, 0); 5111 mtx_unlock(mtxp); 5112 } 5113 5114 int 5115 bufsync(struct bufobj *bo, int waitfor) 5116 { 5117 5118 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 5119 } 5120 5121 void 5122 bufstrategy(struct bufobj *bo, struct buf *bp) 5123 { 5124 int i __unused; 5125 struct vnode *vp; 5126 5127 vp = bp->b_vp; 5128 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5129 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5130 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5131 i = VOP_STRATEGY(vp, bp); 5132 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5133 } 5134 5135 /* 5136 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5137 */ 5138 void 5139 bufobj_init(struct bufobj *bo, void *private) 5140 { 5141 static volatile int bufobj_cleanq; 5142 5143 bo->bo_domain = 5144 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5145 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5146 bo->bo_private = private; 5147 TAILQ_INIT(&bo->bo_clean.bv_hd); 5148 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5149 } 5150 5151 void 5152 bufobj_wrefl(struct bufobj *bo) 5153 { 5154 5155 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5156 ASSERT_BO_WLOCKED(bo); 5157 bo->bo_numoutput++; 5158 } 5159 5160 void 5161 bufobj_wref(struct bufobj *bo) 5162 { 5163 5164 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5165 BO_LOCK(bo); 5166 bo->bo_numoutput++; 5167 BO_UNLOCK(bo); 5168 } 5169 5170 void 5171 bufobj_wdrop(struct bufobj *bo) 5172 { 5173 5174 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5175 BO_LOCK(bo); 5176 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5177 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5178 bo->bo_flag &= ~BO_WWAIT; 5179 wakeup(&bo->bo_numoutput); 5180 } 5181 BO_UNLOCK(bo); 5182 } 5183 5184 int 5185 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5186 { 5187 int error; 5188 5189 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5190 ASSERT_BO_WLOCKED(bo); 5191 error = 0; 5192 while (bo->bo_numoutput) { 5193 bo->bo_flag |= BO_WWAIT; 5194 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5195 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5196 if (error) 5197 break; 5198 } 5199 return (error); 5200 } 5201 5202 /* 5203 * Set bio_data or bio_ma for struct bio from the struct buf. 5204 */ 5205 void 5206 bdata2bio(struct buf *bp, struct bio *bip) 5207 { 5208 5209 if (!buf_mapped(bp)) { 5210 KASSERT(unmapped_buf_allowed, ("unmapped")); 5211 bip->bio_ma = bp->b_pages; 5212 bip->bio_ma_n = bp->b_npages; 5213 bip->bio_data = unmapped_buf; 5214 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5215 bip->bio_flags |= BIO_UNMAPPED; 5216 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5217 PAGE_SIZE == bp->b_npages, 5218 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5219 (long long)bip->bio_length, bip->bio_ma_n)); 5220 } else { 5221 bip->bio_data = bp->b_data; 5222 bip->bio_ma = NULL; 5223 } 5224 } 5225 5226 static int buf_pager_relbuf; 5227 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5228 &buf_pager_relbuf, 0, 5229 "Make buffer pager release buffers after reading"); 5230 5231 /* 5232 * The buffer pager. It uses buffer reads to validate pages. 5233 * 5234 * In contrast to the generic local pager from vm/vnode_pager.c, this 5235 * pager correctly and easily handles volumes where the underlying 5236 * device block size is greater than the machine page size. The 5237 * buffer cache transparently extends the requested page run to be 5238 * aligned at the block boundary, and does the necessary bogus page 5239 * replacements in the addends to avoid obliterating already valid 5240 * pages. 5241 * 5242 * The only non-trivial issue is that the exclusive busy state for 5243 * pages, which is assumed by the vm_pager_getpages() interface, is 5244 * incompatible with the VMIO buffer cache's desire to share-busy the 5245 * pages. This function performs a trivial downgrade of the pages' 5246 * state before reading buffers, and a less trivial upgrade from the 5247 * shared-busy to excl-busy state after the read. 5248 */ 5249 int 5250 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5251 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5252 vbg_get_blksize_t get_blksize) 5253 { 5254 vm_page_t m; 5255 vm_object_t object; 5256 struct buf *bp; 5257 struct mount *mp; 5258 daddr_t lbn, lbnp; 5259 vm_ooffset_t la, lb, poff, poffe; 5260 long bo_bs, bsize; 5261 int br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5262 bool redo, lpart; 5263 5264 object = vp->v_object; 5265 mp = vp->v_mount; 5266 error = 0; 5267 la = IDX_TO_OFF(ma[count - 1]->pindex); 5268 if (la >= object->un_pager.vnp.vnp_size) 5269 return (VM_PAGER_BAD); 5270 5271 /* 5272 * Change the meaning of la from where the last requested page starts 5273 * to where it ends, because that's the end of the requested region 5274 * and the start of the potential read-ahead region. 5275 */ 5276 la += PAGE_SIZE; 5277 lpart = la > object->un_pager.vnp.vnp_size; 5278 error = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)), 5279 &bo_bs); 5280 if (error != 0) 5281 return (VM_PAGER_ERROR); 5282 5283 /* 5284 * Calculate read-ahead, behind and total pages. 5285 */ 5286 pgsin = count; 5287 lb = IDX_TO_OFF(ma[0]->pindex); 5288 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5289 pgsin += pgsin_b; 5290 if (rbehind != NULL) 5291 *rbehind = pgsin_b; 5292 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5293 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5294 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5295 PAGE_SIZE) - la); 5296 pgsin += pgsin_a; 5297 if (rahead != NULL) 5298 *rahead = pgsin_a; 5299 VM_CNT_INC(v_vnodein); 5300 VM_CNT_ADD(v_vnodepgsin, pgsin); 5301 5302 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5303 != 0) ? GB_UNMAPPED : 0; 5304 again: 5305 for (i = 0; i < count; i++) { 5306 if (ma[i] != bogus_page) 5307 vm_page_busy_downgrade(ma[i]); 5308 } 5309 5310 lbnp = -1; 5311 for (i = 0; i < count; i++) { 5312 m = ma[i]; 5313 if (m == bogus_page) 5314 continue; 5315 5316 /* 5317 * Pages are shared busy and the object lock is not 5318 * owned, which together allow for the pages' 5319 * invalidation. The racy test for validity avoids 5320 * useless creation of the buffer for the most typical 5321 * case when invalidation is not used in redo or for 5322 * parallel read. The shared->excl upgrade loop at 5323 * the end of the function catches the race in a 5324 * reliable way (protected by the object lock). 5325 */ 5326 if (vm_page_all_valid(m)) 5327 continue; 5328 5329 poff = IDX_TO_OFF(m->pindex); 5330 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5331 for (; poff < poffe; poff += bsize) { 5332 lbn = get_lblkno(vp, poff); 5333 if (lbn == lbnp) 5334 goto next_page; 5335 lbnp = lbn; 5336 5337 error = get_blksize(vp, lbn, &bsize); 5338 if (error == 0) 5339 error = bread_gb(vp, lbn, bsize, 5340 curthread->td_ucred, br_flags, &bp); 5341 if (error != 0) 5342 goto end_pages; 5343 if (bp->b_rcred == curthread->td_ucred) { 5344 crfree(bp->b_rcred); 5345 bp->b_rcred = NOCRED; 5346 } 5347 if (LIST_EMPTY(&bp->b_dep)) { 5348 /* 5349 * Invalidation clears m->valid, but 5350 * may leave B_CACHE flag if the 5351 * buffer existed at the invalidation 5352 * time. In this case, recycle the 5353 * buffer to do real read on next 5354 * bread() after redo. 5355 * 5356 * Otherwise B_RELBUF is not strictly 5357 * necessary, enable to reduce buf 5358 * cache pressure. 5359 */ 5360 if (buf_pager_relbuf || 5361 !vm_page_all_valid(m)) 5362 bp->b_flags |= B_RELBUF; 5363 5364 bp->b_flags &= ~B_NOCACHE; 5365 brelse(bp); 5366 } else { 5367 bqrelse(bp); 5368 } 5369 } 5370 KASSERT(1 /* racy, enable for debugging */ || 5371 vm_page_all_valid(m) || i == count - 1, 5372 ("buf %d %p invalid", i, m)); 5373 if (i == count - 1 && lpart) { 5374 if (!vm_page_none_valid(m) && 5375 !vm_page_all_valid(m)) 5376 vm_page_zero_invalid(m, TRUE); 5377 } 5378 next_page:; 5379 } 5380 end_pages: 5381 5382 redo = false; 5383 for (i = 0; i < count; i++) { 5384 if (ma[i] == bogus_page) 5385 continue; 5386 if (vm_page_busy_tryupgrade(ma[i]) == 0) { 5387 vm_page_sunbusy(ma[i]); 5388 ma[i] = vm_page_grab_unlocked(object, ma[i]->pindex, 5389 VM_ALLOC_NORMAL); 5390 } 5391 5392 /* 5393 * Since the pages were only sbusy while neither the 5394 * buffer nor the object lock was held by us, or 5395 * reallocated while vm_page_grab() slept for busy 5396 * relinguish, they could have been invalidated. 5397 * Recheck the valid bits and re-read as needed. 5398 * 5399 * Note that the last page is made fully valid in the 5400 * read loop, and partial validity for the page at 5401 * index count - 1 could mean that the page was 5402 * invalidated or removed, so we must restart for 5403 * safety as well. 5404 */ 5405 if (!vm_page_all_valid(ma[i])) 5406 redo = true; 5407 } 5408 if (redo && error == 0) 5409 goto again; 5410 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5411 } 5412 5413 #include "opt_ddb.h" 5414 #ifdef DDB 5415 #include <ddb/ddb.h> 5416 5417 /* DDB command to show buffer data */ 5418 DB_SHOW_COMMAND(buffer, db_show_buffer) 5419 { 5420 /* get args */ 5421 struct buf *bp = (struct buf *)addr; 5422 #ifdef FULL_BUF_TRACKING 5423 uint32_t i, j; 5424 #endif 5425 5426 if (!have_addr) { 5427 db_printf("usage: show buffer <addr>\n"); 5428 return; 5429 } 5430 5431 db_printf("buf at %p\n", bp); 5432 db_printf("b_flags = 0x%b, b_xflags=0x%b\n", 5433 (u_int)bp->b_flags, PRINT_BUF_FLAGS, 5434 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS); 5435 db_printf("b_vflags=0x%b b_ioflags0x%b\n", 5436 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS, 5437 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS); 5438 db_printf( 5439 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5440 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, " 5441 "b_vp = %p, b_dep = %p\n", 5442 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5443 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5444 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first); 5445 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5446 bp->b_kvabase, bp->b_kvasize); 5447 if (bp->b_npages) { 5448 int i; 5449 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5450 for (i = 0; i < bp->b_npages; i++) { 5451 vm_page_t m; 5452 m = bp->b_pages[i]; 5453 if (m != NULL) 5454 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5455 (u_long)m->pindex, 5456 (u_long)VM_PAGE_TO_PHYS(m)); 5457 else 5458 db_printf("( ??? )"); 5459 if ((i + 1) < bp->b_npages) 5460 db_printf(","); 5461 } 5462 db_printf("\n"); 5463 } 5464 BUF_LOCKPRINTINFO(bp); 5465 #if defined(FULL_BUF_TRACKING) 5466 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5467 5468 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5469 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5470 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5471 continue; 5472 db_printf(" %2u: %s\n", j, 5473 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5474 } 5475 #elif defined(BUF_TRACKING) 5476 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5477 #endif 5478 db_printf(" "); 5479 } 5480 5481 DB_SHOW_COMMAND_FLAGS(bufqueues, bufqueues, DB_CMD_MEMSAFE) 5482 { 5483 struct bufdomain *bd; 5484 struct buf *bp; 5485 long total; 5486 int i, j, cnt; 5487 5488 db_printf("bqempty: %d\n", bqempty.bq_len); 5489 5490 for (i = 0; i < buf_domains; i++) { 5491 bd = &bdomain[i]; 5492 db_printf("Buf domain %d\n", i); 5493 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5494 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5495 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5496 db_printf("\n"); 5497 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5498 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5499 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5500 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5501 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5502 db_printf("\n"); 5503 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5504 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5505 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5506 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5507 db_printf("\n"); 5508 total = 0; 5509 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5510 total += bp->b_bufsize; 5511 db_printf("\tcleanq count\t%d (%ld)\n", 5512 bd->bd_cleanq->bq_len, total); 5513 total = 0; 5514 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5515 total += bp->b_bufsize; 5516 db_printf("\tdirtyq count\t%d (%ld)\n", 5517 bd->bd_dirtyq.bq_len, total); 5518 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5519 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5520 db_printf("\tCPU "); 5521 for (j = 0; j <= mp_maxid; j++) 5522 db_printf("%d, ", bd->bd_subq[j].bq_len); 5523 db_printf("\n"); 5524 cnt = 0; 5525 total = 0; 5526 for (j = 0; j < nbuf; j++) { 5527 bp = nbufp(j); 5528 if (bp->b_domain == i && BUF_ISLOCKED(bp)) { 5529 cnt++; 5530 total += bp->b_bufsize; 5531 } 5532 } 5533 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5534 cnt = 0; 5535 total = 0; 5536 for (j = 0; j < nbuf; j++) { 5537 bp = nbufp(j); 5538 if (bp->b_domain == i) { 5539 cnt++; 5540 total += bp->b_bufsize; 5541 } 5542 } 5543 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5544 } 5545 } 5546 5547 DB_SHOW_COMMAND_FLAGS(lockedbufs, lockedbufs, DB_CMD_MEMSAFE) 5548 { 5549 struct buf *bp; 5550 int i; 5551 5552 for (i = 0; i < nbuf; i++) { 5553 bp = nbufp(i); 5554 if (BUF_ISLOCKED(bp)) { 5555 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5556 db_printf("\n"); 5557 if (db_pager_quit) 5558 break; 5559 } 5560 } 5561 } 5562 5563 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5564 { 5565 struct vnode *vp; 5566 struct buf *bp; 5567 5568 if (!have_addr) { 5569 db_printf("usage: show vnodebufs <addr>\n"); 5570 return; 5571 } 5572 vp = (struct vnode *)addr; 5573 db_printf("Clean buffers:\n"); 5574 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5575 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5576 db_printf("\n"); 5577 } 5578 db_printf("Dirty buffers:\n"); 5579 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5580 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5581 db_printf("\n"); 5582 } 5583 } 5584 5585 DB_COMMAND_FLAGS(countfreebufs, db_coundfreebufs, DB_CMD_MEMSAFE) 5586 { 5587 struct buf *bp; 5588 int i, used = 0, nfree = 0; 5589 5590 if (have_addr) { 5591 db_printf("usage: countfreebufs\n"); 5592 return; 5593 } 5594 5595 for (i = 0; i < nbuf; i++) { 5596 bp = nbufp(i); 5597 if (bp->b_qindex == QUEUE_EMPTY) 5598 nfree++; 5599 else 5600 used++; 5601 } 5602 5603 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5604 nfree + used); 5605 db_printf("numfreebuffers is %d\n", numfreebuffers); 5606 } 5607 #endif /* DDB */ 5608