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