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