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