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