1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2004 Poul-Henning Kamp 5 * Copyright (c) 1994,1997 John S. Dyson 6 * Copyright (c) 2013 The FreeBSD Foundation 7 * All rights reserved. 8 * 9 * Portions of this software were developed by Konstantin Belousov 10 * under sponsorship from the FreeBSD Foundation. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 /* 35 * this file contains a new buffer I/O scheme implementing a coherent 36 * VM object and buffer cache scheme. Pains have been taken to make 37 * sure that the performance degradation associated with schemes such 38 * as this is not realized. 39 * 40 * Author: John S. Dyson 41 * Significant help during the development and debugging phases 42 * had been provided by David Greenman, also of the FreeBSD core team. 43 * 44 * see man buf(9) for more info. 45 */ 46 47 #include <sys/cdefs.h> 48 __FBSDID("$FreeBSD$"); 49 50 #include <sys/param.h> 51 #include <sys/systm.h> 52 #include <sys/bio.h> 53 #include <sys/bitset.h> 54 #include <sys/conf.h> 55 #include <sys/counter.h> 56 #include <sys/buf.h> 57 #include <sys/devicestat.h> 58 #include <sys/eventhandler.h> 59 #include <sys/fail.h> 60 #include <sys/ktr.h> 61 #include <sys/limits.h> 62 #include <sys/lock.h> 63 #include <sys/malloc.h> 64 #include <sys/mount.h> 65 #include <sys/mutex.h> 66 #include <sys/kernel.h> 67 #include <sys/kthread.h> 68 #include <sys/proc.h> 69 #include <sys/racct.h> 70 #include <sys/refcount.h> 71 #include <sys/resourcevar.h> 72 #include <sys/rwlock.h> 73 #include <sys/smp.h> 74 #include <sys/sysctl.h> 75 #include <sys/sysproto.h> 76 #include <sys/vmem.h> 77 #include <sys/vmmeter.h> 78 #include <sys/vnode.h> 79 #include <sys/watchdog.h> 80 #include <geom/geom.h> 81 #include <vm/vm.h> 82 #include <vm/vm_param.h> 83 #include <vm/vm_kern.h> 84 #include <vm/vm_object.h> 85 #include <vm/vm_page.h> 86 #include <vm/vm_pageout.h> 87 #include <vm/vm_pager.h> 88 #include <vm/vm_extern.h> 89 #include <vm/vm_map.h> 90 #include <vm/swap_pager.h> 91 92 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 93 94 struct bio_ops bioops; /* I/O operation notification */ 95 96 struct buf_ops buf_ops_bio = { 97 .bop_name = "buf_ops_bio", 98 .bop_write = bufwrite, 99 .bop_strategy = bufstrategy, 100 .bop_sync = bufsync, 101 .bop_bdflush = bufbdflush, 102 }; 103 104 struct bufqueue { 105 struct mtx_padalign bq_lock; 106 TAILQ_HEAD(, buf) bq_queue; 107 uint8_t bq_index; 108 uint16_t bq_subqueue; 109 int bq_len; 110 } __aligned(CACHE_LINE_SIZE); 111 112 #define BQ_LOCKPTR(bq) (&(bq)->bq_lock) 113 #define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq))) 114 #define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq))) 115 #define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED) 116 117 struct bufdomain { 118 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */ 119 struct bufqueue bd_dirtyq; 120 struct bufqueue *bd_cleanq; 121 struct mtx_padalign bd_run_lock; 122 /* Constants */ 123 long bd_maxbufspace; 124 long bd_hibufspace; 125 long bd_lobufspace; 126 long bd_bufspacethresh; 127 int bd_hifreebuffers; 128 int bd_lofreebuffers; 129 int bd_hidirtybuffers; 130 int bd_lodirtybuffers; 131 int bd_dirtybufthresh; 132 int bd_lim; 133 /* atomics */ 134 int bd_wanted; 135 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers; 136 int __aligned(CACHE_LINE_SIZE) bd_running; 137 long __aligned(CACHE_LINE_SIZE) bd_bufspace; 138 int __aligned(CACHE_LINE_SIZE) bd_freebuffers; 139 } __aligned(CACHE_LINE_SIZE); 140 141 #define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock) 142 #define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd))) 143 #define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd))) 144 #define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED) 145 #define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock) 146 #define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd))) 147 #define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd))) 148 #define BD_DOMAIN(bd) (bd - bdomain) 149 150 static struct buf *buf; /* buffer header pool */ 151 extern struct buf *swbuf; /* Swap buffer header pool. */ 152 caddr_t unmapped_buf; 153 154 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 155 struct proc *bufdaemonproc; 156 157 static int inmem(struct vnode *vp, daddr_t blkno); 158 static void vm_hold_free_pages(struct buf *bp, int newbsize); 159 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 160 vm_offset_t to); 161 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 162 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 163 vm_page_t m); 164 static void vfs_clean_pages_dirty_buf(struct buf *bp); 165 static void vfs_setdirty_locked_object(struct buf *bp); 166 static void vfs_vmio_invalidate(struct buf *bp); 167 static void vfs_vmio_truncate(struct buf *bp, int npages); 168 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 169 static int vfs_bio_clcheck(struct vnode *vp, int size, 170 daddr_t lblkno, daddr_t blkno); 171 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int, 172 void (*)(struct buf *)); 173 static int buf_flush(struct vnode *vp, struct bufdomain *, int); 174 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int); 175 static void buf_daemon(void); 176 static __inline void bd_wakeup(void); 177 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 178 static void bufkva_reclaim(vmem_t *, int); 179 static void bufkva_free(struct buf *); 180 static int buf_import(void *, void **, int, int, int); 181 static void buf_release(void *, void **, int); 182 static void maxbcachebuf_adjust(void); 183 static inline struct bufdomain *bufdomain(struct buf *); 184 static void bq_remove(struct bufqueue *bq, struct buf *bp); 185 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock); 186 static int buf_recycle(struct bufdomain *, bool kva); 187 static void bq_init(struct bufqueue *bq, int qindex, int cpu, 188 const char *lockname); 189 static void bd_init(struct bufdomain *bd); 190 static int bd_flushall(struct bufdomain *bd); 191 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS); 192 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS); 193 194 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 195 int vmiodirenable = TRUE; 196 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 197 "Use the VM system for directory writes"); 198 long runningbufspace; 199 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 200 "Amount of presently outstanding async buffer io"); 201 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 202 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers"); 203 static counter_u64_t bufkvaspace; 204 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 205 "Kernel virtual memory used for buffers"); 206 static long maxbufspace; 207 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace, 208 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace, 209 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L", 210 "Maximum allowed value of bufspace (including metadata)"); 211 static long bufmallocspace; 212 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 213 "Amount of malloced memory for buffers"); 214 static long maxbufmallocspace; 215 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 216 0, "Maximum amount of malloced memory for buffers"); 217 static long lobufspace; 218 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace, 219 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace, 220 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L", 221 "Minimum amount of buffers we want to have"); 222 long hibufspace; 223 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace, 224 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace, 225 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L", 226 "Maximum allowed value of bufspace (excluding metadata)"); 227 long bufspacethresh; 228 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh, 229 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh, 230 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L", 231 "Bufspace consumed before waking the daemon to free some"); 232 static counter_u64_t buffreekvacnt; 233 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 234 "Number of times we have freed the KVA space from some buffer"); 235 static counter_u64_t bufdefragcnt; 236 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 237 "Number of times we have had to repeat buffer allocation to defragment"); 238 static long lorunningspace; 239 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 240 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 241 "Minimum preferred space used for in-progress I/O"); 242 static long hirunningspace; 243 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 244 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 245 "Maximum amount of space to use for in-progress I/O"); 246 int dirtybufferflushes; 247 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 248 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 249 int bdwriteskip; 250 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 251 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 252 int altbufferflushes; 253 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW | CTLFLAG_STATS, 254 &altbufferflushes, 0, "Number of fsync flushes to limit dirty buffers"); 255 static int recursiveflushes; 256 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW | CTLFLAG_STATS, 257 &recursiveflushes, 0, "Number of flushes skipped due to being recursive"); 258 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS); 259 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers, 260 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I", 261 "Number of buffers that are dirty (has unwritten changes) at the moment"); 262 static int lodirtybuffers; 263 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers, 264 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers, 265 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I", 266 "How many buffers we want to have free before bufdaemon can sleep"); 267 static int hidirtybuffers; 268 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers, 269 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers, 270 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I", 271 "When the number of dirty buffers is considered severe"); 272 int dirtybufthresh; 273 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh, 274 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh, 275 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I", 276 "Number of bdwrite to bawrite conversions to clear dirty buffers"); 277 static int numfreebuffers; 278 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 279 "Number of free buffers"); 280 static int lofreebuffers; 281 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers, 282 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers, 283 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I", 284 "Target number of free buffers"); 285 static int hifreebuffers; 286 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers, 287 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers, 288 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I", 289 "Threshold for clean buffer recycling"); 290 static counter_u64_t getnewbufcalls; 291 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, 292 &getnewbufcalls, "Number of calls to getnewbuf"); 293 static counter_u64_t getnewbufrestarts; 294 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, 295 &getnewbufrestarts, 296 "Number of times getnewbuf has had to restart a buffer acquisition"); 297 static counter_u64_t mappingrestarts; 298 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD, 299 &mappingrestarts, 300 "Number of times getblk has had to restart a buffer mapping for " 301 "unmapped buffer"); 302 static counter_u64_t numbufallocfails; 303 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, 304 &numbufallocfails, "Number of times buffer allocations failed"); 305 static int flushbufqtarget = 100; 306 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 307 "Amount of work to do in flushbufqueues when helping bufdaemon"); 308 static counter_u64_t notbufdflushes; 309 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 310 "Number of dirty buffer flushes done by the bufdaemon helpers"); 311 static long barrierwrites; 312 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW | CTLFLAG_STATS, 313 &barrierwrites, 0, "Number of barrier writes"); 314 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 315 &unmapped_buf_allowed, 0, 316 "Permit the use of the unmapped i/o"); 317 int maxbcachebuf = MAXBCACHEBUF; 318 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0, 319 "Maximum size of a buffer cache block"); 320 321 /* 322 * This lock synchronizes access to bd_request. 323 */ 324 static struct mtx_padalign __exclusive_cache_line bdlock; 325 326 /* 327 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 328 * waitrunningbufspace(). 329 */ 330 static struct mtx_padalign __exclusive_cache_line rbreqlock; 331 332 /* 333 * Lock that protects bdirtywait. 334 */ 335 static struct mtx_padalign __exclusive_cache_line bdirtylock; 336 337 /* 338 * Wakeup point for bufdaemon, as well as indicator of whether it is already 339 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 340 * is idling. 341 */ 342 static int bd_request; 343 344 /* 345 * Request for the buf daemon to write more buffers than is indicated by 346 * lodirtybuf. This may be necessary to push out excess dependencies or 347 * defragment the address space where a simple count of the number of dirty 348 * buffers is insufficient to characterize the demand for flushing them. 349 */ 350 static int bd_speedupreq; 351 352 /* 353 * Synchronization (sleep/wakeup) variable for active buffer space requests. 354 * Set when wait starts, cleared prior to wakeup(). 355 * Used in runningbufwakeup() and waitrunningbufspace(). 356 */ 357 static int runningbufreq; 358 359 /* 360 * Synchronization for bwillwrite() waiters. 361 */ 362 static int bdirtywait; 363 364 /* 365 * Definitions for the buffer free lists. 366 */ 367 #define QUEUE_NONE 0 /* on no queue */ 368 #define QUEUE_EMPTY 1 /* empty buffer headers */ 369 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 370 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 371 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */ 372 373 /* Maximum number of buffer domains. */ 374 #define BUF_DOMAINS 8 375 376 struct bufdomainset bdlodirty; /* Domains > lodirty */ 377 struct bufdomainset bdhidirty; /* Domains > hidirty */ 378 379 /* Configured number of clean queues. */ 380 static int __read_mostly buf_domains; 381 382 BITSET_DEFINE(bufdomainset, BUF_DOMAINS); 383 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS]; 384 struct bufqueue __exclusive_cache_line bqempty; 385 386 /* 387 * per-cpu empty buffer cache. 388 */ 389 uma_zone_t buf_zone; 390 391 /* 392 * Single global constant for BUF_WMESG, to avoid getting multiple references. 393 * buf_wmesg is referred from macros. 394 */ 395 const char *buf_wmesg = BUF_WMESG; 396 397 static int 398 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 399 { 400 long value; 401 int error; 402 403 value = *(long *)arg1; 404 error = sysctl_handle_long(oidp, &value, 0, req); 405 if (error != 0 || req->newptr == NULL) 406 return (error); 407 mtx_lock(&rbreqlock); 408 if (arg1 == &hirunningspace) { 409 if (value < lorunningspace) 410 error = EINVAL; 411 else 412 hirunningspace = value; 413 } else { 414 KASSERT(arg1 == &lorunningspace, 415 ("%s: unknown arg1", __func__)); 416 if (value > hirunningspace) 417 error = EINVAL; 418 else 419 lorunningspace = value; 420 } 421 mtx_unlock(&rbreqlock); 422 return (error); 423 } 424 425 static int 426 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS) 427 { 428 int error; 429 int value; 430 int i; 431 432 value = *(int *)arg1; 433 error = sysctl_handle_int(oidp, &value, 0, req); 434 if (error != 0 || req->newptr == NULL) 435 return (error); 436 *(int *)arg1 = value; 437 for (i = 0; i < buf_domains; i++) 438 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 439 value / buf_domains; 440 441 return (error); 442 } 443 444 static int 445 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS) 446 { 447 long value; 448 int error; 449 int i; 450 451 value = *(long *)arg1; 452 error = sysctl_handle_long(oidp, &value, 0, req); 453 if (error != 0 || req->newptr == NULL) 454 return (error); 455 *(long *)arg1 = value; 456 for (i = 0; i < buf_domains; i++) 457 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 458 value / buf_domains; 459 460 return (error); 461 } 462 463 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 464 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 465 static int 466 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 467 { 468 long lvalue; 469 int ivalue; 470 int i; 471 472 lvalue = 0; 473 for (i = 0; i < buf_domains; i++) 474 lvalue += bdomain[i].bd_bufspace; 475 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 476 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 477 if (lvalue > INT_MAX) 478 /* On overflow, still write out a long to trigger ENOMEM. */ 479 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 480 ivalue = lvalue; 481 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 482 } 483 #else 484 static int 485 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 486 { 487 long lvalue; 488 int i; 489 490 lvalue = 0; 491 for (i = 0; i < buf_domains; i++) 492 lvalue += bdomain[i].bd_bufspace; 493 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 494 } 495 #endif 496 497 static int 498 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS) 499 { 500 int value; 501 int i; 502 503 value = 0; 504 for (i = 0; i < buf_domains; i++) 505 value += bdomain[i].bd_numdirtybuffers; 506 return (sysctl_handle_int(oidp, &value, 0, req)); 507 } 508 509 /* 510 * bdirtywakeup: 511 * 512 * Wakeup any bwillwrite() waiters. 513 */ 514 static void 515 bdirtywakeup(void) 516 { 517 mtx_lock(&bdirtylock); 518 if (bdirtywait) { 519 bdirtywait = 0; 520 wakeup(&bdirtywait); 521 } 522 mtx_unlock(&bdirtylock); 523 } 524 525 /* 526 * bd_clear: 527 * 528 * Clear a domain from the appropriate bitsets when dirtybuffers 529 * is decremented. 530 */ 531 static void 532 bd_clear(struct bufdomain *bd) 533 { 534 535 mtx_lock(&bdirtylock); 536 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers) 537 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 538 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers) 539 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 540 mtx_unlock(&bdirtylock); 541 } 542 543 /* 544 * bd_set: 545 * 546 * Set a domain in the appropriate bitsets when dirtybuffers 547 * is incremented. 548 */ 549 static void 550 bd_set(struct bufdomain *bd) 551 { 552 553 mtx_lock(&bdirtylock); 554 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers) 555 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 556 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers) 557 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 558 mtx_unlock(&bdirtylock); 559 } 560 561 /* 562 * bdirtysub: 563 * 564 * Decrement the numdirtybuffers count by one and wakeup any 565 * threads blocked in bwillwrite(). 566 */ 567 static void 568 bdirtysub(struct buf *bp) 569 { 570 struct bufdomain *bd; 571 int num; 572 573 bd = bufdomain(bp); 574 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1); 575 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 576 bdirtywakeup(); 577 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 578 bd_clear(bd); 579 } 580 581 /* 582 * bdirtyadd: 583 * 584 * Increment the numdirtybuffers count by one and wakeup the buf 585 * daemon if needed. 586 */ 587 static void 588 bdirtyadd(struct buf *bp) 589 { 590 struct bufdomain *bd; 591 int num; 592 593 /* 594 * Only do the wakeup once as we cross the boundary. The 595 * buf daemon will keep running until the condition clears. 596 */ 597 bd = bufdomain(bp); 598 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1); 599 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 600 bd_wakeup(); 601 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 602 bd_set(bd); 603 } 604 605 /* 606 * bufspace_daemon_wakeup: 607 * 608 * Wakeup the daemons responsible for freeing clean bufs. 609 */ 610 static void 611 bufspace_daemon_wakeup(struct bufdomain *bd) 612 { 613 614 /* 615 * avoid the lock if the daemon is running. 616 */ 617 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) { 618 BD_RUN_LOCK(bd); 619 atomic_store_int(&bd->bd_running, 1); 620 wakeup(&bd->bd_running); 621 BD_RUN_UNLOCK(bd); 622 } 623 } 624 625 /* 626 * bufspace_daemon_wait: 627 * 628 * Sleep until the domain falls below a limit or one second passes. 629 */ 630 static void 631 bufspace_daemon_wait(struct bufdomain *bd) 632 { 633 /* 634 * Re-check our limits and sleep. bd_running must be 635 * cleared prior to checking the limits to avoid missed 636 * wakeups. The waker will adjust one of bufspace or 637 * freebuffers prior to checking bd_running. 638 */ 639 BD_RUN_LOCK(bd); 640 atomic_store_int(&bd->bd_running, 0); 641 if (bd->bd_bufspace < bd->bd_bufspacethresh && 642 bd->bd_freebuffers > bd->bd_lofreebuffers) { 643 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP, 644 "-", hz); 645 } else { 646 /* Avoid spurious wakeups while running. */ 647 atomic_store_int(&bd->bd_running, 1); 648 BD_RUN_UNLOCK(bd); 649 } 650 } 651 652 /* 653 * bufspace_adjust: 654 * 655 * Adjust the reported bufspace for a KVA managed buffer, possibly 656 * waking any waiters. 657 */ 658 static void 659 bufspace_adjust(struct buf *bp, int bufsize) 660 { 661 struct bufdomain *bd; 662 long space; 663 int diff; 664 665 KASSERT((bp->b_flags & B_MALLOC) == 0, 666 ("bufspace_adjust: malloc buf %p", bp)); 667 bd = bufdomain(bp); 668 diff = bufsize - bp->b_bufsize; 669 if (diff < 0) { 670 atomic_subtract_long(&bd->bd_bufspace, -diff); 671 } else if (diff > 0) { 672 space = atomic_fetchadd_long(&bd->bd_bufspace, diff); 673 /* Wake up the daemon on the transition. */ 674 if (space < bd->bd_bufspacethresh && 675 space + diff >= bd->bd_bufspacethresh) 676 bufspace_daemon_wakeup(bd); 677 } 678 bp->b_bufsize = bufsize; 679 } 680 681 /* 682 * bufspace_reserve: 683 * 684 * Reserve bufspace before calling allocbuf(). metadata has a 685 * different space limit than data. 686 */ 687 static int 688 bufspace_reserve(struct bufdomain *bd, int size, bool metadata) 689 { 690 long limit, new; 691 long space; 692 693 if (metadata) 694 limit = bd->bd_maxbufspace; 695 else 696 limit = bd->bd_hibufspace; 697 space = atomic_fetchadd_long(&bd->bd_bufspace, size); 698 new = space + size; 699 if (new > limit) { 700 atomic_subtract_long(&bd->bd_bufspace, size); 701 return (ENOSPC); 702 } 703 704 /* Wake up the daemon on the transition. */ 705 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh) 706 bufspace_daemon_wakeup(bd); 707 708 return (0); 709 } 710 711 /* 712 * bufspace_release: 713 * 714 * Release reserved bufspace after bufspace_adjust() has consumed it. 715 */ 716 static void 717 bufspace_release(struct bufdomain *bd, int size) 718 { 719 720 atomic_subtract_long(&bd->bd_bufspace, size); 721 } 722 723 /* 724 * bufspace_wait: 725 * 726 * Wait for bufspace, acting as the buf daemon if a locked vnode is 727 * supplied. bd_wanted must be set prior to polling for space. The 728 * operation must be re-tried on return. 729 */ 730 static void 731 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags, 732 int slpflag, int slptimeo) 733 { 734 struct thread *td; 735 int error, fl, norunbuf; 736 737 if ((gbflags & GB_NOWAIT_BD) != 0) 738 return; 739 740 td = curthread; 741 BD_LOCK(bd); 742 while (bd->bd_wanted) { 743 if (vp != NULL && vp->v_type != VCHR && 744 (td->td_pflags & TDP_BUFNEED) == 0) { 745 BD_UNLOCK(bd); 746 /* 747 * getblk() is called with a vnode locked, and 748 * some majority of the dirty buffers may as 749 * well belong to the vnode. Flushing the 750 * buffers there would make a progress that 751 * cannot be achieved by the buf_daemon, that 752 * cannot lock the vnode. 753 */ 754 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 755 (td->td_pflags & TDP_NORUNNINGBUF); 756 757 /* 758 * Play bufdaemon. The getnewbuf() function 759 * may be called while the thread owns lock 760 * for another dirty buffer for the same 761 * vnode, which makes it impossible to use 762 * VOP_FSYNC() there, due to the buffer lock 763 * recursion. 764 */ 765 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 766 fl = buf_flush(vp, bd, flushbufqtarget); 767 td->td_pflags &= norunbuf; 768 BD_LOCK(bd); 769 if (fl != 0) 770 continue; 771 if (bd->bd_wanted == 0) 772 break; 773 } 774 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 775 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 776 if (error != 0) 777 break; 778 } 779 BD_UNLOCK(bd); 780 } 781 782 783 /* 784 * bufspace_daemon: 785 * 786 * buffer space management daemon. Tries to maintain some marginal 787 * amount of free buffer space so that requesting processes neither 788 * block nor work to reclaim buffers. 789 */ 790 static void 791 bufspace_daemon(void *arg) 792 { 793 struct bufdomain *bd; 794 795 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 796 SHUTDOWN_PRI_LAST + 100); 797 798 bd = arg; 799 for (;;) { 800 kthread_suspend_check(); 801 802 /* 803 * Free buffers from the clean queue until we meet our 804 * targets. 805 * 806 * Theory of operation: The buffer cache is most efficient 807 * when some free buffer headers and space are always 808 * available to getnewbuf(). This daemon attempts to prevent 809 * the excessive blocking and synchronization associated 810 * with shortfall. It goes through three phases according 811 * demand: 812 * 813 * 1) The daemon wakes up voluntarily once per-second 814 * during idle periods when the counters are below 815 * the wakeup thresholds (bufspacethresh, lofreebuffers). 816 * 817 * 2) The daemon wakes up as we cross the thresholds 818 * ahead of any potential blocking. This may bounce 819 * slightly according to the rate of consumption and 820 * release. 821 * 822 * 3) The daemon and consumers are starved for working 823 * clean buffers. This is the 'bufspace' sleep below 824 * which will inefficiently trade bufs with bqrelse 825 * until we return to condition 2. 826 */ 827 while (bd->bd_bufspace > bd->bd_lobufspace || 828 bd->bd_freebuffers < bd->bd_hifreebuffers) { 829 if (buf_recycle(bd, false) != 0) { 830 if (bd_flushall(bd)) 831 continue; 832 /* 833 * Speedup dirty if we've run out of clean 834 * buffers. This is possible in particular 835 * because softdep may held many bufs locked 836 * pending writes to other bufs which are 837 * marked for delayed write, exhausting 838 * clean space until they are written. 839 */ 840 bd_speedup(); 841 BD_LOCK(bd); 842 if (bd->bd_wanted) { 843 msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 844 PRIBIO|PDROP, "bufspace", hz/10); 845 } else 846 BD_UNLOCK(bd); 847 } 848 maybe_yield(); 849 } 850 bufspace_daemon_wait(bd); 851 } 852 } 853 854 /* 855 * bufmallocadjust: 856 * 857 * Adjust the reported bufspace for a malloc managed buffer, possibly 858 * waking any waiters. 859 */ 860 static void 861 bufmallocadjust(struct buf *bp, int bufsize) 862 { 863 int diff; 864 865 KASSERT((bp->b_flags & B_MALLOC) != 0, 866 ("bufmallocadjust: non-malloc buf %p", bp)); 867 diff = bufsize - bp->b_bufsize; 868 if (diff < 0) 869 atomic_subtract_long(&bufmallocspace, -diff); 870 else 871 atomic_add_long(&bufmallocspace, diff); 872 bp->b_bufsize = bufsize; 873 } 874 875 /* 876 * runningwakeup: 877 * 878 * Wake up processes that are waiting on asynchronous writes to fall 879 * below lorunningspace. 880 */ 881 static void 882 runningwakeup(void) 883 { 884 885 mtx_lock(&rbreqlock); 886 if (runningbufreq) { 887 runningbufreq = 0; 888 wakeup(&runningbufreq); 889 } 890 mtx_unlock(&rbreqlock); 891 } 892 893 /* 894 * runningbufwakeup: 895 * 896 * Decrement the outstanding write count according. 897 */ 898 void 899 runningbufwakeup(struct buf *bp) 900 { 901 long space, bspace; 902 903 bspace = bp->b_runningbufspace; 904 if (bspace == 0) 905 return; 906 space = atomic_fetchadd_long(&runningbufspace, -bspace); 907 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 908 space, bspace)); 909 bp->b_runningbufspace = 0; 910 /* 911 * Only acquire the lock and wakeup on the transition from exceeding 912 * the threshold to falling below it. 913 */ 914 if (space < lorunningspace) 915 return; 916 if (space - bspace > lorunningspace) 917 return; 918 runningwakeup(); 919 } 920 921 /* 922 * waitrunningbufspace() 923 * 924 * runningbufspace is a measure of the amount of I/O currently 925 * running. This routine is used in async-write situations to 926 * prevent creating huge backups of pending writes to a device. 927 * Only asynchronous writes are governed by this function. 928 * 929 * This does NOT turn an async write into a sync write. It waits 930 * for earlier writes to complete and generally returns before the 931 * caller's write has reached the device. 932 */ 933 void 934 waitrunningbufspace(void) 935 { 936 937 mtx_lock(&rbreqlock); 938 while (runningbufspace > hirunningspace) { 939 runningbufreq = 1; 940 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 941 } 942 mtx_unlock(&rbreqlock); 943 } 944 945 946 /* 947 * vfs_buf_test_cache: 948 * 949 * Called when a buffer is extended. This function clears the B_CACHE 950 * bit if the newly extended portion of the buffer does not contain 951 * valid data. 952 */ 953 static __inline void 954 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 955 vm_offset_t size, vm_page_t m) 956 { 957 958 VM_OBJECT_ASSERT_LOCKED(m->object); 959 960 /* 961 * This function and its results are protected by higher level 962 * synchronization requiring vnode and buf locks to page in and 963 * validate pages. 964 */ 965 if (bp->b_flags & B_CACHE) { 966 int base = (foff + off) & PAGE_MASK; 967 if (vm_page_is_valid(m, base, size) == 0) 968 bp->b_flags &= ~B_CACHE; 969 } 970 } 971 972 /* Wake up the buffer daemon if necessary */ 973 static void 974 bd_wakeup(void) 975 { 976 977 mtx_lock(&bdlock); 978 if (bd_request == 0) { 979 bd_request = 1; 980 wakeup(&bd_request); 981 } 982 mtx_unlock(&bdlock); 983 } 984 985 /* 986 * Adjust the maxbcachbuf tunable. 987 */ 988 static void 989 maxbcachebuf_adjust(void) 990 { 991 int i; 992 993 /* 994 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 995 */ 996 i = 2; 997 while (i * 2 <= maxbcachebuf) 998 i *= 2; 999 maxbcachebuf = i; 1000 if (maxbcachebuf < MAXBSIZE) 1001 maxbcachebuf = MAXBSIZE; 1002 if (maxbcachebuf > MAXPHYS) 1003 maxbcachebuf = MAXPHYS; 1004 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 1005 printf("maxbcachebuf=%d\n", maxbcachebuf); 1006 } 1007 1008 /* 1009 * bd_speedup - speedup the buffer cache flushing code 1010 */ 1011 void 1012 bd_speedup(void) 1013 { 1014 int needwake; 1015 1016 mtx_lock(&bdlock); 1017 needwake = 0; 1018 if (bd_speedupreq == 0 || bd_request == 0) 1019 needwake = 1; 1020 bd_speedupreq = 1; 1021 bd_request = 1; 1022 if (needwake) 1023 wakeup(&bd_request); 1024 mtx_unlock(&bdlock); 1025 } 1026 1027 #ifdef __i386__ 1028 #define TRANSIENT_DENOM 5 1029 #else 1030 #define TRANSIENT_DENOM 10 1031 #endif 1032 1033 /* 1034 * Calculating buffer cache scaling values and reserve space for buffer 1035 * headers. This is called during low level kernel initialization and 1036 * may be called more then once. We CANNOT write to the memory area 1037 * being reserved at this time. 1038 */ 1039 caddr_t 1040 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 1041 { 1042 int tuned_nbuf; 1043 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 1044 1045 /* 1046 * physmem_est is in pages. Convert it to kilobytes (assumes 1047 * PAGE_SIZE is >= 1K) 1048 */ 1049 physmem_est = physmem_est * (PAGE_SIZE / 1024); 1050 1051 maxbcachebuf_adjust(); 1052 /* 1053 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 1054 * For the first 64MB of ram nominally allocate sufficient buffers to 1055 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 1056 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 1057 * the buffer cache we limit the eventual kva reservation to 1058 * maxbcache bytes. 1059 * 1060 * factor represents the 1/4 x ram conversion. 1061 */ 1062 if (nbuf == 0) { 1063 int factor = 4 * BKVASIZE / 1024; 1064 1065 nbuf = 50; 1066 if (physmem_est > 4096) 1067 nbuf += min((physmem_est - 4096) / factor, 1068 65536 / factor); 1069 if (physmem_est > 65536) 1070 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 1071 32 * 1024 * 1024 / (factor * 5)); 1072 1073 if (maxbcache && nbuf > maxbcache / BKVASIZE) 1074 nbuf = maxbcache / BKVASIZE; 1075 tuned_nbuf = 1; 1076 } else 1077 tuned_nbuf = 0; 1078 1079 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 1080 maxbuf = (LONG_MAX / 3) / BKVASIZE; 1081 if (nbuf > maxbuf) { 1082 if (!tuned_nbuf) 1083 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 1084 maxbuf); 1085 nbuf = maxbuf; 1086 } 1087 1088 /* 1089 * Ideal allocation size for the transient bio submap is 10% 1090 * of the maximal space buffer map. This roughly corresponds 1091 * to the amount of the buffer mapped for typical UFS load. 1092 * 1093 * Clip the buffer map to reserve space for the transient 1094 * BIOs, if its extent is bigger than 90% (80% on i386) of the 1095 * maximum buffer map extent on the platform. 1096 * 1097 * The fall-back to the maxbuf in case of maxbcache unset, 1098 * allows to not trim the buffer KVA for the architectures 1099 * with ample KVA space. 1100 */ 1101 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 1102 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 1103 buf_sz = (long)nbuf * BKVASIZE; 1104 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 1105 (TRANSIENT_DENOM - 1)) { 1106 /* 1107 * There is more KVA than memory. Do not 1108 * adjust buffer map size, and assign the rest 1109 * of maxbuf to transient map. 1110 */ 1111 biotmap_sz = maxbuf_sz - buf_sz; 1112 } else { 1113 /* 1114 * Buffer map spans all KVA we could afford on 1115 * this platform. Give 10% (20% on i386) of 1116 * the buffer map to the transient bio map. 1117 */ 1118 biotmap_sz = buf_sz / TRANSIENT_DENOM; 1119 buf_sz -= biotmap_sz; 1120 } 1121 if (biotmap_sz / INT_MAX > MAXPHYS) 1122 bio_transient_maxcnt = INT_MAX; 1123 else 1124 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 1125 /* 1126 * Artificially limit to 1024 simultaneous in-flight I/Os 1127 * using the transient mapping. 1128 */ 1129 if (bio_transient_maxcnt > 1024) 1130 bio_transient_maxcnt = 1024; 1131 if (tuned_nbuf) 1132 nbuf = buf_sz / BKVASIZE; 1133 } 1134 1135 if (nswbuf == 0) { 1136 nswbuf = min(nbuf / 4, 256); 1137 if (nswbuf < NSWBUF_MIN) 1138 nswbuf = NSWBUF_MIN; 1139 } 1140 1141 /* 1142 * Reserve space for the buffer cache buffers 1143 */ 1144 buf = (void *)v; 1145 v = (caddr_t)(buf + nbuf); 1146 1147 return(v); 1148 } 1149 1150 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1151 void 1152 bufinit(void) 1153 { 1154 struct buf *bp; 1155 int i; 1156 1157 KASSERT(maxbcachebuf >= MAXBSIZE, 1158 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1159 MAXBSIZE)); 1160 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock"); 1161 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1162 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1163 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1164 1165 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1166 1167 /* finally, initialize each buffer header and stick on empty q */ 1168 for (i = 0; i < nbuf; i++) { 1169 bp = &buf[i]; 1170 bzero(bp, sizeof *bp); 1171 bp->b_flags = B_INVAL; 1172 bp->b_rcred = NOCRED; 1173 bp->b_wcred = NOCRED; 1174 bp->b_qindex = QUEUE_NONE; 1175 bp->b_domain = -1; 1176 bp->b_subqueue = mp_maxid + 1; 1177 bp->b_xflags = 0; 1178 bp->b_data = bp->b_kvabase = unmapped_buf; 1179 LIST_INIT(&bp->b_dep); 1180 BUF_LOCKINIT(bp); 1181 bq_insert(&bqempty, bp, false); 1182 } 1183 1184 /* 1185 * maxbufspace is the absolute maximum amount of buffer space we are 1186 * allowed to reserve in KVM and in real terms. The absolute maximum 1187 * is nominally used by metadata. hibufspace is the nominal maximum 1188 * used by most other requests. The differential is required to 1189 * ensure that metadata deadlocks don't occur. 1190 * 1191 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1192 * this may result in KVM fragmentation which is not handled optimally 1193 * by the system. XXX This is less true with vmem. We could use 1194 * PAGE_SIZE. 1195 */ 1196 maxbufspace = (long)nbuf * BKVASIZE; 1197 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1198 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1199 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1200 1201 /* 1202 * Note: The 16 MiB upper limit for hirunningspace was chosen 1203 * arbitrarily and may need further tuning. It corresponds to 1204 * 128 outstanding write IO requests (if IO size is 128 KiB), 1205 * which fits with many RAID controllers' tagged queuing limits. 1206 * The lower 1 MiB limit is the historical upper limit for 1207 * hirunningspace. 1208 */ 1209 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1210 16 * 1024 * 1024), 1024 * 1024); 1211 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1212 1213 /* 1214 * Limit the amount of malloc memory since it is wired permanently into 1215 * the kernel space. Even though this is accounted for in the buffer 1216 * allocation, we don't want the malloced region to grow uncontrolled. 1217 * The malloc scheme improves memory utilization significantly on 1218 * average (small) directories. 1219 */ 1220 maxbufmallocspace = hibufspace / 20; 1221 1222 /* 1223 * Reduce the chance of a deadlock occurring by limiting the number 1224 * of delayed-write dirty buffers we allow to stack up. 1225 */ 1226 hidirtybuffers = nbuf / 4 + 20; 1227 dirtybufthresh = hidirtybuffers * 9 / 10; 1228 /* 1229 * To support extreme low-memory systems, make sure hidirtybuffers 1230 * cannot eat up all available buffer space. This occurs when our 1231 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1232 * buffer space assuming BKVASIZE'd buffers. 1233 */ 1234 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1235 hidirtybuffers >>= 1; 1236 } 1237 lodirtybuffers = hidirtybuffers / 2; 1238 1239 /* 1240 * lofreebuffers should be sufficient to avoid stalling waiting on 1241 * buf headers under heavy utilization. The bufs in per-cpu caches 1242 * are counted as free but will be unavailable to threads executing 1243 * on other cpus. 1244 * 1245 * hifreebuffers is the free target for the bufspace daemon. This 1246 * should be set appropriately to limit work per-iteration. 1247 */ 1248 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1249 hifreebuffers = (3 * lofreebuffers) / 2; 1250 numfreebuffers = nbuf; 1251 1252 /* Setup the kva and free list allocators. */ 1253 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1254 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1255 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1256 1257 /* 1258 * Size the clean queue according to the amount of buffer space. 1259 * One queue per-256mb up to the max. More queues gives better 1260 * concurrency but less accurate LRU. 1261 */ 1262 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS); 1263 for (i = 0 ; i < buf_domains; i++) { 1264 struct bufdomain *bd; 1265 1266 bd = &bdomain[i]; 1267 bd_init(bd); 1268 bd->bd_freebuffers = nbuf / buf_domains; 1269 bd->bd_hifreebuffers = hifreebuffers / buf_domains; 1270 bd->bd_lofreebuffers = lofreebuffers / buf_domains; 1271 bd->bd_bufspace = 0; 1272 bd->bd_maxbufspace = maxbufspace / buf_domains; 1273 bd->bd_hibufspace = hibufspace / buf_domains; 1274 bd->bd_lobufspace = lobufspace / buf_domains; 1275 bd->bd_bufspacethresh = bufspacethresh / buf_domains; 1276 bd->bd_numdirtybuffers = 0; 1277 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains; 1278 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains; 1279 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains; 1280 /* Don't allow more than 2% of bufs in the per-cpu caches. */ 1281 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus; 1282 } 1283 getnewbufcalls = counter_u64_alloc(M_WAITOK); 1284 getnewbufrestarts = counter_u64_alloc(M_WAITOK); 1285 mappingrestarts = counter_u64_alloc(M_WAITOK); 1286 numbufallocfails = counter_u64_alloc(M_WAITOK); 1287 notbufdflushes = counter_u64_alloc(M_WAITOK); 1288 buffreekvacnt = counter_u64_alloc(M_WAITOK); 1289 bufdefragcnt = counter_u64_alloc(M_WAITOK); 1290 bufkvaspace = counter_u64_alloc(M_WAITOK); 1291 } 1292 1293 #ifdef INVARIANTS 1294 static inline void 1295 vfs_buf_check_mapped(struct buf *bp) 1296 { 1297 1298 KASSERT(bp->b_kvabase != unmapped_buf, 1299 ("mapped buf: b_kvabase was not updated %p", bp)); 1300 KASSERT(bp->b_data != unmapped_buf, 1301 ("mapped buf: b_data was not updated %p", bp)); 1302 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1303 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1304 } 1305 1306 static inline void 1307 vfs_buf_check_unmapped(struct buf *bp) 1308 { 1309 1310 KASSERT(bp->b_data == unmapped_buf, 1311 ("unmapped buf: corrupted b_data %p", bp)); 1312 } 1313 1314 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1315 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1316 #else 1317 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1318 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1319 #endif 1320 1321 static int 1322 isbufbusy(struct buf *bp) 1323 { 1324 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1325 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1326 return (1); 1327 return (0); 1328 } 1329 1330 /* 1331 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1332 */ 1333 void 1334 bufshutdown(int show_busybufs) 1335 { 1336 static int first_buf_printf = 1; 1337 struct buf *bp; 1338 int iter, nbusy, pbusy; 1339 #ifndef PREEMPTION 1340 int subiter; 1341 #endif 1342 1343 /* 1344 * Sync filesystems for shutdown 1345 */ 1346 wdog_kern_pat(WD_LASTVAL); 1347 sys_sync(curthread, NULL); 1348 1349 /* 1350 * With soft updates, some buffers that are 1351 * written will be remarked as dirty until other 1352 * buffers are written. 1353 */ 1354 for (iter = pbusy = 0; iter < 20; iter++) { 1355 nbusy = 0; 1356 for (bp = &buf[nbuf]; --bp >= buf; ) 1357 if (isbufbusy(bp)) 1358 nbusy++; 1359 if (nbusy == 0) { 1360 if (first_buf_printf) 1361 printf("All buffers synced."); 1362 break; 1363 } 1364 if (first_buf_printf) { 1365 printf("Syncing disks, buffers remaining... "); 1366 first_buf_printf = 0; 1367 } 1368 printf("%d ", nbusy); 1369 if (nbusy < pbusy) 1370 iter = 0; 1371 pbusy = nbusy; 1372 1373 wdog_kern_pat(WD_LASTVAL); 1374 sys_sync(curthread, NULL); 1375 1376 #ifdef PREEMPTION 1377 /* 1378 * Spin for a while to allow interrupt threads to run. 1379 */ 1380 DELAY(50000 * iter); 1381 #else 1382 /* 1383 * Context switch several times to allow interrupt 1384 * threads to run. 1385 */ 1386 for (subiter = 0; subiter < 50 * iter; subiter++) { 1387 thread_lock(curthread); 1388 mi_switch(SW_VOL, NULL); 1389 thread_unlock(curthread); 1390 DELAY(1000); 1391 } 1392 #endif 1393 } 1394 printf("\n"); 1395 /* 1396 * Count only busy local buffers to prevent forcing 1397 * a fsck if we're just a client of a wedged NFS server 1398 */ 1399 nbusy = 0; 1400 for (bp = &buf[nbuf]; --bp >= buf; ) { 1401 if (isbufbusy(bp)) { 1402 #if 0 1403 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1404 if (bp->b_dev == NULL) { 1405 TAILQ_REMOVE(&mountlist, 1406 bp->b_vp->v_mount, mnt_list); 1407 continue; 1408 } 1409 #endif 1410 nbusy++; 1411 if (show_busybufs > 0) { 1412 printf( 1413 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1414 nbusy, bp, bp->b_vp, bp->b_flags, 1415 (intmax_t)bp->b_blkno, 1416 (intmax_t)bp->b_lblkno); 1417 BUF_LOCKPRINTINFO(bp); 1418 if (show_busybufs > 1) 1419 vn_printf(bp->b_vp, 1420 "vnode content: "); 1421 } 1422 } 1423 } 1424 if (nbusy) { 1425 /* 1426 * Failed to sync all blocks. Indicate this and don't 1427 * unmount filesystems (thus forcing an fsck on reboot). 1428 */ 1429 printf("Giving up on %d buffers\n", nbusy); 1430 DELAY(5000000); /* 5 seconds */ 1431 } else { 1432 if (!first_buf_printf) 1433 printf("Final sync complete\n"); 1434 /* 1435 * Unmount filesystems 1436 */ 1437 if (panicstr == NULL) 1438 vfs_unmountall(); 1439 } 1440 swapoff_all(); 1441 DELAY(100000); /* wait for console output to finish */ 1442 } 1443 1444 static void 1445 bpmap_qenter(struct buf *bp) 1446 { 1447 1448 BUF_CHECK_MAPPED(bp); 1449 1450 /* 1451 * bp->b_data is relative to bp->b_offset, but 1452 * bp->b_offset may be offset into the first page. 1453 */ 1454 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1455 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1456 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1457 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1458 } 1459 1460 static inline struct bufdomain * 1461 bufdomain(struct buf *bp) 1462 { 1463 1464 return (&bdomain[bp->b_domain]); 1465 } 1466 1467 static struct bufqueue * 1468 bufqueue(struct buf *bp) 1469 { 1470 1471 switch (bp->b_qindex) { 1472 case QUEUE_NONE: 1473 /* FALLTHROUGH */ 1474 case QUEUE_SENTINEL: 1475 return (NULL); 1476 case QUEUE_EMPTY: 1477 return (&bqempty); 1478 case QUEUE_DIRTY: 1479 return (&bufdomain(bp)->bd_dirtyq); 1480 case QUEUE_CLEAN: 1481 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]); 1482 default: 1483 break; 1484 } 1485 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex); 1486 } 1487 1488 /* 1489 * Return the locked bufqueue that bp is a member of. 1490 */ 1491 static struct bufqueue * 1492 bufqueue_acquire(struct buf *bp) 1493 { 1494 struct bufqueue *bq, *nbq; 1495 1496 /* 1497 * bp can be pushed from a per-cpu queue to the 1498 * cleanq while we're waiting on the lock. Retry 1499 * if the queues don't match. 1500 */ 1501 bq = bufqueue(bp); 1502 BQ_LOCK(bq); 1503 for (;;) { 1504 nbq = bufqueue(bp); 1505 if (bq == nbq) 1506 break; 1507 BQ_UNLOCK(bq); 1508 BQ_LOCK(nbq); 1509 bq = nbq; 1510 } 1511 return (bq); 1512 } 1513 1514 /* 1515 * binsfree: 1516 * 1517 * Insert the buffer into the appropriate free list. Requires a 1518 * locked buffer on entry and buffer is unlocked before return. 1519 */ 1520 static void 1521 binsfree(struct buf *bp, int qindex) 1522 { 1523 struct bufdomain *bd; 1524 struct bufqueue *bq; 1525 1526 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY, 1527 ("binsfree: Invalid qindex %d", qindex)); 1528 BUF_ASSERT_XLOCKED(bp); 1529 1530 /* 1531 * Handle delayed bremfree() processing. 1532 */ 1533 if (bp->b_flags & B_REMFREE) { 1534 if (bp->b_qindex == qindex) { 1535 bp->b_flags |= B_REUSE; 1536 bp->b_flags &= ~B_REMFREE; 1537 BUF_UNLOCK(bp); 1538 return; 1539 } 1540 bq = bufqueue_acquire(bp); 1541 bq_remove(bq, bp); 1542 BQ_UNLOCK(bq); 1543 } 1544 bd = bufdomain(bp); 1545 if (qindex == QUEUE_CLEAN) { 1546 if (bd->bd_lim != 0) 1547 bq = &bd->bd_subq[PCPU_GET(cpuid)]; 1548 else 1549 bq = bd->bd_cleanq; 1550 } else 1551 bq = &bd->bd_dirtyq; 1552 bq_insert(bq, bp, true); 1553 } 1554 1555 /* 1556 * buf_free: 1557 * 1558 * Free a buffer to the buf zone once it no longer has valid contents. 1559 */ 1560 static void 1561 buf_free(struct buf *bp) 1562 { 1563 1564 if (bp->b_flags & B_REMFREE) 1565 bremfreef(bp); 1566 if (bp->b_vflags & BV_BKGRDINPROG) 1567 panic("losing buffer 1"); 1568 if (bp->b_rcred != NOCRED) { 1569 crfree(bp->b_rcred); 1570 bp->b_rcred = NOCRED; 1571 } 1572 if (bp->b_wcred != NOCRED) { 1573 crfree(bp->b_wcred); 1574 bp->b_wcred = NOCRED; 1575 } 1576 if (!LIST_EMPTY(&bp->b_dep)) 1577 buf_deallocate(bp); 1578 bufkva_free(bp); 1579 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1); 1580 BUF_UNLOCK(bp); 1581 uma_zfree(buf_zone, bp); 1582 } 1583 1584 /* 1585 * buf_import: 1586 * 1587 * Import bufs into the uma cache from the buf list. The system still 1588 * expects a static array of bufs and much of the synchronization 1589 * around bufs assumes type stable storage. As a result, UMA is used 1590 * only as a per-cpu cache of bufs still maintained on a global list. 1591 */ 1592 static int 1593 buf_import(void *arg, void **store, int cnt, int domain, int flags) 1594 { 1595 struct buf *bp; 1596 int i; 1597 1598 BQ_LOCK(&bqempty); 1599 for (i = 0; i < cnt; i++) { 1600 bp = TAILQ_FIRST(&bqempty.bq_queue); 1601 if (bp == NULL) 1602 break; 1603 bq_remove(&bqempty, bp); 1604 store[i] = bp; 1605 } 1606 BQ_UNLOCK(&bqempty); 1607 1608 return (i); 1609 } 1610 1611 /* 1612 * buf_release: 1613 * 1614 * Release bufs from the uma cache back to the buffer queues. 1615 */ 1616 static void 1617 buf_release(void *arg, void **store, int cnt) 1618 { 1619 struct bufqueue *bq; 1620 struct buf *bp; 1621 int i; 1622 1623 bq = &bqempty; 1624 BQ_LOCK(bq); 1625 for (i = 0; i < cnt; i++) { 1626 bp = store[i]; 1627 /* Inline bq_insert() to batch locking. */ 1628 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1629 bp->b_flags &= ~(B_AGE | B_REUSE); 1630 bq->bq_len++; 1631 bp->b_qindex = bq->bq_index; 1632 } 1633 BQ_UNLOCK(bq); 1634 } 1635 1636 /* 1637 * buf_alloc: 1638 * 1639 * Allocate an empty buffer header. 1640 */ 1641 static struct buf * 1642 buf_alloc(struct bufdomain *bd) 1643 { 1644 struct buf *bp; 1645 int freebufs; 1646 1647 /* 1648 * We can only run out of bufs in the buf zone if the average buf 1649 * is less than BKVASIZE. In this case the actual wait/block will 1650 * come from buf_reycle() failing to flush one of these small bufs. 1651 */ 1652 bp = NULL; 1653 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1); 1654 if (freebufs > 0) 1655 bp = uma_zalloc(buf_zone, M_NOWAIT); 1656 if (bp == NULL) { 1657 atomic_add_int(&bd->bd_freebuffers, 1); 1658 bufspace_daemon_wakeup(bd); 1659 counter_u64_add(numbufallocfails, 1); 1660 return (NULL); 1661 } 1662 /* 1663 * Wake-up the bufspace daemon on transition below threshold. 1664 */ 1665 if (freebufs == bd->bd_lofreebuffers) 1666 bufspace_daemon_wakeup(bd); 1667 1668 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1669 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1670 1671 KASSERT(bp->b_vp == NULL, 1672 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1673 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1674 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1675 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1676 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1677 KASSERT(bp->b_npages == 0, 1678 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1679 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1680 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1681 1682 bp->b_domain = BD_DOMAIN(bd); 1683 bp->b_flags = 0; 1684 bp->b_ioflags = 0; 1685 bp->b_xflags = 0; 1686 bp->b_vflags = 0; 1687 bp->b_vp = NULL; 1688 bp->b_blkno = bp->b_lblkno = 0; 1689 bp->b_offset = NOOFFSET; 1690 bp->b_iodone = 0; 1691 bp->b_error = 0; 1692 bp->b_resid = 0; 1693 bp->b_bcount = 0; 1694 bp->b_npages = 0; 1695 bp->b_dirtyoff = bp->b_dirtyend = 0; 1696 bp->b_bufobj = NULL; 1697 bp->b_data = bp->b_kvabase = unmapped_buf; 1698 bp->b_fsprivate1 = NULL; 1699 bp->b_fsprivate2 = NULL; 1700 bp->b_fsprivate3 = NULL; 1701 LIST_INIT(&bp->b_dep); 1702 1703 return (bp); 1704 } 1705 1706 /* 1707 * buf_recycle: 1708 * 1709 * Free a buffer from the given bufqueue. kva controls whether the 1710 * freed buf must own some kva resources. This is used for 1711 * defragmenting. 1712 */ 1713 static int 1714 buf_recycle(struct bufdomain *bd, bool kva) 1715 { 1716 struct bufqueue *bq; 1717 struct buf *bp, *nbp; 1718 1719 if (kva) 1720 counter_u64_add(bufdefragcnt, 1); 1721 nbp = NULL; 1722 bq = bd->bd_cleanq; 1723 BQ_LOCK(bq); 1724 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd), 1725 ("buf_recycle: Locks don't match")); 1726 nbp = TAILQ_FIRST(&bq->bq_queue); 1727 1728 /* 1729 * Run scan, possibly freeing data and/or kva mappings on the fly 1730 * depending. 1731 */ 1732 while ((bp = nbp) != NULL) { 1733 /* 1734 * Calculate next bp (we can only use it if we do not 1735 * release the bqlock). 1736 */ 1737 nbp = TAILQ_NEXT(bp, b_freelist); 1738 1739 /* 1740 * If we are defragging then we need a buffer with 1741 * some kva to reclaim. 1742 */ 1743 if (kva && bp->b_kvasize == 0) 1744 continue; 1745 1746 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1747 continue; 1748 1749 /* 1750 * Implement a second chance algorithm for frequently 1751 * accessed buffers. 1752 */ 1753 if ((bp->b_flags & B_REUSE) != 0) { 1754 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1755 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1756 bp->b_flags &= ~B_REUSE; 1757 BUF_UNLOCK(bp); 1758 continue; 1759 } 1760 1761 /* 1762 * Skip buffers with background writes in progress. 1763 */ 1764 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1765 BUF_UNLOCK(bp); 1766 continue; 1767 } 1768 1769 KASSERT(bp->b_qindex == QUEUE_CLEAN, 1770 ("buf_recycle: inconsistent queue %d bp %p", 1771 bp->b_qindex, bp)); 1772 KASSERT(bp->b_domain == BD_DOMAIN(bd), 1773 ("getnewbuf: queue domain %d doesn't match request %d", 1774 bp->b_domain, (int)BD_DOMAIN(bd))); 1775 /* 1776 * NOTE: nbp is now entirely invalid. We can only restart 1777 * the scan from this point on. 1778 */ 1779 bq_remove(bq, bp); 1780 BQ_UNLOCK(bq); 1781 1782 /* 1783 * Requeue the background write buffer with error and 1784 * restart the scan. 1785 */ 1786 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1787 bqrelse(bp); 1788 BQ_LOCK(bq); 1789 nbp = TAILQ_FIRST(&bq->bq_queue); 1790 continue; 1791 } 1792 bp->b_flags |= B_INVAL; 1793 brelse(bp); 1794 return (0); 1795 } 1796 bd->bd_wanted = 1; 1797 BQ_UNLOCK(bq); 1798 1799 return (ENOBUFS); 1800 } 1801 1802 /* 1803 * bremfree: 1804 * 1805 * Mark the buffer for removal from the appropriate free list. 1806 * 1807 */ 1808 void 1809 bremfree(struct buf *bp) 1810 { 1811 1812 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1813 KASSERT((bp->b_flags & B_REMFREE) == 0, 1814 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1815 KASSERT(bp->b_qindex != QUEUE_NONE, 1816 ("bremfree: buffer %p not on a queue.", bp)); 1817 BUF_ASSERT_XLOCKED(bp); 1818 1819 bp->b_flags |= B_REMFREE; 1820 } 1821 1822 /* 1823 * bremfreef: 1824 * 1825 * Force an immediate removal from a free list. Used only in nfs when 1826 * it abuses the b_freelist pointer. 1827 */ 1828 void 1829 bremfreef(struct buf *bp) 1830 { 1831 struct bufqueue *bq; 1832 1833 bq = bufqueue_acquire(bp); 1834 bq_remove(bq, bp); 1835 BQ_UNLOCK(bq); 1836 } 1837 1838 static void 1839 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname) 1840 { 1841 1842 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF); 1843 TAILQ_INIT(&bq->bq_queue); 1844 bq->bq_len = 0; 1845 bq->bq_index = qindex; 1846 bq->bq_subqueue = subqueue; 1847 } 1848 1849 static void 1850 bd_init(struct bufdomain *bd) 1851 { 1852 int i; 1853 1854 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1]; 1855 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock"); 1856 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock"); 1857 for (i = 0; i <= mp_maxid; i++) 1858 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i, 1859 "bufq clean subqueue lock"); 1860 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF); 1861 } 1862 1863 /* 1864 * bq_remove: 1865 * 1866 * Removes a buffer from the free list, must be called with the 1867 * correct qlock held. 1868 */ 1869 static void 1870 bq_remove(struct bufqueue *bq, struct buf *bp) 1871 { 1872 1873 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X", 1874 bp, bp->b_vp, bp->b_flags); 1875 KASSERT(bp->b_qindex != QUEUE_NONE, 1876 ("bq_remove: buffer %p not on a queue.", bp)); 1877 KASSERT(bufqueue(bp) == bq, 1878 ("bq_remove: Remove buffer %p from wrong queue.", bp)); 1879 1880 BQ_ASSERT_LOCKED(bq); 1881 if (bp->b_qindex != QUEUE_EMPTY) { 1882 BUF_ASSERT_XLOCKED(bp); 1883 } 1884 KASSERT(bq->bq_len >= 1, 1885 ("queue %d underflow", bp->b_qindex)); 1886 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1887 bq->bq_len--; 1888 bp->b_qindex = QUEUE_NONE; 1889 bp->b_flags &= ~(B_REMFREE | B_REUSE); 1890 } 1891 1892 static void 1893 bd_flush(struct bufdomain *bd, struct bufqueue *bq) 1894 { 1895 struct buf *bp; 1896 1897 BQ_ASSERT_LOCKED(bq); 1898 if (bq != bd->bd_cleanq) { 1899 BD_LOCK(bd); 1900 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) { 1901 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1902 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp, 1903 b_freelist); 1904 bp->b_subqueue = bd->bd_cleanq->bq_subqueue; 1905 } 1906 bd->bd_cleanq->bq_len += bq->bq_len; 1907 bq->bq_len = 0; 1908 } 1909 if (bd->bd_wanted) { 1910 bd->bd_wanted = 0; 1911 wakeup(&bd->bd_wanted); 1912 } 1913 if (bq != bd->bd_cleanq) 1914 BD_UNLOCK(bd); 1915 } 1916 1917 static int 1918 bd_flushall(struct bufdomain *bd) 1919 { 1920 struct bufqueue *bq; 1921 int flushed; 1922 int i; 1923 1924 if (bd->bd_lim == 0) 1925 return (0); 1926 flushed = 0; 1927 for (i = 0; i <= mp_maxid; i++) { 1928 bq = &bd->bd_subq[i]; 1929 if (bq->bq_len == 0) 1930 continue; 1931 BQ_LOCK(bq); 1932 bd_flush(bd, bq); 1933 BQ_UNLOCK(bq); 1934 flushed++; 1935 } 1936 1937 return (flushed); 1938 } 1939 1940 static void 1941 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock) 1942 { 1943 struct bufdomain *bd; 1944 1945 if (bp->b_qindex != QUEUE_NONE) 1946 panic("bq_insert: free buffer %p onto another queue?", bp); 1947 1948 bd = bufdomain(bp); 1949 if (bp->b_flags & B_AGE) { 1950 /* Place this buf directly on the real queue. */ 1951 if (bq->bq_index == QUEUE_CLEAN) 1952 bq = bd->bd_cleanq; 1953 BQ_LOCK(bq); 1954 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist); 1955 } else { 1956 BQ_LOCK(bq); 1957 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1958 } 1959 bp->b_flags &= ~(B_AGE | B_REUSE); 1960 bq->bq_len++; 1961 bp->b_qindex = bq->bq_index; 1962 bp->b_subqueue = bq->bq_subqueue; 1963 1964 /* 1965 * Unlock before we notify so that we don't wakeup a waiter that 1966 * fails a trylock on the buf and sleeps again. 1967 */ 1968 if (unlock) 1969 BUF_UNLOCK(bp); 1970 1971 if (bp->b_qindex == QUEUE_CLEAN) { 1972 /* 1973 * Flush the per-cpu queue and notify any waiters. 1974 */ 1975 if (bd->bd_wanted || (bq != bd->bd_cleanq && 1976 bq->bq_len >= bd->bd_lim)) 1977 bd_flush(bd, bq); 1978 } 1979 BQ_UNLOCK(bq); 1980 } 1981 1982 /* 1983 * bufkva_free: 1984 * 1985 * Free the kva allocation for a buffer. 1986 * 1987 */ 1988 static void 1989 bufkva_free(struct buf *bp) 1990 { 1991 1992 #ifdef INVARIANTS 1993 if (bp->b_kvasize == 0) { 1994 KASSERT(bp->b_kvabase == unmapped_buf && 1995 bp->b_data == unmapped_buf, 1996 ("Leaked KVA space on %p", bp)); 1997 } else if (buf_mapped(bp)) 1998 BUF_CHECK_MAPPED(bp); 1999 else 2000 BUF_CHECK_UNMAPPED(bp); 2001 #endif 2002 if (bp->b_kvasize == 0) 2003 return; 2004 2005 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 2006 counter_u64_add(bufkvaspace, -bp->b_kvasize); 2007 counter_u64_add(buffreekvacnt, 1); 2008 bp->b_data = bp->b_kvabase = unmapped_buf; 2009 bp->b_kvasize = 0; 2010 } 2011 2012 /* 2013 * bufkva_alloc: 2014 * 2015 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 2016 */ 2017 static int 2018 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 2019 { 2020 vm_offset_t addr; 2021 int error; 2022 2023 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 2024 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 2025 2026 bufkva_free(bp); 2027 2028 addr = 0; 2029 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 2030 if (error != 0) { 2031 /* 2032 * Buffer map is too fragmented. Request the caller 2033 * to defragment the map. 2034 */ 2035 return (error); 2036 } 2037 bp->b_kvabase = (caddr_t)addr; 2038 bp->b_kvasize = maxsize; 2039 counter_u64_add(bufkvaspace, bp->b_kvasize); 2040 if ((gbflags & GB_UNMAPPED) != 0) { 2041 bp->b_data = unmapped_buf; 2042 BUF_CHECK_UNMAPPED(bp); 2043 } else { 2044 bp->b_data = bp->b_kvabase; 2045 BUF_CHECK_MAPPED(bp); 2046 } 2047 return (0); 2048 } 2049 2050 /* 2051 * bufkva_reclaim: 2052 * 2053 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 2054 * callback that fires to avoid returning failure. 2055 */ 2056 static void 2057 bufkva_reclaim(vmem_t *vmem, int flags) 2058 { 2059 bool done; 2060 int q; 2061 int i; 2062 2063 done = false; 2064 for (i = 0; i < 5; i++) { 2065 for (q = 0; q < buf_domains; q++) 2066 if (buf_recycle(&bdomain[q], true) != 0) 2067 done = true; 2068 if (done) 2069 break; 2070 } 2071 return; 2072 } 2073 2074 /* 2075 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 2076 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 2077 * the buffer is valid and we do not have to do anything. 2078 */ 2079 static void 2080 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt, 2081 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *)) 2082 { 2083 struct buf *rabp; 2084 struct thread *td; 2085 int i; 2086 2087 td = curthread; 2088 2089 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 2090 if (inmem(vp, *rablkno)) 2091 continue; 2092 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 2093 if ((rabp->b_flags & B_CACHE) != 0) { 2094 brelse(rabp); 2095 continue; 2096 } 2097 #ifdef RACCT 2098 if (racct_enable) { 2099 PROC_LOCK(curproc); 2100 racct_add_buf(curproc, rabp, 0); 2101 PROC_UNLOCK(curproc); 2102 } 2103 #endif /* RACCT */ 2104 td->td_ru.ru_inblock++; 2105 rabp->b_flags |= B_ASYNC; 2106 rabp->b_flags &= ~B_INVAL; 2107 if ((flags & GB_CKHASH) != 0) { 2108 rabp->b_flags |= B_CKHASH; 2109 rabp->b_ckhashcalc = ckhashfunc; 2110 } 2111 rabp->b_ioflags &= ~BIO_ERROR; 2112 rabp->b_iocmd = BIO_READ; 2113 if (rabp->b_rcred == NOCRED && cred != NOCRED) 2114 rabp->b_rcred = crhold(cred); 2115 vfs_busy_pages(rabp, 0); 2116 BUF_KERNPROC(rabp); 2117 rabp->b_iooffset = dbtob(rabp->b_blkno); 2118 bstrategy(rabp); 2119 } 2120 } 2121 2122 /* 2123 * Entry point for bread() and breadn() via #defines in sys/buf.h. 2124 * 2125 * Get a buffer with the specified data. Look in the cache first. We 2126 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 2127 * is set, the buffer is valid and we do not have to do anything, see 2128 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 2129 * 2130 * Always return a NULL buffer pointer (in bpp) when returning an error. 2131 */ 2132 int 2133 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 2134 int *rabsize, int cnt, struct ucred *cred, int flags, 2135 void (*ckhashfunc)(struct buf *), struct buf **bpp) 2136 { 2137 struct buf *bp; 2138 struct thread *td; 2139 int error, readwait, rv; 2140 2141 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 2142 td = curthread; 2143 /* 2144 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags 2145 * are specified. 2146 */ 2147 error = getblkx(vp, blkno, size, 0, 0, flags, &bp); 2148 if (error != 0) { 2149 *bpp = NULL; 2150 return (error); 2151 } 2152 flags &= ~GB_NOSPARSE; 2153 *bpp = bp; 2154 2155 /* 2156 * If not found in cache, do some I/O 2157 */ 2158 readwait = 0; 2159 if ((bp->b_flags & B_CACHE) == 0) { 2160 #ifdef RACCT 2161 if (racct_enable) { 2162 PROC_LOCK(td->td_proc); 2163 racct_add_buf(td->td_proc, bp, 0); 2164 PROC_UNLOCK(td->td_proc); 2165 } 2166 #endif /* RACCT */ 2167 td->td_ru.ru_inblock++; 2168 bp->b_iocmd = BIO_READ; 2169 bp->b_flags &= ~B_INVAL; 2170 if ((flags & GB_CKHASH) != 0) { 2171 bp->b_flags |= B_CKHASH; 2172 bp->b_ckhashcalc = ckhashfunc; 2173 } 2174 bp->b_ioflags &= ~BIO_ERROR; 2175 if (bp->b_rcred == NOCRED && cred != NOCRED) 2176 bp->b_rcred = crhold(cred); 2177 vfs_busy_pages(bp, 0); 2178 bp->b_iooffset = dbtob(bp->b_blkno); 2179 bstrategy(bp); 2180 ++readwait; 2181 } 2182 2183 /* 2184 * Attempt to initiate asynchronous I/O on read-ahead blocks. 2185 */ 2186 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 2187 2188 rv = 0; 2189 if (readwait) { 2190 rv = bufwait(bp); 2191 if (rv != 0) { 2192 brelse(bp); 2193 *bpp = NULL; 2194 } 2195 } 2196 return (rv); 2197 } 2198 2199 /* 2200 * Write, release buffer on completion. (Done by iodone 2201 * if async). Do not bother writing anything if the buffer 2202 * is invalid. 2203 * 2204 * Note that we set B_CACHE here, indicating that buffer is 2205 * fully valid and thus cacheable. This is true even of NFS 2206 * now so we set it generally. This could be set either here 2207 * or in biodone() since the I/O is synchronous. We put it 2208 * here. 2209 */ 2210 int 2211 bufwrite(struct buf *bp) 2212 { 2213 int oldflags; 2214 struct vnode *vp; 2215 long space; 2216 int vp_md; 2217 2218 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2219 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 2220 bp->b_flags |= B_INVAL | B_RELBUF; 2221 bp->b_flags &= ~B_CACHE; 2222 brelse(bp); 2223 return (ENXIO); 2224 } 2225 if (bp->b_flags & B_INVAL) { 2226 brelse(bp); 2227 return (0); 2228 } 2229 2230 if (bp->b_flags & B_BARRIER) 2231 atomic_add_long(&barrierwrites, 1); 2232 2233 oldflags = bp->b_flags; 2234 2235 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 2236 ("FFS background buffer should not get here %p", bp)); 2237 2238 vp = bp->b_vp; 2239 if (vp) 2240 vp_md = vp->v_vflag & VV_MD; 2241 else 2242 vp_md = 0; 2243 2244 /* 2245 * Mark the buffer clean. Increment the bufobj write count 2246 * before bundirty() call, to prevent other thread from seeing 2247 * empty dirty list and zero counter for writes in progress, 2248 * falsely indicating that the bufobj is clean. 2249 */ 2250 bufobj_wref(bp->b_bufobj); 2251 bundirty(bp); 2252 2253 bp->b_flags &= ~B_DONE; 2254 bp->b_ioflags &= ~BIO_ERROR; 2255 bp->b_flags |= B_CACHE; 2256 bp->b_iocmd = BIO_WRITE; 2257 2258 vfs_busy_pages(bp, 1); 2259 2260 /* 2261 * Normal bwrites pipeline writes 2262 */ 2263 bp->b_runningbufspace = bp->b_bufsize; 2264 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 2265 2266 #ifdef RACCT 2267 if (racct_enable) { 2268 PROC_LOCK(curproc); 2269 racct_add_buf(curproc, bp, 1); 2270 PROC_UNLOCK(curproc); 2271 } 2272 #endif /* RACCT */ 2273 curthread->td_ru.ru_oublock++; 2274 if (oldflags & B_ASYNC) 2275 BUF_KERNPROC(bp); 2276 bp->b_iooffset = dbtob(bp->b_blkno); 2277 buf_track(bp, __func__); 2278 bstrategy(bp); 2279 2280 if ((oldflags & B_ASYNC) == 0) { 2281 int rtval = bufwait(bp); 2282 brelse(bp); 2283 return (rtval); 2284 } else if (space > hirunningspace) { 2285 /* 2286 * don't allow the async write to saturate the I/O 2287 * system. We will not deadlock here because 2288 * we are blocking waiting for I/O that is already in-progress 2289 * to complete. We do not block here if it is the update 2290 * or syncer daemon trying to clean up as that can lead 2291 * to deadlock. 2292 */ 2293 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2294 waitrunningbufspace(); 2295 } 2296 2297 return (0); 2298 } 2299 2300 void 2301 bufbdflush(struct bufobj *bo, struct buf *bp) 2302 { 2303 struct buf *nbp; 2304 2305 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 2306 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2307 altbufferflushes++; 2308 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 2309 BO_LOCK(bo); 2310 /* 2311 * Try to find a buffer to flush. 2312 */ 2313 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2314 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2315 BUF_LOCK(nbp, 2316 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2317 continue; 2318 if (bp == nbp) 2319 panic("bdwrite: found ourselves"); 2320 BO_UNLOCK(bo); 2321 /* Don't countdeps with the bo lock held. */ 2322 if (buf_countdeps(nbp, 0)) { 2323 BO_LOCK(bo); 2324 BUF_UNLOCK(nbp); 2325 continue; 2326 } 2327 if (nbp->b_flags & B_CLUSTEROK) { 2328 vfs_bio_awrite(nbp); 2329 } else { 2330 bremfree(nbp); 2331 bawrite(nbp); 2332 } 2333 dirtybufferflushes++; 2334 break; 2335 } 2336 if (nbp == NULL) 2337 BO_UNLOCK(bo); 2338 } 2339 } 2340 2341 /* 2342 * Delayed write. (Buffer is marked dirty). Do not bother writing 2343 * anything if the buffer is marked invalid. 2344 * 2345 * Note that since the buffer must be completely valid, we can safely 2346 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2347 * biodone() in order to prevent getblk from writing the buffer 2348 * out synchronously. 2349 */ 2350 void 2351 bdwrite(struct buf *bp) 2352 { 2353 struct thread *td = curthread; 2354 struct vnode *vp; 2355 struct bufobj *bo; 2356 2357 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2358 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2359 KASSERT((bp->b_flags & B_BARRIER) == 0, 2360 ("Barrier request in delayed write %p", bp)); 2361 2362 if (bp->b_flags & B_INVAL) { 2363 brelse(bp); 2364 return; 2365 } 2366 2367 /* 2368 * If we have too many dirty buffers, don't create any more. 2369 * If we are wildly over our limit, then force a complete 2370 * cleanup. Otherwise, just keep the situation from getting 2371 * out of control. Note that we have to avoid a recursive 2372 * disaster and not try to clean up after our own cleanup! 2373 */ 2374 vp = bp->b_vp; 2375 bo = bp->b_bufobj; 2376 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2377 td->td_pflags |= TDP_INBDFLUSH; 2378 BO_BDFLUSH(bo, bp); 2379 td->td_pflags &= ~TDP_INBDFLUSH; 2380 } else 2381 recursiveflushes++; 2382 2383 bdirty(bp); 2384 /* 2385 * Set B_CACHE, indicating that the buffer is fully valid. This is 2386 * true even of NFS now. 2387 */ 2388 bp->b_flags |= B_CACHE; 2389 2390 /* 2391 * This bmap keeps the system from needing to do the bmap later, 2392 * perhaps when the system is attempting to do a sync. Since it 2393 * is likely that the indirect block -- or whatever other datastructure 2394 * that the filesystem needs is still in memory now, it is a good 2395 * thing to do this. Note also, that if the pageout daemon is 2396 * requesting a sync -- there might not be enough memory to do 2397 * the bmap then... So, this is important to do. 2398 */ 2399 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2400 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2401 } 2402 2403 buf_track(bp, __func__); 2404 2405 /* 2406 * Set the *dirty* buffer range based upon the VM system dirty 2407 * pages. 2408 * 2409 * Mark the buffer pages as clean. We need to do this here to 2410 * satisfy the vnode_pager and the pageout daemon, so that it 2411 * thinks that the pages have been "cleaned". Note that since 2412 * the pages are in a delayed write buffer -- the VFS layer 2413 * "will" see that the pages get written out on the next sync, 2414 * or perhaps the cluster will be completed. 2415 */ 2416 vfs_clean_pages_dirty_buf(bp); 2417 bqrelse(bp); 2418 2419 /* 2420 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2421 * due to the softdep code. 2422 */ 2423 } 2424 2425 /* 2426 * bdirty: 2427 * 2428 * Turn buffer into delayed write request. We must clear BIO_READ and 2429 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2430 * itself to properly update it in the dirty/clean lists. We mark it 2431 * B_DONE to ensure that any asynchronization of the buffer properly 2432 * clears B_DONE ( else a panic will occur later ). 2433 * 2434 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2435 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2436 * should only be called if the buffer is known-good. 2437 * 2438 * Since the buffer is not on a queue, we do not update the numfreebuffers 2439 * count. 2440 * 2441 * The buffer must be on QUEUE_NONE. 2442 */ 2443 void 2444 bdirty(struct buf *bp) 2445 { 2446 2447 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2448 bp, bp->b_vp, bp->b_flags); 2449 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2450 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2451 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2452 bp->b_flags &= ~(B_RELBUF); 2453 bp->b_iocmd = BIO_WRITE; 2454 2455 if ((bp->b_flags & B_DELWRI) == 0) { 2456 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2457 reassignbuf(bp); 2458 bdirtyadd(bp); 2459 } 2460 } 2461 2462 /* 2463 * bundirty: 2464 * 2465 * Clear B_DELWRI for buffer. 2466 * 2467 * Since the buffer is not on a queue, we do not update the numfreebuffers 2468 * count. 2469 * 2470 * The buffer must be on QUEUE_NONE. 2471 */ 2472 2473 void 2474 bundirty(struct buf *bp) 2475 { 2476 2477 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2478 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2479 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2480 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2481 2482 if (bp->b_flags & B_DELWRI) { 2483 bp->b_flags &= ~B_DELWRI; 2484 reassignbuf(bp); 2485 bdirtysub(bp); 2486 } 2487 /* 2488 * Since it is now being written, we can clear its deferred write flag. 2489 */ 2490 bp->b_flags &= ~B_DEFERRED; 2491 } 2492 2493 /* 2494 * bawrite: 2495 * 2496 * Asynchronous write. Start output on a buffer, but do not wait for 2497 * it to complete. The buffer is released when the output completes. 2498 * 2499 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2500 * B_INVAL buffers. Not us. 2501 */ 2502 void 2503 bawrite(struct buf *bp) 2504 { 2505 2506 bp->b_flags |= B_ASYNC; 2507 (void) bwrite(bp); 2508 } 2509 2510 /* 2511 * babarrierwrite: 2512 * 2513 * Asynchronous barrier write. Start output on a buffer, but do not 2514 * wait for it to complete. Place a write barrier after this write so 2515 * that this buffer and all buffers written before it are committed to 2516 * the disk before any buffers written after this write are committed 2517 * to the disk. The buffer is released when the output completes. 2518 */ 2519 void 2520 babarrierwrite(struct buf *bp) 2521 { 2522 2523 bp->b_flags |= B_ASYNC | B_BARRIER; 2524 (void) bwrite(bp); 2525 } 2526 2527 /* 2528 * bbarrierwrite: 2529 * 2530 * Synchronous barrier write. Start output on a buffer and wait for 2531 * it to complete. Place a write barrier after this write so that 2532 * this buffer and all buffers written before it are committed to 2533 * the disk before any buffers written after this write are committed 2534 * to the disk. The buffer is released when the output completes. 2535 */ 2536 int 2537 bbarrierwrite(struct buf *bp) 2538 { 2539 2540 bp->b_flags |= B_BARRIER; 2541 return (bwrite(bp)); 2542 } 2543 2544 /* 2545 * bwillwrite: 2546 * 2547 * Called prior to the locking of any vnodes when we are expecting to 2548 * write. We do not want to starve the buffer cache with too many 2549 * dirty buffers so we block here. By blocking prior to the locking 2550 * of any vnodes we attempt to avoid the situation where a locked vnode 2551 * prevents the various system daemons from flushing related buffers. 2552 */ 2553 void 2554 bwillwrite(void) 2555 { 2556 2557 if (buf_dirty_count_severe()) { 2558 mtx_lock(&bdirtylock); 2559 while (buf_dirty_count_severe()) { 2560 bdirtywait = 1; 2561 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2562 "flswai", 0); 2563 } 2564 mtx_unlock(&bdirtylock); 2565 } 2566 } 2567 2568 /* 2569 * Return true if we have too many dirty buffers. 2570 */ 2571 int 2572 buf_dirty_count_severe(void) 2573 { 2574 2575 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty)); 2576 } 2577 2578 /* 2579 * brelse: 2580 * 2581 * Release a busy buffer and, if requested, free its resources. The 2582 * buffer will be stashed in the appropriate bufqueue[] allowing it 2583 * to be accessed later as a cache entity or reused for other purposes. 2584 */ 2585 void 2586 brelse(struct buf *bp) 2587 { 2588 struct mount *v_mnt; 2589 int qindex; 2590 2591 /* 2592 * Many functions erroneously call brelse with a NULL bp under rare 2593 * error conditions. Simply return when called with a NULL bp. 2594 */ 2595 if (bp == NULL) 2596 return; 2597 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2598 bp, bp->b_vp, bp->b_flags); 2599 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2600 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2601 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2602 ("brelse: non-VMIO buffer marked NOREUSE")); 2603 2604 if (BUF_LOCKRECURSED(bp)) { 2605 /* 2606 * Do not process, in particular, do not handle the 2607 * B_INVAL/B_RELBUF and do not release to free list. 2608 */ 2609 BUF_UNLOCK(bp); 2610 return; 2611 } 2612 2613 if (bp->b_flags & B_MANAGED) { 2614 bqrelse(bp); 2615 return; 2616 } 2617 2618 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2619 BO_LOCK(bp->b_bufobj); 2620 bp->b_vflags &= ~BV_BKGRDERR; 2621 BO_UNLOCK(bp->b_bufobj); 2622 bdirty(bp); 2623 } 2624 2625 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2626 (bp->b_flags & B_INVALONERR)) { 2627 /* 2628 * Forced invalidation of dirty buffer contents, to be used 2629 * after a failed write in the rare case that the loss of the 2630 * contents is acceptable. The buffer is invalidated and 2631 * freed. 2632 */ 2633 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE; 2634 bp->b_flags &= ~(B_ASYNC | B_CACHE); 2635 } 2636 2637 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2638 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2639 !(bp->b_flags & B_INVAL)) { 2640 /* 2641 * Failed write, redirty. All errors except ENXIO (which 2642 * means the device is gone) are treated as being 2643 * transient. 2644 * 2645 * XXX Treating EIO as transient is not correct; the 2646 * contract with the local storage device drivers is that 2647 * they will only return EIO once the I/O is no longer 2648 * retriable. Network I/O also respects this through the 2649 * guarantees of TCP and/or the internal retries of NFS. 2650 * ENOMEM might be transient, but we also have no way of 2651 * knowing when its ok to retry/reschedule. In general, 2652 * this entire case should be made obsolete through better 2653 * error handling/recovery and resource scheduling. 2654 * 2655 * Do this also for buffers that failed with ENXIO, but have 2656 * non-empty dependencies - the soft updates code might need 2657 * to access the buffer to untangle them. 2658 * 2659 * Must clear BIO_ERROR to prevent pages from being scrapped. 2660 */ 2661 bp->b_ioflags &= ~BIO_ERROR; 2662 bdirty(bp); 2663 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2664 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2665 /* 2666 * Either a failed read I/O, or we were asked to free or not 2667 * cache the buffer, or we failed to write to a device that's 2668 * no longer present. 2669 */ 2670 bp->b_flags |= B_INVAL; 2671 if (!LIST_EMPTY(&bp->b_dep)) 2672 buf_deallocate(bp); 2673 if (bp->b_flags & B_DELWRI) 2674 bdirtysub(bp); 2675 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2676 if ((bp->b_flags & B_VMIO) == 0) { 2677 allocbuf(bp, 0); 2678 if (bp->b_vp) 2679 brelvp(bp); 2680 } 2681 } 2682 2683 /* 2684 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2685 * is called with B_DELWRI set, the underlying pages may wind up 2686 * getting freed causing a previous write (bdwrite()) to get 'lost' 2687 * because pages associated with a B_DELWRI bp are marked clean. 2688 * 2689 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2690 * if B_DELWRI is set. 2691 */ 2692 if (bp->b_flags & B_DELWRI) 2693 bp->b_flags &= ~B_RELBUF; 2694 2695 /* 2696 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2697 * constituted, not even NFS buffers now. Two flags effect this. If 2698 * B_INVAL, the struct buf is invalidated but the VM object is kept 2699 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2700 * 2701 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2702 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2703 * buffer is also B_INVAL because it hits the re-dirtying code above. 2704 * 2705 * Normally we can do this whether a buffer is B_DELWRI or not. If 2706 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2707 * the commit state and we cannot afford to lose the buffer. If the 2708 * buffer has a background write in progress, we need to keep it 2709 * around to prevent it from being reconstituted and starting a second 2710 * background write. 2711 */ 2712 2713 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL; 2714 2715 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2716 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2717 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 || 2718 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) { 2719 vfs_vmio_invalidate(bp); 2720 allocbuf(bp, 0); 2721 } 2722 2723 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2724 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2725 allocbuf(bp, 0); 2726 bp->b_flags &= ~B_NOREUSE; 2727 if (bp->b_vp != NULL) 2728 brelvp(bp); 2729 } 2730 2731 /* 2732 * If the buffer has junk contents signal it and eventually 2733 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2734 * doesn't find it. 2735 */ 2736 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2737 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2738 bp->b_flags |= B_INVAL; 2739 if (bp->b_flags & B_INVAL) { 2740 if (bp->b_flags & B_DELWRI) 2741 bundirty(bp); 2742 if (bp->b_vp) 2743 brelvp(bp); 2744 } 2745 2746 buf_track(bp, __func__); 2747 2748 /* buffers with no memory */ 2749 if (bp->b_bufsize == 0) { 2750 buf_free(bp); 2751 return; 2752 } 2753 /* buffers with junk contents */ 2754 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2755 (bp->b_ioflags & BIO_ERROR)) { 2756 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2757 if (bp->b_vflags & BV_BKGRDINPROG) 2758 panic("losing buffer 2"); 2759 qindex = QUEUE_CLEAN; 2760 bp->b_flags |= B_AGE; 2761 /* remaining buffers */ 2762 } else if (bp->b_flags & B_DELWRI) 2763 qindex = QUEUE_DIRTY; 2764 else 2765 qindex = QUEUE_CLEAN; 2766 2767 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2768 panic("brelse: not dirty"); 2769 2770 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT); 2771 /* binsfree unlocks bp. */ 2772 binsfree(bp, qindex); 2773 } 2774 2775 /* 2776 * Release a buffer back to the appropriate queue but do not try to free 2777 * it. The buffer is expected to be used again soon. 2778 * 2779 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2780 * biodone() to requeue an async I/O on completion. It is also used when 2781 * known good buffers need to be requeued but we think we may need the data 2782 * again soon. 2783 * 2784 * XXX we should be able to leave the B_RELBUF hint set on completion. 2785 */ 2786 void 2787 bqrelse(struct buf *bp) 2788 { 2789 int qindex; 2790 2791 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2792 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2793 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2794 2795 qindex = QUEUE_NONE; 2796 if (BUF_LOCKRECURSED(bp)) { 2797 /* do not release to free list */ 2798 BUF_UNLOCK(bp); 2799 return; 2800 } 2801 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2802 2803 if (bp->b_flags & B_MANAGED) { 2804 if (bp->b_flags & B_REMFREE) 2805 bremfreef(bp); 2806 goto out; 2807 } 2808 2809 /* buffers with stale but valid contents */ 2810 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2811 BV_BKGRDERR)) == BV_BKGRDERR) { 2812 BO_LOCK(bp->b_bufobj); 2813 bp->b_vflags &= ~BV_BKGRDERR; 2814 BO_UNLOCK(bp->b_bufobj); 2815 qindex = QUEUE_DIRTY; 2816 } else { 2817 if ((bp->b_flags & B_DELWRI) == 0 && 2818 (bp->b_xflags & BX_VNDIRTY)) 2819 panic("bqrelse: not dirty"); 2820 if ((bp->b_flags & B_NOREUSE) != 0) { 2821 brelse(bp); 2822 return; 2823 } 2824 qindex = QUEUE_CLEAN; 2825 } 2826 buf_track(bp, __func__); 2827 /* binsfree unlocks bp. */ 2828 binsfree(bp, qindex); 2829 return; 2830 2831 out: 2832 buf_track(bp, __func__); 2833 /* unlock */ 2834 BUF_UNLOCK(bp); 2835 } 2836 2837 /* 2838 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2839 * restore bogus pages. 2840 */ 2841 static void 2842 vfs_vmio_iodone(struct buf *bp) 2843 { 2844 vm_ooffset_t foff; 2845 vm_page_t m; 2846 vm_object_t obj; 2847 struct vnode *vp __unused; 2848 int i, iosize, resid; 2849 bool bogus; 2850 2851 obj = bp->b_bufobj->bo_object; 2852 KASSERT(REFCOUNT_COUNT(obj->paging_in_progress) >= bp->b_npages, 2853 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2854 REFCOUNT_COUNT(obj->paging_in_progress), bp->b_npages)); 2855 2856 vp = bp->b_vp; 2857 KASSERT(vp->v_holdcnt > 0, 2858 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2859 KASSERT(vp->v_object != NULL, 2860 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2861 2862 foff = bp->b_offset; 2863 KASSERT(bp->b_offset != NOOFFSET, 2864 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2865 2866 bogus = false; 2867 iosize = bp->b_bcount - bp->b_resid; 2868 VM_OBJECT_WLOCK(obj); 2869 for (i = 0; i < bp->b_npages; i++) { 2870 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2871 if (resid > iosize) 2872 resid = iosize; 2873 2874 /* 2875 * cleanup bogus pages, restoring the originals 2876 */ 2877 m = bp->b_pages[i]; 2878 if (m == bogus_page) { 2879 bogus = true; 2880 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2881 if (m == NULL) 2882 panic("biodone: page disappeared!"); 2883 bp->b_pages[i] = m; 2884 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2885 /* 2886 * In the write case, the valid and clean bits are 2887 * already changed correctly ( see bdwrite() ), so we 2888 * only need to do this here in the read case. 2889 */ 2890 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2891 resid)) == 0, ("vfs_vmio_iodone: page %p " 2892 "has unexpected dirty bits", m)); 2893 vfs_page_set_valid(bp, foff, m); 2894 } 2895 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2896 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2897 (intmax_t)foff, (uintmax_t)m->pindex)); 2898 2899 vm_page_sunbusy(m); 2900 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2901 iosize -= resid; 2902 } 2903 vm_object_pip_wakeupn(obj, bp->b_npages); 2904 VM_OBJECT_WUNLOCK(obj); 2905 if (bogus && buf_mapped(bp)) { 2906 BUF_CHECK_MAPPED(bp); 2907 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2908 bp->b_pages, bp->b_npages); 2909 } 2910 } 2911 2912 /* 2913 * Perform page invalidation when a buffer is released. The fully invalid 2914 * pages will be reclaimed later in vfs_vmio_truncate(). 2915 */ 2916 static void 2917 vfs_vmio_invalidate(struct buf *bp) 2918 { 2919 vm_object_t obj; 2920 vm_page_t m; 2921 int flags, i, resid, poffset, presid; 2922 2923 if (buf_mapped(bp)) { 2924 BUF_CHECK_MAPPED(bp); 2925 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2926 } else 2927 BUF_CHECK_UNMAPPED(bp); 2928 /* 2929 * Get the base offset and length of the buffer. Note that 2930 * in the VMIO case if the buffer block size is not 2931 * page-aligned then b_data pointer may not be page-aligned. 2932 * But our b_pages[] array *IS* page aligned. 2933 * 2934 * block sizes less then DEV_BSIZE (usually 512) are not 2935 * supported due to the page granularity bits (m->valid, 2936 * m->dirty, etc...). 2937 * 2938 * See man buf(9) for more information 2939 */ 2940 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 2941 obj = bp->b_bufobj->bo_object; 2942 resid = bp->b_bufsize; 2943 poffset = bp->b_offset & PAGE_MASK; 2944 VM_OBJECT_WLOCK(obj); 2945 for (i = 0; i < bp->b_npages; i++) { 2946 m = bp->b_pages[i]; 2947 if (m == bogus_page) 2948 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2949 bp->b_pages[i] = NULL; 2950 2951 presid = resid > (PAGE_SIZE - poffset) ? 2952 (PAGE_SIZE - poffset) : resid; 2953 KASSERT(presid >= 0, ("brelse: extra page")); 2954 vm_page_busy_acquire(m, VM_ALLOC_SBUSY); 2955 if (pmap_page_wired_mappings(m) == 0) 2956 vm_page_set_invalid(m, poffset, presid); 2957 vm_page_sunbusy(m); 2958 vm_page_release_locked(m, flags); 2959 resid -= presid; 2960 poffset = 0; 2961 } 2962 VM_OBJECT_WUNLOCK(obj); 2963 bp->b_npages = 0; 2964 } 2965 2966 /* 2967 * Page-granular truncation of an existing VMIO buffer. 2968 */ 2969 static void 2970 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2971 { 2972 vm_object_t obj; 2973 vm_page_t m; 2974 int flags, i; 2975 2976 if (bp->b_npages == desiredpages) 2977 return; 2978 2979 if (buf_mapped(bp)) { 2980 BUF_CHECK_MAPPED(bp); 2981 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2982 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2983 } else 2984 BUF_CHECK_UNMAPPED(bp); 2985 2986 /* 2987 * The object lock is needed only if we will attempt to free pages. 2988 */ 2989 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 2990 if ((bp->b_flags & B_DIRECT) != 0) { 2991 flags |= VPR_TRYFREE; 2992 obj = bp->b_bufobj->bo_object; 2993 VM_OBJECT_WLOCK(obj); 2994 } else { 2995 obj = NULL; 2996 } 2997 for (i = desiredpages; i < bp->b_npages; i++) { 2998 m = bp->b_pages[i]; 2999 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3000 bp->b_pages[i] = NULL; 3001 if (obj != NULL) 3002 vm_page_release_locked(m, flags); 3003 else 3004 vm_page_release(m, flags); 3005 } 3006 if (obj != NULL) 3007 VM_OBJECT_WUNLOCK(obj); 3008 bp->b_npages = desiredpages; 3009 } 3010 3011 /* 3012 * Byte granular extension of VMIO buffers. 3013 */ 3014 static void 3015 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3016 { 3017 /* 3018 * We are growing the buffer, possibly in a 3019 * byte-granular fashion. 3020 */ 3021 vm_object_t obj; 3022 vm_offset_t toff; 3023 vm_offset_t tinc; 3024 vm_page_t m; 3025 3026 /* 3027 * Step 1, bring in the VM pages from the object, allocating 3028 * them if necessary. We must clear B_CACHE if these pages 3029 * are not valid for the range covered by the buffer. 3030 */ 3031 obj = bp->b_bufobj->bo_object; 3032 VM_OBJECT_WLOCK(obj); 3033 if (bp->b_npages < desiredpages) { 3034 /* 3035 * We must allocate system pages since blocking 3036 * here could interfere with paging I/O, no 3037 * matter which process we are. 3038 * 3039 * Only exclusive busy can be tested here. 3040 * Blocking on shared busy might lead to 3041 * deadlocks once allocbuf() is called after 3042 * pages are vfs_busy_pages(). 3043 */ 3044 (void)vm_page_grab_pages(obj, 3045 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3046 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3047 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3048 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3049 bp->b_npages = desiredpages; 3050 } 3051 3052 /* 3053 * Step 2. We've loaded the pages into the buffer, 3054 * we have to figure out if we can still have B_CACHE 3055 * set. Note that B_CACHE is set according to the 3056 * byte-granular range ( bcount and size ), not the 3057 * aligned range ( newbsize ). 3058 * 3059 * The VM test is against m->valid, which is DEV_BSIZE 3060 * aligned. Needless to say, the validity of the data 3061 * needs to also be DEV_BSIZE aligned. Note that this 3062 * fails with NFS if the server or some other client 3063 * extends the file's EOF. If our buffer is resized, 3064 * B_CACHE may remain set! XXX 3065 */ 3066 toff = bp->b_bcount; 3067 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3068 while ((bp->b_flags & B_CACHE) && toff < size) { 3069 vm_pindex_t pi; 3070 3071 if (tinc > (size - toff)) 3072 tinc = size - toff; 3073 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3074 m = bp->b_pages[pi]; 3075 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3076 toff += tinc; 3077 tinc = PAGE_SIZE; 3078 } 3079 VM_OBJECT_WUNLOCK(obj); 3080 3081 /* 3082 * Step 3, fixup the KVA pmap. 3083 */ 3084 if (buf_mapped(bp)) 3085 bpmap_qenter(bp); 3086 else 3087 BUF_CHECK_UNMAPPED(bp); 3088 } 3089 3090 /* 3091 * Check to see if a block at a particular lbn is available for a clustered 3092 * write. 3093 */ 3094 static int 3095 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3096 { 3097 struct buf *bpa; 3098 int match; 3099 3100 match = 0; 3101 3102 /* If the buf isn't in core skip it */ 3103 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3104 return (0); 3105 3106 /* If the buf is busy we don't want to wait for it */ 3107 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3108 return (0); 3109 3110 /* Only cluster with valid clusterable delayed write buffers */ 3111 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3112 (B_DELWRI | B_CLUSTEROK)) 3113 goto done; 3114 3115 if (bpa->b_bufsize != size) 3116 goto done; 3117 3118 /* 3119 * Check to see if it is in the expected place on disk and that the 3120 * block has been mapped. 3121 */ 3122 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3123 match = 1; 3124 done: 3125 BUF_UNLOCK(bpa); 3126 return (match); 3127 } 3128 3129 /* 3130 * vfs_bio_awrite: 3131 * 3132 * Implement clustered async writes for clearing out B_DELWRI buffers. 3133 * This is much better then the old way of writing only one buffer at 3134 * a time. Note that we may not be presented with the buffers in the 3135 * correct order, so we search for the cluster in both directions. 3136 */ 3137 int 3138 vfs_bio_awrite(struct buf *bp) 3139 { 3140 struct bufobj *bo; 3141 int i; 3142 int j; 3143 daddr_t lblkno = bp->b_lblkno; 3144 struct vnode *vp = bp->b_vp; 3145 int ncl; 3146 int nwritten; 3147 int size; 3148 int maxcl; 3149 int gbflags; 3150 3151 bo = &vp->v_bufobj; 3152 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3153 /* 3154 * right now we support clustered writing only to regular files. If 3155 * we find a clusterable block we could be in the middle of a cluster 3156 * rather then at the beginning. 3157 */ 3158 if ((vp->v_type == VREG) && 3159 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3160 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3161 3162 size = vp->v_mount->mnt_stat.f_iosize; 3163 maxcl = MAXPHYS / size; 3164 3165 BO_RLOCK(bo); 3166 for (i = 1; i < maxcl; i++) 3167 if (vfs_bio_clcheck(vp, size, lblkno + i, 3168 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3169 break; 3170 3171 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3172 if (vfs_bio_clcheck(vp, size, lblkno - j, 3173 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3174 break; 3175 BO_RUNLOCK(bo); 3176 --j; 3177 ncl = i + j; 3178 /* 3179 * this is a possible cluster write 3180 */ 3181 if (ncl != 1) { 3182 BUF_UNLOCK(bp); 3183 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3184 gbflags); 3185 return (nwritten); 3186 } 3187 } 3188 bremfree(bp); 3189 bp->b_flags |= B_ASYNC; 3190 /* 3191 * default (old) behavior, writing out only one block 3192 * 3193 * XXX returns b_bufsize instead of b_bcount for nwritten? 3194 */ 3195 nwritten = bp->b_bufsize; 3196 (void) bwrite(bp); 3197 3198 return (nwritten); 3199 } 3200 3201 /* 3202 * getnewbuf_kva: 3203 * 3204 * Allocate KVA for an empty buf header according to gbflags. 3205 */ 3206 static int 3207 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3208 { 3209 3210 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3211 /* 3212 * In order to keep fragmentation sane we only allocate kva 3213 * in BKVASIZE chunks. XXX with vmem we can do page size. 3214 */ 3215 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3216 3217 if (maxsize != bp->b_kvasize && 3218 bufkva_alloc(bp, maxsize, gbflags)) 3219 return (ENOSPC); 3220 } 3221 return (0); 3222 } 3223 3224 /* 3225 * getnewbuf: 3226 * 3227 * Find and initialize a new buffer header, freeing up existing buffers 3228 * in the bufqueues as necessary. The new buffer is returned locked. 3229 * 3230 * We block if: 3231 * We have insufficient buffer headers 3232 * We have insufficient buffer space 3233 * buffer_arena is too fragmented ( space reservation fails ) 3234 * If we have to flush dirty buffers ( but we try to avoid this ) 3235 * 3236 * The caller is responsible for releasing the reserved bufspace after 3237 * allocbuf() is called. 3238 */ 3239 static struct buf * 3240 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3241 { 3242 struct bufdomain *bd; 3243 struct buf *bp; 3244 bool metadata, reserved; 3245 3246 bp = NULL; 3247 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3248 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3249 if (!unmapped_buf_allowed) 3250 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3251 3252 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3253 vp->v_type == VCHR) 3254 metadata = true; 3255 else 3256 metadata = false; 3257 if (vp == NULL) 3258 bd = &bdomain[0]; 3259 else 3260 bd = &bdomain[vp->v_bufobj.bo_domain]; 3261 3262 counter_u64_add(getnewbufcalls, 1); 3263 reserved = false; 3264 do { 3265 if (reserved == false && 3266 bufspace_reserve(bd, maxsize, metadata) != 0) { 3267 counter_u64_add(getnewbufrestarts, 1); 3268 continue; 3269 } 3270 reserved = true; 3271 if ((bp = buf_alloc(bd)) == NULL) { 3272 counter_u64_add(getnewbufrestarts, 1); 3273 continue; 3274 } 3275 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3276 return (bp); 3277 break; 3278 } while (buf_recycle(bd, false) == 0); 3279 3280 if (reserved) 3281 bufspace_release(bd, maxsize); 3282 if (bp != NULL) { 3283 bp->b_flags |= B_INVAL; 3284 brelse(bp); 3285 } 3286 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3287 3288 return (NULL); 3289 } 3290 3291 /* 3292 * buf_daemon: 3293 * 3294 * buffer flushing daemon. Buffers are normally flushed by the 3295 * update daemon but if it cannot keep up this process starts to 3296 * take the load in an attempt to prevent getnewbuf() from blocking. 3297 */ 3298 static struct kproc_desc buf_kp = { 3299 "bufdaemon", 3300 buf_daemon, 3301 &bufdaemonproc 3302 }; 3303 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3304 3305 static int 3306 buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3307 { 3308 int flushed; 3309 3310 flushed = flushbufqueues(vp, bd, target, 0); 3311 if (flushed == 0) { 3312 /* 3313 * Could not find any buffers without rollback 3314 * dependencies, so just write the first one 3315 * in the hopes of eventually making progress. 3316 */ 3317 if (vp != NULL && target > 2) 3318 target /= 2; 3319 flushbufqueues(vp, bd, target, 1); 3320 } 3321 return (flushed); 3322 } 3323 3324 static void 3325 buf_daemon() 3326 { 3327 struct bufdomain *bd; 3328 int speedupreq; 3329 int lodirty; 3330 int i; 3331 3332 /* 3333 * This process needs to be suspended prior to shutdown sync. 3334 */ 3335 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 3336 SHUTDOWN_PRI_LAST + 100); 3337 3338 /* 3339 * Start the buf clean daemons as children threads. 3340 */ 3341 for (i = 0 ; i < buf_domains; i++) { 3342 int error; 3343 3344 error = kthread_add((void (*)(void *))bufspace_daemon, 3345 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3346 if (error) 3347 panic("error %d spawning bufspace daemon", error); 3348 } 3349 3350 /* 3351 * This process is allowed to take the buffer cache to the limit 3352 */ 3353 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3354 mtx_lock(&bdlock); 3355 for (;;) { 3356 bd_request = 0; 3357 mtx_unlock(&bdlock); 3358 3359 kthread_suspend_check(); 3360 3361 /* 3362 * Save speedupreq for this pass and reset to capture new 3363 * requests. 3364 */ 3365 speedupreq = bd_speedupreq; 3366 bd_speedupreq = 0; 3367 3368 /* 3369 * Flush each domain sequentially according to its level and 3370 * the speedup request. 3371 */ 3372 for (i = 0; i < buf_domains; i++) { 3373 bd = &bdomain[i]; 3374 if (speedupreq) 3375 lodirty = bd->bd_numdirtybuffers / 2; 3376 else 3377 lodirty = bd->bd_lodirtybuffers; 3378 while (bd->bd_numdirtybuffers > lodirty) { 3379 if (buf_flush(NULL, bd, 3380 bd->bd_numdirtybuffers - lodirty) == 0) 3381 break; 3382 kern_yield(PRI_USER); 3383 } 3384 } 3385 3386 /* 3387 * Only clear bd_request if we have reached our low water 3388 * mark. The buf_daemon normally waits 1 second and 3389 * then incrementally flushes any dirty buffers that have 3390 * built up, within reason. 3391 * 3392 * If we were unable to hit our low water mark and couldn't 3393 * find any flushable buffers, we sleep for a short period 3394 * to avoid endless loops on unlockable buffers. 3395 */ 3396 mtx_lock(&bdlock); 3397 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3398 /* 3399 * We reached our low water mark, reset the 3400 * request and sleep until we are needed again. 3401 * The sleep is just so the suspend code works. 3402 */ 3403 bd_request = 0; 3404 /* 3405 * Do an extra wakeup in case dirty threshold 3406 * changed via sysctl and the explicit transition 3407 * out of shortfall was missed. 3408 */ 3409 bdirtywakeup(); 3410 if (runningbufspace <= lorunningspace) 3411 runningwakeup(); 3412 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3413 } else { 3414 /* 3415 * We couldn't find any flushable dirty buffers but 3416 * still have too many dirty buffers, we 3417 * have to sleep and try again. (rare) 3418 */ 3419 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3420 } 3421 } 3422 } 3423 3424 /* 3425 * flushbufqueues: 3426 * 3427 * Try to flush a buffer in the dirty queue. We must be careful to 3428 * free up B_INVAL buffers instead of write them, which NFS is 3429 * particularly sensitive to. 3430 */ 3431 static int flushwithdeps = 0; 3432 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS, 3433 &flushwithdeps, 0, 3434 "Number of buffers flushed with dependecies that require rollbacks"); 3435 3436 static int 3437 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3438 int flushdeps) 3439 { 3440 struct bufqueue *bq; 3441 struct buf *sentinel; 3442 struct vnode *vp; 3443 struct mount *mp; 3444 struct buf *bp; 3445 int hasdeps; 3446 int flushed; 3447 int error; 3448 bool unlock; 3449 3450 flushed = 0; 3451 bq = &bd->bd_dirtyq; 3452 bp = NULL; 3453 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3454 sentinel->b_qindex = QUEUE_SENTINEL; 3455 BQ_LOCK(bq); 3456 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3457 BQ_UNLOCK(bq); 3458 while (flushed != target) { 3459 maybe_yield(); 3460 BQ_LOCK(bq); 3461 bp = TAILQ_NEXT(sentinel, b_freelist); 3462 if (bp != NULL) { 3463 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3464 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3465 b_freelist); 3466 } else { 3467 BQ_UNLOCK(bq); 3468 break; 3469 } 3470 /* 3471 * Skip sentinels inserted by other invocations of the 3472 * flushbufqueues(), taking care to not reorder them. 3473 * 3474 * Only flush the buffers that belong to the 3475 * vnode locked by the curthread. 3476 */ 3477 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3478 bp->b_vp != lvp)) { 3479 BQ_UNLOCK(bq); 3480 continue; 3481 } 3482 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3483 BQ_UNLOCK(bq); 3484 if (error != 0) 3485 continue; 3486 3487 /* 3488 * BKGRDINPROG can only be set with the buf and bufobj 3489 * locks both held. We tolerate a race to clear it here. 3490 */ 3491 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3492 (bp->b_flags & B_DELWRI) == 0) { 3493 BUF_UNLOCK(bp); 3494 continue; 3495 } 3496 if (bp->b_flags & B_INVAL) { 3497 bremfreef(bp); 3498 brelse(bp); 3499 flushed++; 3500 continue; 3501 } 3502 3503 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3504 if (flushdeps == 0) { 3505 BUF_UNLOCK(bp); 3506 continue; 3507 } 3508 hasdeps = 1; 3509 } else 3510 hasdeps = 0; 3511 /* 3512 * We must hold the lock on a vnode before writing 3513 * one of its buffers. Otherwise we may confuse, or 3514 * in the case of a snapshot vnode, deadlock the 3515 * system. 3516 * 3517 * The lock order here is the reverse of the normal 3518 * of vnode followed by buf lock. This is ok because 3519 * the NOWAIT will prevent deadlock. 3520 */ 3521 vp = bp->b_vp; 3522 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3523 BUF_UNLOCK(bp); 3524 continue; 3525 } 3526 if (lvp == NULL) { 3527 unlock = true; 3528 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3529 } else { 3530 ASSERT_VOP_LOCKED(vp, "getbuf"); 3531 unlock = false; 3532 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3533 vn_lock(vp, LK_TRYUPGRADE); 3534 } 3535 if (error == 0) { 3536 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3537 bp, bp->b_vp, bp->b_flags); 3538 if (curproc == bufdaemonproc) { 3539 vfs_bio_awrite(bp); 3540 } else { 3541 bremfree(bp); 3542 bwrite(bp); 3543 counter_u64_add(notbufdflushes, 1); 3544 } 3545 vn_finished_write(mp); 3546 if (unlock) 3547 VOP_UNLOCK(vp, 0); 3548 flushwithdeps += hasdeps; 3549 flushed++; 3550 3551 /* 3552 * Sleeping on runningbufspace while holding 3553 * vnode lock leads to deadlock. 3554 */ 3555 if (curproc == bufdaemonproc && 3556 runningbufspace > hirunningspace) 3557 waitrunningbufspace(); 3558 continue; 3559 } 3560 vn_finished_write(mp); 3561 BUF_UNLOCK(bp); 3562 } 3563 BQ_LOCK(bq); 3564 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3565 BQ_UNLOCK(bq); 3566 free(sentinel, M_TEMP); 3567 return (flushed); 3568 } 3569 3570 /* 3571 * Check to see if a block is currently memory resident. 3572 */ 3573 struct buf * 3574 incore(struct bufobj *bo, daddr_t blkno) 3575 { 3576 struct buf *bp; 3577 3578 BO_RLOCK(bo); 3579 bp = gbincore(bo, blkno); 3580 BO_RUNLOCK(bo); 3581 return (bp); 3582 } 3583 3584 /* 3585 * Returns true if no I/O is needed to access the 3586 * associated VM object. This is like incore except 3587 * it also hunts around in the VM system for the data. 3588 */ 3589 3590 static int 3591 inmem(struct vnode * vp, daddr_t blkno) 3592 { 3593 vm_object_t obj; 3594 vm_offset_t toff, tinc, size; 3595 vm_page_t m; 3596 vm_ooffset_t off; 3597 3598 ASSERT_VOP_LOCKED(vp, "inmem"); 3599 3600 if (incore(&vp->v_bufobj, blkno)) 3601 return 1; 3602 if (vp->v_mount == NULL) 3603 return 0; 3604 obj = vp->v_object; 3605 if (obj == NULL) 3606 return (0); 3607 3608 size = PAGE_SIZE; 3609 if (size > vp->v_mount->mnt_stat.f_iosize) 3610 size = vp->v_mount->mnt_stat.f_iosize; 3611 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3612 3613 VM_OBJECT_RLOCK(obj); 3614 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3615 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3616 if (!m) 3617 goto notinmem; 3618 tinc = size; 3619 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3620 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3621 if (vm_page_is_valid(m, 3622 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3623 goto notinmem; 3624 } 3625 VM_OBJECT_RUNLOCK(obj); 3626 return 1; 3627 3628 notinmem: 3629 VM_OBJECT_RUNLOCK(obj); 3630 return (0); 3631 } 3632 3633 /* 3634 * Set the dirty range for a buffer based on the status of the dirty 3635 * bits in the pages comprising the buffer. The range is limited 3636 * to the size of the buffer. 3637 * 3638 * Tell the VM system that the pages associated with this buffer 3639 * are clean. This is used for delayed writes where the data is 3640 * going to go to disk eventually without additional VM intevention. 3641 * 3642 * Note that while we only really need to clean through to b_bcount, we 3643 * just go ahead and clean through to b_bufsize. 3644 */ 3645 static void 3646 vfs_clean_pages_dirty_buf(struct buf *bp) 3647 { 3648 vm_ooffset_t foff, noff, eoff; 3649 vm_page_t m; 3650 int i; 3651 3652 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3653 return; 3654 3655 foff = bp->b_offset; 3656 KASSERT(bp->b_offset != NOOFFSET, 3657 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3658 3659 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3660 vfs_busy_pages_acquire(bp); 3661 vfs_setdirty_locked_object(bp); 3662 for (i = 0; i < bp->b_npages; i++) { 3663 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3664 eoff = noff; 3665 if (eoff > bp->b_offset + bp->b_bufsize) 3666 eoff = bp->b_offset + bp->b_bufsize; 3667 m = bp->b_pages[i]; 3668 vfs_page_set_validclean(bp, foff, m); 3669 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3670 foff = noff; 3671 } 3672 vfs_busy_pages_release(bp); 3673 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3674 } 3675 3676 static void 3677 vfs_setdirty_locked_object(struct buf *bp) 3678 { 3679 vm_object_t object; 3680 int i; 3681 3682 object = bp->b_bufobj->bo_object; 3683 VM_OBJECT_ASSERT_WLOCKED(object); 3684 3685 /* 3686 * We qualify the scan for modified pages on whether the 3687 * object has been flushed yet. 3688 */ 3689 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3690 vm_offset_t boffset; 3691 vm_offset_t eoffset; 3692 3693 /* 3694 * test the pages to see if they have been modified directly 3695 * by users through the VM system. 3696 */ 3697 for (i = 0; i < bp->b_npages; i++) 3698 vm_page_test_dirty(bp->b_pages[i]); 3699 3700 /* 3701 * Calculate the encompassing dirty range, boffset and eoffset, 3702 * (eoffset - boffset) bytes. 3703 */ 3704 3705 for (i = 0; i < bp->b_npages; i++) { 3706 if (bp->b_pages[i]->dirty) 3707 break; 3708 } 3709 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3710 3711 for (i = bp->b_npages - 1; i >= 0; --i) { 3712 if (bp->b_pages[i]->dirty) { 3713 break; 3714 } 3715 } 3716 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3717 3718 /* 3719 * Fit it to the buffer. 3720 */ 3721 3722 if (eoffset > bp->b_bcount) 3723 eoffset = bp->b_bcount; 3724 3725 /* 3726 * If we have a good dirty range, merge with the existing 3727 * dirty range. 3728 */ 3729 3730 if (boffset < eoffset) { 3731 if (bp->b_dirtyoff > boffset) 3732 bp->b_dirtyoff = boffset; 3733 if (bp->b_dirtyend < eoffset) 3734 bp->b_dirtyend = eoffset; 3735 } 3736 } 3737 } 3738 3739 /* 3740 * Allocate the KVA mapping for an existing buffer. 3741 * If an unmapped buffer is provided but a mapped buffer is requested, take 3742 * also care to properly setup mappings between pages and KVA. 3743 */ 3744 static void 3745 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3746 { 3747 int bsize, maxsize, need_mapping, need_kva; 3748 off_t offset; 3749 3750 need_mapping = bp->b_data == unmapped_buf && 3751 (gbflags & GB_UNMAPPED) == 0; 3752 need_kva = bp->b_kvabase == unmapped_buf && 3753 bp->b_data == unmapped_buf && 3754 (gbflags & GB_KVAALLOC) != 0; 3755 if (!need_mapping && !need_kva) 3756 return; 3757 3758 BUF_CHECK_UNMAPPED(bp); 3759 3760 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3761 /* 3762 * Buffer is not mapped, but the KVA was already 3763 * reserved at the time of the instantiation. Use the 3764 * allocated space. 3765 */ 3766 goto has_addr; 3767 } 3768 3769 /* 3770 * Calculate the amount of the address space we would reserve 3771 * if the buffer was mapped. 3772 */ 3773 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3774 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3775 offset = blkno * bsize; 3776 maxsize = size + (offset & PAGE_MASK); 3777 maxsize = imax(maxsize, bsize); 3778 3779 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3780 if ((gbflags & GB_NOWAIT_BD) != 0) { 3781 /* 3782 * XXXKIB: defragmentation cannot 3783 * succeed, not sure what else to do. 3784 */ 3785 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3786 } 3787 counter_u64_add(mappingrestarts, 1); 3788 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3789 } 3790 has_addr: 3791 if (need_mapping) { 3792 /* b_offset is handled by bpmap_qenter. */ 3793 bp->b_data = bp->b_kvabase; 3794 BUF_CHECK_MAPPED(bp); 3795 bpmap_qenter(bp); 3796 } 3797 } 3798 3799 struct buf * 3800 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3801 int flags) 3802 { 3803 struct buf *bp; 3804 int error; 3805 3806 error = getblkx(vp, blkno, size, slpflag, slptimeo, flags, &bp); 3807 if (error != 0) 3808 return (NULL); 3809 return (bp); 3810 } 3811 3812 /* 3813 * getblkx: 3814 * 3815 * Get a block given a specified block and offset into a file/device. 3816 * The buffers B_DONE bit will be cleared on return, making it almost 3817 * ready for an I/O initiation. B_INVAL may or may not be set on 3818 * return. The caller should clear B_INVAL prior to initiating a 3819 * READ. 3820 * 3821 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3822 * an existing buffer. 3823 * 3824 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3825 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3826 * and then cleared based on the backing VM. If the previous buffer is 3827 * non-0-sized but invalid, B_CACHE will be cleared. 3828 * 3829 * If getblk() must create a new buffer, the new buffer is returned with 3830 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3831 * case it is returned with B_INVAL clear and B_CACHE set based on the 3832 * backing VM. 3833 * 3834 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3835 * B_CACHE bit is clear. 3836 * 3837 * What this means, basically, is that the caller should use B_CACHE to 3838 * determine whether the buffer is fully valid or not and should clear 3839 * B_INVAL prior to issuing a read. If the caller intends to validate 3840 * the buffer by loading its data area with something, the caller needs 3841 * to clear B_INVAL. If the caller does this without issuing an I/O, 3842 * the caller should set B_CACHE ( as an optimization ), else the caller 3843 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3844 * a write attempt or if it was a successful read. If the caller 3845 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3846 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3847 */ 3848 int 3849 getblkx(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3850 int flags, struct buf **bpp) 3851 { 3852 struct buf *bp; 3853 struct bufobj *bo; 3854 daddr_t d_blkno; 3855 int bsize, error, maxsize, vmio; 3856 off_t offset; 3857 3858 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3859 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3860 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3861 ASSERT_VOP_LOCKED(vp, "getblk"); 3862 if (size > maxbcachebuf) 3863 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3864 maxbcachebuf); 3865 if (!unmapped_buf_allowed) 3866 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3867 3868 bo = &vp->v_bufobj; 3869 d_blkno = blkno; 3870 loop: 3871 BO_RLOCK(bo); 3872 bp = gbincore(bo, blkno); 3873 if (bp != NULL) { 3874 int lockflags; 3875 /* 3876 * Buffer is in-core. If the buffer is not busy nor managed, 3877 * it must be on a queue. 3878 */ 3879 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3880 3881 if ((flags & GB_LOCK_NOWAIT) != 0) 3882 lockflags |= LK_NOWAIT; 3883 3884 error = BUF_TIMELOCK(bp, lockflags, 3885 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3886 3887 /* 3888 * If we slept and got the lock we have to restart in case 3889 * the buffer changed identities. 3890 */ 3891 if (error == ENOLCK) 3892 goto loop; 3893 /* We timed out or were interrupted. */ 3894 else if (error != 0) 3895 return (error); 3896 /* If recursed, assume caller knows the rules. */ 3897 else if (BUF_LOCKRECURSED(bp)) 3898 goto end; 3899 3900 /* 3901 * The buffer is locked. B_CACHE is cleared if the buffer is 3902 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3903 * and for a VMIO buffer B_CACHE is adjusted according to the 3904 * backing VM cache. 3905 */ 3906 if (bp->b_flags & B_INVAL) 3907 bp->b_flags &= ~B_CACHE; 3908 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3909 bp->b_flags |= B_CACHE; 3910 if (bp->b_flags & B_MANAGED) 3911 MPASS(bp->b_qindex == QUEUE_NONE); 3912 else 3913 bremfree(bp); 3914 3915 /* 3916 * check for size inconsistencies for non-VMIO case. 3917 */ 3918 if (bp->b_bcount != size) { 3919 if ((bp->b_flags & B_VMIO) == 0 || 3920 (size > bp->b_kvasize)) { 3921 if (bp->b_flags & B_DELWRI) { 3922 bp->b_flags |= B_NOCACHE; 3923 bwrite(bp); 3924 } else { 3925 if (LIST_EMPTY(&bp->b_dep)) { 3926 bp->b_flags |= B_RELBUF; 3927 brelse(bp); 3928 } else { 3929 bp->b_flags |= B_NOCACHE; 3930 bwrite(bp); 3931 } 3932 } 3933 goto loop; 3934 } 3935 } 3936 3937 /* 3938 * Handle the case of unmapped buffer which should 3939 * become mapped, or the buffer for which KVA 3940 * reservation is requested. 3941 */ 3942 bp_unmapped_get_kva(bp, blkno, size, flags); 3943 3944 /* 3945 * If the size is inconsistent in the VMIO case, we can resize 3946 * the buffer. This might lead to B_CACHE getting set or 3947 * cleared. If the size has not changed, B_CACHE remains 3948 * unchanged from its previous state. 3949 */ 3950 allocbuf(bp, size); 3951 3952 KASSERT(bp->b_offset != NOOFFSET, 3953 ("getblk: no buffer offset")); 3954 3955 /* 3956 * A buffer with B_DELWRI set and B_CACHE clear must 3957 * be committed before we can return the buffer in 3958 * order to prevent the caller from issuing a read 3959 * ( due to B_CACHE not being set ) and overwriting 3960 * it. 3961 * 3962 * Most callers, including NFS and FFS, need this to 3963 * operate properly either because they assume they 3964 * can issue a read if B_CACHE is not set, or because 3965 * ( for example ) an uncached B_DELWRI might loop due 3966 * to softupdates re-dirtying the buffer. In the latter 3967 * case, B_CACHE is set after the first write completes, 3968 * preventing further loops. 3969 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3970 * above while extending the buffer, we cannot allow the 3971 * buffer to remain with B_CACHE set after the write 3972 * completes or it will represent a corrupt state. To 3973 * deal with this we set B_NOCACHE to scrap the buffer 3974 * after the write. 3975 * 3976 * We might be able to do something fancy, like setting 3977 * B_CACHE in bwrite() except if B_DELWRI is already set, 3978 * so the below call doesn't set B_CACHE, but that gets real 3979 * confusing. This is much easier. 3980 */ 3981 3982 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3983 bp->b_flags |= B_NOCACHE; 3984 bwrite(bp); 3985 goto loop; 3986 } 3987 bp->b_flags &= ~B_DONE; 3988 } else { 3989 /* 3990 * Buffer is not in-core, create new buffer. The buffer 3991 * returned by getnewbuf() is locked. Note that the returned 3992 * buffer is also considered valid (not marked B_INVAL). 3993 */ 3994 BO_RUNLOCK(bo); 3995 /* 3996 * If the user does not want us to create the buffer, bail out 3997 * here. 3998 */ 3999 if (flags & GB_NOCREAT) 4000 return (EEXIST); 4001 4002 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 4003 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4004 offset = blkno * bsize; 4005 vmio = vp->v_object != NULL; 4006 if (vmio) { 4007 maxsize = size + (offset & PAGE_MASK); 4008 } else { 4009 maxsize = size; 4010 /* Do not allow non-VMIO notmapped buffers. */ 4011 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4012 } 4013 maxsize = imax(maxsize, bsize); 4014 if ((flags & GB_NOSPARSE) != 0 && vmio && 4015 !vn_isdisk(vp, NULL)) { 4016 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4017 KASSERT(error != EOPNOTSUPP, 4018 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4019 vp)); 4020 if (error != 0) 4021 return (error); 4022 if (d_blkno == -1) 4023 return (EJUSTRETURN); 4024 } 4025 4026 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4027 if (bp == NULL) { 4028 if (slpflag || slptimeo) 4029 return (ETIMEDOUT); 4030 /* 4031 * XXX This is here until the sleep path is diagnosed 4032 * enough to work under very low memory conditions. 4033 * 4034 * There's an issue on low memory, 4BSD+non-preempt 4035 * systems (eg MIPS routers with 32MB RAM) where buffer 4036 * exhaustion occurs without sleeping for buffer 4037 * reclaimation. This just sticks in a loop and 4038 * constantly attempts to allocate a buffer, which 4039 * hits exhaustion and tries to wakeup bufdaemon. 4040 * This never happens because we never yield. 4041 * 4042 * The real solution is to identify and fix these cases 4043 * so we aren't effectively busy-waiting in a loop 4044 * until the reclaimation path has cycles to run. 4045 */ 4046 kern_yield(PRI_USER); 4047 goto loop; 4048 } 4049 4050 /* 4051 * This code is used to make sure that a buffer is not 4052 * created while the getnewbuf routine is blocked. 4053 * This can be a problem whether the vnode is locked or not. 4054 * If the buffer is created out from under us, we have to 4055 * throw away the one we just created. 4056 * 4057 * Note: this must occur before we associate the buffer 4058 * with the vp especially considering limitations in 4059 * the splay tree implementation when dealing with duplicate 4060 * lblkno's. 4061 */ 4062 BO_LOCK(bo); 4063 if (gbincore(bo, blkno)) { 4064 BO_UNLOCK(bo); 4065 bp->b_flags |= B_INVAL; 4066 bufspace_release(bufdomain(bp), maxsize); 4067 brelse(bp); 4068 goto loop; 4069 } 4070 4071 /* 4072 * Insert the buffer into the hash, so that it can 4073 * be found by incore. 4074 */ 4075 bp->b_lblkno = blkno; 4076 bp->b_blkno = d_blkno; 4077 bp->b_offset = offset; 4078 bgetvp(vp, bp); 4079 BO_UNLOCK(bo); 4080 4081 /* 4082 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4083 * buffer size starts out as 0, B_CACHE will be set by 4084 * allocbuf() for the VMIO case prior to it testing the 4085 * backing store for validity. 4086 */ 4087 4088 if (vmio) { 4089 bp->b_flags |= B_VMIO; 4090 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4091 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4092 bp, vp->v_object, bp->b_bufobj->bo_object)); 4093 } else { 4094 bp->b_flags &= ~B_VMIO; 4095 KASSERT(bp->b_bufobj->bo_object == NULL, 4096 ("ARGH! has b_bufobj->bo_object %p %p\n", 4097 bp, bp->b_bufobj->bo_object)); 4098 BUF_CHECK_MAPPED(bp); 4099 } 4100 4101 allocbuf(bp, size); 4102 bufspace_release(bufdomain(bp), maxsize); 4103 bp->b_flags &= ~B_DONE; 4104 } 4105 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4106 end: 4107 buf_track(bp, __func__); 4108 KASSERT(bp->b_bufobj == bo, 4109 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4110 *bpp = bp; 4111 return (0); 4112 } 4113 4114 /* 4115 * Get an empty, disassociated buffer of given size. The buffer is initially 4116 * set to B_INVAL. 4117 */ 4118 struct buf * 4119 geteblk(int size, int flags) 4120 { 4121 struct buf *bp; 4122 int maxsize; 4123 4124 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4125 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4126 if ((flags & GB_NOWAIT_BD) && 4127 (curthread->td_pflags & TDP_BUFNEED) != 0) 4128 return (NULL); 4129 } 4130 allocbuf(bp, size); 4131 bufspace_release(bufdomain(bp), maxsize); 4132 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4133 return (bp); 4134 } 4135 4136 /* 4137 * Truncate the backing store for a non-vmio buffer. 4138 */ 4139 static void 4140 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4141 { 4142 4143 if (bp->b_flags & B_MALLOC) { 4144 /* 4145 * malloced buffers are not shrunk 4146 */ 4147 if (newbsize == 0) { 4148 bufmallocadjust(bp, 0); 4149 free(bp->b_data, M_BIOBUF); 4150 bp->b_data = bp->b_kvabase; 4151 bp->b_flags &= ~B_MALLOC; 4152 } 4153 return; 4154 } 4155 vm_hold_free_pages(bp, newbsize); 4156 bufspace_adjust(bp, newbsize); 4157 } 4158 4159 /* 4160 * Extend the backing for a non-VMIO buffer. 4161 */ 4162 static void 4163 vfs_nonvmio_extend(struct buf *bp, int newbsize) 4164 { 4165 caddr_t origbuf; 4166 int origbufsize; 4167 4168 /* 4169 * We only use malloced memory on the first allocation. 4170 * and revert to page-allocated memory when the buffer 4171 * grows. 4172 * 4173 * There is a potential smp race here that could lead 4174 * to bufmallocspace slightly passing the max. It 4175 * is probably extremely rare and not worth worrying 4176 * over. 4177 */ 4178 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4179 bufmallocspace < maxbufmallocspace) { 4180 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4181 bp->b_flags |= B_MALLOC; 4182 bufmallocadjust(bp, newbsize); 4183 return; 4184 } 4185 4186 /* 4187 * If the buffer is growing on its other-than-first 4188 * allocation then we revert to the page-allocation 4189 * scheme. 4190 */ 4191 origbuf = NULL; 4192 origbufsize = 0; 4193 if (bp->b_flags & B_MALLOC) { 4194 origbuf = bp->b_data; 4195 origbufsize = bp->b_bufsize; 4196 bp->b_data = bp->b_kvabase; 4197 bufmallocadjust(bp, 0); 4198 bp->b_flags &= ~B_MALLOC; 4199 newbsize = round_page(newbsize); 4200 } 4201 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4202 (vm_offset_t) bp->b_data + newbsize); 4203 if (origbuf != NULL) { 4204 bcopy(origbuf, bp->b_data, origbufsize); 4205 free(origbuf, M_BIOBUF); 4206 } 4207 bufspace_adjust(bp, newbsize); 4208 } 4209 4210 /* 4211 * This code constitutes the buffer memory from either anonymous system 4212 * memory (in the case of non-VMIO operations) or from an associated 4213 * VM object (in the case of VMIO operations). This code is able to 4214 * resize a buffer up or down. 4215 * 4216 * Note that this code is tricky, and has many complications to resolve 4217 * deadlock or inconsistent data situations. Tread lightly!!! 4218 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4219 * the caller. Calling this code willy nilly can result in the loss of data. 4220 * 4221 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4222 * B_CACHE for the non-VMIO case. 4223 */ 4224 int 4225 allocbuf(struct buf *bp, int size) 4226 { 4227 int newbsize; 4228 4229 if (bp->b_bcount == size) 4230 return (1); 4231 4232 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 4233 panic("allocbuf: buffer too small"); 4234 4235 newbsize = roundup2(size, DEV_BSIZE); 4236 if ((bp->b_flags & B_VMIO) == 0) { 4237 if ((bp->b_flags & B_MALLOC) == 0) 4238 newbsize = round_page(newbsize); 4239 /* 4240 * Just get anonymous memory from the kernel. Don't 4241 * mess with B_CACHE. 4242 */ 4243 if (newbsize < bp->b_bufsize) 4244 vfs_nonvmio_truncate(bp, newbsize); 4245 else if (newbsize > bp->b_bufsize) 4246 vfs_nonvmio_extend(bp, newbsize); 4247 } else { 4248 int desiredpages; 4249 4250 desiredpages = (size == 0) ? 0 : 4251 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4252 4253 if (bp->b_flags & B_MALLOC) 4254 panic("allocbuf: VMIO buffer can't be malloced"); 4255 /* 4256 * Set B_CACHE initially if buffer is 0 length or will become 4257 * 0-length. 4258 */ 4259 if (size == 0 || bp->b_bufsize == 0) 4260 bp->b_flags |= B_CACHE; 4261 4262 if (newbsize < bp->b_bufsize) 4263 vfs_vmio_truncate(bp, desiredpages); 4264 /* XXX This looks as if it should be newbsize > b_bufsize */ 4265 else if (size > bp->b_bcount) 4266 vfs_vmio_extend(bp, desiredpages, size); 4267 bufspace_adjust(bp, newbsize); 4268 } 4269 bp->b_bcount = size; /* requested buffer size. */ 4270 return (1); 4271 } 4272 4273 extern int inflight_transient_maps; 4274 4275 static struct bio_queue nondump_bios; 4276 4277 void 4278 biodone(struct bio *bp) 4279 { 4280 struct mtx *mtxp; 4281 void (*done)(struct bio *); 4282 vm_offset_t start, end; 4283 4284 biotrack(bp, __func__); 4285 4286 /* 4287 * Avoid completing I/O when dumping after a panic since that may 4288 * result in a deadlock in the filesystem or pager code. Note that 4289 * this doesn't affect dumps that were started manually since we aim 4290 * to keep the system usable after it has been resumed. 4291 */ 4292 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4293 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4294 return; 4295 } 4296 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4297 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4298 bp->bio_flags |= BIO_UNMAPPED; 4299 start = trunc_page((vm_offset_t)bp->bio_data); 4300 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4301 bp->bio_data = unmapped_buf; 4302 pmap_qremove(start, atop(end - start)); 4303 vmem_free(transient_arena, start, end - start); 4304 atomic_add_int(&inflight_transient_maps, -1); 4305 } 4306 done = bp->bio_done; 4307 if (done == NULL) { 4308 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4309 mtx_lock(mtxp); 4310 bp->bio_flags |= BIO_DONE; 4311 wakeup(bp); 4312 mtx_unlock(mtxp); 4313 } else 4314 done(bp); 4315 } 4316 4317 /* 4318 * Wait for a BIO to finish. 4319 */ 4320 int 4321 biowait(struct bio *bp, const char *wchan) 4322 { 4323 struct mtx *mtxp; 4324 4325 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4326 mtx_lock(mtxp); 4327 while ((bp->bio_flags & BIO_DONE) == 0) 4328 msleep(bp, mtxp, PRIBIO, wchan, 0); 4329 mtx_unlock(mtxp); 4330 if (bp->bio_error != 0) 4331 return (bp->bio_error); 4332 if (!(bp->bio_flags & BIO_ERROR)) 4333 return (0); 4334 return (EIO); 4335 } 4336 4337 void 4338 biofinish(struct bio *bp, struct devstat *stat, int error) 4339 { 4340 4341 if (error) { 4342 bp->bio_error = error; 4343 bp->bio_flags |= BIO_ERROR; 4344 } 4345 if (stat != NULL) 4346 devstat_end_transaction_bio(stat, bp); 4347 biodone(bp); 4348 } 4349 4350 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4351 void 4352 biotrack_buf(struct bio *bp, const char *location) 4353 { 4354 4355 buf_track(bp->bio_track_bp, location); 4356 } 4357 #endif 4358 4359 /* 4360 * bufwait: 4361 * 4362 * Wait for buffer I/O completion, returning error status. The buffer 4363 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4364 * error and cleared. 4365 */ 4366 int 4367 bufwait(struct buf *bp) 4368 { 4369 if (bp->b_iocmd == BIO_READ) 4370 bwait(bp, PRIBIO, "biord"); 4371 else 4372 bwait(bp, PRIBIO, "biowr"); 4373 if (bp->b_flags & B_EINTR) { 4374 bp->b_flags &= ~B_EINTR; 4375 return (EINTR); 4376 } 4377 if (bp->b_ioflags & BIO_ERROR) { 4378 return (bp->b_error ? bp->b_error : EIO); 4379 } else { 4380 return (0); 4381 } 4382 } 4383 4384 /* 4385 * bufdone: 4386 * 4387 * Finish I/O on a buffer, optionally calling a completion function. 4388 * This is usually called from an interrupt so process blocking is 4389 * not allowed. 4390 * 4391 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4392 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4393 * assuming B_INVAL is clear. 4394 * 4395 * For the VMIO case, we set B_CACHE if the op was a read and no 4396 * read error occurred, or if the op was a write. B_CACHE is never 4397 * set if the buffer is invalid or otherwise uncacheable. 4398 * 4399 * bufdone does not mess with B_INVAL, allowing the I/O routine or the 4400 * initiator to leave B_INVAL set to brelse the buffer out of existence 4401 * in the biodone routine. 4402 */ 4403 void 4404 bufdone(struct buf *bp) 4405 { 4406 struct bufobj *dropobj; 4407 void (*biodone)(struct buf *); 4408 4409 buf_track(bp, __func__); 4410 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4411 dropobj = NULL; 4412 4413 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4414 4415 runningbufwakeup(bp); 4416 if (bp->b_iocmd == BIO_WRITE) 4417 dropobj = bp->b_bufobj; 4418 /* call optional completion function if requested */ 4419 if (bp->b_iodone != NULL) { 4420 biodone = bp->b_iodone; 4421 bp->b_iodone = NULL; 4422 (*biodone) (bp); 4423 if (dropobj) 4424 bufobj_wdrop(dropobj); 4425 return; 4426 } 4427 if (bp->b_flags & B_VMIO) { 4428 /* 4429 * Set B_CACHE if the op was a normal read and no error 4430 * occurred. B_CACHE is set for writes in the b*write() 4431 * routines. 4432 */ 4433 if (bp->b_iocmd == BIO_READ && 4434 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4435 !(bp->b_ioflags & BIO_ERROR)) 4436 bp->b_flags |= B_CACHE; 4437 vfs_vmio_iodone(bp); 4438 } 4439 if (!LIST_EMPTY(&bp->b_dep)) 4440 buf_complete(bp); 4441 if ((bp->b_flags & B_CKHASH) != 0) { 4442 KASSERT(bp->b_iocmd == BIO_READ, 4443 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4444 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4445 (*bp->b_ckhashcalc)(bp); 4446 } 4447 /* 4448 * For asynchronous completions, release the buffer now. The brelse 4449 * will do a wakeup there if necessary - so no need to do a wakeup 4450 * here in the async case. The sync case always needs to do a wakeup. 4451 */ 4452 if (bp->b_flags & B_ASYNC) { 4453 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4454 (bp->b_ioflags & BIO_ERROR)) 4455 brelse(bp); 4456 else 4457 bqrelse(bp); 4458 } else 4459 bdone(bp); 4460 if (dropobj) 4461 bufobj_wdrop(dropobj); 4462 } 4463 4464 /* 4465 * This routine is called in lieu of iodone in the case of 4466 * incomplete I/O. This keeps the busy status for pages 4467 * consistent. 4468 */ 4469 void 4470 vfs_unbusy_pages(struct buf *bp) 4471 { 4472 int i; 4473 vm_object_t obj; 4474 vm_page_t m; 4475 4476 runningbufwakeup(bp); 4477 if (!(bp->b_flags & B_VMIO)) 4478 return; 4479 4480 obj = bp->b_bufobj->bo_object; 4481 VM_OBJECT_WLOCK(obj); 4482 for (i = 0; i < bp->b_npages; i++) { 4483 m = bp->b_pages[i]; 4484 if (m == bogus_page) { 4485 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4486 if (!m) 4487 panic("vfs_unbusy_pages: page missing\n"); 4488 bp->b_pages[i] = m; 4489 if (buf_mapped(bp)) { 4490 BUF_CHECK_MAPPED(bp); 4491 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4492 bp->b_pages, bp->b_npages); 4493 } else 4494 BUF_CHECK_UNMAPPED(bp); 4495 } 4496 vm_page_sunbusy(m); 4497 } 4498 vm_object_pip_wakeupn(obj, bp->b_npages); 4499 VM_OBJECT_WUNLOCK(obj); 4500 } 4501 4502 /* 4503 * vfs_page_set_valid: 4504 * 4505 * Set the valid bits in a page based on the supplied offset. The 4506 * range is restricted to the buffer's size. 4507 * 4508 * This routine is typically called after a read completes. 4509 */ 4510 static void 4511 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4512 { 4513 vm_ooffset_t eoff; 4514 4515 /* 4516 * Compute the end offset, eoff, such that [off, eoff) does not span a 4517 * page boundary and eoff is not greater than the end of the buffer. 4518 * The end of the buffer, in this case, is our file EOF, not the 4519 * allocation size of the buffer. 4520 */ 4521 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4522 if (eoff > bp->b_offset + bp->b_bcount) 4523 eoff = bp->b_offset + bp->b_bcount; 4524 4525 /* 4526 * Set valid range. This is typically the entire buffer and thus the 4527 * entire page. 4528 */ 4529 if (eoff > off) 4530 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4531 } 4532 4533 /* 4534 * vfs_page_set_validclean: 4535 * 4536 * Set the valid bits and clear the dirty bits in a page based on the 4537 * supplied offset. The range is restricted to the buffer's size. 4538 */ 4539 static void 4540 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4541 { 4542 vm_ooffset_t soff, eoff; 4543 4544 /* 4545 * Start and end offsets in buffer. eoff - soff may not cross a 4546 * page boundary or cross the end of the buffer. The end of the 4547 * buffer, in this case, is our file EOF, not the allocation size 4548 * of the buffer. 4549 */ 4550 soff = off; 4551 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4552 if (eoff > bp->b_offset + bp->b_bcount) 4553 eoff = bp->b_offset + bp->b_bcount; 4554 4555 /* 4556 * Set valid range. This is typically the entire buffer and thus the 4557 * entire page. 4558 */ 4559 if (eoff > soff) { 4560 vm_page_set_validclean( 4561 m, 4562 (vm_offset_t) (soff & PAGE_MASK), 4563 (vm_offset_t) (eoff - soff) 4564 ); 4565 } 4566 } 4567 4568 /* 4569 * Acquire a shared busy on all pages in the buf. 4570 */ 4571 void 4572 vfs_busy_pages_acquire(struct buf *bp) 4573 { 4574 int i; 4575 4576 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4577 for (i = 0; i < bp->b_npages; i++) 4578 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY); 4579 } 4580 4581 void 4582 vfs_busy_pages_release(struct buf *bp) 4583 { 4584 int i; 4585 4586 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4587 for (i = 0; i < bp->b_npages; i++) 4588 vm_page_sunbusy(bp->b_pages[i]); 4589 } 4590 4591 /* 4592 * This routine is called before a device strategy routine. 4593 * It is used to tell the VM system that paging I/O is in 4594 * progress, and treat the pages associated with the buffer 4595 * almost as being exclusive busy. Also the object paging_in_progress 4596 * flag is handled to make sure that the object doesn't become 4597 * inconsistent. 4598 * 4599 * Since I/O has not been initiated yet, certain buffer flags 4600 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4601 * and should be ignored. 4602 */ 4603 void 4604 vfs_busy_pages(struct buf *bp, int clear_modify) 4605 { 4606 vm_object_t obj; 4607 vm_ooffset_t foff; 4608 vm_page_t m; 4609 int i; 4610 bool bogus; 4611 4612 if (!(bp->b_flags & B_VMIO)) 4613 return; 4614 4615 obj = bp->b_bufobj->bo_object; 4616 foff = bp->b_offset; 4617 KASSERT(bp->b_offset != NOOFFSET, 4618 ("vfs_busy_pages: no buffer offset")); 4619 VM_OBJECT_WLOCK(obj); 4620 if ((bp->b_flags & B_CLUSTER) == 0) { 4621 vm_object_pip_add(obj, bp->b_npages); 4622 vfs_busy_pages_acquire(bp); 4623 } 4624 if (bp->b_bufsize != 0) 4625 vfs_setdirty_locked_object(bp); 4626 bogus = false; 4627 for (i = 0; i < bp->b_npages; i++) { 4628 m = bp->b_pages[i]; 4629 vm_page_assert_sbusied(m); 4630 4631 /* 4632 * When readying a buffer for a read ( i.e 4633 * clear_modify == 0 ), it is important to do 4634 * bogus_page replacement for valid pages in 4635 * partially instantiated buffers. Partially 4636 * instantiated buffers can, in turn, occur when 4637 * reconstituting a buffer from its VM backing store 4638 * base. We only have to do this if B_CACHE is 4639 * clear ( which causes the I/O to occur in the 4640 * first place ). The replacement prevents the read 4641 * I/O from overwriting potentially dirty VM-backed 4642 * pages. XXX bogus page replacement is, uh, bogus. 4643 * It may not work properly with small-block devices. 4644 * We need to find a better way. 4645 */ 4646 if (clear_modify) { 4647 pmap_remove_write(m); 4648 vfs_page_set_validclean(bp, foff, m); 4649 } else if (vm_page_all_valid(m) && 4650 (bp->b_flags & B_CACHE) == 0) { 4651 bp->b_pages[i] = bogus_page; 4652 bogus = true; 4653 } 4654 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4655 } 4656 VM_OBJECT_WUNLOCK(obj); 4657 if (bogus && buf_mapped(bp)) { 4658 BUF_CHECK_MAPPED(bp); 4659 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4660 bp->b_pages, bp->b_npages); 4661 } 4662 } 4663 4664 /* 4665 * vfs_bio_set_valid: 4666 * 4667 * Set the range within the buffer to valid. The range is 4668 * relative to the beginning of the buffer, b_offset. Note that 4669 * b_offset itself may be offset from the beginning of the first 4670 * page. 4671 */ 4672 void 4673 vfs_bio_set_valid(struct buf *bp, int base, int size) 4674 { 4675 int i, n; 4676 vm_page_t m; 4677 4678 if (!(bp->b_flags & B_VMIO)) 4679 return; 4680 4681 /* 4682 * Fixup base to be relative to beginning of first page. 4683 * Set initial n to be the maximum number of bytes in the 4684 * first page that can be validated. 4685 */ 4686 base += (bp->b_offset & PAGE_MASK); 4687 n = PAGE_SIZE - (base & PAGE_MASK); 4688 4689 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4690 4691 /* 4692 * Busy may not be strictly necessary here because the pages are 4693 * unlikely to be fully valid and the vnode lock will synchronize 4694 * their access via getpages. It is grabbed for consistency with 4695 * other page validation. 4696 */ 4697 vfs_busy_pages_acquire(bp); 4698 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4699 m = bp->b_pages[i]; 4700 if (n > size) 4701 n = size; 4702 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4703 base += n; 4704 size -= n; 4705 n = PAGE_SIZE; 4706 } 4707 vfs_busy_pages_release(bp); 4708 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4709 } 4710 4711 /* 4712 * vfs_bio_clrbuf: 4713 * 4714 * If the specified buffer is a non-VMIO buffer, clear the entire 4715 * buffer. If the specified buffer is a VMIO buffer, clear and 4716 * validate only the previously invalid portions of the buffer. 4717 * This routine essentially fakes an I/O, so we need to clear 4718 * BIO_ERROR and B_INVAL. 4719 * 4720 * Note that while we only theoretically need to clear through b_bcount, 4721 * we go ahead and clear through b_bufsize. 4722 */ 4723 void 4724 vfs_bio_clrbuf(struct buf *bp) 4725 { 4726 int i, j, mask, sa, ea, slide; 4727 4728 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4729 clrbuf(bp); 4730 return; 4731 } 4732 bp->b_flags &= ~B_INVAL; 4733 bp->b_ioflags &= ~BIO_ERROR; 4734 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4735 vfs_busy_pages_acquire(bp); 4736 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4737 (bp->b_offset & PAGE_MASK) == 0) { 4738 if (bp->b_pages[0] == bogus_page) 4739 goto unlock; 4740 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4741 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4742 if ((bp->b_pages[0]->valid & mask) == mask) 4743 goto unlock; 4744 if ((bp->b_pages[0]->valid & mask) == 0) { 4745 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4746 bp->b_pages[0]->valid |= mask; 4747 goto unlock; 4748 } 4749 } 4750 sa = bp->b_offset & PAGE_MASK; 4751 slide = 0; 4752 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4753 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4754 ea = slide & PAGE_MASK; 4755 if (ea == 0) 4756 ea = PAGE_SIZE; 4757 if (bp->b_pages[i] == bogus_page) 4758 continue; 4759 j = sa / DEV_BSIZE; 4760 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4761 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4762 if ((bp->b_pages[i]->valid & mask) == mask) 4763 continue; 4764 if ((bp->b_pages[i]->valid & mask) == 0) 4765 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4766 else { 4767 for (; sa < ea; sa += DEV_BSIZE, j++) { 4768 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4769 pmap_zero_page_area(bp->b_pages[i], 4770 sa, DEV_BSIZE); 4771 } 4772 } 4773 } 4774 bp->b_pages[i]->valid |= mask; 4775 } 4776 unlock: 4777 vfs_busy_pages_release(bp); 4778 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4779 bp->b_resid = 0; 4780 } 4781 4782 void 4783 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4784 { 4785 vm_page_t m; 4786 int i, n; 4787 4788 if (buf_mapped(bp)) { 4789 BUF_CHECK_MAPPED(bp); 4790 bzero(bp->b_data + base, size); 4791 } else { 4792 BUF_CHECK_UNMAPPED(bp); 4793 n = PAGE_SIZE - (base & PAGE_MASK); 4794 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4795 m = bp->b_pages[i]; 4796 if (n > size) 4797 n = size; 4798 pmap_zero_page_area(m, base & PAGE_MASK, n); 4799 base += n; 4800 size -= n; 4801 n = PAGE_SIZE; 4802 } 4803 } 4804 } 4805 4806 /* 4807 * Update buffer flags based on I/O request parameters, optionally releasing the 4808 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4809 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4810 * I/O). Otherwise the buffer is released to the cache. 4811 */ 4812 static void 4813 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4814 { 4815 4816 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4817 ("buf %p non-VMIO noreuse", bp)); 4818 4819 if ((ioflag & IO_DIRECT) != 0) 4820 bp->b_flags |= B_DIRECT; 4821 if ((ioflag & IO_EXT) != 0) 4822 bp->b_xflags |= BX_ALTDATA; 4823 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4824 bp->b_flags |= B_RELBUF; 4825 if ((ioflag & IO_NOREUSE) != 0) 4826 bp->b_flags |= B_NOREUSE; 4827 if (release) 4828 brelse(bp); 4829 } else if (release) 4830 bqrelse(bp); 4831 } 4832 4833 void 4834 vfs_bio_brelse(struct buf *bp, int ioflag) 4835 { 4836 4837 b_io_dismiss(bp, ioflag, true); 4838 } 4839 4840 void 4841 vfs_bio_set_flags(struct buf *bp, int ioflag) 4842 { 4843 4844 b_io_dismiss(bp, ioflag, false); 4845 } 4846 4847 /* 4848 * vm_hold_load_pages and vm_hold_free_pages get pages into 4849 * a buffers address space. The pages are anonymous and are 4850 * not associated with a file object. 4851 */ 4852 static void 4853 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4854 { 4855 vm_offset_t pg; 4856 vm_page_t p; 4857 int index; 4858 4859 BUF_CHECK_MAPPED(bp); 4860 4861 to = round_page(to); 4862 from = round_page(from); 4863 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4864 4865 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4866 /* 4867 * note: must allocate system pages since blocking here 4868 * could interfere with paging I/O, no matter which 4869 * process we are. 4870 */ 4871 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4872 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | 4873 VM_ALLOC_WAITOK); 4874 pmap_qenter(pg, &p, 1); 4875 bp->b_pages[index] = p; 4876 } 4877 bp->b_npages = index; 4878 } 4879 4880 /* Return pages associated with this buf to the vm system */ 4881 static void 4882 vm_hold_free_pages(struct buf *bp, int newbsize) 4883 { 4884 vm_offset_t from; 4885 vm_page_t p; 4886 int index, newnpages; 4887 4888 BUF_CHECK_MAPPED(bp); 4889 4890 from = round_page((vm_offset_t)bp->b_data + newbsize); 4891 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4892 if (bp->b_npages > newnpages) 4893 pmap_qremove(from, bp->b_npages - newnpages); 4894 for (index = newnpages; index < bp->b_npages; index++) { 4895 p = bp->b_pages[index]; 4896 bp->b_pages[index] = NULL; 4897 vm_page_unwire_noq(p); 4898 vm_page_free(p); 4899 } 4900 bp->b_npages = newnpages; 4901 } 4902 4903 /* 4904 * Map an IO request into kernel virtual address space. 4905 * 4906 * All requests are (re)mapped into kernel VA space. 4907 * Notice that we use b_bufsize for the size of the buffer 4908 * to be mapped. b_bcount might be modified by the driver. 4909 * 4910 * Note that even if the caller determines that the address space should 4911 * be valid, a race or a smaller-file mapped into a larger space may 4912 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4913 * check the return value. 4914 * 4915 * This function only works with pager buffers. 4916 */ 4917 int 4918 vmapbuf(struct buf *bp, int mapbuf) 4919 { 4920 vm_prot_t prot; 4921 int pidx; 4922 4923 if (bp->b_bufsize < 0) 4924 return (-1); 4925 prot = VM_PROT_READ; 4926 if (bp->b_iocmd == BIO_READ) 4927 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4928 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4929 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4930 btoc(MAXPHYS))) < 0) 4931 return (-1); 4932 bp->b_npages = pidx; 4933 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4934 if (mapbuf || !unmapped_buf_allowed) { 4935 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4936 bp->b_data = bp->b_kvabase + bp->b_offset; 4937 } else 4938 bp->b_data = unmapped_buf; 4939 return(0); 4940 } 4941 4942 /* 4943 * Free the io map PTEs associated with this IO operation. 4944 * We also invalidate the TLB entries and restore the original b_addr. 4945 * 4946 * This function only works with pager buffers. 4947 */ 4948 void 4949 vunmapbuf(struct buf *bp) 4950 { 4951 int npages; 4952 4953 npages = bp->b_npages; 4954 if (buf_mapped(bp)) 4955 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4956 vm_page_unhold_pages(bp->b_pages, npages); 4957 4958 bp->b_data = unmapped_buf; 4959 } 4960 4961 void 4962 bdone(struct buf *bp) 4963 { 4964 struct mtx *mtxp; 4965 4966 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4967 mtx_lock(mtxp); 4968 bp->b_flags |= B_DONE; 4969 wakeup(bp); 4970 mtx_unlock(mtxp); 4971 } 4972 4973 void 4974 bwait(struct buf *bp, u_char pri, const char *wchan) 4975 { 4976 struct mtx *mtxp; 4977 4978 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4979 mtx_lock(mtxp); 4980 while ((bp->b_flags & B_DONE) == 0) 4981 msleep(bp, mtxp, pri, wchan, 0); 4982 mtx_unlock(mtxp); 4983 } 4984 4985 int 4986 bufsync(struct bufobj *bo, int waitfor) 4987 { 4988 4989 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 4990 } 4991 4992 void 4993 bufstrategy(struct bufobj *bo, struct buf *bp) 4994 { 4995 int i __unused; 4996 struct vnode *vp; 4997 4998 vp = bp->b_vp; 4999 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5000 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5001 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5002 i = VOP_STRATEGY(vp, bp); 5003 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5004 } 5005 5006 /* 5007 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5008 */ 5009 void 5010 bufobj_init(struct bufobj *bo, void *private) 5011 { 5012 static volatile int bufobj_cleanq; 5013 5014 bo->bo_domain = 5015 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5016 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5017 bo->bo_private = private; 5018 TAILQ_INIT(&bo->bo_clean.bv_hd); 5019 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5020 } 5021 5022 void 5023 bufobj_wrefl(struct bufobj *bo) 5024 { 5025 5026 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5027 ASSERT_BO_WLOCKED(bo); 5028 bo->bo_numoutput++; 5029 } 5030 5031 void 5032 bufobj_wref(struct bufobj *bo) 5033 { 5034 5035 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5036 BO_LOCK(bo); 5037 bo->bo_numoutput++; 5038 BO_UNLOCK(bo); 5039 } 5040 5041 void 5042 bufobj_wdrop(struct bufobj *bo) 5043 { 5044 5045 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5046 BO_LOCK(bo); 5047 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5048 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5049 bo->bo_flag &= ~BO_WWAIT; 5050 wakeup(&bo->bo_numoutput); 5051 } 5052 BO_UNLOCK(bo); 5053 } 5054 5055 int 5056 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5057 { 5058 int error; 5059 5060 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5061 ASSERT_BO_WLOCKED(bo); 5062 error = 0; 5063 while (bo->bo_numoutput) { 5064 bo->bo_flag |= BO_WWAIT; 5065 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5066 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5067 if (error) 5068 break; 5069 } 5070 return (error); 5071 } 5072 5073 /* 5074 * Set bio_data or bio_ma for struct bio from the struct buf. 5075 */ 5076 void 5077 bdata2bio(struct buf *bp, struct bio *bip) 5078 { 5079 5080 if (!buf_mapped(bp)) { 5081 KASSERT(unmapped_buf_allowed, ("unmapped")); 5082 bip->bio_ma = bp->b_pages; 5083 bip->bio_ma_n = bp->b_npages; 5084 bip->bio_data = unmapped_buf; 5085 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5086 bip->bio_flags |= BIO_UNMAPPED; 5087 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5088 PAGE_SIZE == bp->b_npages, 5089 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5090 (long long)bip->bio_length, bip->bio_ma_n)); 5091 } else { 5092 bip->bio_data = bp->b_data; 5093 bip->bio_ma = NULL; 5094 } 5095 } 5096 5097 /* 5098 * The MIPS pmap code currently doesn't handle aliased pages. 5099 * The VIPT caches may not handle page aliasing themselves, leading 5100 * to data corruption. 5101 * 5102 * As such, this code makes a system extremely unhappy if said 5103 * system doesn't support unaliasing the above situation in hardware. 5104 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 5105 * this feature at build time, so it has to be handled in software. 5106 * 5107 * Once the MIPS pmap/cache code grows to support this function on 5108 * earlier chips, it should be flipped back off. 5109 */ 5110 #ifdef __mips__ 5111 static int buf_pager_relbuf = 1; 5112 #else 5113 static int buf_pager_relbuf = 0; 5114 #endif 5115 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5116 &buf_pager_relbuf, 0, 5117 "Make buffer pager release buffers after reading"); 5118 5119 /* 5120 * The buffer pager. It uses buffer reads to validate pages. 5121 * 5122 * In contrast to the generic local pager from vm/vnode_pager.c, this 5123 * pager correctly and easily handles volumes where the underlying 5124 * device block size is greater than the machine page size. The 5125 * buffer cache transparently extends the requested page run to be 5126 * aligned at the block boundary, and does the necessary bogus page 5127 * replacements in the addends to avoid obliterating already valid 5128 * pages. 5129 * 5130 * The only non-trivial issue is that the exclusive busy state for 5131 * pages, which is assumed by the vm_pager_getpages() interface, is 5132 * incompatible with the VMIO buffer cache's desire to share-busy the 5133 * pages. This function performs a trivial downgrade of the pages' 5134 * state before reading buffers, and a less trivial upgrade from the 5135 * shared-busy to excl-busy state after the read. 5136 */ 5137 int 5138 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5139 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5140 vbg_get_blksize_t get_blksize) 5141 { 5142 vm_page_t m; 5143 vm_object_t object; 5144 struct buf *bp; 5145 struct mount *mp; 5146 daddr_t lbn, lbnp; 5147 vm_ooffset_t la, lb, poff, poffe; 5148 long bsize; 5149 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5150 bool redo, lpart; 5151 5152 object = vp->v_object; 5153 mp = vp->v_mount; 5154 error = 0; 5155 la = IDX_TO_OFF(ma[count - 1]->pindex); 5156 if (la >= object->un_pager.vnp.vnp_size) 5157 return (VM_PAGER_BAD); 5158 5159 /* 5160 * Change the meaning of la from where the last requested page starts 5161 * to where it ends, because that's the end of the requested region 5162 * and the start of the potential read-ahead region. 5163 */ 5164 la += PAGE_SIZE; 5165 lpart = la > object->un_pager.vnp.vnp_size; 5166 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 5167 5168 /* 5169 * Calculate read-ahead, behind and total pages. 5170 */ 5171 pgsin = count; 5172 lb = IDX_TO_OFF(ma[0]->pindex); 5173 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5174 pgsin += pgsin_b; 5175 if (rbehind != NULL) 5176 *rbehind = pgsin_b; 5177 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5178 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5179 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5180 PAGE_SIZE) - la); 5181 pgsin += pgsin_a; 5182 if (rahead != NULL) 5183 *rahead = pgsin_a; 5184 VM_CNT_INC(v_vnodein); 5185 VM_CNT_ADD(v_vnodepgsin, pgsin); 5186 5187 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5188 != 0) ? GB_UNMAPPED : 0; 5189 VM_OBJECT_WLOCK(object); 5190 again: 5191 for (i = 0; i < count; i++) 5192 vm_page_busy_downgrade(ma[i]); 5193 VM_OBJECT_WUNLOCK(object); 5194 5195 lbnp = -1; 5196 for (i = 0; i < count; i++) { 5197 m = ma[i]; 5198 5199 /* 5200 * Pages are shared busy and the object lock is not 5201 * owned, which together allow for the pages' 5202 * invalidation. The racy test for validity avoids 5203 * useless creation of the buffer for the most typical 5204 * case when invalidation is not used in redo or for 5205 * parallel read. The shared->excl upgrade loop at 5206 * the end of the function catches the race in a 5207 * reliable way (protected by the object lock). 5208 */ 5209 if (vm_page_all_valid(m)) 5210 continue; 5211 5212 poff = IDX_TO_OFF(m->pindex); 5213 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5214 for (; poff < poffe; poff += bsize) { 5215 lbn = get_lblkno(vp, poff); 5216 if (lbn == lbnp) 5217 goto next_page; 5218 lbnp = lbn; 5219 5220 bsize = get_blksize(vp, lbn); 5221 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 5222 br_flags, &bp); 5223 if (error != 0) 5224 goto end_pages; 5225 if (LIST_EMPTY(&bp->b_dep)) { 5226 /* 5227 * Invalidation clears m->valid, but 5228 * may leave B_CACHE flag if the 5229 * buffer existed at the invalidation 5230 * time. In this case, recycle the 5231 * buffer to do real read on next 5232 * bread() after redo. 5233 * 5234 * Otherwise B_RELBUF is not strictly 5235 * necessary, enable to reduce buf 5236 * cache pressure. 5237 */ 5238 if (buf_pager_relbuf || 5239 !vm_page_all_valid(m)) 5240 bp->b_flags |= B_RELBUF; 5241 5242 bp->b_flags &= ~B_NOCACHE; 5243 brelse(bp); 5244 } else { 5245 bqrelse(bp); 5246 } 5247 } 5248 KASSERT(1 /* racy, enable for debugging */ || 5249 vm_page_all_valid(m) || i == count - 1, 5250 ("buf %d %p invalid", i, m)); 5251 if (i == count - 1 && lpart) { 5252 VM_OBJECT_WLOCK(object); 5253 if (!vm_page_none_valid(m) && 5254 !vm_page_all_valid(m)) 5255 vm_page_zero_invalid(m, TRUE); 5256 VM_OBJECT_WUNLOCK(object); 5257 } 5258 next_page:; 5259 } 5260 end_pages: 5261 5262 VM_OBJECT_WLOCK(object); 5263 redo = false; 5264 for (i = 0; i < count; i++) { 5265 vm_page_sunbusy(ma[i]); 5266 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 5267 5268 /* 5269 * Since the pages were only sbusy while neither the 5270 * buffer nor the object lock was held by us, or 5271 * reallocated while vm_page_grab() slept for busy 5272 * relinguish, they could have been invalidated. 5273 * Recheck the valid bits and re-read as needed. 5274 * 5275 * Note that the last page is made fully valid in the 5276 * read loop, and partial validity for the page at 5277 * index count - 1 could mean that the page was 5278 * invalidated or removed, so we must restart for 5279 * safety as well. 5280 */ 5281 if (!vm_page_all_valid(ma[i])) 5282 redo = true; 5283 } 5284 if (redo && error == 0) 5285 goto again; 5286 VM_OBJECT_WUNLOCK(object); 5287 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5288 } 5289 5290 #include "opt_ddb.h" 5291 #ifdef DDB 5292 #include <ddb/ddb.h> 5293 5294 /* DDB command to show buffer data */ 5295 DB_SHOW_COMMAND(buffer, db_show_buffer) 5296 { 5297 /* get args */ 5298 struct buf *bp = (struct buf *)addr; 5299 #ifdef FULL_BUF_TRACKING 5300 uint32_t i, j; 5301 #endif 5302 5303 if (!have_addr) { 5304 db_printf("usage: show buffer <addr>\n"); 5305 return; 5306 } 5307 5308 db_printf("buf at %p\n", bp); 5309 db_printf("b_flags = 0x%b, b_xflags=0x%b\n", 5310 (u_int)bp->b_flags, PRINT_BUF_FLAGS, 5311 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS); 5312 db_printf("b_vflags=0x%b b_ioflags0x%b\n", 5313 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS, 5314 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS); 5315 db_printf( 5316 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5317 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, " 5318 "b_vp = %p, b_dep = %p\n", 5319 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5320 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5321 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first); 5322 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5323 bp->b_kvabase, bp->b_kvasize); 5324 if (bp->b_npages) { 5325 int i; 5326 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5327 for (i = 0; i < bp->b_npages; i++) { 5328 vm_page_t m; 5329 m = bp->b_pages[i]; 5330 if (m != NULL) 5331 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5332 (u_long)m->pindex, 5333 (u_long)VM_PAGE_TO_PHYS(m)); 5334 else 5335 db_printf("( ??? )"); 5336 if ((i + 1) < bp->b_npages) 5337 db_printf(","); 5338 } 5339 db_printf("\n"); 5340 } 5341 BUF_LOCKPRINTINFO(bp); 5342 #if defined(FULL_BUF_TRACKING) 5343 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5344 5345 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5346 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5347 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5348 continue; 5349 db_printf(" %2u: %s\n", j, 5350 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5351 } 5352 #elif defined(BUF_TRACKING) 5353 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5354 #endif 5355 db_printf(" "); 5356 } 5357 5358 DB_SHOW_COMMAND(bufqueues, bufqueues) 5359 { 5360 struct bufdomain *bd; 5361 struct buf *bp; 5362 long total; 5363 int i, j, cnt; 5364 5365 db_printf("bqempty: %d\n", bqempty.bq_len); 5366 5367 for (i = 0; i < buf_domains; i++) { 5368 bd = &bdomain[i]; 5369 db_printf("Buf domain %d\n", i); 5370 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5371 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5372 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5373 db_printf("\n"); 5374 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5375 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5376 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5377 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5378 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5379 db_printf("\n"); 5380 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5381 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5382 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5383 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5384 db_printf("\n"); 5385 total = 0; 5386 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5387 total += bp->b_bufsize; 5388 db_printf("\tcleanq count\t%d (%ld)\n", 5389 bd->bd_cleanq->bq_len, total); 5390 total = 0; 5391 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5392 total += bp->b_bufsize; 5393 db_printf("\tdirtyq count\t%d (%ld)\n", 5394 bd->bd_dirtyq.bq_len, total); 5395 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5396 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5397 db_printf("\tCPU "); 5398 for (j = 0; j <= mp_maxid; j++) 5399 db_printf("%d, ", bd->bd_subq[j].bq_len); 5400 db_printf("\n"); 5401 cnt = 0; 5402 total = 0; 5403 for (j = 0; j < nbuf; j++) 5404 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) { 5405 cnt++; 5406 total += buf[j].b_bufsize; 5407 } 5408 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5409 cnt = 0; 5410 total = 0; 5411 for (j = 0; j < nbuf; j++) 5412 if (buf[j].b_domain == i) { 5413 cnt++; 5414 total += buf[j].b_bufsize; 5415 } 5416 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5417 } 5418 } 5419 5420 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 5421 { 5422 struct buf *bp; 5423 int i; 5424 5425 for (i = 0; i < nbuf; i++) { 5426 bp = &buf[i]; 5427 if (BUF_ISLOCKED(bp)) { 5428 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5429 db_printf("\n"); 5430 if (db_pager_quit) 5431 break; 5432 } 5433 } 5434 } 5435 5436 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5437 { 5438 struct vnode *vp; 5439 struct buf *bp; 5440 5441 if (!have_addr) { 5442 db_printf("usage: show vnodebufs <addr>\n"); 5443 return; 5444 } 5445 vp = (struct vnode *)addr; 5446 db_printf("Clean buffers:\n"); 5447 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5448 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5449 db_printf("\n"); 5450 } 5451 db_printf("Dirty buffers:\n"); 5452 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5453 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5454 db_printf("\n"); 5455 } 5456 } 5457 5458 DB_COMMAND(countfreebufs, db_coundfreebufs) 5459 { 5460 struct buf *bp; 5461 int i, used = 0, nfree = 0; 5462 5463 if (have_addr) { 5464 db_printf("usage: countfreebufs\n"); 5465 return; 5466 } 5467 5468 for (i = 0; i < nbuf; i++) { 5469 bp = &buf[i]; 5470 if (bp->b_qindex == QUEUE_EMPTY) 5471 nfree++; 5472 else 5473 used++; 5474 } 5475 5476 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5477 nfree + used); 5478 db_printf("numfreebuffers is %d\n", numfreebuffers); 5479 } 5480 #endif /* DDB */ 5481