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