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_swap.h" 90 91 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 92 93 struct bio_ops bioops; /* I/O operation notification */ 94 95 struct buf_ops buf_ops_bio = { 96 .bop_name = "buf_ops_bio", 97 .bop_write = bufwrite, 98 .bop_strategy = bufstrategy, 99 .bop_sync = bufsync, 100 .bop_bdflush = bufbdflush, 101 }; 102 103 struct bufqueue { 104 struct mtx_padalign bq_lock; 105 TAILQ_HEAD(, buf) bq_queue; 106 uint8_t bq_index; 107 uint16_t bq_subqueue; 108 int bq_len; 109 } __aligned(CACHE_LINE_SIZE); 110 111 #define BQ_LOCKPTR(bq) (&(bq)->bq_lock) 112 #define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq))) 113 #define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq))) 114 #define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED) 115 116 struct bufdomain { 117 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */ 118 struct bufqueue bd_dirtyq; 119 struct bufqueue *bd_cleanq; 120 struct mtx_padalign bd_run_lock; 121 /* Constants */ 122 long bd_maxbufspace; 123 long bd_hibufspace; 124 long bd_lobufspace; 125 long bd_bufspacethresh; 126 int bd_hifreebuffers; 127 int bd_lofreebuffers; 128 int bd_hidirtybuffers; 129 int bd_lodirtybuffers; 130 int bd_dirtybufthresh; 131 int bd_lim; 132 /* atomics */ 133 int bd_wanted; 134 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers; 135 int __aligned(CACHE_LINE_SIZE) bd_running; 136 long __aligned(CACHE_LINE_SIZE) bd_bufspace; 137 int __aligned(CACHE_LINE_SIZE) bd_freebuffers; 138 } __aligned(CACHE_LINE_SIZE); 139 140 #define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock) 141 #define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd))) 142 #define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd))) 143 #define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED) 144 #define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock) 145 #define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd))) 146 #define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd))) 147 #define BD_DOMAIN(bd) (bd - bdomain) 148 149 static struct buf *buf; /* buffer header pool */ 150 extern struct buf *swbuf; /* Swap buffer header pool. */ 151 caddr_t unmapped_buf; 152 153 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 154 struct proc *bufdaemonproc; 155 156 static int inmem(struct vnode *vp, daddr_t blkno); 157 static void vm_hold_free_pages(struct buf *bp, int newbsize); 158 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 159 vm_offset_t to); 160 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 161 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 162 vm_page_t m); 163 static void vfs_clean_pages_dirty_buf(struct buf *bp); 164 static void vfs_setdirty_locked_object(struct buf *bp); 165 static void vfs_vmio_invalidate(struct buf *bp); 166 static void vfs_vmio_truncate(struct buf *bp, int npages); 167 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 168 static int vfs_bio_clcheck(struct vnode *vp, int size, 169 daddr_t lblkno, daddr_t blkno); 170 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int, 171 void (*)(struct buf *)); 172 static int buf_flush(struct vnode *vp, struct bufdomain *, int); 173 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int); 174 static void buf_daemon(void); 175 static __inline void bd_wakeup(void); 176 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 177 static void bufkva_reclaim(vmem_t *, int); 178 static void bufkva_free(struct buf *); 179 static int buf_import(void *, void **, int, int, int); 180 static void buf_release(void *, void **, int); 181 static void maxbcachebuf_adjust(void); 182 static inline struct bufdomain *bufdomain(struct buf *); 183 static void bq_remove(struct bufqueue *bq, struct buf *bp); 184 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock); 185 static int buf_recycle(struct bufdomain *, bool kva); 186 static void bq_init(struct bufqueue *bq, int qindex, int cpu, 187 const char *lockname); 188 static void bd_init(struct bufdomain *bd); 189 static int bd_flushall(struct bufdomain *bd); 190 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS); 191 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS); 192 193 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 194 int vmiodirenable = TRUE; 195 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 196 "Use the VM system for directory writes"); 197 long runningbufspace; 198 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 199 "Amount of presently outstanding async buffer io"); 200 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 201 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers"); 202 static counter_u64_t bufkvaspace; 203 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 204 "Kernel virtual memory used for buffers"); 205 static long maxbufspace; 206 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace, 207 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace, 208 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L", 209 "Maximum allowed value of bufspace (including metadata)"); 210 static long bufmallocspace; 211 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 212 "Amount of malloced memory for buffers"); 213 static long maxbufmallocspace; 214 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 215 0, "Maximum amount of malloced memory for buffers"); 216 static long lobufspace; 217 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace, 218 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace, 219 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L", 220 "Minimum amount of buffers we want to have"); 221 long hibufspace; 222 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace, 223 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace, 224 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L", 225 "Maximum allowed value of bufspace (excluding metadata)"); 226 long bufspacethresh; 227 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh, 228 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh, 229 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L", 230 "Bufspace consumed before waking the daemon to free some"); 231 static counter_u64_t buffreekvacnt; 232 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 233 "Number of times we have freed the KVA space from some buffer"); 234 static counter_u64_t bufdefragcnt; 235 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 236 "Number of times we have had to repeat buffer allocation to defragment"); 237 static long lorunningspace; 238 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 239 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 240 "Minimum preferred space used for in-progress I/O"); 241 static long hirunningspace; 242 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 243 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 244 "Maximum amount of space to use for in-progress I/O"); 245 int dirtybufferflushes; 246 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 247 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 248 int bdwriteskip; 249 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 250 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 251 int altbufferflushes; 252 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 253 0, "Number of fsync flushes to limit dirty buffers"); 254 static int recursiveflushes; 255 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 256 0, "Number of flushes skipped due to being recursive"); 257 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS); 258 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers, 259 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I", 260 "Number of buffers that are dirty (has unwritten changes) at the moment"); 261 static int lodirtybuffers; 262 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers, 263 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers, 264 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I", 265 "How many buffers we want to have free before bufdaemon can sleep"); 266 static int hidirtybuffers; 267 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers, 268 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers, 269 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I", 270 "When the number of dirty buffers is considered severe"); 271 int dirtybufthresh; 272 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh, 273 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh, 274 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I", 275 "Number of bdwrite to bawrite conversions to clear dirty buffers"); 276 static int numfreebuffers; 277 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 278 "Number of free buffers"); 279 static int lofreebuffers; 280 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers, 281 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers, 282 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I", 283 "Target number of free buffers"); 284 static int hifreebuffers; 285 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers, 286 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers, 287 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I", 288 "Threshold for clean buffer recycling"); 289 static counter_u64_t getnewbufcalls; 290 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, 291 &getnewbufcalls, "Number of calls to getnewbuf"); 292 static counter_u64_t getnewbufrestarts; 293 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, 294 &getnewbufrestarts, 295 "Number of times getnewbuf has had to restart a buffer acquisition"); 296 static counter_u64_t mappingrestarts; 297 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD, 298 &mappingrestarts, 299 "Number of times getblk has had to restart a buffer mapping for " 300 "unmapped buffer"); 301 static counter_u64_t numbufallocfails; 302 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, 303 &numbufallocfails, "Number of times buffer allocations failed"); 304 static int flushbufqtarget = 100; 305 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 306 "Amount of work to do in flushbufqueues when helping bufdaemon"); 307 static counter_u64_t notbufdflushes; 308 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 309 "Number of dirty buffer flushes done by the bufdaemon helpers"); 310 static long barrierwrites; 311 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 312 "Number of barrier writes"); 313 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 314 &unmapped_buf_allowed, 0, 315 "Permit the use of the unmapped i/o"); 316 int maxbcachebuf = MAXBCACHEBUF; 317 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0, 318 "Maximum size of a buffer cache block"); 319 320 /* 321 * This lock synchronizes access to bd_request. 322 */ 323 static struct mtx_padalign __exclusive_cache_line bdlock; 324 325 /* 326 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 327 * waitrunningbufspace(). 328 */ 329 static struct mtx_padalign __exclusive_cache_line rbreqlock; 330 331 /* 332 * Lock that protects bdirtywait. 333 */ 334 static struct mtx_padalign __exclusive_cache_line bdirtylock; 335 336 /* 337 * Wakeup point for bufdaemon, as well as indicator of whether it is already 338 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 339 * is idling. 340 */ 341 static int bd_request; 342 343 /* 344 * Request for the buf daemon to write more buffers than is indicated by 345 * lodirtybuf. This may be necessary to push out excess dependencies or 346 * defragment the address space where a simple count of the number of dirty 347 * buffers is insufficient to characterize the demand for flushing them. 348 */ 349 static int bd_speedupreq; 350 351 /* 352 * Synchronization (sleep/wakeup) variable for active buffer space requests. 353 * Set when wait starts, cleared prior to wakeup(). 354 * Used in runningbufwakeup() and waitrunningbufspace(). 355 */ 356 static int runningbufreq; 357 358 /* 359 * Synchronization for bwillwrite() waiters. 360 */ 361 static int bdirtywait; 362 363 /* 364 * Definitions for the buffer free lists. 365 */ 366 #define QUEUE_NONE 0 /* on no queue */ 367 #define QUEUE_EMPTY 1 /* empty buffer headers */ 368 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 369 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 370 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */ 371 372 /* Maximum number of buffer domains. */ 373 #define BUF_DOMAINS 8 374 375 struct bufdomainset bdlodirty; /* Domains > lodirty */ 376 struct bufdomainset bdhidirty; /* Domains > hidirty */ 377 378 /* Configured number of clean queues. */ 379 static int __read_mostly buf_domains; 380 381 BITSET_DEFINE(bufdomainset, BUF_DOMAINS); 382 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS]; 383 struct bufqueue __exclusive_cache_line bqempty; 384 385 /* 386 * per-cpu empty buffer cache. 387 */ 388 uma_zone_t buf_zone; 389 390 /* 391 * Single global constant for BUF_WMESG, to avoid getting multiple references. 392 * buf_wmesg is referred from macros. 393 */ 394 const char *buf_wmesg = BUF_WMESG; 395 396 static int 397 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 398 { 399 long value; 400 int error; 401 402 value = *(long *)arg1; 403 error = sysctl_handle_long(oidp, &value, 0, req); 404 if (error != 0 || req->newptr == NULL) 405 return (error); 406 mtx_lock(&rbreqlock); 407 if (arg1 == &hirunningspace) { 408 if (value < lorunningspace) 409 error = EINVAL; 410 else 411 hirunningspace = value; 412 } else { 413 KASSERT(arg1 == &lorunningspace, 414 ("%s: unknown arg1", __func__)); 415 if (value > hirunningspace) 416 error = EINVAL; 417 else 418 lorunningspace = value; 419 } 420 mtx_unlock(&rbreqlock); 421 return (error); 422 } 423 424 static int 425 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS) 426 { 427 int error; 428 int value; 429 int i; 430 431 value = *(int *)arg1; 432 error = sysctl_handle_int(oidp, &value, 0, req); 433 if (error != 0 || req->newptr == NULL) 434 return (error); 435 *(int *)arg1 = value; 436 for (i = 0; i < buf_domains; i++) 437 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 438 value / buf_domains; 439 440 return (error); 441 } 442 443 static int 444 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS) 445 { 446 long value; 447 int error; 448 int i; 449 450 value = *(long *)arg1; 451 error = sysctl_handle_long(oidp, &value, 0, req); 452 if (error != 0 || req->newptr == NULL) 453 return (error); 454 *(long *)arg1 = value; 455 for (i = 0; i < buf_domains; i++) 456 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 457 value / buf_domains; 458 459 return (error); 460 } 461 462 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 463 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 464 static int 465 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 466 { 467 long lvalue; 468 int ivalue; 469 int i; 470 471 lvalue = 0; 472 for (i = 0; i < buf_domains; i++) 473 lvalue += bdomain[i].bd_bufspace; 474 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 475 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 476 if (lvalue > INT_MAX) 477 /* On overflow, still write out a long to trigger ENOMEM. */ 478 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 479 ivalue = lvalue; 480 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 481 } 482 #else 483 static int 484 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 485 { 486 long lvalue; 487 int i; 488 489 lvalue = 0; 490 for (i = 0; i < buf_domains; i++) 491 lvalue += bdomain[i].bd_bufspace; 492 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 493 } 494 #endif 495 496 static int 497 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS) 498 { 499 int value; 500 int i; 501 502 value = 0; 503 for (i = 0; i < buf_domains; i++) 504 value += bdomain[i].bd_numdirtybuffers; 505 return (sysctl_handle_int(oidp, &value, 0, req)); 506 } 507 508 /* 509 * bdirtywakeup: 510 * 511 * Wakeup any bwillwrite() waiters. 512 */ 513 static void 514 bdirtywakeup(void) 515 { 516 mtx_lock(&bdirtylock); 517 if (bdirtywait) { 518 bdirtywait = 0; 519 wakeup(&bdirtywait); 520 } 521 mtx_unlock(&bdirtylock); 522 } 523 524 /* 525 * bd_clear: 526 * 527 * Clear a domain from the appropriate bitsets when dirtybuffers 528 * is decremented. 529 */ 530 static void 531 bd_clear(struct bufdomain *bd) 532 { 533 534 mtx_lock(&bdirtylock); 535 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers) 536 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 537 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers) 538 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 539 mtx_unlock(&bdirtylock); 540 } 541 542 /* 543 * bd_set: 544 * 545 * Set a domain in the appropriate bitsets when dirtybuffers 546 * is incremented. 547 */ 548 static void 549 bd_set(struct bufdomain *bd) 550 { 551 552 mtx_lock(&bdirtylock); 553 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers) 554 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 555 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers) 556 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 557 mtx_unlock(&bdirtylock); 558 } 559 560 /* 561 * bdirtysub: 562 * 563 * Decrement the numdirtybuffers count by one and wakeup any 564 * threads blocked in bwillwrite(). 565 */ 566 static void 567 bdirtysub(struct buf *bp) 568 { 569 struct bufdomain *bd; 570 int num; 571 572 bd = bufdomain(bp); 573 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1); 574 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 575 bdirtywakeup(); 576 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 577 bd_clear(bd); 578 } 579 580 /* 581 * bdirtyadd: 582 * 583 * Increment the numdirtybuffers count by one and wakeup the buf 584 * daemon if needed. 585 */ 586 static void 587 bdirtyadd(struct buf *bp) 588 { 589 struct bufdomain *bd; 590 int num; 591 592 /* 593 * Only do the wakeup once as we cross the boundary. The 594 * buf daemon will keep running until the condition clears. 595 */ 596 bd = bufdomain(bp); 597 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1); 598 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 599 bd_wakeup(); 600 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 601 bd_set(bd); 602 } 603 604 /* 605 * bufspace_daemon_wakeup: 606 * 607 * Wakeup the daemons responsible for freeing clean bufs. 608 */ 609 static void 610 bufspace_daemon_wakeup(struct bufdomain *bd) 611 { 612 613 /* 614 * avoid the lock if the daemon is running. 615 */ 616 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) { 617 BD_RUN_LOCK(bd); 618 atomic_store_int(&bd->bd_running, 1); 619 wakeup(&bd->bd_running); 620 BD_RUN_UNLOCK(bd); 621 } 622 } 623 624 /* 625 * bufspace_daemon_wait: 626 * 627 * Sleep until the domain falls below a limit or one second passes. 628 */ 629 static void 630 bufspace_daemon_wait(struct bufdomain *bd) 631 { 632 /* 633 * Re-check our limits and sleep. bd_running must be 634 * cleared prior to checking the limits to avoid missed 635 * wakeups. The waker will adjust one of bufspace or 636 * freebuffers prior to checking bd_running. 637 */ 638 BD_RUN_LOCK(bd); 639 atomic_store_int(&bd->bd_running, 0); 640 if (bd->bd_bufspace < bd->bd_bufspacethresh && 641 bd->bd_freebuffers > bd->bd_lofreebuffers) { 642 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP, 643 "-", hz); 644 } else { 645 /* Avoid spurious wakeups while running. */ 646 atomic_store_int(&bd->bd_running, 1); 647 BD_RUN_UNLOCK(bd); 648 } 649 } 650 651 /* 652 * bufspace_adjust: 653 * 654 * Adjust the reported bufspace for a KVA managed buffer, possibly 655 * waking any waiters. 656 */ 657 static void 658 bufspace_adjust(struct buf *bp, int bufsize) 659 { 660 struct bufdomain *bd; 661 long space; 662 int diff; 663 664 KASSERT((bp->b_flags & B_MALLOC) == 0, 665 ("bufspace_adjust: malloc buf %p", bp)); 666 bd = bufdomain(bp); 667 diff = bufsize - bp->b_bufsize; 668 if (diff < 0) { 669 atomic_subtract_long(&bd->bd_bufspace, -diff); 670 } else if (diff > 0) { 671 space = atomic_fetchadd_long(&bd->bd_bufspace, diff); 672 /* Wake up the daemon on the transition. */ 673 if (space < bd->bd_bufspacethresh && 674 space + diff >= bd->bd_bufspacethresh) 675 bufspace_daemon_wakeup(bd); 676 } 677 bp->b_bufsize = bufsize; 678 } 679 680 /* 681 * bufspace_reserve: 682 * 683 * Reserve bufspace before calling allocbuf(). metadata has a 684 * different space limit than data. 685 */ 686 static int 687 bufspace_reserve(struct bufdomain *bd, int size, bool metadata) 688 { 689 long limit, new; 690 long space; 691 692 if (metadata) 693 limit = bd->bd_maxbufspace; 694 else 695 limit = bd->bd_hibufspace; 696 space = atomic_fetchadd_long(&bd->bd_bufspace, size); 697 new = space + size; 698 if (new > limit) { 699 atomic_subtract_long(&bd->bd_bufspace, size); 700 return (ENOSPC); 701 } 702 703 /* Wake up the daemon on the transition. */ 704 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh) 705 bufspace_daemon_wakeup(bd); 706 707 return (0); 708 } 709 710 /* 711 * bufspace_release: 712 * 713 * Release reserved bufspace after bufspace_adjust() has consumed it. 714 */ 715 static void 716 bufspace_release(struct bufdomain *bd, int size) 717 { 718 719 atomic_subtract_long(&bd->bd_bufspace, size); 720 } 721 722 /* 723 * bufspace_wait: 724 * 725 * Wait for bufspace, acting as the buf daemon if a locked vnode is 726 * supplied. bd_wanted must be set prior to polling for space. The 727 * operation must be re-tried on return. 728 */ 729 static void 730 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags, 731 int slpflag, int slptimeo) 732 { 733 struct thread *td; 734 int error, fl, norunbuf; 735 736 if ((gbflags & GB_NOWAIT_BD) != 0) 737 return; 738 739 td = curthread; 740 BD_LOCK(bd); 741 while (bd->bd_wanted) { 742 if (vp != NULL && vp->v_type != VCHR && 743 (td->td_pflags & TDP_BUFNEED) == 0) { 744 BD_UNLOCK(bd); 745 /* 746 * getblk() is called with a vnode locked, and 747 * some majority of the dirty buffers may as 748 * well belong to the vnode. Flushing the 749 * buffers there would make a progress that 750 * cannot be achieved by the buf_daemon, that 751 * cannot lock the vnode. 752 */ 753 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 754 (td->td_pflags & TDP_NORUNNINGBUF); 755 756 /* 757 * Play bufdaemon. The getnewbuf() function 758 * may be called while the thread owns lock 759 * for another dirty buffer for the same 760 * vnode, which makes it impossible to use 761 * VOP_FSYNC() there, due to the buffer lock 762 * recursion. 763 */ 764 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 765 fl = buf_flush(vp, bd, flushbufqtarget); 766 td->td_pflags &= norunbuf; 767 BD_LOCK(bd); 768 if (fl != 0) 769 continue; 770 if (bd->bd_wanted == 0) 771 break; 772 } 773 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 774 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 775 if (error != 0) 776 break; 777 } 778 BD_UNLOCK(bd); 779 } 780 781 782 /* 783 * bufspace_daemon: 784 * 785 * buffer space management daemon. Tries to maintain some marginal 786 * amount of free buffer space so that requesting processes neither 787 * block nor work to reclaim buffers. 788 */ 789 static void 790 bufspace_daemon(void *arg) 791 { 792 struct bufdomain *bd; 793 794 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 795 SHUTDOWN_PRI_LAST + 100); 796 797 bd = arg; 798 for (;;) { 799 kthread_suspend_check(); 800 801 /* 802 * Free buffers from the clean queue until we meet our 803 * targets. 804 * 805 * Theory of operation: The buffer cache is most efficient 806 * when some free buffer headers and space are always 807 * available to getnewbuf(). This daemon attempts to prevent 808 * the excessive blocking and synchronization associated 809 * with shortfall. It goes through three phases according 810 * demand: 811 * 812 * 1) The daemon wakes up voluntarily once per-second 813 * during idle periods when the counters are below 814 * the wakeup thresholds (bufspacethresh, lofreebuffers). 815 * 816 * 2) The daemon wakes up as we cross the thresholds 817 * ahead of any potential blocking. This may bounce 818 * slightly according to the rate of consumption and 819 * release. 820 * 821 * 3) The daemon and consumers are starved for working 822 * clean buffers. This is the 'bufspace' sleep below 823 * which will inefficiently trade bufs with bqrelse 824 * until we return to condition 2. 825 */ 826 while (bd->bd_bufspace > bd->bd_lobufspace || 827 bd->bd_freebuffers < bd->bd_hifreebuffers) { 828 if (buf_recycle(bd, false) != 0) { 829 if (bd_flushall(bd)) 830 continue; 831 /* 832 * Speedup dirty if we've run out of clean 833 * buffers. This is possible in particular 834 * because softdep may held many bufs locked 835 * pending writes to other bufs which are 836 * marked for delayed write, exhausting 837 * clean space until they are written. 838 */ 839 bd_speedup(); 840 BD_LOCK(bd); 841 if (bd->bd_wanted) { 842 msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 843 PRIBIO|PDROP, "bufspace", hz/10); 844 } else 845 BD_UNLOCK(bd); 846 } 847 maybe_yield(); 848 } 849 bufspace_daemon_wait(bd); 850 } 851 } 852 853 /* 854 * bufmallocadjust: 855 * 856 * Adjust the reported bufspace for a malloc managed buffer, possibly 857 * waking any waiters. 858 */ 859 static void 860 bufmallocadjust(struct buf *bp, int bufsize) 861 { 862 int diff; 863 864 KASSERT((bp->b_flags & B_MALLOC) != 0, 865 ("bufmallocadjust: non-malloc buf %p", bp)); 866 diff = bufsize - bp->b_bufsize; 867 if (diff < 0) 868 atomic_subtract_long(&bufmallocspace, -diff); 869 else 870 atomic_add_long(&bufmallocspace, diff); 871 bp->b_bufsize = bufsize; 872 } 873 874 /* 875 * runningwakeup: 876 * 877 * Wake up processes that are waiting on asynchronous writes to fall 878 * below lorunningspace. 879 */ 880 static void 881 runningwakeup(void) 882 { 883 884 mtx_lock(&rbreqlock); 885 if (runningbufreq) { 886 runningbufreq = 0; 887 wakeup(&runningbufreq); 888 } 889 mtx_unlock(&rbreqlock); 890 } 891 892 /* 893 * runningbufwakeup: 894 * 895 * Decrement the outstanding write count according. 896 */ 897 void 898 runningbufwakeup(struct buf *bp) 899 { 900 long space, bspace; 901 902 bspace = bp->b_runningbufspace; 903 if (bspace == 0) 904 return; 905 space = atomic_fetchadd_long(&runningbufspace, -bspace); 906 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 907 space, bspace)); 908 bp->b_runningbufspace = 0; 909 /* 910 * Only acquire the lock and wakeup on the transition from exceeding 911 * the threshold to falling below it. 912 */ 913 if (space < lorunningspace) 914 return; 915 if (space - bspace > lorunningspace) 916 return; 917 runningwakeup(); 918 } 919 920 /* 921 * waitrunningbufspace() 922 * 923 * runningbufspace is a measure of the amount of I/O currently 924 * running. This routine is used in async-write situations to 925 * prevent creating huge backups of pending writes to a device. 926 * Only asynchronous writes are governed by this function. 927 * 928 * This does NOT turn an async write into a sync write. It waits 929 * for earlier writes to complete and generally returns before the 930 * caller's write has reached the device. 931 */ 932 void 933 waitrunningbufspace(void) 934 { 935 936 mtx_lock(&rbreqlock); 937 while (runningbufspace > hirunningspace) { 938 runningbufreq = 1; 939 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 940 } 941 mtx_unlock(&rbreqlock); 942 } 943 944 945 /* 946 * vfs_buf_test_cache: 947 * 948 * Called when a buffer is extended. This function clears the B_CACHE 949 * bit if the newly extended portion of the buffer does not contain 950 * valid data. 951 */ 952 static __inline void 953 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 954 vm_offset_t size, vm_page_t m) 955 { 956 957 VM_OBJECT_ASSERT_LOCKED(m->object); 958 if (bp->b_flags & B_CACHE) { 959 int base = (foff + off) & PAGE_MASK; 960 if (vm_page_is_valid(m, base, size) == 0) 961 bp->b_flags &= ~B_CACHE; 962 } 963 } 964 965 /* Wake up the buffer daemon if necessary */ 966 static void 967 bd_wakeup(void) 968 { 969 970 mtx_lock(&bdlock); 971 if (bd_request == 0) { 972 bd_request = 1; 973 wakeup(&bd_request); 974 } 975 mtx_unlock(&bdlock); 976 } 977 978 /* 979 * Adjust the maxbcachbuf tunable. 980 */ 981 static void 982 maxbcachebuf_adjust(void) 983 { 984 int i; 985 986 /* 987 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 988 */ 989 i = 2; 990 while (i * 2 <= maxbcachebuf) 991 i *= 2; 992 maxbcachebuf = i; 993 if (maxbcachebuf < MAXBSIZE) 994 maxbcachebuf = MAXBSIZE; 995 if (maxbcachebuf > MAXPHYS) 996 maxbcachebuf = MAXPHYS; 997 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 998 printf("maxbcachebuf=%d\n", maxbcachebuf); 999 } 1000 1001 /* 1002 * bd_speedup - speedup the buffer cache flushing code 1003 */ 1004 void 1005 bd_speedup(void) 1006 { 1007 int needwake; 1008 1009 mtx_lock(&bdlock); 1010 needwake = 0; 1011 if (bd_speedupreq == 0 || bd_request == 0) 1012 needwake = 1; 1013 bd_speedupreq = 1; 1014 bd_request = 1; 1015 if (needwake) 1016 wakeup(&bd_request); 1017 mtx_unlock(&bdlock); 1018 } 1019 1020 #ifndef NSWBUF_MIN 1021 #define NSWBUF_MIN 16 1022 #endif 1023 1024 #ifdef __i386__ 1025 #define TRANSIENT_DENOM 5 1026 #else 1027 #define TRANSIENT_DENOM 10 1028 #endif 1029 1030 /* 1031 * Calculating buffer cache scaling values and reserve space for buffer 1032 * headers. This is called during low level kernel initialization and 1033 * may be called more then once. We CANNOT write to the memory area 1034 * being reserved at this time. 1035 */ 1036 caddr_t 1037 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 1038 { 1039 int tuned_nbuf; 1040 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 1041 1042 /* 1043 * physmem_est is in pages. Convert it to kilobytes (assumes 1044 * PAGE_SIZE is >= 1K) 1045 */ 1046 physmem_est = physmem_est * (PAGE_SIZE / 1024); 1047 1048 maxbcachebuf_adjust(); 1049 /* 1050 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 1051 * For the first 64MB of ram nominally allocate sufficient buffers to 1052 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 1053 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 1054 * the buffer cache we limit the eventual kva reservation to 1055 * maxbcache bytes. 1056 * 1057 * factor represents the 1/4 x ram conversion. 1058 */ 1059 if (nbuf == 0) { 1060 int factor = 4 * BKVASIZE / 1024; 1061 1062 nbuf = 50; 1063 if (physmem_est > 4096) 1064 nbuf += min((physmem_est - 4096) / factor, 1065 65536 / factor); 1066 if (physmem_est > 65536) 1067 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 1068 32 * 1024 * 1024 / (factor * 5)); 1069 1070 if (maxbcache && nbuf > maxbcache / BKVASIZE) 1071 nbuf = maxbcache / BKVASIZE; 1072 tuned_nbuf = 1; 1073 } else 1074 tuned_nbuf = 0; 1075 1076 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 1077 maxbuf = (LONG_MAX / 3) / BKVASIZE; 1078 if (nbuf > maxbuf) { 1079 if (!tuned_nbuf) 1080 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 1081 maxbuf); 1082 nbuf = maxbuf; 1083 } 1084 1085 /* 1086 * Ideal allocation size for the transient bio submap is 10% 1087 * of the maximal space buffer map. This roughly corresponds 1088 * to the amount of the buffer mapped for typical UFS load. 1089 * 1090 * Clip the buffer map to reserve space for the transient 1091 * BIOs, if its extent is bigger than 90% (80% on i386) of the 1092 * maximum buffer map extent on the platform. 1093 * 1094 * The fall-back to the maxbuf in case of maxbcache unset, 1095 * allows to not trim the buffer KVA for the architectures 1096 * with ample KVA space. 1097 */ 1098 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 1099 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 1100 buf_sz = (long)nbuf * BKVASIZE; 1101 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 1102 (TRANSIENT_DENOM - 1)) { 1103 /* 1104 * There is more KVA than memory. Do not 1105 * adjust buffer map size, and assign the rest 1106 * of maxbuf to transient map. 1107 */ 1108 biotmap_sz = maxbuf_sz - buf_sz; 1109 } else { 1110 /* 1111 * Buffer map spans all KVA we could afford on 1112 * this platform. Give 10% (20% on i386) of 1113 * the buffer map to the transient bio map. 1114 */ 1115 biotmap_sz = buf_sz / TRANSIENT_DENOM; 1116 buf_sz -= biotmap_sz; 1117 } 1118 if (biotmap_sz / INT_MAX > MAXPHYS) 1119 bio_transient_maxcnt = INT_MAX; 1120 else 1121 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 1122 /* 1123 * Artificially limit to 1024 simultaneous in-flight I/Os 1124 * using the transient mapping. 1125 */ 1126 if (bio_transient_maxcnt > 1024) 1127 bio_transient_maxcnt = 1024; 1128 if (tuned_nbuf) 1129 nbuf = buf_sz / BKVASIZE; 1130 } 1131 1132 /* 1133 * swbufs are used as temporary holders for I/O, such as paging I/O. 1134 * We have no less then 16 and no more then 256. 1135 */ 1136 nswbuf = min(nbuf / 4, 256); 1137 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 1138 if (nswbuf < NSWBUF_MIN) 1139 nswbuf = NSWBUF_MIN; 1140 1141 /* 1142 * Reserve space for the buffer cache buffers 1143 */ 1144 swbuf = (void *)v; 1145 v = (caddr_t)(swbuf + nswbuf); 1146 buf = (void *)v; 1147 v = (caddr_t)(buf + nbuf); 1148 1149 return(v); 1150 } 1151 1152 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1153 void 1154 bufinit(void) 1155 { 1156 struct buf *bp; 1157 int i; 1158 1159 KASSERT(maxbcachebuf >= MAXBSIZE, 1160 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1161 MAXBSIZE)); 1162 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock"); 1163 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1164 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1165 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1166 1167 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1168 1169 /* finally, initialize each buffer header and stick on empty q */ 1170 for (i = 0; i < nbuf; i++) { 1171 bp = &buf[i]; 1172 bzero(bp, sizeof *bp); 1173 bp->b_flags = B_INVAL; 1174 bp->b_rcred = NOCRED; 1175 bp->b_wcred = NOCRED; 1176 bp->b_qindex = QUEUE_NONE; 1177 bp->b_domain = -1; 1178 bp->b_subqueue = mp_maxid + 1; 1179 bp->b_xflags = 0; 1180 bp->b_data = bp->b_kvabase = unmapped_buf; 1181 LIST_INIT(&bp->b_dep); 1182 BUF_LOCKINIT(bp); 1183 bq_insert(&bqempty, bp, false); 1184 } 1185 1186 /* 1187 * maxbufspace is the absolute maximum amount of buffer space we are 1188 * allowed to reserve in KVM and in real terms. The absolute maximum 1189 * is nominally used by metadata. hibufspace is the nominal maximum 1190 * used by most other requests. The differential is required to 1191 * ensure that metadata deadlocks don't occur. 1192 * 1193 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1194 * this may result in KVM fragmentation which is not handled optimally 1195 * by the system. XXX This is less true with vmem. We could use 1196 * PAGE_SIZE. 1197 */ 1198 maxbufspace = (long)nbuf * BKVASIZE; 1199 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1200 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1201 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1202 1203 /* 1204 * Note: The 16 MiB upper limit for hirunningspace was chosen 1205 * arbitrarily and may need further tuning. It corresponds to 1206 * 128 outstanding write IO requests (if IO size is 128 KiB), 1207 * which fits with many RAID controllers' tagged queuing limits. 1208 * The lower 1 MiB limit is the historical upper limit for 1209 * hirunningspace. 1210 */ 1211 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1212 16 * 1024 * 1024), 1024 * 1024); 1213 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1214 1215 /* 1216 * Limit the amount of malloc memory since it is wired permanently into 1217 * the kernel space. Even though this is accounted for in the buffer 1218 * allocation, we don't want the malloced region to grow uncontrolled. 1219 * The malloc scheme improves memory utilization significantly on 1220 * average (small) directories. 1221 */ 1222 maxbufmallocspace = hibufspace / 20; 1223 1224 /* 1225 * Reduce the chance of a deadlock occurring by limiting the number 1226 * of delayed-write dirty buffers we allow to stack up. 1227 */ 1228 hidirtybuffers = nbuf / 4 + 20; 1229 dirtybufthresh = hidirtybuffers * 9 / 10; 1230 /* 1231 * To support extreme low-memory systems, make sure hidirtybuffers 1232 * cannot eat up all available buffer space. This occurs when our 1233 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1234 * buffer space assuming BKVASIZE'd buffers. 1235 */ 1236 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1237 hidirtybuffers >>= 1; 1238 } 1239 lodirtybuffers = hidirtybuffers / 2; 1240 1241 /* 1242 * lofreebuffers should be sufficient to avoid stalling waiting on 1243 * buf headers under heavy utilization. The bufs in per-cpu caches 1244 * are counted as free but will be unavailable to threads executing 1245 * on other cpus. 1246 * 1247 * hifreebuffers is the free target for the bufspace daemon. This 1248 * should be set appropriately to limit work per-iteration. 1249 */ 1250 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1251 hifreebuffers = (3 * lofreebuffers) / 2; 1252 numfreebuffers = nbuf; 1253 1254 /* Setup the kva and free list allocators. */ 1255 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1256 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1257 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1258 1259 /* 1260 * Size the clean queue according to the amount of buffer space. 1261 * One queue per-256mb up to the max. More queues gives better 1262 * concurrency but less accurate LRU. 1263 */ 1264 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS); 1265 for (i = 0 ; i < buf_domains; i++) { 1266 struct bufdomain *bd; 1267 1268 bd = &bdomain[i]; 1269 bd_init(bd); 1270 bd->bd_freebuffers = nbuf / buf_domains; 1271 bd->bd_hifreebuffers = hifreebuffers / buf_domains; 1272 bd->bd_lofreebuffers = lofreebuffers / buf_domains; 1273 bd->bd_bufspace = 0; 1274 bd->bd_maxbufspace = maxbufspace / buf_domains; 1275 bd->bd_hibufspace = hibufspace / buf_domains; 1276 bd->bd_lobufspace = lobufspace / buf_domains; 1277 bd->bd_bufspacethresh = bufspacethresh / buf_domains; 1278 bd->bd_numdirtybuffers = 0; 1279 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains; 1280 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains; 1281 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains; 1282 /* Don't allow more than 2% of bufs in the per-cpu caches. */ 1283 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus; 1284 } 1285 getnewbufcalls = counter_u64_alloc(M_WAITOK); 1286 getnewbufrestarts = counter_u64_alloc(M_WAITOK); 1287 mappingrestarts = counter_u64_alloc(M_WAITOK); 1288 numbufallocfails = counter_u64_alloc(M_WAITOK); 1289 notbufdflushes = counter_u64_alloc(M_WAITOK); 1290 buffreekvacnt = counter_u64_alloc(M_WAITOK); 1291 bufdefragcnt = counter_u64_alloc(M_WAITOK); 1292 bufkvaspace = counter_u64_alloc(M_WAITOK); 1293 } 1294 1295 #ifdef INVARIANTS 1296 static inline void 1297 vfs_buf_check_mapped(struct buf *bp) 1298 { 1299 1300 KASSERT(bp->b_kvabase != unmapped_buf, 1301 ("mapped buf: b_kvabase was not updated %p", bp)); 1302 KASSERT(bp->b_data != unmapped_buf, 1303 ("mapped buf: b_data was not updated %p", bp)); 1304 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1305 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1306 } 1307 1308 static inline void 1309 vfs_buf_check_unmapped(struct buf *bp) 1310 { 1311 1312 KASSERT(bp->b_data == unmapped_buf, 1313 ("unmapped buf: corrupted b_data %p", bp)); 1314 } 1315 1316 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1317 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1318 #else 1319 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1320 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1321 #endif 1322 1323 static int 1324 isbufbusy(struct buf *bp) 1325 { 1326 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1327 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1328 return (1); 1329 return (0); 1330 } 1331 1332 /* 1333 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1334 */ 1335 void 1336 bufshutdown(int show_busybufs) 1337 { 1338 static int first_buf_printf = 1; 1339 struct buf *bp; 1340 int iter, nbusy, pbusy; 1341 #ifndef PREEMPTION 1342 int subiter; 1343 #endif 1344 1345 /* 1346 * Sync filesystems for shutdown 1347 */ 1348 wdog_kern_pat(WD_LASTVAL); 1349 sys_sync(curthread, NULL); 1350 1351 /* 1352 * With soft updates, some buffers that are 1353 * written will be remarked as dirty until other 1354 * buffers are written. 1355 */ 1356 for (iter = pbusy = 0; iter < 20; iter++) { 1357 nbusy = 0; 1358 for (bp = &buf[nbuf]; --bp >= buf; ) 1359 if (isbufbusy(bp)) 1360 nbusy++; 1361 if (nbusy == 0) { 1362 if (first_buf_printf) 1363 printf("All buffers synced."); 1364 break; 1365 } 1366 if (first_buf_printf) { 1367 printf("Syncing disks, buffers remaining... "); 1368 first_buf_printf = 0; 1369 } 1370 printf("%d ", nbusy); 1371 if (nbusy < pbusy) 1372 iter = 0; 1373 pbusy = nbusy; 1374 1375 wdog_kern_pat(WD_LASTVAL); 1376 sys_sync(curthread, NULL); 1377 1378 #ifdef PREEMPTION 1379 /* 1380 * Spin for a while to allow interrupt threads to run. 1381 */ 1382 DELAY(50000 * iter); 1383 #else 1384 /* 1385 * Context switch several times to allow interrupt 1386 * threads to run. 1387 */ 1388 for (subiter = 0; subiter < 50 * iter; subiter++) { 1389 thread_lock(curthread); 1390 mi_switch(SW_VOL, NULL); 1391 thread_unlock(curthread); 1392 DELAY(1000); 1393 } 1394 #endif 1395 } 1396 printf("\n"); 1397 /* 1398 * Count only busy local buffers to prevent forcing 1399 * a fsck if we're just a client of a wedged NFS server 1400 */ 1401 nbusy = 0; 1402 for (bp = &buf[nbuf]; --bp >= buf; ) { 1403 if (isbufbusy(bp)) { 1404 #if 0 1405 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1406 if (bp->b_dev == NULL) { 1407 TAILQ_REMOVE(&mountlist, 1408 bp->b_vp->v_mount, mnt_list); 1409 continue; 1410 } 1411 #endif 1412 nbusy++; 1413 if (show_busybufs > 0) { 1414 printf( 1415 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1416 nbusy, bp, bp->b_vp, bp->b_flags, 1417 (intmax_t)bp->b_blkno, 1418 (intmax_t)bp->b_lblkno); 1419 BUF_LOCKPRINTINFO(bp); 1420 if (show_busybufs > 1) 1421 vn_printf(bp->b_vp, 1422 "vnode content: "); 1423 } 1424 } 1425 } 1426 if (nbusy) { 1427 /* 1428 * Failed to sync all blocks. Indicate this and don't 1429 * unmount filesystems (thus forcing an fsck on reboot). 1430 */ 1431 printf("Giving up on %d buffers\n", nbusy); 1432 DELAY(5000000); /* 5 seconds */ 1433 } else { 1434 if (!first_buf_printf) 1435 printf("Final sync complete\n"); 1436 /* 1437 * Unmount filesystems 1438 */ 1439 if (panicstr == NULL) 1440 vfs_unmountall(); 1441 } 1442 swapoff_all(); 1443 DELAY(100000); /* wait for console output to finish */ 1444 } 1445 1446 static void 1447 bpmap_qenter(struct buf *bp) 1448 { 1449 1450 BUF_CHECK_MAPPED(bp); 1451 1452 /* 1453 * bp->b_data is relative to bp->b_offset, but 1454 * bp->b_offset may be offset into the first page. 1455 */ 1456 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1457 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1458 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1459 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1460 } 1461 1462 static inline struct bufdomain * 1463 bufdomain(struct buf *bp) 1464 { 1465 1466 return (&bdomain[bp->b_domain]); 1467 } 1468 1469 static struct bufqueue * 1470 bufqueue(struct buf *bp) 1471 { 1472 1473 switch (bp->b_qindex) { 1474 case QUEUE_NONE: 1475 /* FALLTHROUGH */ 1476 case QUEUE_SENTINEL: 1477 return (NULL); 1478 case QUEUE_EMPTY: 1479 return (&bqempty); 1480 case QUEUE_DIRTY: 1481 return (&bufdomain(bp)->bd_dirtyq); 1482 case QUEUE_CLEAN: 1483 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]); 1484 default: 1485 break; 1486 } 1487 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex); 1488 } 1489 1490 /* 1491 * Return the locked bufqueue that bp is a member of. 1492 */ 1493 static struct bufqueue * 1494 bufqueue_acquire(struct buf *bp) 1495 { 1496 struct bufqueue *bq, *nbq; 1497 1498 /* 1499 * bp can be pushed from a per-cpu queue to the 1500 * cleanq while we're waiting on the lock. Retry 1501 * if the queues don't match. 1502 */ 1503 bq = bufqueue(bp); 1504 BQ_LOCK(bq); 1505 for (;;) { 1506 nbq = bufqueue(bp); 1507 if (bq == nbq) 1508 break; 1509 BQ_UNLOCK(bq); 1510 BQ_LOCK(nbq); 1511 bq = nbq; 1512 } 1513 return (bq); 1514 } 1515 1516 /* 1517 * binsfree: 1518 * 1519 * Insert the buffer into the appropriate free list. Requires a 1520 * locked buffer on entry and buffer is unlocked before return. 1521 */ 1522 static void 1523 binsfree(struct buf *bp, int qindex) 1524 { 1525 struct bufdomain *bd; 1526 struct bufqueue *bq; 1527 1528 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY, 1529 ("binsfree: Invalid qindex %d", qindex)); 1530 BUF_ASSERT_XLOCKED(bp); 1531 1532 /* 1533 * Handle delayed bremfree() processing. 1534 */ 1535 if (bp->b_flags & B_REMFREE) { 1536 if (bp->b_qindex == qindex) { 1537 bp->b_flags |= B_REUSE; 1538 bp->b_flags &= ~B_REMFREE; 1539 BUF_UNLOCK(bp); 1540 return; 1541 } 1542 bq = bufqueue_acquire(bp); 1543 bq_remove(bq, bp); 1544 BQ_UNLOCK(bq); 1545 } 1546 bd = bufdomain(bp); 1547 if (qindex == QUEUE_CLEAN) { 1548 if (bd->bd_lim != 0) 1549 bq = &bd->bd_subq[PCPU_GET(cpuid)]; 1550 else 1551 bq = bd->bd_cleanq; 1552 } else 1553 bq = &bd->bd_dirtyq; 1554 bq_insert(bq, bp, true); 1555 } 1556 1557 /* 1558 * buf_free: 1559 * 1560 * Free a buffer to the buf zone once it no longer has valid contents. 1561 */ 1562 static void 1563 buf_free(struct buf *bp) 1564 { 1565 1566 if (bp->b_flags & B_REMFREE) 1567 bremfreef(bp); 1568 if (bp->b_vflags & BV_BKGRDINPROG) 1569 panic("losing buffer 1"); 1570 if (bp->b_rcred != NOCRED) { 1571 crfree(bp->b_rcred); 1572 bp->b_rcred = NOCRED; 1573 } 1574 if (bp->b_wcred != NOCRED) { 1575 crfree(bp->b_wcred); 1576 bp->b_wcred = NOCRED; 1577 } 1578 if (!LIST_EMPTY(&bp->b_dep)) 1579 buf_deallocate(bp); 1580 bufkva_free(bp); 1581 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1); 1582 BUF_UNLOCK(bp); 1583 uma_zfree(buf_zone, bp); 1584 } 1585 1586 /* 1587 * buf_import: 1588 * 1589 * Import bufs into the uma cache from the buf list. The system still 1590 * expects a static array of bufs and much of the synchronization 1591 * around bufs assumes type stable storage. As a result, UMA is used 1592 * only as a per-cpu cache of bufs still maintained on a global list. 1593 */ 1594 static int 1595 buf_import(void *arg, void **store, int cnt, int domain, int flags) 1596 { 1597 struct buf *bp; 1598 int i; 1599 1600 BQ_LOCK(&bqempty); 1601 for (i = 0; i < cnt; i++) { 1602 bp = TAILQ_FIRST(&bqempty.bq_queue); 1603 if (bp == NULL) 1604 break; 1605 bq_remove(&bqempty, bp); 1606 store[i] = bp; 1607 } 1608 BQ_UNLOCK(&bqempty); 1609 1610 return (i); 1611 } 1612 1613 /* 1614 * buf_release: 1615 * 1616 * Release bufs from the uma cache back to the buffer queues. 1617 */ 1618 static void 1619 buf_release(void *arg, void **store, int cnt) 1620 { 1621 struct bufqueue *bq; 1622 struct buf *bp; 1623 int i; 1624 1625 bq = &bqempty; 1626 BQ_LOCK(bq); 1627 for (i = 0; i < cnt; i++) { 1628 bp = store[i]; 1629 /* Inline bq_insert() to batch locking. */ 1630 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1631 bp->b_flags &= ~(B_AGE | B_REUSE); 1632 bq->bq_len++; 1633 bp->b_qindex = bq->bq_index; 1634 } 1635 BQ_UNLOCK(bq); 1636 } 1637 1638 /* 1639 * buf_alloc: 1640 * 1641 * Allocate an empty buffer header. 1642 */ 1643 static struct buf * 1644 buf_alloc(struct bufdomain *bd) 1645 { 1646 struct buf *bp; 1647 int freebufs; 1648 1649 /* 1650 * We can only run out of bufs in the buf zone if the average buf 1651 * is less than BKVASIZE. In this case the actual wait/block will 1652 * come from buf_reycle() failing to flush one of these small bufs. 1653 */ 1654 bp = NULL; 1655 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1); 1656 if (freebufs > 0) 1657 bp = uma_zalloc(buf_zone, M_NOWAIT); 1658 if (bp == NULL) { 1659 atomic_fetchadd_int(&bd->bd_freebuffers, 1); 1660 bufspace_daemon_wakeup(bd); 1661 counter_u64_add(numbufallocfails, 1); 1662 return (NULL); 1663 } 1664 /* 1665 * Wake-up the bufspace daemon on transition below threshold. 1666 */ 1667 if (freebufs == bd->bd_lofreebuffers) 1668 bufspace_daemon_wakeup(bd); 1669 1670 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1671 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1672 1673 KASSERT(bp->b_vp == NULL, 1674 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1675 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1676 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1677 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1678 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1679 KASSERT(bp->b_npages == 0, 1680 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1681 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1682 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1683 1684 bp->b_domain = BD_DOMAIN(bd); 1685 bp->b_flags = 0; 1686 bp->b_ioflags = 0; 1687 bp->b_xflags = 0; 1688 bp->b_vflags = 0; 1689 bp->b_vp = NULL; 1690 bp->b_blkno = bp->b_lblkno = 0; 1691 bp->b_offset = NOOFFSET; 1692 bp->b_iodone = 0; 1693 bp->b_error = 0; 1694 bp->b_resid = 0; 1695 bp->b_bcount = 0; 1696 bp->b_npages = 0; 1697 bp->b_dirtyoff = bp->b_dirtyend = 0; 1698 bp->b_bufobj = NULL; 1699 bp->b_data = bp->b_kvabase = unmapped_buf; 1700 bp->b_fsprivate1 = NULL; 1701 bp->b_fsprivate2 = NULL; 1702 bp->b_fsprivate3 = NULL; 1703 LIST_INIT(&bp->b_dep); 1704 1705 return (bp); 1706 } 1707 1708 /* 1709 * buf_recycle: 1710 * 1711 * Free a buffer from the given bufqueue. kva controls whether the 1712 * freed buf must own some kva resources. This is used for 1713 * defragmenting. 1714 */ 1715 static int 1716 buf_recycle(struct bufdomain *bd, bool kva) 1717 { 1718 struct bufqueue *bq; 1719 struct buf *bp, *nbp; 1720 1721 if (kva) 1722 counter_u64_add(bufdefragcnt, 1); 1723 nbp = NULL; 1724 bq = bd->bd_cleanq; 1725 BQ_LOCK(bq); 1726 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd), 1727 ("buf_recycle: Locks don't match")); 1728 nbp = TAILQ_FIRST(&bq->bq_queue); 1729 1730 /* 1731 * Run scan, possibly freeing data and/or kva mappings on the fly 1732 * depending. 1733 */ 1734 while ((bp = nbp) != NULL) { 1735 /* 1736 * Calculate next bp (we can only use it if we do not 1737 * release the bqlock). 1738 */ 1739 nbp = TAILQ_NEXT(bp, b_freelist); 1740 1741 /* 1742 * If we are defragging then we need a buffer with 1743 * some kva to reclaim. 1744 */ 1745 if (kva && bp->b_kvasize == 0) 1746 continue; 1747 1748 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1749 continue; 1750 1751 /* 1752 * Implement a second chance algorithm for frequently 1753 * accessed buffers. 1754 */ 1755 if ((bp->b_flags & B_REUSE) != 0) { 1756 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1757 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1758 bp->b_flags &= ~B_REUSE; 1759 BUF_UNLOCK(bp); 1760 continue; 1761 } 1762 1763 /* 1764 * Skip buffers with background writes in progress. 1765 */ 1766 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1767 BUF_UNLOCK(bp); 1768 continue; 1769 } 1770 1771 KASSERT(bp->b_qindex == QUEUE_CLEAN, 1772 ("buf_recycle: inconsistent queue %d bp %p", 1773 bp->b_qindex, bp)); 1774 KASSERT(bp->b_domain == BD_DOMAIN(bd), 1775 ("getnewbuf: queue domain %d doesn't match request %d", 1776 bp->b_domain, (int)BD_DOMAIN(bd))); 1777 /* 1778 * NOTE: nbp is now entirely invalid. We can only restart 1779 * the scan from this point on. 1780 */ 1781 bq_remove(bq, bp); 1782 BQ_UNLOCK(bq); 1783 1784 /* 1785 * Requeue the background write buffer with error and 1786 * restart the scan. 1787 */ 1788 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1789 bqrelse(bp); 1790 BQ_LOCK(bq); 1791 nbp = TAILQ_FIRST(&bq->bq_queue); 1792 continue; 1793 } 1794 bp->b_flags |= B_INVAL; 1795 brelse(bp); 1796 return (0); 1797 } 1798 bd->bd_wanted = 1; 1799 BQ_UNLOCK(bq); 1800 1801 return (ENOBUFS); 1802 } 1803 1804 /* 1805 * bremfree: 1806 * 1807 * Mark the buffer for removal from the appropriate free list. 1808 * 1809 */ 1810 void 1811 bremfree(struct buf *bp) 1812 { 1813 1814 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1815 KASSERT((bp->b_flags & B_REMFREE) == 0, 1816 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1817 KASSERT(bp->b_qindex != QUEUE_NONE, 1818 ("bremfree: buffer %p not on a queue.", bp)); 1819 BUF_ASSERT_XLOCKED(bp); 1820 1821 bp->b_flags |= B_REMFREE; 1822 } 1823 1824 /* 1825 * bremfreef: 1826 * 1827 * Force an immediate removal from a free list. Used only in nfs when 1828 * it abuses the b_freelist pointer. 1829 */ 1830 void 1831 bremfreef(struct buf *bp) 1832 { 1833 struct bufqueue *bq; 1834 1835 bq = bufqueue_acquire(bp); 1836 bq_remove(bq, bp); 1837 BQ_UNLOCK(bq); 1838 } 1839 1840 static void 1841 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname) 1842 { 1843 1844 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF); 1845 TAILQ_INIT(&bq->bq_queue); 1846 bq->bq_len = 0; 1847 bq->bq_index = qindex; 1848 bq->bq_subqueue = subqueue; 1849 } 1850 1851 static void 1852 bd_init(struct bufdomain *bd) 1853 { 1854 int i; 1855 1856 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1]; 1857 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock"); 1858 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock"); 1859 for (i = 0; i <= mp_maxid; i++) 1860 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i, 1861 "bufq clean subqueue lock"); 1862 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF); 1863 } 1864 1865 /* 1866 * bq_remove: 1867 * 1868 * Removes a buffer from the free list, must be called with the 1869 * correct qlock held. 1870 */ 1871 static void 1872 bq_remove(struct bufqueue *bq, struct buf *bp) 1873 { 1874 1875 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X", 1876 bp, bp->b_vp, bp->b_flags); 1877 KASSERT(bp->b_qindex != QUEUE_NONE, 1878 ("bq_remove: buffer %p not on a queue.", bp)); 1879 KASSERT(bufqueue(bp) == bq, 1880 ("bq_remove: Remove buffer %p from wrong queue.", bp)); 1881 1882 BQ_ASSERT_LOCKED(bq); 1883 if (bp->b_qindex != QUEUE_EMPTY) { 1884 BUF_ASSERT_XLOCKED(bp); 1885 } 1886 KASSERT(bq->bq_len >= 1, 1887 ("queue %d underflow", bp->b_qindex)); 1888 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1889 bq->bq_len--; 1890 bp->b_qindex = QUEUE_NONE; 1891 bp->b_flags &= ~(B_REMFREE | B_REUSE); 1892 } 1893 1894 static void 1895 bd_flush(struct bufdomain *bd, struct bufqueue *bq) 1896 { 1897 struct buf *bp; 1898 1899 BQ_ASSERT_LOCKED(bq); 1900 if (bq != bd->bd_cleanq) { 1901 BD_LOCK(bd); 1902 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) { 1903 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1904 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp, 1905 b_freelist); 1906 bp->b_subqueue = bd->bd_cleanq->bq_subqueue; 1907 } 1908 bd->bd_cleanq->bq_len += bq->bq_len; 1909 bq->bq_len = 0; 1910 } 1911 if (bd->bd_wanted) { 1912 bd->bd_wanted = 0; 1913 wakeup(&bd->bd_wanted); 1914 } 1915 if (bq != bd->bd_cleanq) 1916 BD_UNLOCK(bd); 1917 } 1918 1919 static int 1920 bd_flushall(struct bufdomain *bd) 1921 { 1922 struct bufqueue *bq; 1923 int flushed; 1924 int i; 1925 1926 if (bd->bd_lim == 0) 1927 return (0); 1928 flushed = 0; 1929 for (i = 0; i <= mp_maxid; i++) { 1930 bq = &bd->bd_subq[i]; 1931 if (bq->bq_len == 0) 1932 continue; 1933 BQ_LOCK(bq); 1934 bd_flush(bd, bq); 1935 BQ_UNLOCK(bq); 1936 flushed++; 1937 } 1938 1939 return (flushed); 1940 } 1941 1942 static void 1943 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock) 1944 { 1945 struct bufdomain *bd; 1946 1947 if (bp->b_qindex != QUEUE_NONE) 1948 panic("bq_insert: free buffer %p onto another queue?", bp); 1949 1950 bd = bufdomain(bp); 1951 if (bp->b_flags & B_AGE) { 1952 /* Place this buf directly on the real queue. */ 1953 if (bq->bq_index == QUEUE_CLEAN) 1954 bq = bd->bd_cleanq; 1955 BQ_LOCK(bq); 1956 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist); 1957 } else { 1958 BQ_LOCK(bq); 1959 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1960 } 1961 bp->b_flags &= ~(B_AGE | B_REUSE); 1962 bq->bq_len++; 1963 bp->b_qindex = bq->bq_index; 1964 bp->b_subqueue = bq->bq_subqueue; 1965 1966 /* 1967 * Unlock before we notify so that we don't wakeup a waiter that 1968 * fails a trylock on the buf and sleeps again. 1969 */ 1970 if (unlock) 1971 BUF_UNLOCK(bp); 1972 1973 if (bp->b_qindex == QUEUE_CLEAN) { 1974 /* 1975 * Flush the per-cpu queue and notify any waiters. 1976 */ 1977 if (bd->bd_wanted || (bq != bd->bd_cleanq && 1978 bq->bq_len >= bd->bd_lim)) 1979 bd_flush(bd, bq); 1980 } 1981 BQ_UNLOCK(bq); 1982 } 1983 1984 /* 1985 * bufkva_free: 1986 * 1987 * Free the kva allocation for a buffer. 1988 * 1989 */ 1990 static void 1991 bufkva_free(struct buf *bp) 1992 { 1993 1994 #ifdef INVARIANTS 1995 if (bp->b_kvasize == 0) { 1996 KASSERT(bp->b_kvabase == unmapped_buf && 1997 bp->b_data == unmapped_buf, 1998 ("Leaked KVA space on %p", bp)); 1999 } else if (buf_mapped(bp)) 2000 BUF_CHECK_MAPPED(bp); 2001 else 2002 BUF_CHECK_UNMAPPED(bp); 2003 #endif 2004 if (bp->b_kvasize == 0) 2005 return; 2006 2007 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 2008 counter_u64_add(bufkvaspace, -bp->b_kvasize); 2009 counter_u64_add(buffreekvacnt, 1); 2010 bp->b_data = bp->b_kvabase = unmapped_buf; 2011 bp->b_kvasize = 0; 2012 } 2013 2014 /* 2015 * bufkva_alloc: 2016 * 2017 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 2018 */ 2019 static int 2020 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 2021 { 2022 vm_offset_t addr; 2023 int error; 2024 2025 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 2026 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 2027 2028 bufkva_free(bp); 2029 2030 addr = 0; 2031 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 2032 if (error != 0) { 2033 /* 2034 * Buffer map is too fragmented. Request the caller 2035 * to defragment the map. 2036 */ 2037 return (error); 2038 } 2039 bp->b_kvabase = (caddr_t)addr; 2040 bp->b_kvasize = maxsize; 2041 counter_u64_add(bufkvaspace, bp->b_kvasize); 2042 if ((gbflags & GB_UNMAPPED) != 0) { 2043 bp->b_data = unmapped_buf; 2044 BUF_CHECK_UNMAPPED(bp); 2045 } else { 2046 bp->b_data = bp->b_kvabase; 2047 BUF_CHECK_MAPPED(bp); 2048 } 2049 return (0); 2050 } 2051 2052 /* 2053 * bufkva_reclaim: 2054 * 2055 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 2056 * callback that fires to avoid returning failure. 2057 */ 2058 static void 2059 bufkva_reclaim(vmem_t *vmem, int flags) 2060 { 2061 bool done; 2062 int q; 2063 int i; 2064 2065 done = false; 2066 for (i = 0; i < 5; i++) { 2067 for (q = 0; q < buf_domains; q++) 2068 if (buf_recycle(&bdomain[q], true) != 0) 2069 done = true; 2070 if (done) 2071 break; 2072 } 2073 return; 2074 } 2075 2076 /* 2077 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 2078 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 2079 * the buffer is valid and we do not have to do anything. 2080 */ 2081 static void 2082 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt, 2083 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *)) 2084 { 2085 struct buf *rabp; 2086 int i; 2087 2088 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 2089 if (inmem(vp, *rablkno)) 2090 continue; 2091 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 2092 if ((rabp->b_flags & B_CACHE) != 0) { 2093 brelse(rabp); 2094 continue; 2095 } 2096 if (!TD_IS_IDLETHREAD(curthread)) { 2097 #ifdef RACCT 2098 if (racct_enable) { 2099 PROC_LOCK(curproc); 2100 racct_add_buf(curproc, rabp, 0); 2101 PROC_UNLOCK(curproc); 2102 } 2103 #endif /* RACCT */ 2104 curthread->td_ru.ru_inblock++; 2105 } 2106 rabp->b_flags |= B_ASYNC; 2107 rabp->b_flags &= ~B_INVAL; 2108 if ((flags & GB_CKHASH) != 0) { 2109 rabp->b_flags |= B_CKHASH; 2110 rabp->b_ckhashcalc = ckhashfunc; 2111 } 2112 rabp->b_ioflags &= ~BIO_ERROR; 2113 rabp->b_iocmd = BIO_READ; 2114 if (rabp->b_rcred == NOCRED && cred != NOCRED) 2115 rabp->b_rcred = crhold(cred); 2116 vfs_busy_pages(rabp, 0); 2117 BUF_KERNPROC(rabp); 2118 rabp->b_iooffset = dbtob(rabp->b_blkno); 2119 bstrategy(rabp); 2120 } 2121 } 2122 2123 /* 2124 * Entry point for bread() and breadn() via #defines in sys/buf.h. 2125 * 2126 * Get a buffer with the specified data. Look in the cache first. We 2127 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 2128 * is set, the buffer is valid and we do not have to do anything, see 2129 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 2130 * 2131 * Always return a NULL buffer pointer (in bpp) when returning an error. 2132 */ 2133 int 2134 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 2135 int *rabsize, int cnt, struct ucred *cred, int flags, 2136 void (*ckhashfunc)(struct buf *), struct buf **bpp) 2137 { 2138 struct buf *bp; 2139 struct thread *td; 2140 int error, readwait, rv; 2141 2142 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 2143 td = curthread; 2144 /* 2145 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags 2146 * are specified. 2147 */ 2148 error = getblkx(vp, blkno, size, 0, 0, flags, &bp); 2149 if (error != 0) { 2150 *bpp = NULL; 2151 return (error); 2152 } 2153 flags &= ~GB_NOSPARSE; 2154 *bpp = bp; 2155 2156 /* 2157 * If not found in cache, do some I/O 2158 */ 2159 readwait = 0; 2160 if ((bp->b_flags & B_CACHE) == 0) { 2161 if (!TD_IS_IDLETHREAD(td)) { 2162 #ifdef RACCT 2163 if (racct_enable) { 2164 PROC_LOCK(td->td_proc); 2165 racct_add_buf(td->td_proc, bp, 0); 2166 PROC_UNLOCK(td->td_proc); 2167 } 2168 #endif /* RACCT */ 2169 td->td_ru.ru_inblock++; 2170 } 2171 bp->b_iocmd = BIO_READ; 2172 bp->b_flags &= ~B_INVAL; 2173 if ((flags & GB_CKHASH) != 0) { 2174 bp->b_flags |= B_CKHASH; 2175 bp->b_ckhashcalc = ckhashfunc; 2176 } 2177 bp->b_ioflags &= ~BIO_ERROR; 2178 if (bp->b_rcred == NOCRED && cred != NOCRED) 2179 bp->b_rcred = crhold(cred); 2180 vfs_busy_pages(bp, 0); 2181 bp->b_iooffset = dbtob(bp->b_blkno); 2182 bstrategy(bp); 2183 ++readwait; 2184 } 2185 2186 /* 2187 * Attempt to initiate asynchronous I/O on read-ahead blocks. 2188 */ 2189 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 2190 2191 rv = 0; 2192 if (readwait) { 2193 rv = bufwait(bp); 2194 if (rv != 0) { 2195 brelse(bp); 2196 *bpp = NULL; 2197 } 2198 } 2199 return (rv); 2200 } 2201 2202 /* 2203 * Write, release buffer on completion. (Done by iodone 2204 * if async). Do not bother writing anything if the buffer 2205 * is invalid. 2206 * 2207 * Note that we set B_CACHE here, indicating that buffer is 2208 * fully valid and thus cacheable. This is true even of NFS 2209 * now so we set it generally. This could be set either here 2210 * or in biodone() since the I/O is synchronous. We put it 2211 * here. 2212 */ 2213 int 2214 bufwrite(struct buf *bp) 2215 { 2216 int oldflags; 2217 struct vnode *vp; 2218 long space; 2219 int vp_md; 2220 2221 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2222 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 2223 bp->b_flags |= B_INVAL | B_RELBUF; 2224 bp->b_flags &= ~B_CACHE; 2225 brelse(bp); 2226 return (ENXIO); 2227 } 2228 if (bp->b_flags & B_INVAL) { 2229 brelse(bp); 2230 return (0); 2231 } 2232 2233 if (bp->b_flags & B_BARRIER) 2234 barrierwrites++; 2235 2236 oldflags = bp->b_flags; 2237 2238 BUF_ASSERT_HELD(bp); 2239 2240 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 2241 ("FFS background buffer should not get here %p", bp)); 2242 2243 vp = bp->b_vp; 2244 if (vp) 2245 vp_md = vp->v_vflag & VV_MD; 2246 else 2247 vp_md = 0; 2248 2249 /* 2250 * Mark the buffer clean. Increment the bufobj write count 2251 * before bundirty() call, to prevent other thread from seeing 2252 * empty dirty list and zero counter for writes in progress, 2253 * falsely indicating that the bufobj is clean. 2254 */ 2255 bufobj_wref(bp->b_bufobj); 2256 bundirty(bp); 2257 2258 bp->b_flags &= ~B_DONE; 2259 bp->b_ioflags &= ~BIO_ERROR; 2260 bp->b_flags |= B_CACHE; 2261 bp->b_iocmd = BIO_WRITE; 2262 2263 vfs_busy_pages(bp, 1); 2264 2265 /* 2266 * Normal bwrites pipeline writes 2267 */ 2268 bp->b_runningbufspace = bp->b_bufsize; 2269 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 2270 2271 if (!TD_IS_IDLETHREAD(curthread)) { 2272 #ifdef RACCT 2273 if (racct_enable) { 2274 PROC_LOCK(curproc); 2275 racct_add_buf(curproc, bp, 1); 2276 PROC_UNLOCK(curproc); 2277 } 2278 #endif /* RACCT */ 2279 curthread->td_ru.ru_oublock++; 2280 } 2281 if (oldflags & B_ASYNC) 2282 BUF_KERNPROC(bp); 2283 bp->b_iooffset = dbtob(bp->b_blkno); 2284 buf_track(bp, __func__); 2285 bstrategy(bp); 2286 2287 if ((oldflags & B_ASYNC) == 0) { 2288 int rtval = bufwait(bp); 2289 brelse(bp); 2290 return (rtval); 2291 } else if (space > hirunningspace) { 2292 /* 2293 * don't allow the async write to saturate the I/O 2294 * system. We will not deadlock here because 2295 * we are blocking waiting for I/O that is already in-progress 2296 * to complete. We do not block here if it is the update 2297 * or syncer daemon trying to clean up as that can lead 2298 * to deadlock. 2299 */ 2300 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2301 waitrunningbufspace(); 2302 } 2303 2304 return (0); 2305 } 2306 2307 void 2308 bufbdflush(struct bufobj *bo, struct buf *bp) 2309 { 2310 struct buf *nbp; 2311 2312 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 2313 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2314 altbufferflushes++; 2315 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 2316 BO_LOCK(bo); 2317 /* 2318 * Try to find a buffer to flush. 2319 */ 2320 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2321 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2322 BUF_LOCK(nbp, 2323 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2324 continue; 2325 if (bp == nbp) 2326 panic("bdwrite: found ourselves"); 2327 BO_UNLOCK(bo); 2328 /* Don't countdeps with the bo lock held. */ 2329 if (buf_countdeps(nbp, 0)) { 2330 BO_LOCK(bo); 2331 BUF_UNLOCK(nbp); 2332 continue; 2333 } 2334 if (nbp->b_flags & B_CLUSTEROK) { 2335 vfs_bio_awrite(nbp); 2336 } else { 2337 bremfree(nbp); 2338 bawrite(nbp); 2339 } 2340 dirtybufferflushes++; 2341 break; 2342 } 2343 if (nbp == NULL) 2344 BO_UNLOCK(bo); 2345 } 2346 } 2347 2348 /* 2349 * Delayed write. (Buffer is marked dirty). Do not bother writing 2350 * anything if the buffer is marked invalid. 2351 * 2352 * Note that since the buffer must be completely valid, we can safely 2353 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2354 * biodone() in order to prevent getblk from writing the buffer 2355 * out synchronously. 2356 */ 2357 void 2358 bdwrite(struct buf *bp) 2359 { 2360 struct thread *td = curthread; 2361 struct vnode *vp; 2362 struct bufobj *bo; 2363 2364 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2365 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2366 KASSERT((bp->b_flags & B_BARRIER) == 0, 2367 ("Barrier request in delayed write %p", bp)); 2368 BUF_ASSERT_HELD(bp); 2369 2370 if (bp->b_flags & B_INVAL) { 2371 brelse(bp); 2372 return; 2373 } 2374 2375 /* 2376 * If we have too many dirty buffers, don't create any more. 2377 * If we are wildly over our limit, then force a complete 2378 * cleanup. Otherwise, just keep the situation from getting 2379 * out of control. Note that we have to avoid a recursive 2380 * disaster and not try to clean up after our own cleanup! 2381 */ 2382 vp = bp->b_vp; 2383 bo = bp->b_bufobj; 2384 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2385 td->td_pflags |= TDP_INBDFLUSH; 2386 BO_BDFLUSH(bo, bp); 2387 td->td_pflags &= ~TDP_INBDFLUSH; 2388 } else 2389 recursiveflushes++; 2390 2391 bdirty(bp); 2392 /* 2393 * Set B_CACHE, indicating that the buffer is fully valid. This is 2394 * true even of NFS now. 2395 */ 2396 bp->b_flags |= B_CACHE; 2397 2398 /* 2399 * This bmap keeps the system from needing to do the bmap later, 2400 * perhaps when the system is attempting to do a sync. Since it 2401 * is likely that the indirect block -- or whatever other datastructure 2402 * that the filesystem needs is still in memory now, it is a good 2403 * thing to do this. Note also, that if the pageout daemon is 2404 * requesting a sync -- there might not be enough memory to do 2405 * the bmap then... So, this is important to do. 2406 */ 2407 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2408 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2409 } 2410 2411 buf_track(bp, __func__); 2412 2413 /* 2414 * Set the *dirty* buffer range based upon the VM system dirty 2415 * pages. 2416 * 2417 * Mark the buffer pages as clean. We need to do this here to 2418 * satisfy the vnode_pager and the pageout daemon, so that it 2419 * thinks that the pages have been "cleaned". Note that since 2420 * the pages are in a delayed write buffer -- the VFS layer 2421 * "will" see that the pages get written out on the next sync, 2422 * or perhaps the cluster will be completed. 2423 */ 2424 vfs_clean_pages_dirty_buf(bp); 2425 bqrelse(bp); 2426 2427 /* 2428 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2429 * due to the softdep code. 2430 */ 2431 } 2432 2433 /* 2434 * bdirty: 2435 * 2436 * Turn buffer into delayed write request. We must clear BIO_READ and 2437 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2438 * itself to properly update it in the dirty/clean lists. We mark it 2439 * B_DONE to ensure that any asynchronization of the buffer properly 2440 * clears B_DONE ( else a panic will occur later ). 2441 * 2442 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2443 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2444 * should only be called if the buffer is known-good. 2445 * 2446 * Since the buffer is not on a queue, we do not update the numfreebuffers 2447 * count. 2448 * 2449 * The buffer must be on QUEUE_NONE. 2450 */ 2451 void 2452 bdirty(struct buf *bp) 2453 { 2454 2455 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2456 bp, bp->b_vp, bp->b_flags); 2457 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2458 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2459 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2460 BUF_ASSERT_HELD(bp); 2461 bp->b_flags &= ~(B_RELBUF); 2462 bp->b_iocmd = BIO_WRITE; 2463 2464 if ((bp->b_flags & B_DELWRI) == 0) { 2465 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2466 reassignbuf(bp); 2467 bdirtyadd(bp); 2468 } 2469 } 2470 2471 /* 2472 * bundirty: 2473 * 2474 * Clear B_DELWRI for buffer. 2475 * 2476 * Since the buffer is not on a queue, we do not update the numfreebuffers 2477 * count. 2478 * 2479 * The buffer must be on QUEUE_NONE. 2480 */ 2481 2482 void 2483 bundirty(struct buf *bp) 2484 { 2485 2486 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2487 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2488 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2489 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2490 BUF_ASSERT_HELD(bp); 2491 2492 if (bp->b_flags & B_DELWRI) { 2493 bp->b_flags &= ~B_DELWRI; 2494 reassignbuf(bp); 2495 bdirtysub(bp); 2496 } 2497 /* 2498 * Since it is now being written, we can clear its deferred write flag. 2499 */ 2500 bp->b_flags &= ~B_DEFERRED; 2501 } 2502 2503 /* 2504 * bawrite: 2505 * 2506 * Asynchronous write. Start output on a buffer, but do not wait for 2507 * it to complete. The buffer is released when the output completes. 2508 * 2509 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2510 * B_INVAL buffers. Not us. 2511 */ 2512 void 2513 bawrite(struct buf *bp) 2514 { 2515 2516 bp->b_flags |= B_ASYNC; 2517 (void) bwrite(bp); 2518 } 2519 2520 /* 2521 * babarrierwrite: 2522 * 2523 * Asynchronous barrier write. Start output on a buffer, but do not 2524 * wait for it to complete. Place a write barrier after this write so 2525 * that this buffer and all buffers written before it are committed to 2526 * the disk before any buffers written after this write are committed 2527 * to the disk. The buffer is released when the output completes. 2528 */ 2529 void 2530 babarrierwrite(struct buf *bp) 2531 { 2532 2533 bp->b_flags |= B_ASYNC | B_BARRIER; 2534 (void) bwrite(bp); 2535 } 2536 2537 /* 2538 * bbarrierwrite: 2539 * 2540 * Synchronous barrier write. Start output on a buffer and wait for 2541 * it to complete. Place a write barrier after this write so that 2542 * this buffer and all buffers written before it are committed to 2543 * the disk before any buffers written after this write are committed 2544 * to the disk. The buffer is released when the output completes. 2545 */ 2546 int 2547 bbarrierwrite(struct buf *bp) 2548 { 2549 2550 bp->b_flags |= B_BARRIER; 2551 return (bwrite(bp)); 2552 } 2553 2554 /* 2555 * bwillwrite: 2556 * 2557 * Called prior to the locking of any vnodes when we are expecting to 2558 * write. We do not want to starve the buffer cache with too many 2559 * dirty buffers so we block here. By blocking prior to the locking 2560 * of any vnodes we attempt to avoid the situation where a locked vnode 2561 * prevents the various system daemons from flushing related buffers. 2562 */ 2563 void 2564 bwillwrite(void) 2565 { 2566 2567 if (buf_dirty_count_severe()) { 2568 mtx_lock(&bdirtylock); 2569 while (buf_dirty_count_severe()) { 2570 bdirtywait = 1; 2571 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2572 "flswai", 0); 2573 } 2574 mtx_unlock(&bdirtylock); 2575 } 2576 } 2577 2578 /* 2579 * Return true if we have too many dirty buffers. 2580 */ 2581 int 2582 buf_dirty_count_severe(void) 2583 { 2584 2585 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty)); 2586 } 2587 2588 /* 2589 * brelse: 2590 * 2591 * Release a busy buffer and, if requested, free its resources. The 2592 * buffer will be stashed in the appropriate bufqueue[] allowing it 2593 * to be accessed later as a cache entity or reused for other purposes. 2594 */ 2595 void 2596 brelse(struct buf *bp) 2597 { 2598 struct mount *v_mnt; 2599 int qindex; 2600 2601 /* 2602 * Many functions erroneously call brelse with a NULL bp under rare 2603 * error conditions. Simply return when called with a NULL bp. 2604 */ 2605 if (bp == NULL) 2606 return; 2607 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2608 bp, bp->b_vp, bp->b_flags); 2609 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2610 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2611 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2612 ("brelse: non-VMIO buffer marked NOREUSE")); 2613 2614 if (BUF_LOCKRECURSED(bp)) { 2615 /* 2616 * Do not process, in particular, do not handle the 2617 * B_INVAL/B_RELBUF and do not release to free list. 2618 */ 2619 BUF_UNLOCK(bp); 2620 return; 2621 } 2622 2623 if (bp->b_flags & B_MANAGED) { 2624 bqrelse(bp); 2625 return; 2626 } 2627 2628 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2629 BO_LOCK(bp->b_bufobj); 2630 bp->b_vflags &= ~BV_BKGRDERR; 2631 BO_UNLOCK(bp->b_bufobj); 2632 bdirty(bp); 2633 } 2634 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2635 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2636 !(bp->b_flags & B_INVAL)) { 2637 /* 2638 * Failed write, redirty. All errors except ENXIO (which 2639 * means the device is gone) are treated as being 2640 * transient. 2641 * 2642 * XXX Treating EIO as transient is not correct; the 2643 * contract with the local storage device drivers is that 2644 * they will only return EIO once the I/O is no longer 2645 * retriable. Network I/O also respects this through the 2646 * guarantees of TCP and/or the internal retries of NFS. 2647 * ENOMEM might be transient, but we also have no way of 2648 * knowing when its ok to retry/reschedule. In general, 2649 * this entire case should be made obsolete through better 2650 * error handling/recovery and resource scheduling. 2651 * 2652 * Do this also for buffers that failed with ENXIO, but have 2653 * non-empty dependencies - the soft updates code might need 2654 * to access the buffer to untangle them. 2655 * 2656 * Must clear BIO_ERROR to prevent pages from being scrapped. 2657 */ 2658 bp->b_ioflags &= ~BIO_ERROR; 2659 bdirty(bp); 2660 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2661 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2662 /* 2663 * Either a failed read I/O, or we were asked to free or not 2664 * cache the buffer, or we failed to write to a device that's 2665 * no longer present. 2666 */ 2667 bp->b_flags |= B_INVAL; 2668 if (!LIST_EMPTY(&bp->b_dep)) 2669 buf_deallocate(bp); 2670 if (bp->b_flags & B_DELWRI) 2671 bdirtysub(bp); 2672 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2673 if ((bp->b_flags & B_VMIO) == 0) { 2674 allocbuf(bp, 0); 2675 if (bp->b_vp) 2676 brelvp(bp); 2677 } 2678 } 2679 2680 /* 2681 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2682 * is called with B_DELWRI set, the underlying pages may wind up 2683 * getting freed causing a previous write (bdwrite()) to get 'lost' 2684 * because pages associated with a B_DELWRI bp are marked clean. 2685 * 2686 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2687 * if B_DELWRI is set. 2688 */ 2689 if (bp->b_flags & B_DELWRI) 2690 bp->b_flags &= ~B_RELBUF; 2691 2692 /* 2693 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2694 * constituted, not even NFS buffers now. Two flags effect this. If 2695 * B_INVAL, the struct buf is invalidated but the VM object is kept 2696 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2697 * 2698 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2699 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2700 * buffer is also B_INVAL because it hits the re-dirtying code above. 2701 * 2702 * Normally we can do this whether a buffer is B_DELWRI or not. If 2703 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2704 * the commit state and we cannot afford to lose the buffer. If the 2705 * buffer has a background write in progress, we need to keep it 2706 * around to prevent it from being reconstituted and starting a second 2707 * background write. 2708 */ 2709 2710 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL; 2711 2712 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2713 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2714 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 || 2715 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) { 2716 vfs_vmio_invalidate(bp); 2717 allocbuf(bp, 0); 2718 } 2719 2720 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2721 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2722 allocbuf(bp, 0); 2723 bp->b_flags &= ~B_NOREUSE; 2724 if (bp->b_vp != NULL) 2725 brelvp(bp); 2726 } 2727 2728 /* 2729 * If the buffer has junk contents signal it and eventually 2730 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2731 * doesn't find it. 2732 */ 2733 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2734 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2735 bp->b_flags |= B_INVAL; 2736 if (bp->b_flags & B_INVAL) { 2737 if (bp->b_flags & B_DELWRI) 2738 bundirty(bp); 2739 if (bp->b_vp) 2740 brelvp(bp); 2741 } 2742 2743 buf_track(bp, __func__); 2744 2745 /* buffers with no memory */ 2746 if (bp->b_bufsize == 0) { 2747 buf_free(bp); 2748 return; 2749 } 2750 /* buffers with junk contents */ 2751 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2752 (bp->b_ioflags & BIO_ERROR)) { 2753 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2754 if (bp->b_vflags & BV_BKGRDINPROG) 2755 panic("losing buffer 2"); 2756 qindex = QUEUE_CLEAN; 2757 bp->b_flags |= B_AGE; 2758 /* remaining buffers */ 2759 } else if (bp->b_flags & B_DELWRI) 2760 qindex = QUEUE_DIRTY; 2761 else 2762 qindex = QUEUE_CLEAN; 2763 2764 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2765 panic("brelse: not dirty"); 2766 2767 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT); 2768 /* binsfree unlocks bp. */ 2769 binsfree(bp, qindex); 2770 } 2771 2772 /* 2773 * Release a buffer back to the appropriate queue but do not try to free 2774 * it. The buffer is expected to be used again soon. 2775 * 2776 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2777 * biodone() to requeue an async I/O on completion. It is also used when 2778 * known good buffers need to be requeued but we think we may need the data 2779 * again soon. 2780 * 2781 * XXX we should be able to leave the B_RELBUF hint set on completion. 2782 */ 2783 void 2784 bqrelse(struct buf *bp) 2785 { 2786 int qindex; 2787 2788 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2789 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2790 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2791 2792 qindex = QUEUE_NONE; 2793 if (BUF_LOCKRECURSED(bp)) { 2794 /* do not release to free list */ 2795 BUF_UNLOCK(bp); 2796 return; 2797 } 2798 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2799 2800 if (bp->b_flags & B_MANAGED) { 2801 if (bp->b_flags & B_REMFREE) 2802 bremfreef(bp); 2803 goto out; 2804 } 2805 2806 /* buffers with stale but valid contents */ 2807 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2808 BV_BKGRDERR)) == BV_BKGRDERR) { 2809 BO_LOCK(bp->b_bufobj); 2810 bp->b_vflags &= ~BV_BKGRDERR; 2811 BO_UNLOCK(bp->b_bufobj); 2812 qindex = QUEUE_DIRTY; 2813 } else { 2814 if ((bp->b_flags & B_DELWRI) == 0 && 2815 (bp->b_xflags & BX_VNDIRTY)) 2816 panic("bqrelse: not dirty"); 2817 if ((bp->b_flags & B_NOREUSE) != 0) { 2818 brelse(bp); 2819 return; 2820 } 2821 qindex = QUEUE_CLEAN; 2822 } 2823 buf_track(bp, __func__); 2824 /* binsfree unlocks bp. */ 2825 binsfree(bp, qindex); 2826 return; 2827 2828 out: 2829 buf_track(bp, __func__); 2830 /* unlock */ 2831 BUF_UNLOCK(bp); 2832 } 2833 2834 /* 2835 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2836 * restore bogus pages. 2837 */ 2838 static void 2839 vfs_vmio_iodone(struct buf *bp) 2840 { 2841 vm_ooffset_t foff; 2842 vm_page_t m; 2843 vm_object_t obj; 2844 struct vnode *vp __unused; 2845 int i, iosize, resid; 2846 bool bogus; 2847 2848 obj = bp->b_bufobj->bo_object; 2849 KASSERT(obj->paging_in_progress >= bp->b_npages, 2850 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2851 obj->paging_in_progress, bp->b_npages)); 2852 2853 vp = bp->b_vp; 2854 KASSERT(vp->v_holdcnt > 0, 2855 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2856 KASSERT(vp->v_object != NULL, 2857 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2858 2859 foff = bp->b_offset; 2860 KASSERT(bp->b_offset != NOOFFSET, 2861 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2862 2863 bogus = false; 2864 iosize = bp->b_bcount - bp->b_resid; 2865 VM_OBJECT_WLOCK(obj); 2866 for (i = 0; i < bp->b_npages; i++) { 2867 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2868 if (resid > iosize) 2869 resid = iosize; 2870 2871 /* 2872 * cleanup bogus pages, restoring the originals 2873 */ 2874 m = bp->b_pages[i]; 2875 if (m == bogus_page) { 2876 bogus = true; 2877 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2878 if (m == NULL) 2879 panic("biodone: page disappeared!"); 2880 bp->b_pages[i] = m; 2881 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2882 /* 2883 * In the write case, the valid and clean bits are 2884 * already changed correctly ( see bdwrite() ), so we 2885 * only need to do this here in the read case. 2886 */ 2887 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2888 resid)) == 0, ("vfs_vmio_iodone: page %p " 2889 "has unexpected dirty bits", m)); 2890 vfs_page_set_valid(bp, foff, m); 2891 } 2892 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2893 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2894 (intmax_t)foff, (uintmax_t)m->pindex)); 2895 2896 vm_page_sunbusy(m); 2897 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2898 iosize -= resid; 2899 } 2900 vm_object_pip_wakeupn(obj, bp->b_npages); 2901 VM_OBJECT_WUNLOCK(obj); 2902 if (bogus && buf_mapped(bp)) { 2903 BUF_CHECK_MAPPED(bp); 2904 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2905 bp->b_pages, bp->b_npages); 2906 } 2907 } 2908 2909 /* 2910 * Unwire a page held by a buf and either free it or update the page queues to 2911 * reflect its recent use. 2912 */ 2913 static void 2914 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2915 { 2916 bool freed; 2917 2918 vm_page_lock(m); 2919 if (vm_page_unwire_noq(m)) { 2920 if ((bp->b_flags & B_DIRECT) != 0) 2921 freed = vm_page_try_to_free(m); 2922 else 2923 freed = false; 2924 if (!freed) { 2925 /* 2926 * Use a racy check of the valid bits to determine 2927 * whether we can accelerate reclamation of the page. 2928 * The valid bits will be stable unless the page is 2929 * being mapped or is referenced by multiple buffers, 2930 * and in those cases we expect races to be rare. At 2931 * worst we will either accelerate reclamation of a 2932 * valid page and violate LRU, or unnecessarily defer 2933 * reclamation of an invalid page. 2934 * 2935 * The B_NOREUSE flag marks data that is not expected to 2936 * be reused, so accelerate reclamation in that case 2937 * too. Otherwise, maintain LRU. 2938 */ 2939 if (m->valid == 0 || (bp->b_flags & B_NOREUSE) != 0) 2940 vm_page_deactivate_noreuse(m); 2941 else if (vm_page_active(m)) 2942 vm_page_reference(m); 2943 else 2944 vm_page_deactivate(m); 2945 } 2946 } 2947 vm_page_unlock(m); 2948 } 2949 2950 /* 2951 * Perform page invalidation when a buffer is released. The fully invalid 2952 * pages will be reclaimed later in vfs_vmio_truncate(). 2953 */ 2954 static void 2955 vfs_vmio_invalidate(struct buf *bp) 2956 { 2957 vm_object_t obj; 2958 vm_page_t m; 2959 int i, resid, poffset, presid; 2960 2961 if (buf_mapped(bp)) { 2962 BUF_CHECK_MAPPED(bp); 2963 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2964 } else 2965 BUF_CHECK_UNMAPPED(bp); 2966 /* 2967 * Get the base offset and length of the buffer. Note that 2968 * in the VMIO case if the buffer block size is not 2969 * page-aligned then b_data pointer may not be page-aligned. 2970 * But our b_pages[] array *IS* page aligned. 2971 * 2972 * block sizes less then DEV_BSIZE (usually 512) are not 2973 * supported due to the page granularity bits (m->valid, 2974 * m->dirty, etc...). 2975 * 2976 * See man buf(9) for more information 2977 */ 2978 obj = bp->b_bufobj->bo_object; 2979 resid = bp->b_bufsize; 2980 poffset = bp->b_offset & PAGE_MASK; 2981 VM_OBJECT_WLOCK(obj); 2982 for (i = 0; i < bp->b_npages; i++) { 2983 m = bp->b_pages[i]; 2984 if (m == bogus_page) 2985 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2986 bp->b_pages[i] = NULL; 2987 2988 presid = resid > (PAGE_SIZE - poffset) ? 2989 (PAGE_SIZE - poffset) : resid; 2990 KASSERT(presid >= 0, ("brelse: extra page")); 2991 while (vm_page_xbusied(m)) { 2992 vm_page_lock(m); 2993 VM_OBJECT_WUNLOCK(obj); 2994 vm_page_busy_sleep(m, "mbncsh", true); 2995 VM_OBJECT_WLOCK(obj); 2996 } 2997 if (pmap_page_wired_mappings(m) == 0) 2998 vm_page_set_invalid(m, poffset, presid); 2999 vfs_vmio_unwire(bp, m); 3000 resid -= presid; 3001 poffset = 0; 3002 } 3003 VM_OBJECT_WUNLOCK(obj); 3004 bp->b_npages = 0; 3005 } 3006 3007 /* 3008 * Page-granular truncation of an existing VMIO buffer. 3009 */ 3010 static void 3011 vfs_vmio_truncate(struct buf *bp, int desiredpages) 3012 { 3013 vm_object_t obj; 3014 vm_page_t m; 3015 int i; 3016 3017 if (bp->b_npages == desiredpages) 3018 return; 3019 3020 if (buf_mapped(bp)) { 3021 BUF_CHECK_MAPPED(bp); 3022 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 3023 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 3024 } else 3025 BUF_CHECK_UNMAPPED(bp); 3026 3027 /* 3028 * The object lock is needed only if we will attempt to free pages. 3029 */ 3030 obj = (bp->b_flags & B_DIRECT) != 0 ? bp->b_bufobj->bo_object : NULL; 3031 if (obj != NULL) 3032 VM_OBJECT_WLOCK(obj); 3033 for (i = desiredpages; i < bp->b_npages; i++) { 3034 m = bp->b_pages[i]; 3035 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3036 bp->b_pages[i] = NULL; 3037 vfs_vmio_unwire(bp, m); 3038 } 3039 if (obj != NULL) 3040 VM_OBJECT_WUNLOCK(obj); 3041 bp->b_npages = desiredpages; 3042 } 3043 3044 /* 3045 * Byte granular extension of VMIO buffers. 3046 */ 3047 static void 3048 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3049 { 3050 /* 3051 * We are growing the buffer, possibly in a 3052 * byte-granular fashion. 3053 */ 3054 vm_object_t obj; 3055 vm_offset_t toff; 3056 vm_offset_t tinc; 3057 vm_page_t m; 3058 3059 /* 3060 * Step 1, bring in the VM pages from the object, allocating 3061 * them if necessary. We must clear B_CACHE if these pages 3062 * are not valid for the range covered by the buffer. 3063 */ 3064 obj = bp->b_bufobj->bo_object; 3065 VM_OBJECT_WLOCK(obj); 3066 if (bp->b_npages < desiredpages) { 3067 /* 3068 * We must allocate system pages since blocking 3069 * here could interfere with paging I/O, no 3070 * matter which process we are. 3071 * 3072 * Only exclusive busy can be tested here. 3073 * Blocking on shared busy might lead to 3074 * deadlocks once allocbuf() is called after 3075 * pages are vfs_busy_pages(). 3076 */ 3077 (void)vm_page_grab_pages(obj, 3078 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3079 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3080 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3081 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3082 bp->b_npages = desiredpages; 3083 } 3084 3085 /* 3086 * Step 2. We've loaded the pages into the buffer, 3087 * we have to figure out if we can still have B_CACHE 3088 * set. Note that B_CACHE is set according to the 3089 * byte-granular range ( bcount and size ), not the 3090 * aligned range ( newbsize ). 3091 * 3092 * The VM test is against m->valid, which is DEV_BSIZE 3093 * aligned. Needless to say, the validity of the data 3094 * needs to also be DEV_BSIZE aligned. Note that this 3095 * fails with NFS if the server or some other client 3096 * extends the file's EOF. If our buffer is resized, 3097 * B_CACHE may remain set! XXX 3098 */ 3099 toff = bp->b_bcount; 3100 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3101 while ((bp->b_flags & B_CACHE) && toff < size) { 3102 vm_pindex_t pi; 3103 3104 if (tinc > (size - toff)) 3105 tinc = size - toff; 3106 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3107 m = bp->b_pages[pi]; 3108 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3109 toff += tinc; 3110 tinc = PAGE_SIZE; 3111 } 3112 VM_OBJECT_WUNLOCK(obj); 3113 3114 /* 3115 * Step 3, fixup the KVA pmap. 3116 */ 3117 if (buf_mapped(bp)) 3118 bpmap_qenter(bp); 3119 else 3120 BUF_CHECK_UNMAPPED(bp); 3121 } 3122 3123 /* 3124 * Check to see if a block at a particular lbn is available for a clustered 3125 * write. 3126 */ 3127 static int 3128 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3129 { 3130 struct buf *bpa; 3131 int match; 3132 3133 match = 0; 3134 3135 /* If the buf isn't in core skip it */ 3136 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3137 return (0); 3138 3139 /* If the buf is busy we don't want to wait for it */ 3140 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3141 return (0); 3142 3143 /* Only cluster with valid clusterable delayed write buffers */ 3144 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3145 (B_DELWRI | B_CLUSTEROK)) 3146 goto done; 3147 3148 if (bpa->b_bufsize != size) 3149 goto done; 3150 3151 /* 3152 * Check to see if it is in the expected place on disk and that the 3153 * block has been mapped. 3154 */ 3155 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3156 match = 1; 3157 done: 3158 BUF_UNLOCK(bpa); 3159 return (match); 3160 } 3161 3162 /* 3163 * vfs_bio_awrite: 3164 * 3165 * Implement clustered async writes for clearing out B_DELWRI buffers. 3166 * This is much better then the old way of writing only one buffer at 3167 * a time. Note that we may not be presented with the buffers in the 3168 * correct order, so we search for the cluster in both directions. 3169 */ 3170 int 3171 vfs_bio_awrite(struct buf *bp) 3172 { 3173 struct bufobj *bo; 3174 int i; 3175 int j; 3176 daddr_t lblkno = bp->b_lblkno; 3177 struct vnode *vp = bp->b_vp; 3178 int ncl; 3179 int nwritten; 3180 int size; 3181 int maxcl; 3182 int gbflags; 3183 3184 bo = &vp->v_bufobj; 3185 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3186 /* 3187 * right now we support clustered writing only to regular files. If 3188 * we find a clusterable block we could be in the middle of a cluster 3189 * rather then at the beginning. 3190 */ 3191 if ((vp->v_type == VREG) && 3192 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3193 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3194 3195 size = vp->v_mount->mnt_stat.f_iosize; 3196 maxcl = MAXPHYS / size; 3197 3198 BO_RLOCK(bo); 3199 for (i = 1; i < maxcl; i++) 3200 if (vfs_bio_clcheck(vp, size, lblkno + i, 3201 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3202 break; 3203 3204 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3205 if (vfs_bio_clcheck(vp, size, lblkno - j, 3206 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3207 break; 3208 BO_RUNLOCK(bo); 3209 --j; 3210 ncl = i + j; 3211 /* 3212 * this is a possible cluster write 3213 */ 3214 if (ncl != 1) { 3215 BUF_UNLOCK(bp); 3216 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3217 gbflags); 3218 return (nwritten); 3219 } 3220 } 3221 bremfree(bp); 3222 bp->b_flags |= B_ASYNC; 3223 /* 3224 * default (old) behavior, writing out only one block 3225 * 3226 * XXX returns b_bufsize instead of b_bcount for nwritten? 3227 */ 3228 nwritten = bp->b_bufsize; 3229 (void) bwrite(bp); 3230 3231 return (nwritten); 3232 } 3233 3234 /* 3235 * getnewbuf_kva: 3236 * 3237 * Allocate KVA for an empty buf header according to gbflags. 3238 */ 3239 static int 3240 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3241 { 3242 3243 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3244 /* 3245 * In order to keep fragmentation sane we only allocate kva 3246 * in BKVASIZE chunks. XXX with vmem we can do page size. 3247 */ 3248 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3249 3250 if (maxsize != bp->b_kvasize && 3251 bufkva_alloc(bp, maxsize, gbflags)) 3252 return (ENOSPC); 3253 } 3254 return (0); 3255 } 3256 3257 /* 3258 * getnewbuf: 3259 * 3260 * Find and initialize a new buffer header, freeing up existing buffers 3261 * in the bufqueues as necessary. The new buffer is returned locked. 3262 * 3263 * We block if: 3264 * We have insufficient buffer headers 3265 * We have insufficient buffer space 3266 * buffer_arena is too fragmented ( space reservation fails ) 3267 * If we have to flush dirty buffers ( but we try to avoid this ) 3268 * 3269 * The caller is responsible for releasing the reserved bufspace after 3270 * allocbuf() is called. 3271 */ 3272 static struct buf * 3273 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3274 { 3275 struct bufdomain *bd; 3276 struct buf *bp; 3277 bool metadata, reserved; 3278 3279 bp = NULL; 3280 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3281 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3282 if (!unmapped_buf_allowed) 3283 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3284 3285 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3286 vp->v_type == VCHR) 3287 metadata = true; 3288 else 3289 metadata = false; 3290 if (vp == NULL) 3291 bd = &bdomain[0]; 3292 else 3293 bd = &bdomain[vp->v_bufobj.bo_domain]; 3294 3295 counter_u64_add(getnewbufcalls, 1); 3296 reserved = false; 3297 do { 3298 if (reserved == false && 3299 bufspace_reserve(bd, maxsize, metadata) != 0) { 3300 counter_u64_add(getnewbufrestarts, 1); 3301 continue; 3302 } 3303 reserved = true; 3304 if ((bp = buf_alloc(bd)) == NULL) { 3305 counter_u64_add(getnewbufrestarts, 1); 3306 continue; 3307 } 3308 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3309 return (bp); 3310 break; 3311 } while (buf_recycle(bd, false) == 0); 3312 3313 if (reserved) 3314 bufspace_release(bd, maxsize); 3315 if (bp != NULL) { 3316 bp->b_flags |= B_INVAL; 3317 brelse(bp); 3318 } 3319 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3320 3321 return (NULL); 3322 } 3323 3324 /* 3325 * buf_daemon: 3326 * 3327 * buffer flushing daemon. Buffers are normally flushed by the 3328 * update daemon but if it cannot keep up this process starts to 3329 * take the load in an attempt to prevent getnewbuf() from blocking. 3330 */ 3331 static struct kproc_desc buf_kp = { 3332 "bufdaemon", 3333 buf_daemon, 3334 &bufdaemonproc 3335 }; 3336 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3337 3338 static int 3339 buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3340 { 3341 int flushed; 3342 3343 flushed = flushbufqueues(vp, bd, target, 0); 3344 if (flushed == 0) { 3345 /* 3346 * Could not find any buffers without rollback 3347 * dependencies, so just write the first one 3348 * in the hopes of eventually making progress. 3349 */ 3350 if (vp != NULL && target > 2) 3351 target /= 2; 3352 flushbufqueues(vp, bd, target, 1); 3353 } 3354 return (flushed); 3355 } 3356 3357 static void 3358 buf_daemon() 3359 { 3360 struct bufdomain *bd; 3361 int speedupreq; 3362 int lodirty; 3363 int i; 3364 3365 /* 3366 * This process needs to be suspended prior to shutdown sync. 3367 */ 3368 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 3369 SHUTDOWN_PRI_LAST + 100); 3370 3371 /* 3372 * Start the buf clean daemons as children threads. 3373 */ 3374 for (i = 0 ; i < buf_domains; i++) { 3375 int error; 3376 3377 error = kthread_add((void (*)(void *))bufspace_daemon, 3378 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3379 if (error) 3380 panic("error %d spawning bufspace daemon", error); 3381 } 3382 3383 /* 3384 * This process is allowed to take the buffer cache to the limit 3385 */ 3386 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3387 mtx_lock(&bdlock); 3388 for (;;) { 3389 bd_request = 0; 3390 mtx_unlock(&bdlock); 3391 3392 kthread_suspend_check(); 3393 3394 /* 3395 * Save speedupreq for this pass and reset to capture new 3396 * requests. 3397 */ 3398 speedupreq = bd_speedupreq; 3399 bd_speedupreq = 0; 3400 3401 /* 3402 * Flush each domain sequentially according to its level and 3403 * the speedup request. 3404 */ 3405 for (i = 0; i < buf_domains; i++) { 3406 bd = &bdomain[i]; 3407 if (speedupreq) 3408 lodirty = bd->bd_numdirtybuffers / 2; 3409 else 3410 lodirty = bd->bd_lodirtybuffers; 3411 while (bd->bd_numdirtybuffers > lodirty) { 3412 if (buf_flush(NULL, bd, 3413 bd->bd_numdirtybuffers - lodirty) == 0) 3414 break; 3415 kern_yield(PRI_USER); 3416 } 3417 } 3418 3419 /* 3420 * Only clear bd_request if we have reached our low water 3421 * mark. The buf_daemon normally waits 1 second and 3422 * then incrementally flushes any dirty buffers that have 3423 * built up, within reason. 3424 * 3425 * If we were unable to hit our low water mark and couldn't 3426 * find any flushable buffers, we sleep for a short period 3427 * to avoid endless loops on unlockable buffers. 3428 */ 3429 mtx_lock(&bdlock); 3430 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3431 /* 3432 * We reached our low water mark, reset the 3433 * request and sleep until we are needed again. 3434 * The sleep is just so the suspend code works. 3435 */ 3436 bd_request = 0; 3437 /* 3438 * Do an extra wakeup in case dirty threshold 3439 * changed via sysctl and the explicit transition 3440 * out of shortfall was missed. 3441 */ 3442 bdirtywakeup(); 3443 if (runningbufspace <= lorunningspace) 3444 runningwakeup(); 3445 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3446 } else { 3447 /* 3448 * We couldn't find any flushable dirty buffers but 3449 * still have too many dirty buffers, we 3450 * have to sleep and try again. (rare) 3451 */ 3452 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3453 } 3454 } 3455 } 3456 3457 /* 3458 * flushbufqueues: 3459 * 3460 * Try to flush a buffer in the dirty queue. We must be careful to 3461 * free up B_INVAL buffers instead of write them, which NFS is 3462 * particularly sensitive to. 3463 */ 3464 static int flushwithdeps = 0; 3465 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3466 0, "Number of buffers flushed with dependecies that require rollbacks"); 3467 3468 static int 3469 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3470 int flushdeps) 3471 { 3472 struct bufqueue *bq; 3473 struct buf *sentinel; 3474 struct vnode *vp; 3475 struct mount *mp; 3476 struct buf *bp; 3477 int hasdeps; 3478 int flushed; 3479 int error; 3480 bool unlock; 3481 3482 flushed = 0; 3483 bq = &bd->bd_dirtyq; 3484 bp = NULL; 3485 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3486 sentinel->b_qindex = QUEUE_SENTINEL; 3487 BQ_LOCK(bq); 3488 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3489 BQ_UNLOCK(bq); 3490 while (flushed != target) { 3491 maybe_yield(); 3492 BQ_LOCK(bq); 3493 bp = TAILQ_NEXT(sentinel, b_freelist); 3494 if (bp != NULL) { 3495 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3496 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3497 b_freelist); 3498 } else { 3499 BQ_UNLOCK(bq); 3500 break; 3501 } 3502 /* 3503 * Skip sentinels inserted by other invocations of the 3504 * flushbufqueues(), taking care to not reorder them. 3505 * 3506 * Only flush the buffers that belong to the 3507 * vnode locked by the curthread. 3508 */ 3509 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3510 bp->b_vp != lvp)) { 3511 BQ_UNLOCK(bq); 3512 continue; 3513 } 3514 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3515 BQ_UNLOCK(bq); 3516 if (error != 0) 3517 continue; 3518 3519 /* 3520 * BKGRDINPROG can only be set with the buf and bufobj 3521 * locks both held. We tolerate a race to clear it here. 3522 */ 3523 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3524 (bp->b_flags & B_DELWRI) == 0) { 3525 BUF_UNLOCK(bp); 3526 continue; 3527 } 3528 if (bp->b_flags & B_INVAL) { 3529 bremfreef(bp); 3530 brelse(bp); 3531 flushed++; 3532 continue; 3533 } 3534 3535 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3536 if (flushdeps == 0) { 3537 BUF_UNLOCK(bp); 3538 continue; 3539 } 3540 hasdeps = 1; 3541 } else 3542 hasdeps = 0; 3543 /* 3544 * We must hold the lock on a vnode before writing 3545 * one of its buffers. Otherwise we may confuse, or 3546 * in the case of a snapshot vnode, deadlock the 3547 * system. 3548 * 3549 * The lock order here is the reverse of the normal 3550 * of vnode followed by buf lock. This is ok because 3551 * the NOWAIT will prevent deadlock. 3552 */ 3553 vp = bp->b_vp; 3554 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3555 BUF_UNLOCK(bp); 3556 continue; 3557 } 3558 if (lvp == NULL) { 3559 unlock = true; 3560 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3561 } else { 3562 ASSERT_VOP_LOCKED(vp, "getbuf"); 3563 unlock = false; 3564 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3565 vn_lock(vp, LK_TRYUPGRADE); 3566 } 3567 if (error == 0) { 3568 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3569 bp, bp->b_vp, bp->b_flags); 3570 if (curproc == bufdaemonproc) { 3571 vfs_bio_awrite(bp); 3572 } else { 3573 bremfree(bp); 3574 bwrite(bp); 3575 counter_u64_add(notbufdflushes, 1); 3576 } 3577 vn_finished_write(mp); 3578 if (unlock) 3579 VOP_UNLOCK(vp, 0); 3580 flushwithdeps += hasdeps; 3581 flushed++; 3582 3583 /* 3584 * Sleeping on runningbufspace while holding 3585 * vnode lock leads to deadlock. 3586 */ 3587 if (curproc == bufdaemonproc && 3588 runningbufspace > hirunningspace) 3589 waitrunningbufspace(); 3590 continue; 3591 } 3592 vn_finished_write(mp); 3593 BUF_UNLOCK(bp); 3594 } 3595 BQ_LOCK(bq); 3596 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3597 BQ_UNLOCK(bq); 3598 free(sentinel, M_TEMP); 3599 return (flushed); 3600 } 3601 3602 /* 3603 * Check to see if a block is currently memory resident. 3604 */ 3605 struct buf * 3606 incore(struct bufobj *bo, daddr_t blkno) 3607 { 3608 struct buf *bp; 3609 3610 BO_RLOCK(bo); 3611 bp = gbincore(bo, blkno); 3612 BO_RUNLOCK(bo); 3613 return (bp); 3614 } 3615 3616 /* 3617 * Returns true if no I/O is needed to access the 3618 * associated VM object. This is like incore except 3619 * it also hunts around in the VM system for the data. 3620 */ 3621 3622 static int 3623 inmem(struct vnode * vp, daddr_t blkno) 3624 { 3625 vm_object_t obj; 3626 vm_offset_t toff, tinc, size; 3627 vm_page_t m; 3628 vm_ooffset_t off; 3629 3630 ASSERT_VOP_LOCKED(vp, "inmem"); 3631 3632 if (incore(&vp->v_bufobj, blkno)) 3633 return 1; 3634 if (vp->v_mount == NULL) 3635 return 0; 3636 obj = vp->v_object; 3637 if (obj == NULL) 3638 return (0); 3639 3640 size = PAGE_SIZE; 3641 if (size > vp->v_mount->mnt_stat.f_iosize) 3642 size = vp->v_mount->mnt_stat.f_iosize; 3643 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3644 3645 VM_OBJECT_RLOCK(obj); 3646 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3647 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3648 if (!m) 3649 goto notinmem; 3650 tinc = size; 3651 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3652 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3653 if (vm_page_is_valid(m, 3654 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3655 goto notinmem; 3656 } 3657 VM_OBJECT_RUNLOCK(obj); 3658 return 1; 3659 3660 notinmem: 3661 VM_OBJECT_RUNLOCK(obj); 3662 return (0); 3663 } 3664 3665 /* 3666 * Set the dirty range for a buffer based on the status of the dirty 3667 * bits in the pages comprising the buffer. The range is limited 3668 * to the size of the buffer. 3669 * 3670 * Tell the VM system that the pages associated with this buffer 3671 * are clean. This is used for delayed writes where the data is 3672 * going to go to disk eventually without additional VM intevention. 3673 * 3674 * Note that while we only really need to clean through to b_bcount, we 3675 * just go ahead and clean through to b_bufsize. 3676 */ 3677 static void 3678 vfs_clean_pages_dirty_buf(struct buf *bp) 3679 { 3680 vm_ooffset_t foff, noff, eoff; 3681 vm_page_t m; 3682 int i; 3683 3684 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3685 return; 3686 3687 foff = bp->b_offset; 3688 KASSERT(bp->b_offset != NOOFFSET, 3689 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3690 3691 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3692 vfs_drain_busy_pages(bp); 3693 vfs_setdirty_locked_object(bp); 3694 for (i = 0; i < bp->b_npages; i++) { 3695 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3696 eoff = noff; 3697 if (eoff > bp->b_offset + bp->b_bufsize) 3698 eoff = bp->b_offset + bp->b_bufsize; 3699 m = bp->b_pages[i]; 3700 vfs_page_set_validclean(bp, foff, m); 3701 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3702 foff = noff; 3703 } 3704 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3705 } 3706 3707 static void 3708 vfs_setdirty_locked_object(struct buf *bp) 3709 { 3710 vm_object_t object; 3711 int i; 3712 3713 object = bp->b_bufobj->bo_object; 3714 VM_OBJECT_ASSERT_WLOCKED(object); 3715 3716 /* 3717 * We qualify the scan for modified pages on whether the 3718 * object has been flushed yet. 3719 */ 3720 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3721 vm_offset_t boffset; 3722 vm_offset_t eoffset; 3723 3724 /* 3725 * test the pages to see if they have been modified directly 3726 * by users through the VM system. 3727 */ 3728 for (i = 0; i < bp->b_npages; i++) 3729 vm_page_test_dirty(bp->b_pages[i]); 3730 3731 /* 3732 * Calculate the encompassing dirty range, boffset and eoffset, 3733 * (eoffset - boffset) bytes. 3734 */ 3735 3736 for (i = 0; i < bp->b_npages; i++) { 3737 if (bp->b_pages[i]->dirty) 3738 break; 3739 } 3740 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3741 3742 for (i = bp->b_npages - 1; i >= 0; --i) { 3743 if (bp->b_pages[i]->dirty) { 3744 break; 3745 } 3746 } 3747 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3748 3749 /* 3750 * Fit it to the buffer. 3751 */ 3752 3753 if (eoffset > bp->b_bcount) 3754 eoffset = bp->b_bcount; 3755 3756 /* 3757 * If we have a good dirty range, merge with the existing 3758 * dirty range. 3759 */ 3760 3761 if (boffset < eoffset) { 3762 if (bp->b_dirtyoff > boffset) 3763 bp->b_dirtyoff = boffset; 3764 if (bp->b_dirtyend < eoffset) 3765 bp->b_dirtyend = eoffset; 3766 } 3767 } 3768 } 3769 3770 /* 3771 * Allocate the KVA mapping for an existing buffer. 3772 * If an unmapped buffer is provided but a mapped buffer is requested, take 3773 * also care to properly setup mappings between pages and KVA. 3774 */ 3775 static void 3776 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3777 { 3778 int bsize, maxsize, need_mapping, need_kva; 3779 off_t offset; 3780 3781 need_mapping = bp->b_data == unmapped_buf && 3782 (gbflags & GB_UNMAPPED) == 0; 3783 need_kva = bp->b_kvabase == unmapped_buf && 3784 bp->b_data == unmapped_buf && 3785 (gbflags & GB_KVAALLOC) != 0; 3786 if (!need_mapping && !need_kva) 3787 return; 3788 3789 BUF_CHECK_UNMAPPED(bp); 3790 3791 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3792 /* 3793 * Buffer is not mapped, but the KVA was already 3794 * reserved at the time of the instantiation. Use the 3795 * allocated space. 3796 */ 3797 goto has_addr; 3798 } 3799 3800 /* 3801 * Calculate the amount of the address space we would reserve 3802 * if the buffer was mapped. 3803 */ 3804 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3805 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3806 offset = blkno * bsize; 3807 maxsize = size + (offset & PAGE_MASK); 3808 maxsize = imax(maxsize, bsize); 3809 3810 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3811 if ((gbflags & GB_NOWAIT_BD) != 0) { 3812 /* 3813 * XXXKIB: defragmentation cannot 3814 * succeed, not sure what else to do. 3815 */ 3816 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3817 } 3818 counter_u64_add(mappingrestarts, 1); 3819 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3820 } 3821 has_addr: 3822 if (need_mapping) { 3823 /* b_offset is handled by bpmap_qenter. */ 3824 bp->b_data = bp->b_kvabase; 3825 BUF_CHECK_MAPPED(bp); 3826 bpmap_qenter(bp); 3827 } 3828 } 3829 3830 struct buf * 3831 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3832 int flags) 3833 { 3834 struct buf *bp; 3835 int error; 3836 3837 error = getblkx(vp, blkno, size, slpflag, slptimeo, flags, &bp); 3838 if (error != 0) 3839 return (NULL); 3840 return (bp); 3841 } 3842 3843 /* 3844 * getblkx: 3845 * 3846 * Get a block given a specified block and offset into a file/device. 3847 * The buffers B_DONE bit will be cleared on return, making it almost 3848 * ready for an I/O initiation. B_INVAL may or may not be set on 3849 * return. The caller should clear B_INVAL prior to initiating a 3850 * READ. 3851 * 3852 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3853 * an existing buffer. 3854 * 3855 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3856 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3857 * and then cleared based on the backing VM. If the previous buffer is 3858 * non-0-sized but invalid, B_CACHE will be cleared. 3859 * 3860 * If getblk() must create a new buffer, the new buffer is returned with 3861 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3862 * case it is returned with B_INVAL clear and B_CACHE set based on the 3863 * backing VM. 3864 * 3865 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3866 * B_CACHE bit is clear. 3867 * 3868 * What this means, basically, is that the caller should use B_CACHE to 3869 * determine whether the buffer is fully valid or not and should clear 3870 * B_INVAL prior to issuing a read. If the caller intends to validate 3871 * the buffer by loading its data area with something, the caller needs 3872 * to clear B_INVAL. If the caller does this without issuing an I/O, 3873 * the caller should set B_CACHE ( as an optimization ), else the caller 3874 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3875 * a write attempt or if it was a successful read. If the caller 3876 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3877 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3878 */ 3879 int 3880 getblkx(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3881 int flags, struct buf **bpp) 3882 { 3883 struct buf *bp; 3884 struct bufobj *bo; 3885 daddr_t d_blkno; 3886 int bsize, error, maxsize, vmio; 3887 off_t offset; 3888 3889 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3890 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3891 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3892 ASSERT_VOP_LOCKED(vp, "getblk"); 3893 if (size > maxbcachebuf) 3894 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3895 maxbcachebuf); 3896 if (!unmapped_buf_allowed) 3897 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3898 3899 bo = &vp->v_bufobj; 3900 d_blkno = blkno; 3901 loop: 3902 BO_RLOCK(bo); 3903 bp = gbincore(bo, blkno); 3904 if (bp != NULL) { 3905 int lockflags; 3906 /* 3907 * Buffer is in-core. If the buffer is not busy nor managed, 3908 * it must be on a queue. 3909 */ 3910 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3911 3912 if ((flags & GB_LOCK_NOWAIT) != 0) 3913 lockflags |= LK_NOWAIT; 3914 3915 error = BUF_TIMELOCK(bp, lockflags, 3916 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3917 3918 /* 3919 * If we slept and got the lock we have to restart in case 3920 * the buffer changed identities. 3921 */ 3922 if (error == ENOLCK) 3923 goto loop; 3924 /* We timed out or were interrupted. */ 3925 else if (error != 0) 3926 return (error); 3927 /* If recursed, assume caller knows the rules. */ 3928 else if (BUF_LOCKRECURSED(bp)) 3929 goto end; 3930 3931 /* 3932 * The buffer is locked. B_CACHE is cleared if the buffer is 3933 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3934 * and for a VMIO buffer B_CACHE is adjusted according to the 3935 * backing VM cache. 3936 */ 3937 if (bp->b_flags & B_INVAL) 3938 bp->b_flags &= ~B_CACHE; 3939 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3940 bp->b_flags |= B_CACHE; 3941 if (bp->b_flags & B_MANAGED) 3942 MPASS(bp->b_qindex == QUEUE_NONE); 3943 else 3944 bremfree(bp); 3945 3946 /* 3947 * check for size inconsistencies for non-VMIO case. 3948 */ 3949 if (bp->b_bcount != size) { 3950 if ((bp->b_flags & B_VMIO) == 0 || 3951 (size > bp->b_kvasize)) { 3952 if (bp->b_flags & B_DELWRI) { 3953 bp->b_flags |= B_NOCACHE; 3954 bwrite(bp); 3955 } else { 3956 if (LIST_EMPTY(&bp->b_dep)) { 3957 bp->b_flags |= B_RELBUF; 3958 brelse(bp); 3959 } else { 3960 bp->b_flags |= B_NOCACHE; 3961 bwrite(bp); 3962 } 3963 } 3964 goto loop; 3965 } 3966 } 3967 3968 /* 3969 * Handle the case of unmapped buffer which should 3970 * become mapped, or the buffer for which KVA 3971 * reservation is requested. 3972 */ 3973 bp_unmapped_get_kva(bp, blkno, size, flags); 3974 3975 /* 3976 * If the size is inconsistent in the VMIO case, we can resize 3977 * the buffer. This might lead to B_CACHE getting set or 3978 * cleared. If the size has not changed, B_CACHE remains 3979 * unchanged from its previous state. 3980 */ 3981 allocbuf(bp, size); 3982 3983 KASSERT(bp->b_offset != NOOFFSET, 3984 ("getblk: no buffer offset")); 3985 3986 /* 3987 * A buffer with B_DELWRI set and B_CACHE clear must 3988 * be committed before we can return the buffer in 3989 * order to prevent the caller from issuing a read 3990 * ( due to B_CACHE not being set ) and overwriting 3991 * it. 3992 * 3993 * Most callers, including NFS and FFS, need this to 3994 * operate properly either because they assume they 3995 * can issue a read if B_CACHE is not set, or because 3996 * ( for example ) an uncached B_DELWRI might loop due 3997 * to softupdates re-dirtying the buffer. In the latter 3998 * case, B_CACHE is set after the first write completes, 3999 * preventing further loops. 4000 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 4001 * above while extending the buffer, we cannot allow the 4002 * buffer to remain with B_CACHE set after the write 4003 * completes or it will represent a corrupt state. To 4004 * deal with this we set B_NOCACHE to scrap the buffer 4005 * after the write. 4006 * 4007 * We might be able to do something fancy, like setting 4008 * B_CACHE in bwrite() except if B_DELWRI is already set, 4009 * so the below call doesn't set B_CACHE, but that gets real 4010 * confusing. This is much easier. 4011 */ 4012 4013 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 4014 bp->b_flags |= B_NOCACHE; 4015 bwrite(bp); 4016 goto loop; 4017 } 4018 bp->b_flags &= ~B_DONE; 4019 } else { 4020 /* 4021 * Buffer is not in-core, create new buffer. The buffer 4022 * returned by getnewbuf() is locked. Note that the returned 4023 * buffer is also considered valid (not marked B_INVAL). 4024 */ 4025 BO_RUNLOCK(bo); 4026 /* 4027 * If the user does not want us to create the buffer, bail out 4028 * here. 4029 */ 4030 if (flags & GB_NOCREAT) 4031 return (EEXIST); 4032 if (bdomain[bo->bo_domain].bd_freebuffers == 0 && 4033 TD_IS_IDLETHREAD(curthread)) 4034 return (EBUSY); 4035 4036 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 4037 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4038 offset = blkno * bsize; 4039 vmio = vp->v_object != NULL; 4040 if (vmio) { 4041 maxsize = size + (offset & PAGE_MASK); 4042 } else { 4043 maxsize = size; 4044 /* Do not allow non-VMIO notmapped buffers. */ 4045 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4046 } 4047 maxsize = imax(maxsize, bsize); 4048 if ((flags & GB_NOSPARSE) != 0 && vmio && 4049 !vn_isdisk(vp, NULL)) { 4050 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4051 KASSERT(error != EOPNOTSUPP, 4052 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4053 vp)); 4054 if (error != 0) 4055 return (error); 4056 if (d_blkno == -1) 4057 return (EJUSTRETURN); 4058 } 4059 4060 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4061 if (bp == NULL) { 4062 if (slpflag || slptimeo) 4063 return (ETIMEDOUT); 4064 /* 4065 * XXX This is here until the sleep path is diagnosed 4066 * enough to work under very low memory conditions. 4067 * 4068 * There's an issue on low memory, 4BSD+non-preempt 4069 * systems (eg MIPS routers with 32MB RAM) where buffer 4070 * exhaustion occurs without sleeping for buffer 4071 * reclaimation. This just sticks in a loop and 4072 * constantly attempts to allocate a buffer, which 4073 * hits exhaustion and tries to wakeup bufdaemon. 4074 * This never happens because we never yield. 4075 * 4076 * The real solution is to identify and fix these cases 4077 * so we aren't effectively busy-waiting in a loop 4078 * until the reclaimation path has cycles to run. 4079 */ 4080 kern_yield(PRI_USER); 4081 goto loop; 4082 } 4083 4084 /* 4085 * This code is used to make sure that a buffer is not 4086 * created while the getnewbuf routine is blocked. 4087 * This can be a problem whether the vnode is locked or not. 4088 * If the buffer is created out from under us, we have to 4089 * throw away the one we just created. 4090 * 4091 * Note: this must occur before we associate the buffer 4092 * with the vp especially considering limitations in 4093 * the splay tree implementation when dealing with duplicate 4094 * lblkno's. 4095 */ 4096 BO_LOCK(bo); 4097 if (gbincore(bo, blkno)) { 4098 BO_UNLOCK(bo); 4099 bp->b_flags |= B_INVAL; 4100 bufspace_release(bufdomain(bp), maxsize); 4101 brelse(bp); 4102 goto loop; 4103 } 4104 4105 /* 4106 * Insert the buffer into the hash, so that it can 4107 * be found by incore. 4108 */ 4109 bp->b_lblkno = blkno; 4110 bp->b_blkno = d_blkno; 4111 bp->b_offset = offset; 4112 bgetvp(vp, bp); 4113 BO_UNLOCK(bo); 4114 4115 /* 4116 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4117 * buffer size starts out as 0, B_CACHE will be set by 4118 * allocbuf() for the VMIO case prior to it testing the 4119 * backing store for validity. 4120 */ 4121 4122 if (vmio) { 4123 bp->b_flags |= B_VMIO; 4124 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4125 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4126 bp, vp->v_object, bp->b_bufobj->bo_object)); 4127 } else { 4128 bp->b_flags &= ~B_VMIO; 4129 KASSERT(bp->b_bufobj->bo_object == NULL, 4130 ("ARGH! has b_bufobj->bo_object %p %p\n", 4131 bp, bp->b_bufobj->bo_object)); 4132 BUF_CHECK_MAPPED(bp); 4133 } 4134 4135 allocbuf(bp, size); 4136 bufspace_release(bufdomain(bp), maxsize); 4137 bp->b_flags &= ~B_DONE; 4138 } 4139 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4140 BUF_ASSERT_HELD(bp); 4141 end: 4142 buf_track(bp, __func__); 4143 KASSERT(bp->b_bufobj == bo, 4144 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4145 *bpp = bp; 4146 return (0); 4147 } 4148 4149 /* 4150 * Get an empty, disassociated buffer of given size. The buffer is initially 4151 * set to B_INVAL. 4152 */ 4153 struct buf * 4154 geteblk(int size, int flags) 4155 { 4156 struct buf *bp; 4157 int maxsize; 4158 4159 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4160 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4161 if ((flags & GB_NOWAIT_BD) && 4162 (curthread->td_pflags & TDP_BUFNEED) != 0) 4163 return (NULL); 4164 } 4165 allocbuf(bp, size); 4166 bufspace_release(bufdomain(bp), maxsize); 4167 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4168 BUF_ASSERT_HELD(bp); 4169 return (bp); 4170 } 4171 4172 /* 4173 * Truncate the backing store for a non-vmio buffer. 4174 */ 4175 static void 4176 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4177 { 4178 4179 if (bp->b_flags & B_MALLOC) { 4180 /* 4181 * malloced buffers are not shrunk 4182 */ 4183 if (newbsize == 0) { 4184 bufmallocadjust(bp, 0); 4185 free(bp->b_data, M_BIOBUF); 4186 bp->b_data = bp->b_kvabase; 4187 bp->b_flags &= ~B_MALLOC; 4188 } 4189 return; 4190 } 4191 vm_hold_free_pages(bp, newbsize); 4192 bufspace_adjust(bp, newbsize); 4193 } 4194 4195 /* 4196 * Extend the backing for a non-VMIO buffer. 4197 */ 4198 static void 4199 vfs_nonvmio_extend(struct buf *bp, int newbsize) 4200 { 4201 caddr_t origbuf; 4202 int origbufsize; 4203 4204 /* 4205 * We only use malloced memory on the first allocation. 4206 * and revert to page-allocated memory when the buffer 4207 * grows. 4208 * 4209 * There is a potential smp race here that could lead 4210 * to bufmallocspace slightly passing the max. It 4211 * is probably extremely rare and not worth worrying 4212 * over. 4213 */ 4214 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4215 bufmallocspace < maxbufmallocspace) { 4216 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4217 bp->b_flags |= B_MALLOC; 4218 bufmallocadjust(bp, newbsize); 4219 return; 4220 } 4221 4222 /* 4223 * If the buffer is growing on its other-than-first 4224 * allocation then we revert to the page-allocation 4225 * scheme. 4226 */ 4227 origbuf = NULL; 4228 origbufsize = 0; 4229 if (bp->b_flags & B_MALLOC) { 4230 origbuf = bp->b_data; 4231 origbufsize = bp->b_bufsize; 4232 bp->b_data = bp->b_kvabase; 4233 bufmallocadjust(bp, 0); 4234 bp->b_flags &= ~B_MALLOC; 4235 newbsize = round_page(newbsize); 4236 } 4237 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4238 (vm_offset_t) bp->b_data + newbsize); 4239 if (origbuf != NULL) { 4240 bcopy(origbuf, bp->b_data, origbufsize); 4241 free(origbuf, M_BIOBUF); 4242 } 4243 bufspace_adjust(bp, newbsize); 4244 } 4245 4246 /* 4247 * This code constitutes the buffer memory from either anonymous system 4248 * memory (in the case of non-VMIO operations) or from an associated 4249 * VM object (in the case of VMIO operations). This code is able to 4250 * resize a buffer up or down. 4251 * 4252 * Note that this code is tricky, and has many complications to resolve 4253 * deadlock or inconsistent data situations. Tread lightly!!! 4254 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4255 * the caller. Calling this code willy nilly can result in the loss of data. 4256 * 4257 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4258 * B_CACHE for the non-VMIO case. 4259 */ 4260 int 4261 allocbuf(struct buf *bp, int size) 4262 { 4263 int newbsize; 4264 4265 BUF_ASSERT_HELD(bp); 4266 4267 if (bp->b_bcount == size) 4268 return (1); 4269 4270 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 4271 panic("allocbuf: buffer too small"); 4272 4273 newbsize = roundup2(size, DEV_BSIZE); 4274 if ((bp->b_flags & B_VMIO) == 0) { 4275 if ((bp->b_flags & B_MALLOC) == 0) 4276 newbsize = round_page(newbsize); 4277 /* 4278 * Just get anonymous memory from the kernel. Don't 4279 * mess with B_CACHE. 4280 */ 4281 if (newbsize < bp->b_bufsize) 4282 vfs_nonvmio_truncate(bp, newbsize); 4283 else if (newbsize > bp->b_bufsize) 4284 vfs_nonvmio_extend(bp, newbsize); 4285 } else { 4286 int desiredpages; 4287 4288 desiredpages = (size == 0) ? 0 : 4289 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4290 4291 if (bp->b_flags & B_MALLOC) 4292 panic("allocbuf: VMIO buffer can't be malloced"); 4293 /* 4294 * Set B_CACHE initially if buffer is 0 length or will become 4295 * 0-length. 4296 */ 4297 if (size == 0 || bp->b_bufsize == 0) 4298 bp->b_flags |= B_CACHE; 4299 4300 if (newbsize < bp->b_bufsize) 4301 vfs_vmio_truncate(bp, desiredpages); 4302 /* XXX This looks as if it should be newbsize > b_bufsize */ 4303 else if (size > bp->b_bcount) 4304 vfs_vmio_extend(bp, desiredpages, size); 4305 bufspace_adjust(bp, newbsize); 4306 } 4307 bp->b_bcount = size; /* requested buffer size. */ 4308 return (1); 4309 } 4310 4311 extern int inflight_transient_maps; 4312 4313 static struct bio_queue nondump_bios; 4314 4315 void 4316 biodone(struct bio *bp) 4317 { 4318 struct mtx *mtxp; 4319 void (*done)(struct bio *); 4320 vm_offset_t start, end; 4321 4322 biotrack(bp, __func__); 4323 4324 /* 4325 * Avoid completing I/O when dumping after a panic since that may 4326 * result in a deadlock in the filesystem or pager code. Note that 4327 * this doesn't affect dumps that were started manually since we aim 4328 * to keep the system usable after it has been resumed. 4329 */ 4330 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4331 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4332 return; 4333 } 4334 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4335 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4336 bp->bio_flags |= BIO_UNMAPPED; 4337 start = trunc_page((vm_offset_t)bp->bio_data); 4338 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4339 bp->bio_data = unmapped_buf; 4340 pmap_qremove(start, atop(end - start)); 4341 vmem_free(transient_arena, start, end - start); 4342 atomic_add_int(&inflight_transient_maps, -1); 4343 } 4344 done = bp->bio_done; 4345 if (done == NULL) { 4346 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4347 mtx_lock(mtxp); 4348 bp->bio_flags |= BIO_DONE; 4349 wakeup(bp); 4350 mtx_unlock(mtxp); 4351 } else 4352 done(bp); 4353 } 4354 4355 /* 4356 * Wait for a BIO to finish. 4357 */ 4358 int 4359 biowait(struct bio *bp, const char *wchan) 4360 { 4361 struct mtx *mtxp; 4362 4363 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4364 mtx_lock(mtxp); 4365 while ((bp->bio_flags & BIO_DONE) == 0) 4366 msleep(bp, mtxp, PRIBIO, wchan, 0); 4367 mtx_unlock(mtxp); 4368 if (bp->bio_error != 0) 4369 return (bp->bio_error); 4370 if (!(bp->bio_flags & BIO_ERROR)) 4371 return (0); 4372 return (EIO); 4373 } 4374 4375 void 4376 biofinish(struct bio *bp, struct devstat *stat, int error) 4377 { 4378 4379 if (error) { 4380 bp->bio_error = error; 4381 bp->bio_flags |= BIO_ERROR; 4382 } 4383 if (stat != NULL) 4384 devstat_end_transaction_bio(stat, bp); 4385 biodone(bp); 4386 } 4387 4388 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4389 void 4390 biotrack_buf(struct bio *bp, const char *location) 4391 { 4392 4393 buf_track(bp->bio_track_bp, location); 4394 } 4395 #endif 4396 4397 /* 4398 * bufwait: 4399 * 4400 * Wait for buffer I/O completion, returning error status. The buffer 4401 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4402 * error and cleared. 4403 */ 4404 int 4405 bufwait(struct buf *bp) 4406 { 4407 if (bp->b_iocmd == BIO_READ) 4408 bwait(bp, PRIBIO, "biord"); 4409 else 4410 bwait(bp, PRIBIO, "biowr"); 4411 if (bp->b_flags & B_EINTR) { 4412 bp->b_flags &= ~B_EINTR; 4413 return (EINTR); 4414 } 4415 if (bp->b_ioflags & BIO_ERROR) { 4416 return (bp->b_error ? bp->b_error : EIO); 4417 } else { 4418 return (0); 4419 } 4420 } 4421 4422 /* 4423 * bufdone: 4424 * 4425 * Finish I/O on a buffer, optionally calling a completion function. 4426 * This is usually called from an interrupt so process blocking is 4427 * not allowed. 4428 * 4429 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4430 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4431 * assuming B_INVAL is clear. 4432 * 4433 * For the VMIO case, we set B_CACHE if the op was a read and no 4434 * read error occurred, or if the op was a write. B_CACHE is never 4435 * set if the buffer is invalid or otherwise uncacheable. 4436 * 4437 * biodone does not mess with B_INVAL, allowing the I/O routine or the 4438 * initiator to leave B_INVAL set to brelse the buffer out of existence 4439 * in the biodone routine. 4440 */ 4441 void 4442 bufdone(struct buf *bp) 4443 { 4444 struct bufobj *dropobj; 4445 void (*biodone)(struct buf *); 4446 4447 buf_track(bp, __func__); 4448 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4449 dropobj = NULL; 4450 4451 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4452 BUF_ASSERT_HELD(bp); 4453 4454 runningbufwakeup(bp); 4455 if (bp->b_iocmd == BIO_WRITE) 4456 dropobj = bp->b_bufobj; 4457 /* call optional completion function if requested */ 4458 if (bp->b_iodone != NULL) { 4459 biodone = bp->b_iodone; 4460 bp->b_iodone = NULL; 4461 (*biodone) (bp); 4462 if (dropobj) 4463 bufobj_wdrop(dropobj); 4464 return; 4465 } 4466 if (bp->b_flags & B_VMIO) { 4467 /* 4468 * Set B_CACHE if the op was a normal read and no error 4469 * occurred. B_CACHE is set for writes in the b*write() 4470 * routines. 4471 */ 4472 if (bp->b_iocmd == BIO_READ && 4473 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4474 !(bp->b_ioflags & BIO_ERROR)) 4475 bp->b_flags |= B_CACHE; 4476 vfs_vmio_iodone(bp); 4477 } 4478 if (!LIST_EMPTY(&bp->b_dep)) 4479 buf_complete(bp); 4480 if ((bp->b_flags & B_CKHASH) != 0) { 4481 KASSERT(bp->b_iocmd == BIO_READ, 4482 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4483 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4484 (*bp->b_ckhashcalc)(bp); 4485 } 4486 /* 4487 * For asynchronous completions, release the buffer now. The brelse 4488 * will do a wakeup there if necessary - so no need to do a wakeup 4489 * here in the async case. The sync case always needs to do a wakeup. 4490 */ 4491 if (bp->b_flags & B_ASYNC) { 4492 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4493 (bp->b_ioflags & BIO_ERROR)) 4494 brelse(bp); 4495 else 4496 bqrelse(bp); 4497 } else 4498 bdone(bp); 4499 if (dropobj) 4500 bufobj_wdrop(dropobj); 4501 } 4502 4503 /* 4504 * This routine is called in lieu of iodone in the case of 4505 * incomplete I/O. This keeps the busy status for pages 4506 * consistent. 4507 */ 4508 void 4509 vfs_unbusy_pages(struct buf *bp) 4510 { 4511 int i; 4512 vm_object_t obj; 4513 vm_page_t m; 4514 4515 runningbufwakeup(bp); 4516 if (!(bp->b_flags & B_VMIO)) 4517 return; 4518 4519 obj = bp->b_bufobj->bo_object; 4520 VM_OBJECT_WLOCK(obj); 4521 for (i = 0; i < bp->b_npages; i++) { 4522 m = bp->b_pages[i]; 4523 if (m == bogus_page) { 4524 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4525 if (!m) 4526 panic("vfs_unbusy_pages: page missing\n"); 4527 bp->b_pages[i] = m; 4528 if (buf_mapped(bp)) { 4529 BUF_CHECK_MAPPED(bp); 4530 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4531 bp->b_pages, bp->b_npages); 4532 } else 4533 BUF_CHECK_UNMAPPED(bp); 4534 } 4535 vm_page_sunbusy(m); 4536 } 4537 vm_object_pip_wakeupn(obj, bp->b_npages); 4538 VM_OBJECT_WUNLOCK(obj); 4539 } 4540 4541 /* 4542 * vfs_page_set_valid: 4543 * 4544 * Set the valid bits in a page based on the supplied offset. The 4545 * range is restricted to the buffer's size. 4546 * 4547 * This routine is typically called after a read completes. 4548 */ 4549 static void 4550 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4551 { 4552 vm_ooffset_t eoff; 4553 4554 /* 4555 * Compute the end offset, eoff, such that [off, eoff) does not span a 4556 * page boundary and eoff is not greater than the end of the buffer. 4557 * The end of the buffer, in this case, is our file EOF, not the 4558 * allocation size of the buffer. 4559 */ 4560 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4561 if (eoff > bp->b_offset + bp->b_bcount) 4562 eoff = bp->b_offset + bp->b_bcount; 4563 4564 /* 4565 * Set valid range. This is typically the entire buffer and thus the 4566 * entire page. 4567 */ 4568 if (eoff > off) 4569 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4570 } 4571 4572 /* 4573 * vfs_page_set_validclean: 4574 * 4575 * Set the valid bits and clear the dirty bits in a page based on the 4576 * supplied offset. The range is restricted to the buffer's size. 4577 */ 4578 static void 4579 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4580 { 4581 vm_ooffset_t soff, eoff; 4582 4583 /* 4584 * Start and end offsets in buffer. eoff - soff may not cross a 4585 * page boundary or cross the end of the buffer. The end of the 4586 * buffer, in this case, is our file EOF, not the allocation size 4587 * of the buffer. 4588 */ 4589 soff = off; 4590 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4591 if (eoff > bp->b_offset + bp->b_bcount) 4592 eoff = bp->b_offset + bp->b_bcount; 4593 4594 /* 4595 * Set valid range. This is typically the entire buffer and thus the 4596 * entire page. 4597 */ 4598 if (eoff > soff) { 4599 vm_page_set_validclean( 4600 m, 4601 (vm_offset_t) (soff & PAGE_MASK), 4602 (vm_offset_t) (eoff - soff) 4603 ); 4604 } 4605 } 4606 4607 /* 4608 * Ensure that all buffer pages are not exclusive busied. If any page is 4609 * exclusive busy, drain it. 4610 */ 4611 void 4612 vfs_drain_busy_pages(struct buf *bp) 4613 { 4614 vm_page_t m; 4615 int i, last_busied; 4616 4617 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4618 last_busied = 0; 4619 for (i = 0; i < bp->b_npages; i++) { 4620 m = bp->b_pages[i]; 4621 if (vm_page_xbusied(m)) { 4622 for (; last_busied < i; last_busied++) 4623 vm_page_sbusy(bp->b_pages[last_busied]); 4624 while (vm_page_xbusied(m)) { 4625 vm_page_lock(m); 4626 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4627 vm_page_busy_sleep(m, "vbpage", true); 4628 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4629 } 4630 } 4631 } 4632 for (i = 0; i < last_busied; i++) 4633 vm_page_sunbusy(bp->b_pages[i]); 4634 } 4635 4636 /* 4637 * This routine is called before a device strategy routine. 4638 * It is used to tell the VM system that paging I/O is in 4639 * progress, and treat the pages associated with the buffer 4640 * almost as being exclusive busy. Also the object paging_in_progress 4641 * flag is handled to make sure that the object doesn't become 4642 * inconsistent. 4643 * 4644 * Since I/O has not been initiated yet, certain buffer flags 4645 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4646 * and should be ignored. 4647 */ 4648 void 4649 vfs_busy_pages(struct buf *bp, int clear_modify) 4650 { 4651 vm_object_t obj; 4652 vm_ooffset_t foff; 4653 vm_page_t m; 4654 int i; 4655 bool bogus; 4656 4657 if (!(bp->b_flags & B_VMIO)) 4658 return; 4659 4660 obj = bp->b_bufobj->bo_object; 4661 foff = bp->b_offset; 4662 KASSERT(bp->b_offset != NOOFFSET, 4663 ("vfs_busy_pages: no buffer offset")); 4664 VM_OBJECT_WLOCK(obj); 4665 vfs_drain_busy_pages(bp); 4666 if (bp->b_bufsize != 0) 4667 vfs_setdirty_locked_object(bp); 4668 bogus = false; 4669 for (i = 0; i < bp->b_npages; i++) { 4670 m = bp->b_pages[i]; 4671 4672 if ((bp->b_flags & B_CLUSTER) == 0) { 4673 vm_object_pip_add(obj, 1); 4674 vm_page_sbusy(m); 4675 } 4676 /* 4677 * When readying a buffer for a read ( i.e 4678 * clear_modify == 0 ), it is important to do 4679 * bogus_page replacement for valid pages in 4680 * partially instantiated buffers. Partially 4681 * instantiated buffers can, in turn, occur when 4682 * reconstituting a buffer from its VM backing store 4683 * base. We only have to do this if B_CACHE is 4684 * clear ( which causes the I/O to occur in the 4685 * first place ). The replacement prevents the read 4686 * I/O from overwriting potentially dirty VM-backed 4687 * pages. XXX bogus page replacement is, uh, bogus. 4688 * It may not work properly with small-block devices. 4689 * We need to find a better way. 4690 */ 4691 if (clear_modify) { 4692 pmap_remove_write(m); 4693 vfs_page_set_validclean(bp, foff, m); 4694 } else if (m->valid == VM_PAGE_BITS_ALL && 4695 (bp->b_flags & B_CACHE) == 0) { 4696 bp->b_pages[i] = bogus_page; 4697 bogus = true; 4698 } 4699 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4700 } 4701 VM_OBJECT_WUNLOCK(obj); 4702 if (bogus && buf_mapped(bp)) { 4703 BUF_CHECK_MAPPED(bp); 4704 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4705 bp->b_pages, bp->b_npages); 4706 } 4707 } 4708 4709 /* 4710 * vfs_bio_set_valid: 4711 * 4712 * Set the range within the buffer to valid. The range is 4713 * relative to the beginning of the buffer, b_offset. Note that 4714 * b_offset itself may be offset from the beginning of the first 4715 * page. 4716 */ 4717 void 4718 vfs_bio_set_valid(struct buf *bp, int base, int size) 4719 { 4720 int i, n; 4721 vm_page_t m; 4722 4723 if (!(bp->b_flags & B_VMIO)) 4724 return; 4725 4726 /* 4727 * Fixup base to be relative to beginning of first page. 4728 * Set initial n to be the maximum number of bytes in the 4729 * first page that can be validated. 4730 */ 4731 base += (bp->b_offset & PAGE_MASK); 4732 n = PAGE_SIZE - (base & PAGE_MASK); 4733 4734 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4735 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4736 m = bp->b_pages[i]; 4737 if (n > size) 4738 n = size; 4739 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4740 base += n; 4741 size -= n; 4742 n = PAGE_SIZE; 4743 } 4744 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4745 } 4746 4747 /* 4748 * vfs_bio_clrbuf: 4749 * 4750 * If the specified buffer is a non-VMIO buffer, clear the entire 4751 * buffer. If the specified buffer is a VMIO buffer, clear and 4752 * validate only the previously invalid portions of the buffer. 4753 * This routine essentially fakes an I/O, so we need to clear 4754 * BIO_ERROR and B_INVAL. 4755 * 4756 * Note that while we only theoretically need to clear through b_bcount, 4757 * we go ahead and clear through b_bufsize. 4758 */ 4759 void 4760 vfs_bio_clrbuf(struct buf *bp) 4761 { 4762 int i, j, mask, sa, ea, slide; 4763 4764 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4765 clrbuf(bp); 4766 return; 4767 } 4768 bp->b_flags &= ~B_INVAL; 4769 bp->b_ioflags &= ~BIO_ERROR; 4770 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4771 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4772 (bp->b_offset & PAGE_MASK) == 0) { 4773 if (bp->b_pages[0] == bogus_page) 4774 goto unlock; 4775 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4776 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4777 if ((bp->b_pages[0]->valid & mask) == mask) 4778 goto unlock; 4779 if ((bp->b_pages[0]->valid & mask) == 0) { 4780 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4781 bp->b_pages[0]->valid |= mask; 4782 goto unlock; 4783 } 4784 } 4785 sa = bp->b_offset & PAGE_MASK; 4786 slide = 0; 4787 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4788 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4789 ea = slide & PAGE_MASK; 4790 if (ea == 0) 4791 ea = PAGE_SIZE; 4792 if (bp->b_pages[i] == bogus_page) 4793 continue; 4794 j = sa / DEV_BSIZE; 4795 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4796 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4797 if ((bp->b_pages[i]->valid & mask) == mask) 4798 continue; 4799 if ((bp->b_pages[i]->valid & mask) == 0) 4800 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4801 else { 4802 for (; sa < ea; sa += DEV_BSIZE, j++) { 4803 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4804 pmap_zero_page_area(bp->b_pages[i], 4805 sa, DEV_BSIZE); 4806 } 4807 } 4808 } 4809 bp->b_pages[i]->valid |= mask; 4810 } 4811 unlock: 4812 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4813 bp->b_resid = 0; 4814 } 4815 4816 void 4817 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4818 { 4819 vm_page_t m; 4820 int i, n; 4821 4822 if (buf_mapped(bp)) { 4823 BUF_CHECK_MAPPED(bp); 4824 bzero(bp->b_data + base, size); 4825 } else { 4826 BUF_CHECK_UNMAPPED(bp); 4827 n = PAGE_SIZE - (base & PAGE_MASK); 4828 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4829 m = bp->b_pages[i]; 4830 if (n > size) 4831 n = size; 4832 pmap_zero_page_area(m, base & PAGE_MASK, n); 4833 base += n; 4834 size -= n; 4835 n = PAGE_SIZE; 4836 } 4837 } 4838 } 4839 4840 /* 4841 * Update buffer flags based on I/O request parameters, optionally releasing the 4842 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4843 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4844 * I/O). Otherwise the buffer is released to the cache. 4845 */ 4846 static void 4847 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4848 { 4849 4850 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4851 ("buf %p non-VMIO noreuse", bp)); 4852 4853 if ((ioflag & IO_DIRECT) != 0) 4854 bp->b_flags |= B_DIRECT; 4855 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4856 bp->b_flags |= B_RELBUF; 4857 if ((ioflag & IO_NOREUSE) != 0) 4858 bp->b_flags |= B_NOREUSE; 4859 if (release) 4860 brelse(bp); 4861 } else if (release) 4862 bqrelse(bp); 4863 } 4864 4865 void 4866 vfs_bio_brelse(struct buf *bp, int ioflag) 4867 { 4868 4869 b_io_dismiss(bp, ioflag, true); 4870 } 4871 4872 void 4873 vfs_bio_set_flags(struct buf *bp, int ioflag) 4874 { 4875 4876 b_io_dismiss(bp, ioflag, false); 4877 } 4878 4879 /* 4880 * vm_hold_load_pages and vm_hold_free_pages get pages into 4881 * a buffers address space. The pages are anonymous and are 4882 * not associated with a file object. 4883 */ 4884 static void 4885 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4886 { 4887 vm_offset_t pg; 4888 vm_page_t p; 4889 int index; 4890 4891 BUF_CHECK_MAPPED(bp); 4892 4893 to = round_page(to); 4894 from = round_page(from); 4895 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4896 4897 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4898 /* 4899 * note: must allocate system pages since blocking here 4900 * could interfere with paging I/O, no matter which 4901 * process we are. 4902 */ 4903 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4904 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | 4905 VM_ALLOC_WAITOK); 4906 pmap_qenter(pg, &p, 1); 4907 bp->b_pages[index] = p; 4908 } 4909 bp->b_npages = index; 4910 } 4911 4912 /* Return pages associated with this buf to the vm system */ 4913 static void 4914 vm_hold_free_pages(struct buf *bp, int newbsize) 4915 { 4916 vm_offset_t from; 4917 vm_page_t p; 4918 int index, newnpages; 4919 4920 BUF_CHECK_MAPPED(bp); 4921 4922 from = round_page((vm_offset_t)bp->b_data + newbsize); 4923 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4924 if (bp->b_npages > newnpages) 4925 pmap_qremove(from, bp->b_npages - newnpages); 4926 for (index = newnpages; index < bp->b_npages; index++) { 4927 p = bp->b_pages[index]; 4928 bp->b_pages[index] = NULL; 4929 p->wire_count--; 4930 vm_page_free(p); 4931 } 4932 vm_wire_sub(bp->b_npages - newnpages); 4933 bp->b_npages = newnpages; 4934 } 4935 4936 /* 4937 * Map an IO request into kernel virtual address space. 4938 * 4939 * All requests are (re)mapped into kernel VA space. 4940 * Notice that we use b_bufsize for the size of the buffer 4941 * to be mapped. b_bcount might be modified by the driver. 4942 * 4943 * Note that even if the caller determines that the address space should 4944 * be valid, a race or a smaller-file mapped into a larger space may 4945 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4946 * check the return value. 4947 * 4948 * This function only works with pager buffers. 4949 */ 4950 int 4951 vmapbuf(struct buf *bp, int mapbuf) 4952 { 4953 vm_prot_t prot; 4954 int pidx; 4955 4956 if (bp->b_bufsize < 0) 4957 return (-1); 4958 prot = VM_PROT_READ; 4959 if (bp->b_iocmd == BIO_READ) 4960 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4961 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4962 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4963 btoc(MAXPHYS))) < 0) 4964 return (-1); 4965 bp->b_npages = pidx; 4966 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4967 if (mapbuf || !unmapped_buf_allowed) { 4968 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4969 bp->b_data = bp->b_kvabase + bp->b_offset; 4970 } else 4971 bp->b_data = unmapped_buf; 4972 return(0); 4973 } 4974 4975 /* 4976 * Free the io map PTEs associated with this IO operation. 4977 * We also invalidate the TLB entries and restore the original b_addr. 4978 * 4979 * This function only works with pager buffers. 4980 */ 4981 void 4982 vunmapbuf(struct buf *bp) 4983 { 4984 int npages; 4985 4986 npages = bp->b_npages; 4987 if (buf_mapped(bp)) 4988 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4989 vm_page_unhold_pages(bp->b_pages, npages); 4990 4991 bp->b_data = unmapped_buf; 4992 } 4993 4994 void 4995 bdone(struct buf *bp) 4996 { 4997 struct mtx *mtxp; 4998 4999 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5000 mtx_lock(mtxp); 5001 bp->b_flags |= B_DONE; 5002 wakeup(bp); 5003 mtx_unlock(mtxp); 5004 } 5005 5006 void 5007 bwait(struct buf *bp, u_char pri, const char *wchan) 5008 { 5009 struct mtx *mtxp; 5010 5011 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5012 mtx_lock(mtxp); 5013 while ((bp->b_flags & B_DONE) == 0) 5014 msleep(bp, mtxp, pri, wchan, 0); 5015 mtx_unlock(mtxp); 5016 } 5017 5018 int 5019 bufsync(struct bufobj *bo, int waitfor) 5020 { 5021 5022 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 5023 } 5024 5025 void 5026 bufstrategy(struct bufobj *bo, struct buf *bp) 5027 { 5028 int i __unused; 5029 struct vnode *vp; 5030 5031 vp = bp->b_vp; 5032 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5033 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5034 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5035 i = VOP_STRATEGY(vp, bp); 5036 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5037 } 5038 5039 /* 5040 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5041 */ 5042 void 5043 bufobj_init(struct bufobj *bo, void *private) 5044 { 5045 static volatile int bufobj_cleanq; 5046 5047 bo->bo_domain = 5048 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5049 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5050 bo->bo_private = private; 5051 TAILQ_INIT(&bo->bo_clean.bv_hd); 5052 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5053 } 5054 5055 void 5056 bufobj_wrefl(struct bufobj *bo) 5057 { 5058 5059 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5060 ASSERT_BO_WLOCKED(bo); 5061 bo->bo_numoutput++; 5062 } 5063 5064 void 5065 bufobj_wref(struct bufobj *bo) 5066 { 5067 5068 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5069 BO_LOCK(bo); 5070 bo->bo_numoutput++; 5071 BO_UNLOCK(bo); 5072 } 5073 5074 void 5075 bufobj_wdrop(struct bufobj *bo) 5076 { 5077 5078 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5079 BO_LOCK(bo); 5080 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5081 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5082 bo->bo_flag &= ~BO_WWAIT; 5083 wakeup(&bo->bo_numoutput); 5084 } 5085 BO_UNLOCK(bo); 5086 } 5087 5088 int 5089 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5090 { 5091 int error; 5092 5093 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5094 ASSERT_BO_WLOCKED(bo); 5095 error = 0; 5096 while (bo->bo_numoutput) { 5097 bo->bo_flag |= BO_WWAIT; 5098 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5099 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5100 if (error) 5101 break; 5102 } 5103 return (error); 5104 } 5105 5106 /* 5107 * Set bio_data or bio_ma for struct bio from the struct buf. 5108 */ 5109 void 5110 bdata2bio(struct buf *bp, struct bio *bip) 5111 { 5112 5113 if (!buf_mapped(bp)) { 5114 KASSERT(unmapped_buf_allowed, ("unmapped")); 5115 bip->bio_ma = bp->b_pages; 5116 bip->bio_ma_n = bp->b_npages; 5117 bip->bio_data = unmapped_buf; 5118 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5119 bip->bio_flags |= BIO_UNMAPPED; 5120 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5121 PAGE_SIZE == bp->b_npages, 5122 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5123 (long long)bip->bio_length, bip->bio_ma_n)); 5124 } else { 5125 bip->bio_data = bp->b_data; 5126 bip->bio_ma = NULL; 5127 } 5128 } 5129 5130 /* 5131 * The MIPS pmap code currently doesn't handle aliased pages. 5132 * The VIPT caches may not handle page aliasing themselves, leading 5133 * to data corruption. 5134 * 5135 * As such, this code makes a system extremely unhappy if said 5136 * system doesn't support unaliasing the above situation in hardware. 5137 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 5138 * this feature at build time, so it has to be handled in software. 5139 * 5140 * Once the MIPS pmap/cache code grows to support this function on 5141 * earlier chips, it should be flipped back off. 5142 */ 5143 #ifdef __mips__ 5144 static int buf_pager_relbuf = 1; 5145 #else 5146 static int buf_pager_relbuf = 0; 5147 #endif 5148 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5149 &buf_pager_relbuf, 0, 5150 "Make buffer pager release buffers after reading"); 5151 5152 /* 5153 * The buffer pager. It uses buffer reads to validate pages. 5154 * 5155 * In contrast to the generic local pager from vm/vnode_pager.c, this 5156 * pager correctly and easily handles volumes where the underlying 5157 * device block size is greater than the machine page size. The 5158 * buffer cache transparently extends the requested page run to be 5159 * aligned at the block boundary, and does the necessary bogus page 5160 * replacements in the addends to avoid obliterating already valid 5161 * pages. 5162 * 5163 * The only non-trivial issue is that the exclusive busy state for 5164 * pages, which is assumed by the vm_pager_getpages() interface, is 5165 * incompatible with the VMIO buffer cache's desire to share-busy the 5166 * pages. This function performs a trivial downgrade of the pages' 5167 * state before reading buffers, and a less trivial upgrade from the 5168 * shared-busy to excl-busy state after the read. 5169 */ 5170 int 5171 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5172 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5173 vbg_get_blksize_t get_blksize) 5174 { 5175 vm_page_t m; 5176 vm_object_t object; 5177 struct buf *bp; 5178 struct mount *mp; 5179 daddr_t lbn, lbnp; 5180 vm_ooffset_t la, lb, poff, poffe; 5181 long bsize; 5182 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5183 bool redo, lpart; 5184 5185 object = vp->v_object; 5186 mp = vp->v_mount; 5187 error = 0; 5188 la = IDX_TO_OFF(ma[count - 1]->pindex); 5189 if (la >= object->un_pager.vnp.vnp_size) 5190 return (VM_PAGER_BAD); 5191 5192 /* 5193 * Change the meaning of la from where the last requested page starts 5194 * to where it ends, because that's the end of the requested region 5195 * and the start of the potential read-ahead region. 5196 */ 5197 la += PAGE_SIZE; 5198 lpart = la > object->un_pager.vnp.vnp_size; 5199 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 5200 5201 /* 5202 * Calculate read-ahead, behind and total pages. 5203 */ 5204 pgsin = count; 5205 lb = IDX_TO_OFF(ma[0]->pindex); 5206 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5207 pgsin += pgsin_b; 5208 if (rbehind != NULL) 5209 *rbehind = pgsin_b; 5210 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5211 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5212 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5213 PAGE_SIZE) - la); 5214 pgsin += pgsin_a; 5215 if (rahead != NULL) 5216 *rahead = pgsin_a; 5217 VM_CNT_INC(v_vnodein); 5218 VM_CNT_ADD(v_vnodepgsin, pgsin); 5219 5220 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5221 != 0) ? GB_UNMAPPED : 0; 5222 VM_OBJECT_WLOCK(object); 5223 again: 5224 for (i = 0; i < count; i++) 5225 vm_page_busy_downgrade(ma[i]); 5226 VM_OBJECT_WUNLOCK(object); 5227 5228 lbnp = -1; 5229 for (i = 0; i < count; i++) { 5230 m = ma[i]; 5231 5232 /* 5233 * Pages are shared busy and the object lock is not 5234 * owned, which together allow for the pages' 5235 * invalidation. The racy test for validity avoids 5236 * useless creation of the buffer for the most typical 5237 * case when invalidation is not used in redo or for 5238 * parallel read. The shared->excl upgrade loop at 5239 * the end of the function catches the race in a 5240 * reliable way (protected by the object lock). 5241 */ 5242 if (m->valid == VM_PAGE_BITS_ALL) 5243 continue; 5244 5245 poff = IDX_TO_OFF(m->pindex); 5246 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5247 for (; poff < poffe; poff += bsize) { 5248 lbn = get_lblkno(vp, poff); 5249 if (lbn == lbnp) 5250 goto next_page; 5251 lbnp = lbn; 5252 5253 bsize = get_blksize(vp, lbn); 5254 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 5255 br_flags, &bp); 5256 if (error != 0) 5257 goto end_pages; 5258 if (LIST_EMPTY(&bp->b_dep)) { 5259 /* 5260 * Invalidation clears m->valid, but 5261 * may leave B_CACHE flag if the 5262 * buffer existed at the invalidation 5263 * time. In this case, recycle the 5264 * buffer to do real read on next 5265 * bread() after redo. 5266 * 5267 * Otherwise B_RELBUF is not strictly 5268 * necessary, enable to reduce buf 5269 * cache pressure. 5270 */ 5271 if (buf_pager_relbuf || 5272 m->valid != VM_PAGE_BITS_ALL) 5273 bp->b_flags |= B_RELBUF; 5274 5275 bp->b_flags &= ~B_NOCACHE; 5276 brelse(bp); 5277 } else { 5278 bqrelse(bp); 5279 } 5280 } 5281 KASSERT(1 /* racy, enable for debugging */ || 5282 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 5283 ("buf %d %p invalid", i, m)); 5284 if (i == count - 1 && lpart) { 5285 VM_OBJECT_WLOCK(object); 5286 if (m->valid != 0 && 5287 m->valid != VM_PAGE_BITS_ALL) 5288 vm_page_zero_invalid(m, TRUE); 5289 VM_OBJECT_WUNLOCK(object); 5290 } 5291 next_page:; 5292 } 5293 end_pages: 5294 5295 VM_OBJECT_WLOCK(object); 5296 redo = false; 5297 for (i = 0; i < count; i++) { 5298 vm_page_sunbusy(ma[i]); 5299 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 5300 5301 /* 5302 * Since the pages were only sbusy while neither the 5303 * buffer nor the object lock was held by us, or 5304 * reallocated while vm_page_grab() slept for busy 5305 * relinguish, they could have been invalidated. 5306 * Recheck the valid bits and re-read as needed. 5307 * 5308 * Note that the last page is made fully valid in the 5309 * read loop, and partial validity for the page at 5310 * index count - 1 could mean that the page was 5311 * invalidated or removed, so we must restart for 5312 * safety as well. 5313 */ 5314 if (ma[i]->valid != VM_PAGE_BITS_ALL) 5315 redo = true; 5316 } 5317 if (redo && error == 0) 5318 goto again; 5319 VM_OBJECT_WUNLOCK(object); 5320 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5321 } 5322 5323 #include "opt_ddb.h" 5324 #ifdef DDB 5325 #include <ddb/ddb.h> 5326 5327 /* DDB command to show buffer data */ 5328 DB_SHOW_COMMAND(buffer, db_show_buffer) 5329 { 5330 /* get args */ 5331 struct buf *bp = (struct buf *)addr; 5332 #ifdef FULL_BUF_TRACKING 5333 uint32_t i, j; 5334 #endif 5335 5336 if (!have_addr) { 5337 db_printf("usage: show buffer <addr>\n"); 5338 return; 5339 } 5340 5341 db_printf("buf at %p\n", bp); 5342 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 5343 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 5344 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 5345 db_printf( 5346 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5347 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 5348 "b_dep = %p\n", 5349 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5350 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5351 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 5352 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5353 bp->b_kvabase, bp->b_kvasize); 5354 if (bp->b_npages) { 5355 int i; 5356 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5357 for (i = 0; i < bp->b_npages; i++) { 5358 vm_page_t m; 5359 m = bp->b_pages[i]; 5360 if (m != NULL) 5361 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5362 (u_long)m->pindex, 5363 (u_long)VM_PAGE_TO_PHYS(m)); 5364 else 5365 db_printf("( ??? )"); 5366 if ((i + 1) < bp->b_npages) 5367 db_printf(","); 5368 } 5369 db_printf("\n"); 5370 } 5371 BUF_LOCKPRINTINFO(bp); 5372 #if defined(FULL_BUF_TRACKING) 5373 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5374 5375 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5376 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5377 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5378 continue; 5379 db_printf(" %2u: %s\n", j, 5380 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5381 } 5382 #elif defined(BUF_TRACKING) 5383 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5384 #endif 5385 db_printf(" "); 5386 } 5387 5388 DB_SHOW_COMMAND(bufqueues, bufqueues) 5389 { 5390 struct bufdomain *bd; 5391 struct buf *bp; 5392 long total; 5393 int i, j, cnt; 5394 5395 db_printf("bqempty: %d\n", bqempty.bq_len); 5396 5397 for (i = 0; i < buf_domains; i++) { 5398 bd = &bdomain[i]; 5399 db_printf("Buf domain %d\n", i); 5400 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5401 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5402 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5403 db_printf("\n"); 5404 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5405 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5406 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5407 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5408 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5409 db_printf("\n"); 5410 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5411 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5412 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5413 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5414 db_printf("\n"); 5415 total = 0; 5416 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5417 total += bp->b_bufsize; 5418 db_printf("\tcleanq count\t%d (%ld)\n", 5419 bd->bd_cleanq->bq_len, total); 5420 total = 0; 5421 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5422 total += bp->b_bufsize; 5423 db_printf("\tdirtyq count\t%d (%ld)\n", 5424 bd->bd_dirtyq.bq_len, total); 5425 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5426 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5427 db_printf("\tCPU "); 5428 for (j = 0; j <= mp_maxid; j++) 5429 db_printf("%d, ", bd->bd_subq[j].bq_len); 5430 db_printf("\n"); 5431 cnt = 0; 5432 total = 0; 5433 for (j = 0; j < nbuf; j++) 5434 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) { 5435 cnt++; 5436 total += buf[j].b_bufsize; 5437 } 5438 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5439 cnt = 0; 5440 total = 0; 5441 for (j = 0; j < nbuf; j++) 5442 if (buf[j].b_domain == i) { 5443 cnt++; 5444 total += buf[j].b_bufsize; 5445 } 5446 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5447 } 5448 } 5449 5450 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 5451 { 5452 struct buf *bp; 5453 int i; 5454 5455 for (i = 0; i < nbuf; i++) { 5456 bp = &buf[i]; 5457 if (BUF_ISLOCKED(bp)) { 5458 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5459 db_printf("\n"); 5460 if (db_pager_quit) 5461 break; 5462 } 5463 } 5464 } 5465 5466 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5467 { 5468 struct vnode *vp; 5469 struct buf *bp; 5470 5471 if (!have_addr) { 5472 db_printf("usage: show vnodebufs <addr>\n"); 5473 return; 5474 } 5475 vp = (struct vnode *)addr; 5476 db_printf("Clean buffers:\n"); 5477 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5478 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5479 db_printf("\n"); 5480 } 5481 db_printf("Dirty buffers:\n"); 5482 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5483 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5484 db_printf("\n"); 5485 } 5486 } 5487 5488 DB_COMMAND(countfreebufs, db_coundfreebufs) 5489 { 5490 struct buf *bp; 5491 int i, used = 0, nfree = 0; 5492 5493 if (have_addr) { 5494 db_printf("usage: countfreebufs\n"); 5495 return; 5496 } 5497 5498 for (i = 0; i < nbuf; i++) { 5499 bp = &buf[i]; 5500 if (bp->b_qindex == QUEUE_EMPTY) 5501 nfree++; 5502 else 5503 used++; 5504 } 5505 5506 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5507 nfree + used); 5508 db_printf("numfreebuffers is %d\n", numfreebuffers); 5509 } 5510 #endif /* DDB */ 5511