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 90 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 91 92 struct bio_ops bioops; /* I/O operation notification */ 93 94 struct buf_ops buf_ops_bio = { 95 .bop_name = "buf_ops_bio", 96 .bop_write = bufwrite, 97 .bop_strategy = bufstrategy, 98 .bop_sync = bufsync, 99 .bop_bdflush = bufbdflush, 100 }; 101 102 struct bufqueue { 103 struct mtx_padalign bq_lock; 104 TAILQ_HEAD(, buf) bq_queue; 105 uint8_t bq_index; 106 uint16_t bq_subqueue; 107 int bq_len; 108 } __aligned(CACHE_LINE_SIZE); 109 110 #define BQ_LOCKPTR(bq) (&(bq)->bq_lock) 111 #define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq))) 112 #define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq))) 113 #define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED) 114 115 struct bufdomain { 116 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */ 117 struct bufqueue bd_dirtyq; 118 struct bufqueue *bd_cleanq; 119 struct mtx_padalign bd_run_lock; 120 /* Constants */ 121 long bd_maxbufspace; 122 long bd_hibufspace; 123 long bd_lobufspace; 124 long bd_bufspacethresh; 125 int bd_hifreebuffers; 126 int bd_lofreebuffers; 127 int bd_hidirtybuffers; 128 int bd_lodirtybuffers; 129 int bd_dirtybufthresh; 130 int bd_lim; 131 /* atomics */ 132 int bd_wanted; 133 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers; 134 int __aligned(CACHE_LINE_SIZE) bd_running; 135 long __aligned(CACHE_LINE_SIZE) bd_bufspace; 136 int __aligned(CACHE_LINE_SIZE) bd_freebuffers; 137 } __aligned(CACHE_LINE_SIZE); 138 139 #define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock) 140 #define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd))) 141 #define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd))) 142 #define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED) 143 #define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock) 144 #define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd))) 145 #define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd))) 146 #define BD_DOMAIN(bd) (bd - bdomain) 147 148 static struct buf *buf; /* buffer header pool */ 149 extern struct buf *swbuf; /* Swap buffer header pool. */ 150 caddr_t unmapped_buf; 151 152 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 153 struct proc *bufdaemonproc; 154 155 static int inmem(struct vnode *vp, daddr_t blkno); 156 static void vm_hold_free_pages(struct buf *bp, int newbsize); 157 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 158 vm_offset_t to); 159 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 160 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 161 vm_page_t m); 162 static void vfs_clean_pages_dirty_buf(struct buf *bp); 163 static void vfs_setdirty_locked_object(struct buf *bp); 164 static void vfs_vmio_invalidate(struct buf *bp); 165 static void vfs_vmio_truncate(struct buf *bp, int npages); 166 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 167 static int vfs_bio_clcheck(struct vnode *vp, int size, 168 daddr_t lblkno, daddr_t blkno); 169 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int, 170 void (*)(struct buf *)); 171 static int buf_flush(struct vnode *vp, struct bufdomain *, int); 172 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int); 173 static void buf_daemon(void); 174 static __inline void bd_wakeup(void); 175 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 176 static void bufkva_reclaim(vmem_t *, int); 177 static void bufkva_free(struct buf *); 178 static int buf_import(void *, void **, int, int, int); 179 static void buf_release(void *, void **, int); 180 static void maxbcachebuf_adjust(void); 181 static inline struct bufdomain *bufdomain(struct buf *); 182 static void bq_remove(struct bufqueue *bq, struct buf *bp); 183 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock); 184 static int buf_recycle(struct bufdomain *, bool kva); 185 static void bq_init(struct bufqueue *bq, int qindex, int cpu, 186 const char *lockname); 187 static void bd_init(struct bufdomain *bd); 188 static int bd_flushall(struct bufdomain *bd); 189 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS); 190 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS); 191 192 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 193 int vmiodirenable = TRUE; 194 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 195 "Use the VM system for directory writes"); 196 long runningbufspace; 197 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 198 "Amount of presently outstanding async buffer io"); 199 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 200 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers"); 201 static counter_u64_t bufkvaspace; 202 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 203 "Kernel virtual memory used for buffers"); 204 static long maxbufspace; 205 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace, 206 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace, 207 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L", 208 "Maximum allowed value of bufspace (including metadata)"); 209 static long bufmallocspace; 210 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 211 "Amount of malloced memory for buffers"); 212 static long maxbufmallocspace; 213 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 214 0, "Maximum amount of malloced memory for buffers"); 215 static long lobufspace; 216 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace, 217 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace, 218 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L", 219 "Minimum amount of buffers we want to have"); 220 long hibufspace; 221 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace, 222 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace, 223 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L", 224 "Maximum allowed value of bufspace (excluding metadata)"); 225 long bufspacethresh; 226 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh, 227 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh, 228 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L", 229 "Bufspace consumed before waking the daemon to free some"); 230 static counter_u64_t buffreekvacnt; 231 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 232 "Number of times we have freed the KVA space from some buffer"); 233 static counter_u64_t bufdefragcnt; 234 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 235 "Number of times we have had to repeat buffer allocation to defragment"); 236 static long lorunningspace; 237 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 238 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 239 "Minimum preferred space used for in-progress I/O"); 240 static long hirunningspace; 241 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 242 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 243 "Maximum amount of space to use for in-progress I/O"); 244 int dirtybufferflushes; 245 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 246 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 247 int bdwriteskip; 248 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 249 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 250 int altbufferflushes; 251 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 252 0, "Number of fsync flushes to limit dirty buffers"); 253 static int recursiveflushes; 254 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 255 0, "Number of flushes skipped due to being recursive"); 256 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS); 257 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers, 258 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I", 259 "Number of buffers that are dirty (has unwritten changes) at the moment"); 260 static int lodirtybuffers; 261 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers, 262 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers, 263 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I", 264 "How many buffers we want to have free before bufdaemon can sleep"); 265 static int hidirtybuffers; 266 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers, 267 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers, 268 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I", 269 "When the number of dirty buffers is considered severe"); 270 int dirtybufthresh; 271 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh, 272 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh, 273 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I", 274 "Number of bdwrite to bawrite conversions to clear dirty buffers"); 275 static int numfreebuffers; 276 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 277 "Number of free buffers"); 278 static int lofreebuffers; 279 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers, 280 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers, 281 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I", 282 "Target number of free buffers"); 283 static int hifreebuffers; 284 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers, 285 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers, 286 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I", 287 "Threshold for clean buffer recycling"); 288 static counter_u64_t getnewbufcalls; 289 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, 290 &getnewbufcalls, "Number of calls to getnewbuf"); 291 static counter_u64_t getnewbufrestarts; 292 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, 293 &getnewbufrestarts, 294 "Number of times getnewbuf has had to restart a buffer acquisition"); 295 static counter_u64_t mappingrestarts; 296 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD, 297 &mappingrestarts, 298 "Number of times getblk has had to restart a buffer mapping for " 299 "unmapped buffer"); 300 static counter_u64_t numbufallocfails; 301 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, 302 &numbufallocfails, "Number of times buffer allocations failed"); 303 static int flushbufqtarget = 100; 304 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 305 "Amount of work to do in flushbufqueues when helping bufdaemon"); 306 static counter_u64_t notbufdflushes; 307 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 308 "Number of dirty buffer flushes done by the bufdaemon helpers"); 309 static long barrierwrites; 310 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 311 "Number of barrier writes"); 312 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 313 &unmapped_buf_allowed, 0, 314 "Permit the use of the unmapped i/o"); 315 int maxbcachebuf = MAXBCACHEBUF; 316 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0, 317 "Maximum size of a buffer cache block"); 318 319 /* 320 * This lock synchronizes access to bd_request. 321 */ 322 static struct mtx_padalign __exclusive_cache_line bdlock; 323 324 /* 325 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 326 * waitrunningbufspace(). 327 */ 328 static struct mtx_padalign __exclusive_cache_line rbreqlock; 329 330 /* 331 * Lock that protects bdirtywait. 332 */ 333 static struct mtx_padalign __exclusive_cache_line bdirtylock; 334 335 /* 336 * Wakeup point for bufdaemon, as well as indicator of whether it is already 337 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 338 * is idling. 339 */ 340 static int bd_request; 341 342 /* 343 * Request for the buf daemon to write more buffers than is indicated by 344 * lodirtybuf. This may be necessary to push out excess dependencies or 345 * defragment the address space where a simple count of the number of dirty 346 * buffers is insufficient to characterize the demand for flushing them. 347 */ 348 static int bd_speedupreq; 349 350 /* 351 * Synchronization (sleep/wakeup) variable for active buffer space requests. 352 * Set when wait starts, cleared prior to wakeup(). 353 * Used in runningbufwakeup() and waitrunningbufspace(). 354 */ 355 static int runningbufreq; 356 357 /* 358 * Synchronization for bwillwrite() waiters. 359 */ 360 static int bdirtywait; 361 362 /* 363 * Definitions for the buffer free lists. 364 */ 365 #define QUEUE_NONE 0 /* on no queue */ 366 #define QUEUE_EMPTY 1 /* empty buffer headers */ 367 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 368 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 369 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */ 370 371 /* Maximum number of buffer domains. */ 372 #define BUF_DOMAINS 8 373 374 struct bufdomainset bdlodirty; /* Domains > lodirty */ 375 struct bufdomainset bdhidirty; /* Domains > hidirty */ 376 377 /* Configured number of clean queues. */ 378 static int __read_mostly buf_domains; 379 380 BITSET_DEFINE(bufdomainset, BUF_DOMAINS); 381 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS]; 382 struct bufqueue __exclusive_cache_line bqempty; 383 384 /* 385 * per-cpu empty buffer cache. 386 */ 387 uma_zone_t buf_zone; 388 389 /* 390 * Single global constant for BUF_WMESG, to avoid getting multiple references. 391 * buf_wmesg is referred from macros. 392 */ 393 const char *buf_wmesg = BUF_WMESG; 394 395 static int 396 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 397 { 398 long value; 399 int error; 400 401 value = *(long *)arg1; 402 error = sysctl_handle_long(oidp, &value, 0, req); 403 if (error != 0 || req->newptr == NULL) 404 return (error); 405 mtx_lock(&rbreqlock); 406 if (arg1 == &hirunningspace) { 407 if (value < lorunningspace) 408 error = EINVAL; 409 else 410 hirunningspace = value; 411 } else { 412 KASSERT(arg1 == &lorunningspace, 413 ("%s: unknown arg1", __func__)); 414 if (value > hirunningspace) 415 error = EINVAL; 416 else 417 lorunningspace = value; 418 } 419 mtx_unlock(&rbreqlock); 420 return (error); 421 } 422 423 static int 424 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS) 425 { 426 int error; 427 int value; 428 int i; 429 430 value = *(int *)arg1; 431 error = sysctl_handle_int(oidp, &value, 0, req); 432 if (error != 0 || req->newptr == NULL) 433 return (error); 434 *(int *)arg1 = value; 435 for (i = 0; i < buf_domains; i++) 436 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 437 value / buf_domains; 438 439 return (error); 440 } 441 442 static int 443 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS) 444 { 445 long value; 446 int error; 447 int i; 448 449 value = *(long *)arg1; 450 error = sysctl_handle_long(oidp, &value, 0, req); 451 if (error != 0 || req->newptr == NULL) 452 return (error); 453 *(long *)arg1 = value; 454 for (i = 0; i < buf_domains; i++) 455 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 456 value / buf_domains; 457 458 return (error); 459 } 460 461 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 462 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 463 static int 464 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 465 { 466 long lvalue; 467 int ivalue; 468 int i; 469 470 lvalue = 0; 471 for (i = 0; i < buf_domains; i++) 472 lvalue += bdomain[i].bd_bufspace; 473 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 474 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 475 if (lvalue > INT_MAX) 476 /* On overflow, still write out a long to trigger ENOMEM. */ 477 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 478 ivalue = lvalue; 479 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 480 } 481 #else 482 static int 483 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 484 { 485 long lvalue; 486 int i; 487 488 lvalue = 0; 489 for (i = 0; i < buf_domains; i++) 490 lvalue += bdomain[i].bd_bufspace; 491 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 492 } 493 #endif 494 495 static int 496 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS) 497 { 498 int value; 499 int i; 500 501 value = 0; 502 for (i = 0; i < buf_domains; i++) 503 value += bdomain[i].bd_numdirtybuffers; 504 return (sysctl_handle_int(oidp, &value, 0, req)); 505 } 506 507 /* 508 * bdirtywakeup: 509 * 510 * Wakeup any bwillwrite() waiters. 511 */ 512 static void 513 bdirtywakeup(void) 514 { 515 mtx_lock(&bdirtylock); 516 if (bdirtywait) { 517 bdirtywait = 0; 518 wakeup(&bdirtywait); 519 } 520 mtx_unlock(&bdirtylock); 521 } 522 523 /* 524 * bd_clear: 525 * 526 * Clear a domain from the appropriate bitsets when dirtybuffers 527 * is decremented. 528 */ 529 static void 530 bd_clear(struct bufdomain *bd) 531 { 532 533 mtx_lock(&bdirtylock); 534 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers) 535 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 536 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers) 537 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 538 mtx_unlock(&bdirtylock); 539 } 540 541 /* 542 * bd_set: 543 * 544 * Set a domain in the appropriate bitsets when dirtybuffers 545 * is incremented. 546 */ 547 static void 548 bd_set(struct bufdomain *bd) 549 { 550 551 mtx_lock(&bdirtylock); 552 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers) 553 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 554 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers) 555 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 556 mtx_unlock(&bdirtylock); 557 } 558 559 /* 560 * bdirtysub: 561 * 562 * Decrement the numdirtybuffers count by one and wakeup any 563 * threads blocked in bwillwrite(). 564 */ 565 static void 566 bdirtysub(struct buf *bp) 567 { 568 struct bufdomain *bd; 569 int num; 570 571 bd = bufdomain(bp); 572 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1); 573 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 574 bdirtywakeup(); 575 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 576 bd_clear(bd); 577 } 578 579 /* 580 * bdirtyadd: 581 * 582 * Increment the numdirtybuffers count by one and wakeup the buf 583 * daemon if needed. 584 */ 585 static void 586 bdirtyadd(struct buf *bp) 587 { 588 struct bufdomain *bd; 589 int num; 590 591 /* 592 * Only do the wakeup once as we cross the boundary. The 593 * buf daemon will keep running until the condition clears. 594 */ 595 bd = bufdomain(bp); 596 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1); 597 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 598 bd_wakeup(); 599 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 600 bd_set(bd); 601 } 602 603 /* 604 * bufspace_daemon_wakeup: 605 * 606 * Wakeup the daemons responsible for freeing clean bufs. 607 */ 608 static void 609 bufspace_daemon_wakeup(struct bufdomain *bd) 610 { 611 612 /* 613 * avoid the lock if the daemon is running. 614 */ 615 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) { 616 BD_RUN_LOCK(bd); 617 atomic_store_int(&bd->bd_running, 1); 618 wakeup(&bd->bd_running); 619 BD_RUN_UNLOCK(bd); 620 } 621 } 622 623 /* 624 * bufspace_daemon_wait: 625 * 626 * Sleep until the domain falls below a limit or one second passes. 627 */ 628 static void 629 bufspace_daemon_wait(struct bufdomain *bd) 630 { 631 /* 632 * Re-check our limits and sleep. bd_running must be 633 * cleared prior to checking the limits to avoid missed 634 * wakeups. The waker will adjust one of bufspace or 635 * freebuffers prior to checking bd_running. 636 */ 637 BD_RUN_LOCK(bd); 638 atomic_store_int(&bd->bd_running, 0); 639 if (bd->bd_bufspace < bd->bd_bufspacethresh && 640 bd->bd_freebuffers > bd->bd_lofreebuffers) { 641 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP, 642 "-", hz); 643 } else { 644 /* Avoid spurious wakeups while running. */ 645 atomic_store_int(&bd->bd_running, 1); 646 BD_RUN_UNLOCK(bd); 647 } 648 } 649 650 /* 651 * bufspace_adjust: 652 * 653 * Adjust the reported bufspace for a KVA managed buffer, possibly 654 * waking any waiters. 655 */ 656 static void 657 bufspace_adjust(struct buf *bp, int bufsize) 658 { 659 struct bufdomain *bd; 660 long space; 661 int diff; 662 663 KASSERT((bp->b_flags & B_MALLOC) == 0, 664 ("bufspace_adjust: malloc buf %p", bp)); 665 bd = bufdomain(bp); 666 diff = bufsize - bp->b_bufsize; 667 if (diff < 0) { 668 atomic_subtract_long(&bd->bd_bufspace, -diff); 669 } else if (diff > 0) { 670 space = atomic_fetchadd_long(&bd->bd_bufspace, diff); 671 /* Wake up the daemon on the transition. */ 672 if (space < bd->bd_bufspacethresh && 673 space + diff >= bd->bd_bufspacethresh) 674 bufspace_daemon_wakeup(bd); 675 } 676 bp->b_bufsize = bufsize; 677 } 678 679 /* 680 * bufspace_reserve: 681 * 682 * Reserve bufspace before calling allocbuf(). metadata has a 683 * different space limit than data. 684 */ 685 static int 686 bufspace_reserve(struct bufdomain *bd, int size, bool metadata) 687 { 688 long limit, new; 689 long space; 690 691 if (metadata) 692 limit = bd->bd_maxbufspace; 693 else 694 limit = bd->bd_hibufspace; 695 space = atomic_fetchadd_long(&bd->bd_bufspace, size); 696 new = space + size; 697 if (new > limit) { 698 atomic_subtract_long(&bd->bd_bufspace, size); 699 return (ENOSPC); 700 } 701 702 /* Wake up the daemon on the transition. */ 703 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh) 704 bufspace_daemon_wakeup(bd); 705 706 return (0); 707 } 708 709 /* 710 * bufspace_release: 711 * 712 * Release reserved bufspace after bufspace_adjust() has consumed it. 713 */ 714 static void 715 bufspace_release(struct bufdomain *bd, int size) 716 { 717 718 atomic_subtract_long(&bd->bd_bufspace, size); 719 } 720 721 /* 722 * bufspace_wait: 723 * 724 * Wait for bufspace, acting as the buf daemon if a locked vnode is 725 * supplied. bd_wanted must be set prior to polling for space. The 726 * operation must be re-tried on return. 727 */ 728 static void 729 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags, 730 int slpflag, int slptimeo) 731 { 732 struct thread *td; 733 int error, fl, norunbuf; 734 735 if ((gbflags & GB_NOWAIT_BD) != 0) 736 return; 737 738 td = curthread; 739 BD_LOCK(bd); 740 while (bd->bd_wanted) { 741 if (vp != NULL && vp->v_type != VCHR && 742 (td->td_pflags & TDP_BUFNEED) == 0) { 743 BD_UNLOCK(bd); 744 /* 745 * getblk() is called with a vnode locked, and 746 * some majority of the dirty buffers may as 747 * well belong to the vnode. Flushing the 748 * buffers there would make a progress that 749 * cannot be achieved by the buf_daemon, that 750 * cannot lock the vnode. 751 */ 752 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 753 (td->td_pflags & TDP_NORUNNINGBUF); 754 755 /* 756 * Play bufdaemon. The getnewbuf() function 757 * may be called while the thread owns lock 758 * for another dirty buffer for the same 759 * vnode, which makes it impossible to use 760 * VOP_FSYNC() there, due to the buffer lock 761 * recursion. 762 */ 763 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 764 fl = buf_flush(vp, bd, flushbufqtarget); 765 td->td_pflags &= norunbuf; 766 BD_LOCK(bd); 767 if (fl != 0) 768 continue; 769 if (bd->bd_wanted == 0) 770 break; 771 } 772 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 773 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 774 if (error != 0) 775 break; 776 } 777 BD_UNLOCK(bd); 778 } 779 780 781 /* 782 * bufspace_daemon: 783 * 784 * buffer space management daemon. Tries to maintain some marginal 785 * amount of free buffer space so that requesting processes neither 786 * block nor work to reclaim buffers. 787 */ 788 static void 789 bufspace_daemon(void *arg) 790 { 791 struct bufdomain *bd; 792 793 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 794 SHUTDOWN_PRI_LAST + 100); 795 796 bd = arg; 797 for (;;) { 798 kthread_suspend_check(); 799 800 /* 801 * Free buffers from the clean queue until we meet our 802 * targets. 803 * 804 * Theory of operation: The buffer cache is most efficient 805 * when some free buffer headers and space are always 806 * available to getnewbuf(). This daemon attempts to prevent 807 * the excessive blocking and synchronization associated 808 * with shortfall. It goes through three phases according 809 * demand: 810 * 811 * 1) The daemon wakes up voluntarily once per-second 812 * during idle periods when the counters are below 813 * the wakeup thresholds (bufspacethresh, lofreebuffers). 814 * 815 * 2) The daemon wakes up as we cross the thresholds 816 * ahead of any potential blocking. This may bounce 817 * slightly according to the rate of consumption and 818 * release. 819 * 820 * 3) The daemon and consumers are starved for working 821 * clean buffers. This is the 'bufspace' sleep below 822 * which will inefficiently trade bufs with bqrelse 823 * until we return to condition 2. 824 */ 825 while (bd->bd_bufspace > bd->bd_lobufspace || 826 bd->bd_freebuffers < bd->bd_hifreebuffers) { 827 if (buf_recycle(bd, false) != 0) { 828 if (bd_flushall(bd)) 829 continue; 830 /* 831 * Speedup dirty if we've run out of clean 832 * buffers. This is possible in particular 833 * because softdep may held many bufs locked 834 * pending writes to other bufs which are 835 * marked for delayed write, exhausting 836 * clean space until they are written. 837 */ 838 bd_speedup(); 839 BD_LOCK(bd); 840 if (bd->bd_wanted) { 841 msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 842 PRIBIO|PDROP, "bufspace", hz/10); 843 } else 844 BD_UNLOCK(bd); 845 } 846 maybe_yield(); 847 } 848 bufspace_daemon_wait(bd); 849 } 850 } 851 852 /* 853 * bufmallocadjust: 854 * 855 * Adjust the reported bufspace for a malloc managed buffer, possibly 856 * waking any waiters. 857 */ 858 static void 859 bufmallocadjust(struct buf *bp, int bufsize) 860 { 861 int diff; 862 863 KASSERT((bp->b_flags & B_MALLOC) != 0, 864 ("bufmallocadjust: non-malloc buf %p", bp)); 865 diff = bufsize - bp->b_bufsize; 866 if (diff < 0) 867 atomic_subtract_long(&bufmallocspace, -diff); 868 else 869 atomic_add_long(&bufmallocspace, diff); 870 bp->b_bufsize = bufsize; 871 } 872 873 /* 874 * runningwakeup: 875 * 876 * Wake up processes that are waiting on asynchronous writes to fall 877 * below lorunningspace. 878 */ 879 static void 880 runningwakeup(void) 881 { 882 883 mtx_lock(&rbreqlock); 884 if (runningbufreq) { 885 runningbufreq = 0; 886 wakeup(&runningbufreq); 887 } 888 mtx_unlock(&rbreqlock); 889 } 890 891 /* 892 * runningbufwakeup: 893 * 894 * Decrement the outstanding write count according. 895 */ 896 void 897 runningbufwakeup(struct buf *bp) 898 { 899 long space, bspace; 900 901 bspace = bp->b_runningbufspace; 902 if (bspace == 0) 903 return; 904 space = atomic_fetchadd_long(&runningbufspace, -bspace); 905 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 906 space, bspace)); 907 bp->b_runningbufspace = 0; 908 /* 909 * Only acquire the lock and wakeup on the transition from exceeding 910 * the threshold to falling below it. 911 */ 912 if (space < lorunningspace) 913 return; 914 if (space - bspace > lorunningspace) 915 return; 916 runningwakeup(); 917 } 918 919 /* 920 * waitrunningbufspace() 921 * 922 * runningbufspace is a measure of the amount of I/O currently 923 * running. This routine is used in async-write situations to 924 * prevent creating huge backups of pending writes to a device. 925 * Only asynchronous writes are governed by this function. 926 * 927 * This does NOT turn an async write into a sync write. It waits 928 * for earlier writes to complete and generally returns before the 929 * caller's write has reached the device. 930 */ 931 void 932 waitrunningbufspace(void) 933 { 934 935 mtx_lock(&rbreqlock); 936 while (runningbufspace > hirunningspace) { 937 runningbufreq = 1; 938 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 939 } 940 mtx_unlock(&rbreqlock); 941 } 942 943 944 /* 945 * vfs_buf_test_cache: 946 * 947 * Called when a buffer is extended. This function clears the B_CACHE 948 * bit if the newly extended portion of the buffer does not contain 949 * valid data. 950 */ 951 static __inline void 952 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 953 vm_offset_t size, vm_page_t m) 954 { 955 956 VM_OBJECT_ASSERT_LOCKED(m->object); 957 if (bp->b_flags & B_CACHE) { 958 int base = (foff + off) & PAGE_MASK; 959 if (vm_page_is_valid(m, base, size) == 0) 960 bp->b_flags &= ~B_CACHE; 961 } 962 } 963 964 /* Wake up the buffer daemon if necessary */ 965 static void 966 bd_wakeup(void) 967 { 968 969 mtx_lock(&bdlock); 970 if (bd_request == 0) { 971 bd_request = 1; 972 wakeup(&bd_request); 973 } 974 mtx_unlock(&bdlock); 975 } 976 977 /* 978 * Adjust the maxbcachbuf tunable. 979 */ 980 static void 981 maxbcachebuf_adjust(void) 982 { 983 int i; 984 985 /* 986 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 987 */ 988 i = 2; 989 while (i * 2 <= maxbcachebuf) 990 i *= 2; 991 maxbcachebuf = i; 992 if (maxbcachebuf < MAXBSIZE) 993 maxbcachebuf = MAXBSIZE; 994 if (maxbcachebuf > MAXPHYS) 995 maxbcachebuf = MAXPHYS; 996 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 997 printf("maxbcachebuf=%d\n", maxbcachebuf); 998 } 999 1000 /* 1001 * bd_speedup - speedup the buffer cache flushing code 1002 */ 1003 void 1004 bd_speedup(void) 1005 { 1006 int needwake; 1007 1008 mtx_lock(&bdlock); 1009 needwake = 0; 1010 if (bd_speedupreq == 0 || bd_request == 0) 1011 needwake = 1; 1012 bd_speedupreq = 1; 1013 bd_request = 1; 1014 if (needwake) 1015 wakeup(&bd_request); 1016 mtx_unlock(&bdlock); 1017 } 1018 1019 #ifdef __i386__ 1020 #define TRANSIENT_DENOM 5 1021 #else 1022 #define TRANSIENT_DENOM 10 1023 #endif 1024 1025 /* 1026 * Calculating buffer cache scaling values and reserve space for buffer 1027 * headers. This is called during low level kernel initialization and 1028 * may be called more then once. We CANNOT write to the memory area 1029 * being reserved at this time. 1030 */ 1031 caddr_t 1032 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 1033 { 1034 int tuned_nbuf; 1035 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 1036 1037 /* 1038 * physmem_est is in pages. Convert it to kilobytes (assumes 1039 * PAGE_SIZE is >= 1K) 1040 */ 1041 physmem_est = physmem_est * (PAGE_SIZE / 1024); 1042 1043 maxbcachebuf_adjust(); 1044 /* 1045 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 1046 * For the first 64MB of ram nominally allocate sufficient buffers to 1047 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 1048 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 1049 * the buffer cache we limit the eventual kva reservation to 1050 * maxbcache bytes. 1051 * 1052 * factor represents the 1/4 x ram conversion. 1053 */ 1054 if (nbuf == 0) { 1055 int factor = 4 * BKVASIZE / 1024; 1056 1057 nbuf = 50; 1058 if (physmem_est > 4096) 1059 nbuf += min((physmem_est - 4096) / factor, 1060 65536 / factor); 1061 if (physmem_est > 65536) 1062 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 1063 32 * 1024 * 1024 / (factor * 5)); 1064 1065 if (maxbcache && nbuf > maxbcache / BKVASIZE) 1066 nbuf = maxbcache / BKVASIZE; 1067 tuned_nbuf = 1; 1068 } else 1069 tuned_nbuf = 0; 1070 1071 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 1072 maxbuf = (LONG_MAX / 3) / BKVASIZE; 1073 if (nbuf > maxbuf) { 1074 if (!tuned_nbuf) 1075 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 1076 maxbuf); 1077 nbuf = maxbuf; 1078 } 1079 1080 /* 1081 * Ideal allocation size for the transient bio submap is 10% 1082 * of the maximal space buffer map. This roughly corresponds 1083 * to the amount of the buffer mapped for typical UFS load. 1084 * 1085 * Clip the buffer map to reserve space for the transient 1086 * BIOs, if its extent is bigger than 90% (80% on i386) of the 1087 * maximum buffer map extent on the platform. 1088 * 1089 * The fall-back to the maxbuf in case of maxbcache unset, 1090 * allows to not trim the buffer KVA for the architectures 1091 * with ample KVA space. 1092 */ 1093 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 1094 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 1095 buf_sz = (long)nbuf * BKVASIZE; 1096 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 1097 (TRANSIENT_DENOM - 1)) { 1098 /* 1099 * There is more KVA than memory. Do not 1100 * adjust buffer map size, and assign the rest 1101 * of maxbuf to transient map. 1102 */ 1103 biotmap_sz = maxbuf_sz - buf_sz; 1104 } else { 1105 /* 1106 * Buffer map spans all KVA we could afford on 1107 * this platform. Give 10% (20% on i386) of 1108 * the buffer map to the transient bio map. 1109 */ 1110 biotmap_sz = buf_sz / TRANSIENT_DENOM; 1111 buf_sz -= biotmap_sz; 1112 } 1113 if (biotmap_sz / INT_MAX > MAXPHYS) 1114 bio_transient_maxcnt = INT_MAX; 1115 else 1116 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 1117 /* 1118 * Artificially limit to 1024 simultaneous in-flight I/Os 1119 * using the transient mapping. 1120 */ 1121 if (bio_transient_maxcnt > 1024) 1122 bio_transient_maxcnt = 1024; 1123 if (tuned_nbuf) 1124 nbuf = buf_sz / BKVASIZE; 1125 } 1126 1127 if (nswbuf == 0) { 1128 nswbuf = min(nbuf / 4, 256); 1129 if (nswbuf < NSWBUF_MIN) 1130 nswbuf = NSWBUF_MIN; 1131 } 1132 1133 /* 1134 * Reserve space for the buffer cache buffers 1135 */ 1136 buf = (void *)v; 1137 v = (caddr_t)(buf + nbuf); 1138 1139 return(v); 1140 } 1141 1142 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1143 void 1144 bufinit(void) 1145 { 1146 struct buf *bp; 1147 int i; 1148 1149 KASSERT(maxbcachebuf >= MAXBSIZE, 1150 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1151 MAXBSIZE)); 1152 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock"); 1153 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1154 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1155 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1156 1157 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1158 1159 /* finally, initialize each buffer header and stick on empty q */ 1160 for (i = 0; i < nbuf; i++) { 1161 bp = &buf[i]; 1162 bzero(bp, sizeof *bp); 1163 bp->b_flags = B_INVAL; 1164 bp->b_rcred = NOCRED; 1165 bp->b_wcred = NOCRED; 1166 bp->b_qindex = QUEUE_NONE; 1167 bp->b_domain = -1; 1168 bp->b_subqueue = mp_maxid + 1; 1169 bp->b_xflags = 0; 1170 bp->b_data = bp->b_kvabase = unmapped_buf; 1171 LIST_INIT(&bp->b_dep); 1172 BUF_LOCKINIT(bp); 1173 bq_insert(&bqempty, bp, false); 1174 } 1175 1176 /* 1177 * maxbufspace is the absolute maximum amount of buffer space we are 1178 * allowed to reserve in KVM and in real terms. The absolute maximum 1179 * is nominally used by metadata. hibufspace is the nominal maximum 1180 * used by most other requests. The differential is required to 1181 * ensure that metadata deadlocks don't occur. 1182 * 1183 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1184 * this may result in KVM fragmentation which is not handled optimally 1185 * by the system. XXX This is less true with vmem. We could use 1186 * PAGE_SIZE. 1187 */ 1188 maxbufspace = (long)nbuf * BKVASIZE; 1189 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1190 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1191 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1192 1193 /* 1194 * Note: The 16 MiB upper limit for hirunningspace was chosen 1195 * arbitrarily and may need further tuning. It corresponds to 1196 * 128 outstanding write IO requests (if IO size is 128 KiB), 1197 * which fits with many RAID controllers' tagged queuing limits. 1198 * The lower 1 MiB limit is the historical upper limit for 1199 * hirunningspace. 1200 */ 1201 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1202 16 * 1024 * 1024), 1024 * 1024); 1203 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1204 1205 /* 1206 * Limit the amount of malloc memory since it is wired permanently into 1207 * the kernel space. Even though this is accounted for in the buffer 1208 * allocation, we don't want the malloced region to grow uncontrolled. 1209 * The malloc scheme improves memory utilization significantly on 1210 * average (small) directories. 1211 */ 1212 maxbufmallocspace = hibufspace / 20; 1213 1214 /* 1215 * Reduce the chance of a deadlock occurring by limiting the number 1216 * of delayed-write dirty buffers we allow to stack up. 1217 */ 1218 hidirtybuffers = nbuf / 4 + 20; 1219 dirtybufthresh = hidirtybuffers * 9 / 10; 1220 /* 1221 * To support extreme low-memory systems, make sure hidirtybuffers 1222 * cannot eat up all available buffer space. This occurs when our 1223 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1224 * buffer space assuming BKVASIZE'd buffers. 1225 */ 1226 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1227 hidirtybuffers >>= 1; 1228 } 1229 lodirtybuffers = hidirtybuffers / 2; 1230 1231 /* 1232 * lofreebuffers should be sufficient to avoid stalling waiting on 1233 * buf headers under heavy utilization. The bufs in per-cpu caches 1234 * are counted as free but will be unavailable to threads executing 1235 * on other cpus. 1236 * 1237 * hifreebuffers is the free target for the bufspace daemon. This 1238 * should be set appropriately to limit work per-iteration. 1239 */ 1240 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1241 hifreebuffers = (3 * lofreebuffers) / 2; 1242 numfreebuffers = nbuf; 1243 1244 /* Setup the kva and free list allocators. */ 1245 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1246 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1247 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1248 1249 /* 1250 * Size the clean queue according to the amount of buffer space. 1251 * One queue per-256mb up to the max. More queues gives better 1252 * concurrency but less accurate LRU. 1253 */ 1254 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS); 1255 for (i = 0 ; i < buf_domains; i++) { 1256 struct bufdomain *bd; 1257 1258 bd = &bdomain[i]; 1259 bd_init(bd); 1260 bd->bd_freebuffers = nbuf / buf_domains; 1261 bd->bd_hifreebuffers = hifreebuffers / buf_domains; 1262 bd->bd_lofreebuffers = lofreebuffers / buf_domains; 1263 bd->bd_bufspace = 0; 1264 bd->bd_maxbufspace = maxbufspace / buf_domains; 1265 bd->bd_hibufspace = hibufspace / buf_domains; 1266 bd->bd_lobufspace = lobufspace / buf_domains; 1267 bd->bd_bufspacethresh = bufspacethresh / buf_domains; 1268 bd->bd_numdirtybuffers = 0; 1269 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains; 1270 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains; 1271 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains; 1272 /* Don't allow more than 2% of bufs in the per-cpu caches. */ 1273 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus; 1274 } 1275 getnewbufcalls = counter_u64_alloc(M_WAITOK); 1276 getnewbufrestarts = counter_u64_alloc(M_WAITOK); 1277 mappingrestarts = counter_u64_alloc(M_WAITOK); 1278 numbufallocfails = counter_u64_alloc(M_WAITOK); 1279 notbufdflushes = counter_u64_alloc(M_WAITOK); 1280 buffreekvacnt = counter_u64_alloc(M_WAITOK); 1281 bufdefragcnt = counter_u64_alloc(M_WAITOK); 1282 bufkvaspace = counter_u64_alloc(M_WAITOK); 1283 } 1284 1285 #ifdef INVARIANTS 1286 static inline void 1287 vfs_buf_check_mapped(struct buf *bp) 1288 { 1289 1290 KASSERT(bp->b_kvabase != unmapped_buf, 1291 ("mapped buf: b_kvabase was not updated %p", bp)); 1292 KASSERT(bp->b_data != unmapped_buf, 1293 ("mapped buf: b_data was not updated %p", bp)); 1294 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1295 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1296 } 1297 1298 static inline void 1299 vfs_buf_check_unmapped(struct buf *bp) 1300 { 1301 1302 KASSERT(bp->b_data == unmapped_buf, 1303 ("unmapped buf: corrupted b_data %p", bp)); 1304 } 1305 1306 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1307 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1308 #else 1309 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1310 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1311 #endif 1312 1313 static int 1314 isbufbusy(struct buf *bp) 1315 { 1316 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1317 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1318 return (1); 1319 return (0); 1320 } 1321 1322 /* 1323 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1324 */ 1325 void 1326 bufshutdown(int show_busybufs) 1327 { 1328 static int first_buf_printf = 1; 1329 struct buf *bp; 1330 int iter, nbusy, pbusy; 1331 #ifndef PREEMPTION 1332 int subiter; 1333 #endif 1334 1335 /* 1336 * Sync filesystems for shutdown 1337 */ 1338 wdog_kern_pat(WD_LASTVAL); 1339 sys_sync(curthread, NULL); 1340 1341 /* 1342 * With soft updates, some buffers that are 1343 * written will be remarked as dirty until other 1344 * buffers are written. 1345 */ 1346 for (iter = pbusy = 0; iter < 20; iter++) { 1347 nbusy = 0; 1348 for (bp = &buf[nbuf]; --bp >= buf; ) 1349 if (isbufbusy(bp)) 1350 nbusy++; 1351 if (nbusy == 0) { 1352 if (first_buf_printf) 1353 printf("All buffers synced."); 1354 break; 1355 } 1356 if (first_buf_printf) { 1357 printf("Syncing disks, buffers remaining... "); 1358 first_buf_printf = 0; 1359 } 1360 printf("%d ", nbusy); 1361 if (nbusy < pbusy) 1362 iter = 0; 1363 pbusy = nbusy; 1364 1365 wdog_kern_pat(WD_LASTVAL); 1366 sys_sync(curthread, NULL); 1367 1368 #ifdef PREEMPTION 1369 /* 1370 * Spin for a while to allow interrupt threads to run. 1371 */ 1372 DELAY(50000 * iter); 1373 #else 1374 /* 1375 * Context switch several times to allow interrupt 1376 * threads to run. 1377 */ 1378 for (subiter = 0; subiter < 50 * iter; subiter++) { 1379 thread_lock(curthread); 1380 mi_switch(SW_VOL, NULL); 1381 thread_unlock(curthread); 1382 DELAY(1000); 1383 } 1384 #endif 1385 } 1386 printf("\n"); 1387 /* 1388 * Count only busy local buffers to prevent forcing 1389 * a fsck if we're just a client of a wedged NFS server 1390 */ 1391 nbusy = 0; 1392 for (bp = &buf[nbuf]; --bp >= buf; ) { 1393 if (isbufbusy(bp)) { 1394 #if 0 1395 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1396 if (bp->b_dev == NULL) { 1397 TAILQ_REMOVE(&mountlist, 1398 bp->b_vp->v_mount, mnt_list); 1399 continue; 1400 } 1401 #endif 1402 nbusy++; 1403 if (show_busybufs > 0) { 1404 printf( 1405 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1406 nbusy, bp, bp->b_vp, bp->b_flags, 1407 (intmax_t)bp->b_blkno, 1408 (intmax_t)bp->b_lblkno); 1409 BUF_LOCKPRINTINFO(bp); 1410 if (show_busybufs > 1) 1411 vn_printf(bp->b_vp, 1412 "vnode content: "); 1413 } 1414 } 1415 } 1416 if (nbusy) { 1417 /* 1418 * Failed to sync all blocks. Indicate this and don't 1419 * unmount filesystems (thus forcing an fsck on reboot). 1420 */ 1421 printf("Giving up on %d buffers\n", nbusy); 1422 DELAY(5000000); /* 5 seconds */ 1423 } else { 1424 if (!first_buf_printf) 1425 printf("Final sync complete\n"); 1426 /* 1427 * Unmount filesystems 1428 */ 1429 if (panicstr == NULL) 1430 vfs_unmountall(); 1431 } 1432 swapoff_all(); 1433 DELAY(100000); /* wait for console output to finish */ 1434 } 1435 1436 static void 1437 bpmap_qenter(struct buf *bp) 1438 { 1439 1440 BUF_CHECK_MAPPED(bp); 1441 1442 /* 1443 * bp->b_data is relative to bp->b_offset, but 1444 * bp->b_offset may be offset into the first page. 1445 */ 1446 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1447 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1448 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1449 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1450 } 1451 1452 static inline struct bufdomain * 1453 bufdomain(struct buf *bp) 1454 { 1455 1456 return (&bdomain[bp->b_domain]); 1457 } 1458 1459 static struct bufqueue * 1460 bufqueue(struct buf *bp) 1461 { 1462 1463 switch (bp->b_qindex) { 1464 case QUEUE_NONE: 1465 /* FALLTHROUGH */ 1466 case QUEUE_SENTINEL: 1467 return (NULL); 1468 case QUEUE_EMPTY: 1469 return (&bqempty); 1470 case QUEUE_DIRTY: 1471 return (&bufdomain(bp)->bd_dirtyq); 1472 case QUEUE_CLEAN: 1473 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]); 1474 default: 1475 break; 1476 } 1477 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex); 1478 } 1479 1480 /* 1481 * Return the locked bufqueue that bp is a member of. 1482 */ 1483 static struct bufqueue * 1484 bufqueue_acquire(struct buf *bp) 1485 { 1486 struct bufqueue *bq, *nbq; 1487 1488 /* 1489 * bp can be pushed from a per-cpu queue to the 1490 * cleanq while we're waiting on the lock. Retry 1491 * if the queues don't match. 1492 */ 1493 bq = bufqueue(bp); 1494 BQ_LOCK(bq); 1495 for (;;) { 1496 nbq = bufqueue(bp); 1497 if (bq == nbq) 1498 break; 1499 BQ_UNLOCK(bq); 1500 BQ_LOCK(nbq); 1501 bq = nbq; 1502 } 1503 return (bq); 1504 } 1505 1506 /* 1507 * binsfree: 1508 * 1509 * Insert the buffer into the appropriate free list. Requires a 1510 * locked buffer on entry and buffer is unlocked before return. 1511 */ 1512 static void 1513 binsfree(struct buf *bp, int qindex) 1514 { 1515 struct bufdomain *bd; 1516 struct bufqueue *bq; 1517 1518 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY, 1519 ("binsfree: Invalid qindex %d", qindex)); 1520 BUF_ASSERT_XLOCKED(bp); 1521 1522 /* 1523 * Handle delayed bremfree() processing. 1524 */ 1525 if (bp->b_flags & B_REMFREE) { 1526 if (bp->b_qindex == qindex) { 1527 bp->b_flags |= B_REUSE; 1528 bp->b_flags &= ~B_REMFREE; 1529 BUF_UNLOCK(bp); 1530 return; 1531 } 1532 bq = bufqueue_acquire(bp); 1533 bq_remove(bq, bp); 1534 BQ_UNLOCK(bq); 1535 } 1536 bd = bufdomain(bp); 1537 if (qindex == QUEUE_CLEAN) { 1538 if (bd->bd_lim != 0) 1539 bq = &bd->bd_subq[PCPU_GET(cpuid)]; 1540 else 1541 bq = bd->bd_cleanq; 1542 } else 1543 bq = &bd->bd_dirtyq; 1544 bq_insert(bq, bp, true); 1545 } 1546 1547 /* 1548 * buf_free: 1549 * 1550 * Free a buffer to the buf zone once it no longer has valid contents. 1551 */ 1552 static void 1553 buf_free(struct buf *bp) 1554 { 1555 1556 if (bp->b_flags & B_REMFREE) 1557 bremfreef(bp); 1558 if (bp->b_vflags & BV_BKGRDINPROG) 1559 panic("losing buffer 1"); 1560 if (bp->b_rcred != NOCRED) { 1561 crfree(bp->b_rcred); 1562 bp->b_rcred = NOCRED; 1563 } 1564 if (bp->b_wcred != NOCRED) { 1565 crfree(bp->b_wcred); 1566 bp->b_wcred = NOCRED; 1567 } 1568 if (!LIST_EMPTY(&bp->b_dep)) 1569 buf_deallocate(bp); 1570 bufkva_free(bp); 1571 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1); 1572 BUF_UNLOCK(bp); 1573 uma_zfree(buf_zone, bp); 1574 } 1575 1576 /* 1577 * buf_import: 1578 * 1579 * Import bufs into the uma cache from the buf list. The system still 1580 * expects a static array of bufs and much of the synchronization 1581 * around bufs assumes type stable storage. As a result, UMA is used 1582 * only as a per-cpu cache of bufs still maintained on a global list. 1583 */ 1584 static int 1585 buf_import(void *arg, void **store, int cnt, int domain, int flags) 1586 { 1587 struct buf *bp; 1588 int i; 1589 1590 BQ_LOCK(&bqempty); 1591 for (i = 0; i < cnt; i++) { 1592 bp = TAILQ_FIRST(&bqempty.bq_queue); 1593 if (bp == NULL) 1594 break; 1595 bq_remove(&bqempty, bp); 1596 store[i] = bp; 1597 } 1598 BQ_UNLOCK(&bqempty); 1599 1600 return (i); 1601 } 1602 1603 /* 1604 * buf_release: 1605 * 1606 * Release bufs from the uma cache back to the buffer queues. 1607 */ 1608 static void 1609 buf_release(void *arg, void **store, int cnt) 1610 { 1611 struct bufqueue *bq; 1612 struct buf *bp; 1613 int i; 1614 1615 bq = &bqempty; 1616 BQ_LOCK(bq); 1617 for (i = 0; i < cnt; i++) { 1618 bp = store[i]; 1619 /* Inline bq_insert() to batch locking. */ 1620 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1621 bp->b_flags &= ~(B_AGE | B_REUSE); 1622 bq->bq_len++; 1623 bp->b_qindex = bq->bq_index; 1624 } 1625 BQ_UNLOCK(bq); 1626 } 1627 1628 /* 1629 * buf_alloc: 1630 * 1631 * Allocate an empty buffer header. 1632 */ 1633 static struct buf * 1634 buf_alloc(struct bufdomain *bd) 1635 { 1636 struct buf *bp; 1637 int freebufs; 1638 1639 /* 1640 * We can only run out of bufs in the buf zone if the average buf 1641 * is less than BKVASIZE. In this case the actual wait/block will 1642 * come from buf_reycle() failing to flush one of these small bufs. 1643 */ 1644 bp = NULL; 1645 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1); 1646 if (freebufs > 0) 1647 bp = uma_zalloc(buf_zone, M_NOWAIT); 1648 if (bp == NULL) { 1649 atomic_add_int(&bd->bd_freebuffers, 1); 1650 bufspace_daemon_wakeup(bd); 1651 counter_u64_add(numbufallocfails, 1); 1652 return (NULL); 1653 } 1654 /* 1655 * Wake-up the bufspace daemon on transition below threshold. 1656 */ 1657 if (freebufs == bd->bd_lofreebuffers) 1658 bufspace_daemon_wakeup(bd); 1659 1660 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1661 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1662 1663 KASSERT(bp->b_vp == NULL, 1664 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1665 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1666 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1667 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1668 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1669 KASSERT(bp->b_npages == 0, 1670 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1671 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1672 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1673 1674 bp->b_domain = BD_DOMAIN(bd); 1675 bp->b_flags = 0; 1676 bp->b_ioflags = 0; 1677 bp->b_xflags = 0; 1678 bp->b_vflags = 0; 1679 bp->b_vp = NULL; 1680 bp->b_blkno = bp->b_lblkno = 0; 1681 bp->b_offset = NOOFFSET; 1682 bp->b_iodone = 0; 1683 bp->b_error = 0; 1684 bp->b_resid = 0; 1685 bp->b_bcount = 0; 1686 bp->b_npages = 0; 1687 bp->b_dirtyoff = bp->b_dirtyend = 0; 1688 bp->b_bufobj = NULL; 1689 bp->b_data = bp->b_kvabase = unmapped_buf; 1690 bp->b_fsprivate1 = NULL; 1691 bp->b_fsprivate2 = NULL; 1692 bp->b_fsprivate3 = NULL; 1693 LIST_INIT(&bp->b_dep); 1694 1695 return (bp); 1696 } 1697 1698 /* 1699 * buf_recycle: 1700 * 1701 * Free a buffer from the given bufqueue. kva controls whether the 1702 * freed buf must own some kva resources. This is used for 1703 * defragmenting. 1704 */ 1705 static int 1706 buf_recycle(struct bufdomain *bd, bool kva) 1707 { 1708 struct bufqueue *bq; 1709 struct buf *bp, *nbp; 1710 1711 if (kva) 1712 counter_u64_add(bufdefragcnt, 1); 1713 nbp = NULL; 1714 bq = bd->bd_cleanq; 1715 BQ_LOCK(bq); 1716 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd), 1717 ("buf_recycle: Locks don't match")); 1718 nbp = TAILQ_FIRST(&bq->bq_queue); 1719 1720 /* 1721 * Run scan, possibly freeing data and/or kva mappings on the fly 1722 * depending. 1723 */ 1724 while ((bp = nbp) != NULL) { 1725 /* 1726 * Calculate next bp (we can only use it if we do not 1727 * release the bqlock). 1728 */ 1729 nbp = TAILQ_NEXT(bp, b_freelist); 1730 1731 /* 1732 * If we are defragging then we need a buffer with 1733 * some kva to reclaim. 1734 */ 1735 if (kva && bp->b_kvasize == 0) 1736 continue; 1737 1738 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1739 continue; 1740 1741 /* 1742 * Implement a second chance algorithm for frequently 1743 * accessed buffers. 1744 */ 1745 if ((bp->b_flags & B_REUSE) != 0) { 1746 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1747 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1748 bp->b_flags &= ~B_REUSE; 1749 BUF_UNLOCK(bp); 1750 continue; 1751 } 1752 1753 /* 1754 * Skip buffers with background writes in progress. 1755 */ 1756 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1757 BUF_UNLOCK(bp); 1758 continue; 1759 } 1760 1761 KASSERT(bp->b_qindex == QUEUE_CLEAN, 1762 ("buf_recycle: inconsistent queue %d bp %p", 1763 bp->b_qindex, bp)); 1764 KASSERT(bp->b_domain == BD_DOMAIN(bd), 1765 ("getnewbuf: queue domain %d doesn't match request %d", 1766 bp->b_domain, (int)BD_DOMAIN(bd))); 1767 /* 1768 * NOTE: nbp is now entirely invalid. We can only restart 1769 * the scan from this point on. 1770 */ 1771 bq_remove(bq, bp); 1772 BQ_UNLOCK(bq); 1773 1774 /* 1775 * Requeue the background write buffer with error and 1776 * restart the scan. 1777 */ 1778 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1779 bqrelse(bp); 1780 BQ_LOCK(bq); 1781 nbp = TAILQ_FIRST(&bq->bq_queue); 1782 continue; 1783 } 1784 bp->b_flags |= B_INVAL; 1785 brelse(bp); 1786 return (0); 1787 } 1788 bd->bd_wanted = 1; 1789 BQ_UNLOCK(bq); 1790 1791 return (ENOBUFS); 1792 } 1793 1794 /* 1795 * bremfree: 1796 * 1797 * Mark the buffer for removal from the appropriate free list. 1798 * 1799 */ 1800 void 1801 bremfree(struct buf *bp) 1802 { 1803 1804 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1805 KASSERT((bp->b_flags & B_REMFREE) == 0, 1806 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1807 KASSERT(bp->b_qindex != QUEUE_NONE, 1808 ("bremfree: buffer %p not on a queue.", bp)); 1809 BUF_ASSERT_XLOCKED(bp); 1810 1811 bp->b_flags |= B_REMFREE; 1812 } 1813 1814 /* 1815 * bremfreef: 1816 * 1817 * Force an immediate removal from a free list. Used only in nfs when 1818 * it abuses the b_freelist pointer. 1819 */ 1820 void 1821 bremfreef(struct buf *bp) 1822 { 1823 struct bufqueue *bq; 1824 1825 bq = bufqueue_acquire(bp); 1826 bq_remove(bq, bp); 1827 BQ_UNLOCK(bq); 1828 } 1829 1830 static void 1831 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname) 1832 { 1833 1834 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF); 1835 TAILQ_INIT(&bq->bq_queue); 1836 bq->bq_len = 0; 1837 bq->bq_index = qindex; 1838 bq->bq_subqueue = subqueue; 1839 } 1840 1841 static void 1842 bd_init(struct bufdomain *bd) 1843 { 1844 int i; 1845 1846 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1]; 1847 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock"); 1848 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock"); 1849 for (i = 0; i <= mp_maxid; i++) 1850 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i, 1851 "bufq clean subqueue lock"); 1852 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF); 1853 } 1854 1855 /* 1856 * bq_remove: 1857 * 1858 * Removes a buffer from the free list, must be called with the 1859 * correct qlock held. 1860 */ 1861 static void 1862 bq_remove(struct bufqueue *bq, struct buf *bp) 1863 { 1864 1865 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X", 1866 bp, bp->b_vp, bp->b_flags); 1867 KASSERT(bp->b_qindex != QUEUE_NONE, 1868 ("bq_remove: buffer %p not on a queue.", bp)); 1869 KASSERT(bufqueue(bp) == bq, 1870 ("bq_remove: Remove buffer %p from wrong queue.", bp)); 1871 1872 BQ_ASSERT_LOCKED(bq); 1873 if (bp->b_qindex != QUEUE_EMPTY) { 1874 BUF_ASSERT_XLOCKED(bp); 1875 } 1876 KASSERT(bq->bq_len >= 1, 1877 ("queue %d underflow", bp->b_qindex)); 1878 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1879 bq->bq_len--; 1880 bp->b_qindex = QUEUE_NONE; 1881 bp->b_flags &= ~(B_REMFREE | B_REUSE); 1882 } 1883 1884 static void 1885 bd_flush(struct bufdomain *bd, struct bufqueue *bq) 1886 { 1887 struct buf *bp; 1888 1889 BQ_ASSERT_LOCKED(bq); 1890 if (bq != bd->bd_cleanq) { 1891 BD_LOCK(bd); 1892 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) { 1893 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1894 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp, 1895 b_freelist); 1896 bp->b_subqueue = bd->bd_cleanq->bq_subqueue; 1897 } 1898 bd->bd_cleanq->bq_len += bq->bq_len; 1899 bq->bq_len = 0; 1900 } 1901 if (bd->bd_wanted) { 1902 bd->bd_wanted = 0; 1903 wakeup(&bd->bd_wanted); 1904 } 1905 if (bq != bd->bd_cleanq) 1906 BD_UNLOCK(bd); 1907 } 1908 1909 static int 1910 bd_flushall(struct bufdomain *bd) 1911 { 1912 struct bufqueue *bq; 1913 int flushed; 1914 int i; 1915 1916 if (bd->bd_lim == 0) 1917 return (0); 1918 flushed = 0; 1919 for (i = 0; i <= mp_maxid; i++) { 1920 bq = &bd->bd_subq[i]; 1921 if (bq->bq_len == 0) 1922 continue; 1923 BQ_LOCK(bq); 1924 bd_flush(bd, bq); 1925 BQ_UNLOCK(bq); 1926 flushed++; 1927 } 1928 1929 return (flushed); 1930 } 1931 1932 static void 1933 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock) 1934 { 1935 struct bufdomain *bd; 1936 1937 if (bp->b_qindex != QUEUE_NONE) 1938 panic("bq_insert: free buffer %p onto another queue?", bp); 1939 1940 bd = bufdomain(bp); 1941 if (bp->b_flags & B_AGE) { 1942 /* Place this buf directly on the real queue. */ 1943 if (bq->bq_index == QUEUE_CLEAN) 1944 bq = bd->bd_cleanq; 1945 BQ_LOCK(bq); 1946 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist); 1947 } else { 1948 BQ_LOCK(bq); 1949 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1950 } 1951 bp->b_flags &= ~(B_AGE | B_REUSE); 1952 bq->bq_len++; 1953 bp->b_qindex = bq->bq_index; 1954 bp->b_subqueue = bq->bq_subqueue; 1955 1956 /* 1957 * Unlock before we notify so that we don't wakeup a waiter that 1958 * fails a trylock on the buf and sleeps again. 1959 */ 1960 if (unlock) 1961 BUF_UNLOCK(bp); 1962 1963 if (bp->b_qindex == QUEUE_CLEAN) { 1964 /* 1965 * Flush the per-cpu queue and notify any waiters. 1966 */ 1967 if (bd->bd_wanted || (bq != bd->bd_cleanq && 1968 bq->bq_len >= bd->bd_lim)) 1969 bd_flush(bd, bq); 1970 } 1971 BQ_UNLOCK(bq); 1972 } 1973 1974 /* 1975 * bufkva_free: 1976 * 1977 * Free the kva allocation for a buffer. 1978 * 1979 */ 1980 static void 1981 bufkva_free(struct buf *bp) 1982 { 1983 1984 #ifdef INVARIANTS 1985 if (bp->b_kvasize == 0) { 1986 KASSERT(bp->b_kvabase == unmapped_buf && 1987 bp->b_data == unmapped_buf, 1988 ("Leaked KVA space on %p", bp)); 1989 } else if (buf_mapped(bp)) 1990 BUF_CHECK_MAPPED(bp); 1991 else 1992 BUF_CHECK_UNMAPPED(bp); 1993 #endif 1994 if (bp->b_kvasize == 0) 1995 return; 1996 1997 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1998 counter_u64_add(bufkvaspace, -bp->b_kvasize); 1999 counter_u64_add(buffreekvacnt, 1); 2000 bp->b_data = bp->b_kvabase = unmapped_buf; 2001 bp->b_kvasize = 0; 2002 } 2003 2004 /* 2005 * bufkva_alloc: 2006 * 2007 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 2008 */ 2009 static int 2010 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 2011 { 2012 vm_offset_t addr; 2013 int error; 2014 2015 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 2016 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 2017 2018 bufkva_free(bp); 2019 2020 addr = 0; 2021 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 2022 if (error != 0) { 2023 /* 2024 * Buffer map is too fragmented. Request the caller 2025 * to defragment the map. 2026 */ 2027 return (error); 2028 } 2029 bp->b_kvabase = (caddr_t)addr; 2030 bp->b_kvasize = maxsize; 2031 counter_u64_add(bufkvaspace, bp->b_kvasize); 2032 if ((gbflags & GB_UNMAPPED) != 0) { 2033 bp->b_data = unmapped_buf; 2034 BUF_CHECK_UNMAPPED(bp); 2035 } else { 2036 bp->b_data = bp->b_kvabase; 2037 BUF_CHECK_MAPPED(bp); 2038 } 2039 return (0); 2040 } 2041 2042 /* 2043 * bufkva_reclaim: 2044 * 2045 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 2046 * callback that fires to avoid returning failure. 2047 */ 2048 static void 2049 bufkva_reclaim(vmem_t *vmem, int flags) 2050 { 2051 bool done; 2052 int q; 2053 int i; 2054 2055 done = false; 2056 for (i = 0; i < 5; i++) { 2057 for (q = 0; q < buf_domains; q++) 2058 if (buf_recycle(&bdomain[q], true) != 0) 2059 done = true; 2060 if (done) 2061 break; 2062 } 2063 return; 2064 } 2065 2066 /* 2067 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 2068 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 2069 * the buffer is valid and we do not have to do anything. 2070 */ 2071 static void 2072 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt, 2073 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *)) 2074 { 2075 struct buf *rabp; 2076 int i; 2077 2078 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 2079 if (inmem(vp, *rablkno)) 2080 continue; 2081 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 2082 if ((rabp->b_flags & B_CACHE) != 0) { 2083 brelse(rabp); 2084 continue; 2085 } 2086 if (!TD_IS_IDLETHREAD(curthread)) { 2087 #ifdef RACCT 2088 if (racct_enable) { 2089 PROC_LOCK(curproc); 2090 racct_add_buf(curproc, rabp, 0); 2091 PROC_UNLOCK(curproc); 2092 } 2093 #endif /* RACCT */ 2094 curthread->td_ru.ru_inblock++; 2095 } 2096 rabp->b_flags |= B_ASYNC; 2097 rabp->b_flags &= ~B_INVAL; 2098 if ((flags & GB_CKHASH) != 0) { 2099 rabp->b_flags |= B_CKHASH; 2100 rabp->b_ckhashcalc = ckhashfunc; 2101 } 2102 rabp->b_ioflags &= ~BIO_ERROR; 2103 rabp->b_iocmd = BIO_READ; 2104 if (rabp->b_rcred == NOCRED && cred != NOCRED) 2105 rabp->b_rcred = crhold(cred); 2106 vfs_busy_pages(rabp, 0); 2107 BUF_KERNPROC(rabp); 2108 rabp->b_iooffset = dbtob(rabp->b_blkno); 2109 bstrategy(rabp); 2110 } 2111 } 2112 2113 /* 2114 * Entry point for bread() and breadn() via #defines in sys/buf.h. 2115 * 2116 * Get a buffer with the specified data. Look in the cache first. We 2117 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 2118 * is set, the buffer is valid and we do not have to do anything, see 2119 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 2120 * 2121 * Always return a NULL buffer pointer (in bpp) when returning an error. 2122 */ 2123 int 2124 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 2125 int *rabsize, int cnt, struct ucred *cred, int flags, 2126 void (*ckhashfunc)(struct buf *), struct buf **bpp) 2127 { 2128 struct buf *bp; 2129 struct thread *td; 2130 int error, readwait, rv; 2131 2132 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 2133 td = curthread; 2134 /* 2135 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags 2136 * are specified. 2137 */ 2138 error = getblkx(vp, blkno, size, 0, 0, flags, &bp); 2139 if (error != 0) { 2140 *bpp = NULL; 2141 return (error); 2142 } 2143 flags &= ~GB_NOSPARSE; 2144 *bpp = bp; 2145 2146 /* 2147 * If not found in cache, do some I/O 2148 */ 2149 readwait = 0; 2150 if ((bp->b_flags & B_CACHE) == 0) { 2151 if (!TD_IS_IDLETHREAD(td)) { 2152 #ifdef RACCT 2153 if (racct_enable) { 2154 PROC_LOCK(td->td_proc); 2155 racct_add_buf(td->td_proc, bp, 0); 2156 PROC_UNLOCK(td->td_proc); 2157 } 2158 #endif /* RACCT */ 2159 td->td_ru.ru_inblock++; 2160 } 2161 bp->b_iocmd = BIO_READ; 2162 bp->b_flags &= ~B_INVAL; 2163 if ((flags & GB_CKHASH) != 0) { 2164 bp->b_flags |= B_CKHASH; 2165 bp->b_ckhashcalc = ckhashfunc; 2166 } 2167 bp->b_ioflags &= ~BIO_ERROR; 2168 if (bp->b_rcred == NOCRED && cred != NOCRED) 2169 bp->b_rcred = crhold(cred); 2170 vfs_busy_pages(bp, 0); 2171 bp->b_iooffset = dbtob(bp->b_blkno); 2172 bstrategy(bp); 2173 ++readwait; 2174 } 2175 2176 /* 2177 * Attempt to initiate asynchronous I/O on read-ahead blocks. 2178 */ 2179 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 2180 2181 rv = 0; 2182 if (readwait) { 2183 rv = bufwait(bp); 2184 if (rv != 0) { 2185 brelse(bp); 2186 *bpp = NULL; 2187 } 2188 } 2189 return (rv); 2190 } 2191 2192 /* 2193 * Write, release buffer on completion. (Done by iodone 2194 * if async). Do not bother writing anything if the buffer 2195 * is invalid. 2196 * 2197 * Note that we set B_CACHE here, indicating that buffer is 2198 * fully valid and thus cacheable. This is true even of NFS 2199 * now so we set it generally. This could be set either here 2200 * or in biodone() since the I/O is synchronous. We put it 2201 * here. 2202 */ 2203 int 2204 bufwrite(struct buf *bp) 2205 { 2206 int oldflags; 2207 struct vnode *vp; 2208 long space; 2209 int vp_md; 2210 2211 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2212 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 2213 bp->b_flags |= B_INVAL | B_RELBUF; 2214 bp->b_flags &= ~B_CACHE; 2215 brelse(bp); 2216 return (ENXIO); 2217 } 2218 if (bp->b_flags & B_INVAL) { 2219 brelse(bp); 2220 return (0); 2221 } 2222 2223 if (bp->b_flags & B_BARRIER) 2224 atomic_add_long(&barrierwrites, 1); 2225 2226 oldflags = bp->b_flags; 2227 2228 BUF_ASSERT_HELD(bp); 2229 2230 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 2231 ("FFS background buffer should not get here %p", bp)); 2232 2233 vp = bp->b_vp; 2234 if (vp) 2235 vp_md = vp->v_vflag & VV_MD; 2236 else 2237 vp_md = 0; 2238 2239 /* 2240 * Mark the buffer clean. Increment the bufobj write count 2241 * before bundirty() call, to prevent other thread from seeing 2242 * empty dirty list and zero counter for writes in progress, 2243 * falsely indicating that the bufobj is clean. 2244 */ 2245 bufobj_wref(bp->b_bufobj); 2246 bundirty(bp); 2247 2248 bp->b_flags &= ~B_DONE; 2249 bp->b_ioflags &= ~BIO_ERROR; 2250 bp->b_flags |= B_CACHE; 2251 bp->b_iocmd = BIO_WRITE; 2252 2253 vfs_busy_pages(bp, 1); 2254 2255 /* 2256 * Normal bwrites pipeline writes 2257 */ 2258 bp->b_runningbufspace = bp->b_bufsize; 2259 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 2260 2261 if (!TD_IS_IDLETHREAD(curthread)) { 2262 #ifdef RACCT 2263 if (racct_enable) { 2264 PROC_LOCK(curproc); 2265 racct_add_buf(curproc, bp, 1); 2266 PROC_UNLOCK(curproc); 2267 } 2268 #endif /* RACCT */ 2269 curthread->td_ru.ru_oublock++; 2270 } 2271 if (oldflags & B_ASYNC) 2272 BUF_KERNPROC(bp); 2273 bp->b_iooffset = dbtob(bp->b_blkno); 2274 buf_track(bp, __func__); 2275 bstrategy(bp); 2276 2277 if ((oldflags & B_ASYNC) == 0) { 2278 int rtval = bufwait(bp); 2279 brelse(bp); 2280 return (rtval); 2281 } else if (space > hirunningspace) { 2282 /* 2283 * don't allow the async write to saturate the I/O 2284 * system. We will not deadlock here because 2285 * we are blocking waiting for I/O that is already in-progress 2286 * to complete. We do not block here if it is the update 2287 * or syncer daemon trying to clean up as that can lead 2288 * to deadlock. 2289 */ 2290 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2291 waitrunningbufspace(); 2292 } 2293 2294 return (0); 2295 } 2296 2297 void 2298 bufbdflush(struct bufobj *bo, struct buf *bp) 2299 { 2300 struct buf *nbp; 2301 2302 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 2303 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2304 altbufferflushes++; 2305 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 2306 BO_LOCK(bo); 2307 /* 2308 * Try to find a buffer to flush. 2309 */ 2310 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2311 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2312 BUF_LOCK(nbp, 2313 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2314 continue; 2315 if (bp == nbp) 2316 panic("bdwrite: found ourselves"); 2317 BO_UNLOCK(bo); 2318 /* Don't countdeps with the bo lock held. */ 2319 if (buf_countdeps(nbp, 0)) { 2320 BO_LOCK(bo); 2321 BUF_UNLOCK(nbp); 2322 continue; 2323 } 2324 if (nbp->b_flags & B_CLUSTEROK) { 2325 vfs_bio_awrite(nbp); 2326 } else { 2327 bremfree(nbp); 2328 bawrite(nbp); 2329 } 2330 dirtybufferflushes++; 2331 break; 2332 } 2333 if (nbp == NULL) 2334 BO_UNLOCK(bo); 2335 } 2336 } 2337 2338 /* 2339 * Delayed write. (Buffer is marked dirty). Do not bother writing 2340 * anything if the buffer is marked invalid. 2341 * 2342 * Note that since the buffer must be completely valid, we can safely 2343 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2344 * biodone() in order to prevent getblk from writing the buffer 2345 * out synchronously. 2346 */ 2347 void 2348 bdwrite(struct buf *bp) 2349 { 2350 struct thread *td = curthread; 2351 struct vnode *vp; 2352 struct bufobj *bo; 2353 2354 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2355 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2356 KASSERT((bp->b_flags & B_BARRIER) == 0, 2357 ("Barrier request in delayed write %p", bp)); 2358 BUF_ASSERT_HELD(bp); 2359 2360 if (bp->b_flags & B_INVAL) { 2361 brelse(bp); 2362 return; 2363 } 2364 2365 /* 2366 * If we have too many dirty buffers, don't create any more. 2367 * If we are wildly over our limit, then force a complete 2368 * cleanup. Otherwise, just keep the situation from getting 2369 * out of control. Note that we have to avoid a recursive 2370 * disaster and not try to clean up after our own cleanup! 2371 */ 2372 vp = bp->b_vp; 2373 bo = bp->b_bufobj; 2374 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2375 td->td_pflags |= TDP_INBDFLUSH; 2376 BO_BDFLUSH(bo, bp); 2377 td->td_pflags &= ~TDP_INBDFLUSH; 2378 } else 2379 recursiveflushes++; 2380 2381 bdirty(bp); 2382 /* 2383 * Set B_CACHE, indicating that the buffer is fully valid. This is 2384 * true even of NFS now. 2385 */ 2386 bp->b_flags |= B_CACHE; 2387 2388 /* 2389 * This bmap keeps the system from needing to do the bmap later, 2390 * perhaps when the system is attempting to do a sync. Since it 2391 * is likely that the indirect block -- or whatever other datastructure 2392 * that the filesystem needs is still in memory now, it is a good 2393 * thing to do this. Note also, that if the pageout daemon is 2394 * requesting a sync -- there might not be enough memory to do 2395 * the bmap then... So, this is important to do. 2396 */ 2397 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2398 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2399 } 2400 2401 buf_track(bp, __func__); 2402 2403 /* 2404 * Set the *dirty* buffer range based upon the VM system dirty 2405 * pages. 2406 * 2407 * Mark the buffer pages as clean. We need to do this here to 2408 * satisfy the vnode_pager and the pageout daemon, so that it 2409 * thinks that the pages have been "cleaned". Note that since 2410 * the pages are in a delayed write buffer -- the VFS layer 2411 * "will" see that the pages get written out on the next sync, 2412 * or perhaps the cluster will be completed. 2413 */ 2414 vfs_clean_pages_dirty_buf(bp); 2415 bqrelse(bp); 2416 2417 /* 2418 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2419 * due to the softdep code. 2420 */ 2421 } 2422 2423 /* 2424 * bdirty: 2425 * 2426 * Turn buffer into delayed write request. We must clear BIO_READ and 2427 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2428 * itself to properly update it in the dirty/clean lists. We mark it 2429 * B_DONE to ensure that any asynchronization of the buffer properly 2430 * clears B_DONE ( else a panic will occur later ). 2431 * 2432 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2433 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2434 * should only be called if the buffer is known-good. 2435 * 2436 * Since the buffer is not on a queue, we do not update the numfreebuffers 2437 * count. 2438 * 2439 * The buffer must be on QUEUE_NONE. 2440 */ 2441 void 2442 bdirty(struct buf *bp) 2443 { 2444 2445 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2446 bp, bp->b_vp, bp->b_flags); 2447 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2448 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2449 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2450 BUF_ASSERT_HELD(bp); 2451 bp->b_flags &= ~(B_RELBUF); 2452 bp->b_iocmd = BIO_WRITE; 2453 2454 if ((bp->b_flags & B_DELWRI) == 0) { 2455 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2456 reassignbuf(bp); 2457 bdirtyadd(bp); 2458 } 2459 } 2460 2461 /* 2462 * bundirty: 2463 * 2464 * Clear B_DELWRI for buffer. 2465 * 2466 * Since the buffer is not on a queue, we do not update the numfreebuffers 2467 * count. 2468 * 2469 * The buffer must be on QUEUE_NONE. 2470 */ 2471 2472 void 2473 bundirty(struct buf *bp) 2474 { 2475 2476 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2477 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2478 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2479 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2480 BUF_ASSERT_HELD(bp); 2481 2482 if (bp->b_flags & B_DELWRI) { 2483 bp->b_flags &= ~B_DELWRI; 2484 reassignbuf(bp); 2485 bdirtysub(bp); 2486 } 2487 /* 2488 * Since it is now being written, we can clear its deferred write flag. 2489 */ 2490 bp->b_flags &= ~B_DEFERRED; 2491 } 2492 2493 /* 2494 * bawrite: 2495 * 2496 * Asynchronous write. Start output on a buffer, but do not wait for 2497 * it to complete. The buffer is released when the output completes. 2498 * 2499 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2500 * B_INVAL buffers. Not us. 2501 */ 2502 void 2503 bawrite(struct buf *bp) 2504 { 2505 2506 bp->b_flags |= B_ASYNC; 2507 (void) bwrite(bp); 2508 } 2509 2510 /* 2511 * babarrierwrite: 2512 * 2513 * Asynchronous barrier write. Start output on a buffer, but do not 2514 * wait for it to complete. Place a write barrier after this write so 2515 * that this buffer and all buffers written before it are committed to 2516 * the disk before any buffers written after this write are committed 2517 * to the disk. The buffer is released when the output completes. 2518 */ 2519 void 2520 babarrierwrite(struct buf *bp) 2521 { 2522 2523 bp->b_flags |= B_ASYNC | B_BARRIER; 2524 (void) bwrite(bp); 2525 } 2526 2527 /* 2528 * bbarrierwrite: 2529 * 2530 * Synchronous barrier write. Start output on a buffer and wait for 2531 * it to complete. Place a write barrier after this write so that 2532 * this buffer and all buffers written before it are committed to 2533 * the disk before any buffers written after this write are committed 2534 * to the disk. The buffer is released when the output completes. 2535 */ 2536 int 2537 bbarrierwrite(struct buf *bp) 2538 { 2539 2540 bp->b_flags |= B_BARRIER; 2541 return (bwrite(bp)); 2542 } 2543 2544 /* 2545 * bwillwrite: 2546 * 2547 * Called prior to the locking of any vnodes when we are expecting to 2548 * write. We do not want to starve the buffer cache with too many 2549 * dirty buffers so we block here. By blocking prior to the locking 2550 * of any vnodes we attempt to avoid the situation where a locked vnode 2551 * prevents the various system daemons from flushing related buffers. 2552 */ 2553 void 2554 bwillwrite(void) 2555 { 2556 2557 if (buf_dirty_count_severe()) { 2558 mtx_lock(&bdirtylock); 2559 while (buf_dirty_count_severe()) { 2560 bdirtywait = 1; 2561 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2562 "flswai", 0); 2563 } 2564 mtx_unlock(&bdirtylock); 2565 } 2566 } 2567 2568 /* 2569 * Return true if we have too many dirty buffers. 2570 */ 2571 int 2572 buf_dirty_count_severe(void) 2573 { 2574 2575 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty)); 2576 } 2577 2578 /* 2579 * brelse: 2580 * 2581 * Release a busy buffer and, if requested, free its resources. The 2582 * buffer will be stashed in the appropriate bufqueue[] allowing it 2583 * to be accessed later as a cache entity or reused for other purposes. 2584 */ 2585 void 2586 brelse(struct buf *bp) 2587 { 2588 struct mount *v_mnt; 2589 int qindex; 2590 2591 /* 2592 * Many functions erroneously call brelse with a NULL bp under rare 2593 * error conditions. Simply return when called with a NULL bp. 2594 */ 2595 if (bp == NULL) 2596 return; 2597 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2598 bp, bp->b_vp, bp->b_flags); 2599 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2600 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2601 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2602 ("brelse: non-VMIO buffer marked NOREUSE")); 2603 2604 if (BUF_LOCKRECURSED(bp)) { 2605 /* 2606 * Do not process, in particular, do not handle the 2607 * B_INVAL/B_RELBUF and do not release to free list. 2608 */ 2609 BUF_UNLOCK(bp); 2610 return; 2611 } 2612 2613 if (bp->b_flags & B_MANAGED) { 2614 bqrelse(bp); 2615 return; 2616 } 2617 2618 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2619 BO_LOCK(bp->b_bufobj); 2620 bp->b_vflags &= ~BV_BKGRDERR; 2621 BO_UNLOCK(bp->b_bufobj); 2622 bdirty(bp); 2623 } 2624 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2625 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2626 !(bp->b_flags & B_INVAL)) { 2627 /* 2628 * Failed write, redirty. All errors except ENXIO (which 2629 * means the device is gone) are treated as being 2630 * transient. 2631 * 2632 * XXX Treating EIO as transient is not correct; the 2633 * contract with the local storage device drivers is that 2634 * they will only return EIO once the I/O is no longer 2635 * retriable. Network I/O also respects this through the 2636 * guarantees of TCP and/or the internal retries of NFS. 2637 * ENOMEM might be transient, but we also have no way of 2638 * knowing when its ok to retry/reschedule. In general, 2639 * this entire case should be made obsolete through better 2640 * error handling/recovery and resource scheduling. 2641 * 2642 * Do this also for buffers that failed with ENXIO, but have 2643 * non-empty dependencies - the soft updates code might need 2644 * to access the buffer to untangle them. 2645 * 2646 * Must clear BIO_ERROR to prevent pages from being scrapped. 2647 */ 2648 bp->b_ioflags &= ~BIO_ERROR; 2649 bdirty(bp); 2650 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2651 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2652 /* 2653 * Either a failed read I/O, or we were asked to free or not 2654 * cache the buffer, or we failed to write to a device that's 2655 * no longer present. 2656 */ 2657 bp->b_flags |= B_INVAL; 2658 if (!LIST_EMPTY(&bp->b_dep)) 2659 buf_deallocate(bp); 2660 if (bp->b_flags & B_DELWRI) 2661 bdirtysub(bp); 2662 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2663 if ((bp->b_flags & B_VMIO) == 0) { 2664 allocbuf(bp, 0); 2665 if (bp->b_vp) 2666 brelvp(bp); 2667 } 2668 } 2669 2670 /* 2671 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2672 * is called with B_DELWRI set, the underlying pages may wind up 2673 * getting freed causing a previous write (bdwrite()) to get 'lost' 2674 * because pages associated with a B_DELWRI bp are marked clean. 2675 * 2676 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2677 * if B_DELWRI is set. 2678 */ 2679 if (bp->b_flags & B_DELWRI) 2680 bp->b_flags &= ~B_RELBUF; 2681 2682 /* 2683 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2684 * constituted, not even NFS buffers now. Two flags effect this. If 2685 * B_INVAL, the struct buf is invalidated but the VM object is kept 2686 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2687 * 2688 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2689 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2690 * buffer is also B_INVAL because it hits the re-dirtying code above. 2691 * 2692 * Normally we can do this whether a buffer is B_DELWRI or not. If 2693 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2694 * the commit state and we cannot afford to lose the buffer. If the 2695 * buffer has a background write in progress, we need to keep it 2696 * around to prevent it from being reconstituted and starting a second 2697 * background write. 2698 */ 2699 2700 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL; 2701 2702 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2703 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2704 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 || 2705 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) { 2706 vfs_vmio_invalidate(bp); 2707 allocbuf(bp, 0); 2708 } 2709 2710 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2711 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2712 allocbuf(bp, 0); 2713 bp->b_flags &= ~B_NOREUSE; 2714 if (bp->b_vp != NULL) 2715 brelvp(bp); 2716 } 2717 2718 /* 2719 * If the buffer has junk contents signal it and eventually 2720 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2721 * doesn't find it. 2722 */ 2723 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2724 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2725 bp->b_flags |= B_INVAL; 2726 if (bp->b_flags & B_INVAL) { 2727 if (bp->b_flags & B_DELWRI) 2728 bundirty(bp); 2729 if (bp->b_vp) 2730 brelvp(bp); 2731 } 2732 2733 buf_track(bp, __func__); 2734 2735 /* buffers with no memory */ 2736 if (bp->b_bufsize == 0) { 2737 buf_free(bp); 2738 return; 2739 } 2740 /* buffers with junk contents */ 2741 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2742 (bp->b_ioflags & BIO_ERROR)) { 2743 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2744 if (bp->b_vflags & BV_BKGRDINPROG) 2745 panic("losing buffer 2"); 2746 qindex = QUEUE_CLEAN; 2747 bp->b_flags |= B_AGE; 2748 /* remaining buffers */ 2749 } else if (bp->b_flags & B_DELWRI) 2750 qindex = QUEUE_DIRTY; 2751 else 2752 qindex = QUEUE_CLEAN; 2753 2754 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2755 panic("brelse: not dirty"); 2756 2757 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT); 2758 /* binsfree unlocks bp. */ 2759 binsfree(bp, qindex); 2760 } 2761 2762 /* 2763 * Release a buffer back to the appropriate queue but do not try to free 2764 * it. The buffer is expected to be used again soon. 2765 * 2766 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2767 * biodone() to requeue an async I/O on completion. It is also used when 2768 * known good buffers need to be requeued but we think we may need the data 2769 * again soon. 2770 * 2771 * XXX we should be able to leave the B_RELBUF hint set on completion. 2772 */ 2773 void 2774 bqrelse(struct buf *bp) 2775 { 2776 int qindex; 2777 2778 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2779 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2780 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2781 2782 qindex = QUEUE_NONE; 2783 if (BUF_LOCKRECURSED(bp)) { 2784 /* do not release to free list */ 2785 BUF_UNLOCK(bp); 2786 return; 2787 } 2788 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2789 2790 if (bp->b_flags & B_MANAGED) { 2791 if (bp->b_flags & B_REMFREE) 2792 bremfreef(bp); 2793 goto out; 2794 } 2795 2796 /* buffers with stale but valid contents */ 2797 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2798 BV_BKGRDERR)) == BV_BKGRDERR) { 2799 BO_LOCK(bp->b_bufobj); 2800 bp->b_vflags &= ~BV_BKGRDERR; 2801 BO_UNLOCK(bp->b_bufobj); 2802 qindex = QUEUE_DIRTY; 2803 } else { 2804 if ((bp->b_flags & B_DELWRI) == 0 && 2805 (bp->b_xflags & BX_VNDIRTY)) 2806 panic("bqrelse: not dirty"); 2807 if ((bp->b_flags & B_NOREUSE) != 0) { 2808 brelse(bp); 2809 return; 2810 } 2811 qindex = QUEUE_CLEAN; 2812 } 2813 buf_track(bp, __func__); 2814 /* binsfree unlocks bp. */ 2815 binsfree(bp, qindex); 2816 return; 2817 2818 out: 2819 buf_track(bp, __func__); 2820 /* unlock */ 2821 BUF_UNLOCK(bp); 2822 } 2823 2824 /* 2825 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2826 * restore bogus pages. 2827 */ 2828 static void 2829 vfs_vmio_iodone(struct buf *bp) 2830 { 2831 vm_ooffset_t foff; 2832 vm_page_t m; 2833 vm_object_t obj; 2834 struct vnode *vp __unused; 2835 int i, iosize, resid; 2836 bool bogus; 2837 2838 obj = bp->b_bufobj->bo_object; 2839 KASSERT(obj->paging_in_progress >= bp->b_npages, 2840 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2841 obj->paging_in_progress, bp->b_npages)); 2842 2843 vp = bp->b_vp; 2844 KASSERT(vp->v_holdcnt > 0, 2845 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2846 KASSERT(vp->v_object != NULL, 2847 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2848 2849 foff = bp->b_offset; 2850 KASSERT(bp->b_offset != NOOFFSET, 2851 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2852 2853 bogus = false; 2854 iosize = bp->b_bcount - bp->b_resid; 2855 VM_OBJECT_WLOCK(obj); 2856 for (i = 0; i < bp->b_npages; i++) { 2857 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2858 if (resid > iosize) 2859 resid = iosize; 2860 2861 /* 2862 * cleanup bogus pages, restoring the originals 2863 */ 2864 m = bp->b_pages[i]; 2865 if (m == bogus_page) { 2866 bogus = true; 2867 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2868 if (m == NULL) 2869 panic("biodone: page disappeared!"); 2870 bp->b_pages[i] = m; 2871 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2872 /* 2873 * In the write case, the valid and clean bits are 2874 * already changed correctly ( see bdwrite() ), so we 2875 * only need to do this here in the read case. 2876 */ 2877 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2878 resid)) == 0, ("vfs_vmio_iodone: page %p " 2879 "has unexpected dirty bits", m)); 2880 vfs_page_set_valid(bp, foff, m); 2881 } 2882 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2883 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2884 (intmax_t)foff, (uintmax_t)m->pindex)); 2885 2886 vm_page_sunbusy(m); 2887 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2888 iosize -= resid; 2889 } 2890 vm_object_pip_wakeupn(obj, bp->b_npages); 2891 VM_OBJECT_WUNLOCK(obj); 2892 if (bogus && buf_mapped(bp)) { 2893 BUF_CHECK_MAPPED(bp); 2894 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2895 bp->b_pages, bp->b_npages); 2896 } 2897 } 2898 2899 /* 2900 * Unwire a page held by a buf and either free it or update the page queues to 2901 * reflect its recent use. 2902 */ 2903 static void 2904 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2905 { 2906 bool freed; 2907 2908 vm_page_lock(m); 2909 if (vm_page_unwire_noq(m)) { 2910 if ((bp->b_flags & B_DIRECT) != 0) 2911 freed = vm_page_try_to_free(m); 2912 else 2913 freed = false; 2914 if (!freed) { 2915 /* 2916 * Use a racy check of the valid bits to determine 2917 * whether we can accelerate reclamation of the page. 2918 * The valid bits will be stable unless the page is 2919 * being mapped or is referenced by multiple buffers, 2920 * and in those cases we expect races to be rare. At 2921 * worst we will either accelerate reclamation of a 2922 * valid page and violate LRU, or unnecessarily defer 2923 * reclamation of an invalid page. 2924 * 2925 * The B_NOREUSE flag marks data that is not expected to 2926 * be reused, so accelerate reclamation in that case 2927 * too. Otherwise, maintain LRU. 2928 */ 2929 if (m->valid == 0 || (bp->b_flags & B_NOREUSE) != 0) 2930 vm_page_deactivate_noreuse(m); 2931 else if (vm_page_active(m)) 2932 vm_page_reference(m); 2933 else 2934 vm_page_deactivate(m); 2935 } 2936 } 2937 vm_page_unlock(m); 2938 } 2939 2940 /* 2941 * Perform page invalidation when a buffer is released. The fully invalid 2942 * pages will be reclaimed later in vfs_vmio_truncate(). 2943 */ 2944 static void 2945 vfs_vmio_invalidate(struct buf *bp) 2946 { 2947 vm_object_t obj; 2948 vm_page_t m; 2949 int i, resid, poffset, presid; 2950 2951 if (buf_mapped(bp)) { 2952 BUF_CHECK_MAPPED(bp); 2953 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2954 } else 2955 BUF_CHECK_UNMAPPED(bp); 2956 /* 2957 * Get the base offset and length of the buffer. Note that 2958 * in the VMIO case if the buffer block size is not 2959 * page-aligned then b_data pointer may not be page-aligned. 2960 * But our b_pages[] array *IS* page aligned. 2961 * 2962 * block sizes less then DEV_BSIZE (usually 512) are not 2963 * supported due to the page granularity bits (m->valid, 2964 * m->dirty, etc...). 2965 * 2966 * See man buf(9) for more information 2967 */ 2968 obj = bp->b_bufobj->bo_object; 2969 resid = bp->b_bufsize; 2970 poffset = bp->b_offset & PAGE_MASK; 2971 VM_OBJECT_WLOCK(obj); 2972 for (i = 0; i < bp->b_npages; i++) { 2973 m = bp->b_pages[i]; 2974 if (m == bogus_page) 2975 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2976 bp->b_pages[i] = NULL; 2977 2978 presid = resid > (PAGE_SIZE - poffset) ? 2979 (PAGE_SIZE - poffset) : resid; 2980 KASSERT(presid >= 0, ("brelse: extra page")); 2981 while (vm_page_xbusied(m)) { 2982 vm_page_lock(m); 2983 VM_OBJECT_WUNLOCK(obj); 2984 vm_page_busy_sleep(m, "mbncsh", true); 2985 VM_OBJECT_WLOCK(obj); 2986 } 2987 if (pmap_page_wired_mappings(m) == 0) 2988 vm_page_set_invalid(m, poffset, presid); 2989 vfs_vmio_unwire(bp, m); 2990 resid -= presid; 2991 poffset = 0; 2992 } 2993 VM_OBJECT_WUNLOCK(obj); 2994 bp->b_npages = 0; 2995 } 2996 2997 /* 2998 * Page-granular truncation of an existing VMIO buffer. 2999 */ 3000 static void 3001 vfs_vmio_truncate(struct buf *bp, int desiredpages) 3002 { 3003 vm_object_t obj; 3004 vm_page_t m; 3005 int i; 3006 3007 if (bp->b_npages == desiredpages) 3008 return; 3009 3010 if (buf_mapped(bp)) { 3011 BUF_CHECK_MAPPED(bp); 3012 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 3013 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 3014 } else 3015 BUF_CHECK_UNMAPPED(bp); 3016 3017 /* 3018 * The object lock is needed only if we will attempt to free pages. 3019 */ 3020 obj = (bp->b_flags & B_DIRECT) != 0 ? bp->b_bufobj->bo_object : NULL; 3021 if (obj != NULL) 3022 VM_OBJECT_WLOCK(obj); 3023 for (i = desiredpages; i < bp->b_npages; i++) { 3024 m = bp->b_pages[i]; 3025 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3026 bp->b_pages[i] = NULL; 3027 vfs_vmio_unwire(bp, m); 3028 } 3029 if (obj != NULL) 3030 VM_OBJECT_WUNLOCK(obj); 3031 bp->b_npages = desiredpages; 3032 } 3033 3034 /* 3035 * Byte granular extension of VMIO buffers. 3036 */ 3037 static void 3038 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3039 { 3040 /* 3041 * We are growing the buffer, possibly in a 3042 * byte-granular fashion. 3043 */ 3044 vm_object_t obj; 3045 vm_offset_t toff; 3046 vm_offset_t tinc; 3047 vm_page_t m; 3048 3049 /* 3050 * Step 1, bring in the VM pages from the object, allocating 3051 * them if necessary. We must clear B_CACHE if these pages 3052 * are not valid for the range covered by the buffer. 3053 */ 3054 obj = bp->b_bufobj->bo_object; 3055 VM_OBJECT_WLOCK(obj); 3056 if (bp->b_npages < desiredpages) { 3057 /* 3058 * We must allocate system pages since blocking 3059 * here could interfere with paging I/O, no 3060 * matter which process we are. 3061 * 3062 * Only exclusive busy can be tested here. 3063 * Blocking on shared busy might lead to 3064 * deadlocks once allocbuf() is called after 3065 * pages are vfs_busy_pages(). 3066 */ 3067 (void)vm_page_grab_pages(obj, 3068 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3069 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3070 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3071 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3072 bp->b_npages = desiredpages; 3073 } 3074 3075 /* 3076 * Step 2. We've loaded the pages into the buffer, 3077 * we have to figure out if we can still have B_CACHE 3078 * set. Note that B_CACHE is set according to the 3079 * byte-granular range ( bcount and size ), not the 3080 * aligned range ( newbsize ). 3081 * 3082 * The VM test is against m->valid, which is DEV_BSIZE 3083 * aligned. Needless to say, the validity of the data 3084 * needs to also be DEV_BSIZE aligned. Note that this 3085 * fails with NFS if the server or some other client 3086 * extends the file's EOF. If our buffer is resized, 3087 * B_CACHE may remain set! XXX 3088 */ 3089 toff = bp->b_bcount; 3090 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3091 while ((bp->b_flags & B_CACHE) && toff < size) { 3092 vm_pindex_t pi; 3093 3094 if (tinc > (size - toff)) 3095 tinc = size - toff; 3096 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3097 m = bp->b_pages[pi]; 3098 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3099 toff += tinc; 3100 tinc = PAGE_SIZE; 3101 } 3102 VM_OBJECT_WUNLOCK(obj); 3103 3104 /* 3105 * Step 3, fixup the KVA pmap. 3106 */ 3107 if (buf_mapped(bp)) 3108 bpmap_qenter(bp); 3109 else 3110 BUF_CHECK_UNMAPPED(bp); 3111 } 3112 3113 /* 3114 * Check to see if a block at a particular lbn is available for a clustered 3115 * write. 3116 */ 3117 static int 3118 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3119 { 3120 struct buf *bpa; 3121 int match; 3122 3123 match = 0; 3124 3125 /* If the buf isn't in core skip it */ 3126 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3127 return (0); 3128 3129 /* If the buf is busy we don't want to wait for it */ 3130 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3131 return (0); 3132 3133 /* Only cluster with valid clusterable delayed write buffers */ 3134 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3135 (B_DELWRI | B_CLUSTEROK)) 3136 goto done; 3137 3138 if (bpa->b_bufsize != size) 3139 goto done; 3140 3141 /* 3142 * Check to see if it is in the expected place on disk and that the 3143 * block has been mapped. 3144 */ 3145 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3146 match = 1; 3147 done: 3148 BUF_UNLOCK(bpa); 3149 return (match); 3150 } 3151 3152 /* 3153 * vfs_bio_awrite: 3154 * 3155 * Implement clustered async writes for clearing out B_DELWRI buffers. 3156 * This is much better then the old way of writing only one buffer at 3157 * a time. Note that we may not be presented with the buffers in the 3158 * correct order, so we search for the cluster in both directions. 3159 */ 3160 int 3161 vfs_bio_awrite(struct buf *bp) 3162 { 3163 struct bufobj *bo; 3164 int i; 3165 int j; 3166 daddr_t lblkno = bp->b_lblkno; 3167 struct vnode *vp = bp->b_vp; 3168 int ncl; 3169 int nwritten; 3170 int size; 3171 int maxcl; 3172 int gbflags; 3173 3174 bo = &vp->v_bufobj; 3175 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3176 /* 3177 * right now we support clustered writing only to regular files. If 3178 * we find a clusterable block we could be in the middle of a cluster 3179 * rather then at the beginning. 3180 */ 3181 if ((vp->v_type == VREG) && 3182 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3183 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3184 3185 size = vp->v_mount->mnt_stat.f_iosize; 3186 maxcl = MAXPHYS / size; 3187 3188 BO_RLOCK(bo); 3189 for (i = 1; i < maxcl; i++) 3190 if (vfs_bio_clcheck(vp, size, lblkno + i, 3191 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3192 break; 3193 3194 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3195 if (vfs_bio_clcheck(vp, size, lblkno - j, 3196 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3197 break; 3198 BO_RUNLOCK(bo); 3199 --j; 3200 ncl = i + j; 3201 /* 3202 * this is a possible cluster write 3203 */ 3204 if (ncl != 1) { 3205 BUF_UNLOCK(bp); 3206 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3207 gbflags); 3208 return (nwritten); 3209 } 3210 } 3211 bremfree(bp); 3212 bp->b_flags |= B_ASYNC; 3213 /* 3214 * default (old) behavior, writing out only one block 3215 * 3216 * XXX returns b_bufsize instead of b_bcount for nwritten? 3217 */ 3218 nwritten = bp->b_bufsize; 3219 (void) bwrite(bp); 3220 3221 return (nwritten); 3222 } 3223 3224 /* 3225 * getnewbuf_kva: 3226 * 3227 * Allocate KVA for an empty buf header according to gbflags. 3228 */ 3229 static int 3230 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3231 { 3232 3233 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3234 /* 3235 * In order to keep fragmentation sane we only allocate kva 3236 * in BKVASIZE chunks. XXX with vmem we can do page size. 3237 */ 3238 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3239 3240 if (maxsize != bp->b_kvasize && 3241 bufkva_alloc(bp, maxsize, gbflags)) 3242 return (ENOSPC); 3243 } 3244 return (0); 3245 } 3246 3247 /* 3248 * getnewbuf: 3249 * 3250 * Find and initialize a new buffer header, freeing up existing buffers 3251 * in the bufqueues as necessary. The new buffer is returned locked. 3252 * 3253 * We block if: 3254 * We have insufficient buffer headers 3255 * We have insufficient buffer space 3256 * buffer_arena is too fragmented ( space reservation fails ) 3257 * If we have to flush dirty buffers ( but we try to avoid this ) 3258 * 3259 * The caller is responsible for releasing the reserved bufspace after 3260 * allocbuf() is called. 3261 */ 3262 static struct buf * 3263 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3264 { 3265 struct bufdomain *bd; 3266 struct buf *bp; 3267 bool metadata, reserved; 3268 3269 bp = NULL; 3270 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3271 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3272 if (!unmapped_buf_allowed) 3273 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3274 3275 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3276 vp->v_type == VCHR) 3277 metadata = true; 3278 else 3279 metadata = false; 3280 if (vp == NULL) 3281 bd = &bdomain[0]; 3282 else 3283 bd = &bdomain[vp->v_bufobj.bo_domain]; 3284 3285 counter_u64_add(getnewbufcalls, 1); 3286 reserved = false; 3287 do { 3288 if (reserved == false && 3289 bufspace_reserve(bd, maxsize, metadata) != 0) { 3290 counter_u64_add(getnewbufrestarts, 1); 3291 continue; 3292 } 3293 reserved = true; 3294 if ((bp = buf_alloc(bd)) == NULL) { 3295 counter_u64_add(getnewbufrestarts, 1); 3296 continue; 3297 } 3298 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3299 return (bp); 3300 break; 3301 } while (buf_recycle(bd, false) == 0); 3302 3303 if (reserved) 3304 bufspace_release(bd, maxsize); 3305 if (bp != NULL) { 3306 bp->b_flags |= B_INVAL; 3307 brelse(bp); 3308 } 3309 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3310 3311 return (NULL); 3312 } 3313 3314 /* 3315 * buf_daemon: 3316 * 3317 * buffer flushing daemon. Buffers are normally flushed by the 3318 * update daemon but if it cannot keep up this process starts to 3319 * take the load in an attempt to prevent getnewbuf() from blocking. 3320 */ 3321 static struct kproc_desc buf_kp = { 3322 "bufdaemon", 3323 buf_daemon, 3324 &bufdaemonproc 3325 }; 3326 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3327 3328 static int 3329 buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3330 { 3331 int flushed; 3332 3333 flushed = flushbufqueues(vp, bd, target, 0); 3334 if (flushed == 0) { 3335 /* 3336 * Could not find any buffers without rollback 3337 * dependencies, so just write the first one 3338 * in the hopes of eventually making progress. 3339 */ 3340 if (vp != NULL && target > 2) 3341 target /= 2; 3342 flushbufqueues(vp, bd, target, 1); 3343 } 3344 return (flushed); 3345 } 3346 3347 static void 3348 buf_daemon() 3349 { 3350 struct bufdomain *bd; 3351 int speedupreq; 3352 int lodirty; 3353 int i; 3354 3355 /* 3356 * This process needs to be suspended prior to shutdown sync. 3357 */ 3358 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 3359 SHUTDOWN_PRI_LAST + 100); 3360 3361 /* 3362 * Start the buf clean daemons as children threads. 3363 */ 3364 for (i = 0 ; i < buf_domains; i++) { 3365 int error; 3366 3367 error = kthread_add((void (*)(void *))bufspace_daemon, 3368 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3369 if (error) 3370 panic("error %d spawning bufspace daemon", error); 3371 } 3372 3373 /* 3374 * This process is allowed to take the buffer cache to the limit 3375 */ 3376 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3377 mtx_lock(&bdlock); 3378 for (;;) { 3379 bd_request = 0; 3380 mtx_unlock(&bdlock); 3381 3382 kthread_suspend_check(); 3383 3384 /* 3385 * Save speedupreq for this pass and reset to capture new 3386 * requests. 3387 */ 3388 speedupreq = bd_speedupreq; 3389 bd_speedupreq = 0; 3390 3391 /* 3392 * Flush each domain sequentially according to its level and 3393 * the speedup request. 3394 */ 3395 for (i = 0; i < buf_domains; i++) { 3396 bd = &bdomain[i]; 3397 if (speedupreq) 3398 lodirty = bd->bd_numdirtybuffers / 2; 3399 else 3400 lodirty = bd->bd_lodirtybuffers; 3401 while (bd->bd_numdirtybuffers > lodirty) { 3402 if (buf_flush(NULL, bd, 3403 bd->bd_numdirtybuffers - lodirty) == 0) 3404 break; 3405 kern_yield(PRI_USER); 3406 } 3407 } 3408 3409 /* 3410 * Only clear bd_request if we have reached our low water 3411 * mark. The buf_daemon normally waits 1 second and 3412 * then incrementally flushes any dirty buffers that have 3413 * built up, within reason. 3414 * 3415 * If we were unable to hit our low water mark and couldn't 3416 * find any flushable buffers, we sleep for a short period 3417 * to avoid endless loops on unlockable buffers. 3418 */ 3419 mtx_lock(&bdlock); 3420 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3421 /* 3422 * We reached our low water mark, reset the 3423 * request and sleep until we are needed again. 3424 * The sleep is just so the suspend code works. 3425 */ 3426 bd_request = 0; 3427 /* 3428 * Do an extra wakeup in case dirty threshold 3429 * changed via sysctl and the explicit transition 3430 * out of shortfall was missed. 3431 */ 3432 bdirtywakeup(); 3433 if (runningbufspace <= lorunningspace) 3434 runningwakeup(); 3435 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3436 } else { 3437 /* 3438 * We couldn't find any flushable dirty buffers but 3439 * still have too many dirty buffers, we 3440 * have to sleep and try again. (rare) 3441 */ 3442 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3443 } 3444 } 3445 } 3446 3447 /* 3448 * flushbufqueues: 3449 * 3450 * Try to flush a buffer in the dirty queue. We must be careful to 3451 * free up B_INVAL buffers instead of write them, which NFS is 3452 * particularly sensitive to. 3453 */ 3454 static int flushwithdeps = 0; 3455 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3456 0, "Number of buffers flushed with dependecies that require rollbacks"); 3457 3458 static int 3459 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3460 int flushdeps) 3461 { 3462 struct bufqueue *bq; 3463 struct buf *sentinel; 3464 struct vnode *vp; 3465 struct mount *mp; 3466 struct buf *bp; 3467 int hasdeps; 3468 int flushed; 3469 int error; 3470 bool unlock; 3471 3472 flushed = 0; 3473 bq = &bd->bd_dirtyq; 3474 bp = NULL; 3475 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3476 sentinel->b_qindex = QUEUE_SENTINEL; 3477 BQ_LOCK(bq); 3478 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3479 BQ_UNLOCK(bq); 3480 while (flushed != target) { 3481 maybe_yield(); 3482 BQ_LOCK(bq); 3483 bp = TAILQ_NEXT(sentinel, b_freelist); 3484 if (bp != NULL) { 3485 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3486 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3487 b_freelist); 3488 } else { 3489 BQ_UNLOCK(bq); 3490 break; 3491 } 3492 /* 3493 * Skip sentinels inserted by other invocations of the 3494 * flushbufqueues(), taking care to not reorder them. 3495 * 3496 * Only flush the buffers that belong to the 3497 * vnode locked by the curthread. 3498 */ 3499 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3500 bp->b_vp != lvp)) { 3501 BQ_UNLOCK(bq); 3502 continue; 3503 } 3504 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3505 BQ_UNLOCK(bq); 3506 if (error != 0) 3507 continue; 3508 3509 /* 3510 * BKGRDINPROG can only be set with the buf and bufobj 3511 * locks both held. We tolerate a race to clear it here. 3512 */ 3513 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3514 (bp->b_flags & B_DELWRI) == 0) { 3515 BUF_UNLOCK(bp); 3516 continue; 3517 } 3518 if (bp->b_flags & B_INVAL) { 3519 bremfreef(bp); 3520 brelse(bp); 3521 flushed++; 3522 continue; 3523 } 3524 3525 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3526 if (flushdeps == 0) { 3527 BUF_UNLOCK(bp); 3528 continue; 3529 } 3530 hasdeps = 1; 3531 } else 3532 hasdeps = 0; 3533 /* 3534 * We must hold the lock on a vnode before writing 3535 * one of its buffers. Otherwise we may confuse, or 3536 * in the case of a snapshot vnode, deadlock the 3537 * system. 3538 * 3539 * The lock order here is the reverse of the normal 3540 * of vnode followed by buf lock. This is ok because 3541 * the NOWAIT will prevent deadlock. 3542 */ 3543 vp = bp->b_vp; 3544 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3545 BUF_UNLOCK(bp); 3546 continue; 3547 } 3548 if (lvp == NULL) { 3549 unlock = true; 3550 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3551 } else { 3552 ASSERT_VOP_LOCKED(vp, "getbuf"); 3553 unlock = false; 3554 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3555 vn_lock(vp, LK_TRYUPGRADE); 3556 } 3557 if (error == 0) { 3558 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3559 bp, bp->b_vp, bp->b_flags); 3560 if (curproc == bufdaemonproc) { 3561 vfs_bio_awrite(bp); 3562 } else { 3563 bremfree(bp); 3564 bwrite(bp); 3565 counter_u64_add(notbufdflushes, 1); 3566 } 3567 vn_finished_write(mp); 3568 if (unlock) 3569 VOP_UNLOCK(vp, 0); 3570 flushwithdeps += hasdeps; 3571 flushed++; 3572 3573 /* 3574 * Sleeping on runningbufspace while holding 3575 * vnode lock leads to deadlock. 3576 */ 3577 if (curproc == bufdaemonproc && 3578 runningbufspace > hirunningspace) 3579 waitrunningbufspace(); 3580 continue; 3581 } 3582 vn_finished_write(mp); 3583 BUF_UNLOCK(bp); 3584 } 3585 BQ_LOCK(bq); 3586 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3587 BQ_UNLOCK(bq); 3588 free(sentinel, M_TEMP); 3589 return (flushed); 3590 } 3591 3592 /* 3593 * Check to see if a block is currently memory resident. 3594 */ 3595 struct buf * 3596 incore(struct bufobj *bo, daddr_t blkno) 3597 { 3598 struct buf *bp; 3599 3600 BO_RLOCK(bo); 3601 bp = gbincore(bo, blkno); 3602 BO_RUNLOCK(bo); 3603 return (bp); 3604 } 3605 3606 /* 3607 * Returns true if no I/O is needed to access the 3608 * associated VM object. This is like incore except 3609 * it also hunts around in the VM system for the data. 3610 */ 3611 3612 static int 3613 inmem(struct vnode * vp, daddr_t blkno) 3614 { 3615 vm_object_t obj; 3616 vm_offset_t toff, tinc, size; 3617 vm_page_t m; 3618 vm_ooffset_t off; 3619 3620 ASSERT_VOP_LOCKED(vp, "inmem"); 3621 3622 if (incore(&vp->v_bufobj, blkno)) 3623 return 1; 3624 if (vp->v_mount == NULL) 3625 return 0; 3626 obj = vp->v_object; 3627 if (obj == NULL) 3628 return (0); 3629 3630 size = PAGE_SIZE; 3631 if (size > vp->v_mount->mnt_stat.f_iosize) 3632 size = vp->v_mount->mnt_stat.f_iosize; 3633 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3634 3635 VM_OBJECT_RLOCK(obj); 3636 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3637 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3638 if (!m) 3639 goto notinmem; 3640 tinc = size; 3641 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3642 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3643 if (vm_page_is_valid(m, 3644 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3645 goto notinmem; 3646 } 3647 VM_OBJECT_RUNLOCK(obj); 3648 return 1; 3649 3650 notinmem: 3651 VM_OBJECT_RUNLOCK(obj); 3652 return (0); 3653 } 3654 3655 /* 3656 * Set the dirty range for a buffer based on the status of the dirty 3657 * bits in the pages comprising the buffer. The range is limited 3658 * to the size of the buffer. 3659 * 3660 * Tell the VM system that the pages associated with this buffer 3661 * are clean. This is used for delayed writes where the data is 3662 * going to go to disk eventually without additional VM intevention. 3663 * 3664 * Note that while we only really need to clean through to b_bcount, we 3665 * just go ahead and clean through to b_bufsize. 3666 */ 3667 static void 3668 vfs_clean_pages_dirty_buf(struct buf *bp) 3669 { 3670 vm_ooffset_t foff, noff, eoff; 3671 vm_page_t m; 3672 int i; 3673 3674 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3675 return; 3676 3677 foff = bp->b_offset; 3678 KASSERT(bp->b_offset != NOOFFSET, 3679 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3680 3681 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3682 vfs_drain_busy_pages(bp); 3683 vfs_setdirty_locked_object(bp); 3684 for (i = 0; i < bp->b_npages; i++) { 3685 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3686 eoff = noff; 3687 if (eoff > bp->b_offset + bp->b_bufsize) 3688 eoff = bp->b_offset + bp->b_bufsize; 3689 m = bp->b_pages[i]; 3690 vfs_page_set_validclean(bp, foff, m); 3691 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3692 foff = noff; 3693 } 3694 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3695 } 3696 3697 static void 3698 vfs_setdirty_locked_object(struct buf *bp) 3699 { 3700 vm_object_t object; 3701 int i; 3702 3703 object = bp->b_bufobj->bo_object; 3704 VM_OBJECT_ASSERT_WLOCKED(object); 3705 3706 /* 3707 * We qualify the scan for modified pages on whether the 3708 * object has been flushed yet. 3709 */ 3710 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3711 vm_offset_t boffset; 3712 vm_offset_t eoffset; 3713 3714 /* 3715 * test the pages to see if they have been modified directly 3716 * by users through the VM system. 3717 */ 3718 for (i = 0; i < bp->b_npages; i++) 3719 vm_page_test_dirty(bp->b_pages[i]); 3720 3721 /* 3722 * Calculate the encompassing dirty range, boffset and eoffset, 3723 * (eoffset - boffset) bytes. 3724 */ 3725 3726 for (i = 0; i < bp->b_npages; i++) { 3727 if (bp->b_pages[i]->dirty) 3728 break; 3729 } 3730 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3731 3732 for (i = bp->b_npages - 1; i >= 0; --i) { 3733 if (bp->b_pages[i]->dirty) { 3734 break; 3735 } 3736 } 3737 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3738 3739 /* 3740 * Fit it to the buffer. 3741 */ 3742 3743 if (eoffset > bp->b_bcount) 3744 eoffset = bp->b_bcount; 3745 3746 /* 3747 * If we have a good dirty range, merge with the existing 3748 * dirty range. 3749 */ 3750 3751 if (boffset < eoffset) { 3752 if (bp->b_dirtyoff > boffset) 3753 bp->b_dirtyoff = boffset; 3754 if (bp->b_dirtyend < eoffset) 3755 bp->b_dirtyend = eoffset; 3756 } 3757 } 3758 } 3759 3760 /* 3761 * Allocate the KVA mapping for an existing buffer. 3762 * If an unmapped buffer is provided but a mapped buffer is requested, take 3763 * also care to properly setup mappings between pages and KVA. 3764 */ 3765 static void 3766 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3767 { 3768 int bsize, maxsize, need_mapping, need_kva; 3769 off_t offset; 3770 3771 need_mapping = bp->b_data == unmapped_buf && 3772 (gbflags & GB_UNMAPPED) == 0; 3773 need_kva = bp->b_kvabase == unmapped_buf && 3774 bp->b_data == unmapped_buf && 3775 (gbflags & GB_KVAALLOC) != 0; 3776 if (!need_mapping && !need_kva) 3777 return; 3778 3779 BUF_CHECK_UNMAPPED(bp); 3780 3781 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3782 /* 3783 * Buffer is not mapped, but the KVA was already 3784 * reserved at the time of the instantiation. Use the 3785 * allocated space. 3786 */ 3787 goto has_addr; 3788 } 3789 3790 /* 3791 * Calculate the amount of the address space we would reserve 3792 * if the buffer was mapped. 3793 */ 3794 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3795 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3796 offset = blkno * bsize; 3797 maxsize = size + (offset & PAGE_MASK); 3798 maxsize = imax(maxsize, bsize); 3799 3800 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3801 if ((gbflags & GB_NOWAIT_BD) != 0) { 3802 /* 3803 * XXXKIB: defragmentation cannot 3804 * succeed, not sure what else to do. 3805 */ 3806 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3807 } 3808 counter_u64_add(mappingrestarts, 1); 3809 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3810 } 3811 has_addr: 3812 if (need_mapping) { 3813 /* b_offset is handled by bpmap_qenter. */ 3814 bp->b_data = bp->b_kvabase; 3815 BUF_CHECK_MAPPED(bp); 3816 bpmap_qenter(bp); 3817 } 3818 } 3819 3820 struct buf * 3821 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3822 int flags) 3823 { 3824 struct buf *bp; 3825 int error; 3826 3827 error = getblkx(vp, blkno, size, slpflag, slptimeo, flags, &bp); 3828 if (error != 0) 3829 return (NULL); 3830 return (bp); 3831 } 3832 3833 /* 3834 * getblkx: 3835 * 3836 * Get a block given a specified block and offset into a file/device. 3837 * The buffers B_DONE bit will be cleared on return, making it almost 3838 * ready for an I/O initiation. B_INVAL may or may not be set on 3839 * return. The caller should clear B_INVAL prior to initiating a 3840 * READ. 3841 * 3842 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3843 * an existing buffer. 3844 * 3845 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3846 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3847 * and then cleared based on the backing VM. If the previous buffer is 3848 * non-0-sized but invalid, B_CACHE will be cleared. 3849 * 3850 * If getblk() must create a new buffer, the new buffer is returned with 3851 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3852 * case it is returned with B_INVAL clear and B_CACHE set based on the 3853 * backing VM. 3854 * 3855 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3856 * B_CACHE bit is clear. 3857 * 3858 * What this means, basically, is that the caller should use B_CACHE to 3859 * determine whether the buffer is fully valid or not and should clear 3860 * B_INVAL prior to issuing a read. If the caller intends to validate 3861 * the buffer by loading its data area with something, the caller needs 3862 * to clear B_INVAL. If the caller does this without issuing an I/O, 3863 * the caller should set B_CACHE ( as an optimization ), else the caller 3864 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3865 * a write attempt or if it was a successful read. If the caller 3866 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3867 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3868 */ 3869 int 3870 getblkx(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3871 int flags, struct buf **bpp) 3872 { 3873 struct buf *bp; 3874 struct bufobj *bo; 3875 daddr_t d_blkno; 3876 int bsize, error, maxsize, vmio; 3877 off_t offset; 3878 3879 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3880 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3881 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3882 ASSERT_VOP_LOCKED(vp, "getblk"); 3883 if (size > maxbcachebuf) 3884 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3885 maxbcachebuf); 3886 if (!unmapped_buf_allowed) 3887 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3888 3889 bo = &vp->v_bufobj; 3890 d_blkno = blkno; 3891 loop: 3892 BO_RLOCK(bo); 3893 bp = gbincore(bo, blkno); 3894 if (bp != NULL) { 3895 int lockflags; 3896 /* 3897 * Buffer is in-core. If the buffer is not busy nor managed, 3898 * it must be on a queue. 3899 */ 3900 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3901 3902 if ((flags & GB_LOCK_NOWAIT) != 0) 3903 lockflags |= LK_NOWAIT; 3904 3905 error = BUF_TIMELOCK(bp, lockflags, 3906 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3907 3908 /* 3909 * If we slept and got the lock we have to restart in case 3910 * the buffer changed identities. 3911 */ 3912 if (error == ENOLCK) 3913 goto loop; 3914 /* We timed out or were interrupted. */ 3915 else if (error != 0) 3916 return (error); 3917 /* If recursed, assume caller knows the rules. */ 3918 else if (BUF_LOCKRECURSED(bp)) 3919 goto end; 3920 3921 /* 3922 * The buffer is locked. B_CACHE is cleared if the buffer is 3923 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3924 * and for a VMIO buffer B_CACHE is adjusted according to the 3925 * backing VM cache. 3926 */ 3927 if (bp->b_flags & B_INVAL) 3928 bp->b_flags &= ~B_CACHE; 3929 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3930 bp->b_flags |= B_CACHE; 3931 if (bp->b_flags & B_MANAGED) 3932 MPASS(bp->b_qindex == QUEUE_NONE); 3933 else 3934 bremfree(bp); 3935 3936 /* 3937 * check for size inconsistencies for non-VMIO case. 3938 */ 3939 if (bp->b_bcount != size) { 3940 if ((bp->b_flags & B_VMIO) == 0 || 3941 (size > bp->b_kvasize)) { 3942 if (bp->b_flags & B_DELWRI) { 3943 bp->b_flags |= B_NOCACHE; 3944 bwrite(bp); 3945 } else { 3946 if (LIST_EMPTY(&bp->b_dep)) { 3947 bp->b_flags |= B_RELBUF; 3948 brelse(bp); 3949 } else { 3950 bp->b_flags |= B_NOCACHE; 3951 bwrite(bp); 3952 } 3953 } 3954 goto loop; 3955 } 3956 } 3957 3958 /* 3959 * Handle the case of unmapped buffer which should 3960 * become mapped, or the buffer for which KVA 3961 * reservation is requested. 3962 */ 3963 bp_unmapped_get_kva(bp, blkno, size, flags); 3964 3965 /* 3966 * If the size is inconsistent in the VMIO case, we can resize 3967 * the buffer. This might lead to B_CACHE getting set or 3968 * cleared. If the size has not changed, B_CACHE remains 3969 * unchanged from its previous state. 3970 */ 3971 allocbuf(bp, size); 3972 3973 KASSERT(bp->b_offset != NOOFFSET, 3974 ("getblk: no buffer offset")); 3975 3976 /* 3977 * A buffer with B_DELWRI set and B_CACHE clear must 3978 * be committed before we can return the buffer in 3979 * order to prevent the caller from issuing a read 3980 * ( due to B_CACHE not being set ) and overwriting 3981 * it. 3982 * 3983 * Most callers, including NFS and FFS, need this to 3984 * operate properly either because they assume they 3985 * can issue a read if B_CACHE is not set, or because 3986 * ( for example ) an uncached B_DELWRI might loop due 3987 * to softupdates re-dirtying the buffer. In the latter 3988 * case, B_CACHE is set after the first write completes, 3989 * preventing further loops. 3990 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3991 * above while extending the buffer, we cannot allow the 3992 * buffer to remain with B_CACHE set after the write 3993 * completes or it will represent a corrupt state. To 3994 * deal with this we set B_NOCACHE to scrap the buffer 3995 * after the write. 3996 * 3997 * We might be able to do something fancy, like setting 3998 * B_CACHE in bwrite() except if B_DELWRI is already set, 3999 * so the below call doesn't set B_CACHE, but that gets real 4000 * confusing. This is much easier. 4001 */ 4002 4003 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 4004 bp->b_flags |= B_NOCACHE; 4005 bwrite(bp); 4006 goto loop; 4007 } 4008 bp->b_flags &= ~B_DONE; 4009 } else { 4010 /* 4011 * Buffer is not in-core, create new buffer. The buffer 4012 * returned by getnewbuf() is locked. Note that the returned 4013 * buffer is also considered valid (not marked B_INVAL). 4014 */ 4015 BO_RUNLOCK(bo); 4016 /* 4017 * If the user does not want us to create the buffer, bail out 4018 * here. 4019 */ 4020 if (flags & GB_NOCREAT) 4021 return (EEXIST); 4022 if (bdomain[bo->bo_domain].bd_freebuffers == 0 && 4023 TD_IS_IDLETHREAD(curthread)) 4024 return (EBUSY); 4025 4026 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 4027 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4028 offset = blkno * bsize; 4029 vmio = vp->v_object != NULL; 4030 if (vmio) { 4031 maxsize = size + (offset & PAGE_MASK); 4032 } else { 4033 maxsize = size; 4034 /* Do not allow non-VMIO notmapped buffers. */ 4035 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4036 } 4037 maxsize = imax(maxsize, bsize); 4038 if ((flags & GB_NOSPARSE) != 0 && vmio && 4039 !vn_isdisk(vp, NULL)) { 4040 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4041 KASSERT(error != EOPNOTSUPP, 4042 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4043 vp)); 4044 if (error != 0) 4045 return (error); 4046 if (d_blkno == -1) 4047 return (EJUSTRETURN); 4048 } 4049 4050 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4051 if (bp == NULL) { 4052 if (slpflag || slptimeo) 4053 return (ETIMEDOUT); 4054 /* 4055 * XXX This is here until the sleep path is diagnosed 4056 * enough to work under very low memory conditions. 4057 * 4058 * There's an issue on low memory, 4BSD+non-preempt 4059 * systems (eg MIPS routers with 32MB RAM) where buffer 4060 * exhaustion occurs without sleeping for buffer 4061 * reclaimation. This just sticks in a loop and 4062 * constantly attempts to allocate a buffer, which 4063 * hits exhaustion and tries to wakeup bufdaemon. 4064 * This never happens because we never yield. 4065 * 4066 * The real solution is to identify and fix these cases 4067 * so we aren't effectively busy-waiting in a loop 4068 * until the reclaimation path has cycles to run. 4069 */ 4070 kern_yield(PRI_USER); 4071 goto loop; 4072 } 4073 4074 /* 4075 * This code is used to make sure that a buffer is not 4076 * created while the getnewbuf routine is blocked. 4077 * This can be a problem whether the vnode is locked or not. 4078 * If the buffer is created out from under us, we have to 4079 * throw away the one we just created. 4080 * 4081 * Note: this must occur before we associate the buffer 4082 * with the vp especially considering limitations in 4083 * the splay tree implementation when dealing with duplicate 4084 * lblkno's. 4085 */ 4086 BO_LOCK(bo); 4087 if (gbincore(bo, blkno)) { 4088 BO_UNLOCK(bo); 4089 bp->b_flags |= B_INVAL; 4090 bufspace_release(bufdomain(bp), maxsize); 4091 brelse(bp); 4092 goto loop; 4093 } 4094 4095 /* 4096 * Insert the buffer into the hash, so that it can 4097 * be found by incore. 4098 */ 4099 bp->b_lblkno = blkno; 4100 bp->b_blkno = d_blkno; 4101 bp->b_offset = offset; 4102 bgetvp(vp, bp); 4103 BO_UNLOCK(bo); 4104 4105 /* 4106 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4107 * buffer size starts out as 0, B_CACHE will be set by 4108 * allocbuf() for the VMIO case prior to it testing the 4109 * backing store for validity. 4110 */ 4111 4112 if (vmio) { 4113 bp->b_flags |= B_VMIO; 4114 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4115 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4116 bp, vp->v_object, bp->b_bufobj->bo_object)); 4117 } else { 4118 bp->b_flags &= ~B_VMIO; 4119 KASSERT(bp->b_bufobj->bo_object == NULL, 4120 ("ARGH! has b_bufobj->bo_object %p %p\n", 4121 bp, bp->b_bufobj->bo_object)); 4122 BUF_CHECK_MAPPED(bp); 4123 } 4124 4125 allocbuf(bp, size); 4126 bufspace_release(bufdomain(bp), maxsize); 4127 bp->b_flags &= ~B_DONE; 4128 } 4129 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4130 BUF_ASSERT_HELD(bp); 4131 end: 4132 buf_track(bp, __func__); 4133 KASSERT(bp->b_bufobj == bo, 4134 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4135 *bpp = bp; 4136 return (0); 4137 } 4138 4139 /* 4140 * Get an empty, disassociated buffer of given size. The buffer is initially 4141 * set to B_INVAL. 4142 */ 4143 struct buf * 4144 geteblk(int size, int flags) 4145 { 4146 struct buf *bp; 4147 int maxsize; 4148 4149 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4150 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4151 if ((flags & GB_NOWAIT_BD) && 4152 (curthread->td_pflags & TDP_BUFNEED) != 0) 4153 return (NULL); 4154 } 4155 allocbuf(bp, size); 4156 bufspace_release(bufdomain(bp), maxsize); 4157 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4158 BUF_ASSERT_HELD(bp); 4159 return (bp); 4160 } 4161 4162 /* 4163 * Truncate the backing store for a non-vmio buffer. 4164 */ 4165 static void 4166 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4167 { 4168 4169 if (bp->b_flags & B_MALLOC) { 4170 /* 4171 * malloced buffers are not shrunk 4172 */ 4173 if (newbsize == 0) { 4174 bufmallocadjust(bp, 0); 4175 free(bp->b_data, M_BIOBUF); 4176 bp->b_data = bp->b_kvabase; 4177 bp->b_flags &= ~B_MALLOC; 4178 } 4179 return; 4180 } 4181 vm_hold_free_pages(bp, newbsize); 4182 bufspace_adjust(bp, newbsize); 4183 } 4184 4185 /* 4186 * Extend the backing for a non-VMIO buffer. 4187 */ 4188 static void 4189 vfs_nonvmio_extend(struct buf *bp, int newbsize) 4190 { 4191 caddr_t origbuf; 4192 int origbufsize; 4193 4194 /* 4195 * We only use malloced memory on the first allocation. 4196 * and revert to page-allocated memory when the buffer 4197 * grows. 4198 * 4199 * There is a potential smp race here that could lead 4200 * to bufmallocspace slightly passing the max. It 4201 * is probably extremely rare and not worth worrying 4202 * over. 4203 */ 4204 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4205 bufmallocspace < maxbufmallocspace) { 4206 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4207 bp->b_flags |= B_MALLOC; 4208 bufmallocadjust(bp, newbsize); 4209 return; 4210 } 4211 4212 /* 4213 * If the buffer is growing on its other-than-first 4214 * allocation then we revert to the page-allocation 4215 * scheme. 4216 */ 4217 origbuf = NULL; 4218 origbufsize = 0; 4219 if (bp->b_flags & B_MALLOC) { 4220 origbuf = bp->b_data; 4221 origbufsize = bp->b_bufsize; 4222 bp->b_data = bp->b_kvabase; 4223 bufmallocadjust(bp, 0); 4224 bp->b_flags &= ~B_MALLOC; 4225 newbsize = round_page(newbsize); 4226 } 4227 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4228 (vm_offset_t) bp->b_data + newbsize); 4229 if (origbuf != NULL) { 4230 bcopy(origbuf, bp->b_data, origbufsize); 4231 free(origbuf, M_BIOBUF); 4232 } 4233 bufspace_adjust(bp, newbsize); 4234 } 4235 4236 /* 4237 * This code constitutes the buffer memory from either anonymous system 4238 * memory (in the case of non-VMIO operations) or from an associated 4239 * VM object (in the case of VMIO operations). This code is able to 4240 * resize a buffer up or down. 4241 * 4242 * Note that this code is tricky, and has many complications to resolve 4243 * deadlock or inconsistent data situations. Tread lightly!!! 4244 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4245 * the caller. Calling this code willy nilly can result in the loss of data. 4246 * 4247 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4248 * B_CACHE for the non-VMIO case. 4249 */ 4250 int 4251 allocbuf(struct buf *bp, int size) 4252 { 4253 int newbsize; 4254 4255 BUF_ASSERT_HELD(bp); 4256 4257 if (bp->b_bcount == size) 4258 return (1); 4259 4260 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 4261 panic("allocbuf: buffer too small"); 4262 4263 newbsize = roundup2(size, DEV_BSIZE); 4264 if ((bp->b_flags & B_VMIO) == 0) { 4265 if ((bp->b_flags & B_MALLOC) == 0) 4266 newbsize = round_page(newbsize); 4267 /* 4268 * Just get anonymous memory from the kernel. Don't 4269 * mess with B_CACHE. 4270 */ 4271 if (newbsize < bp->b_bufsize) 4272 vfs_nonvmio_truncate(bp, newbsize); 4273 else if (newbsize > bp->b_bufsize) 4274 vfs_nonvmio_extend(bp, newbsize); 4275 } else { 4276 int desiredpages; 4277 4278 desiredpages = (size == 0) ? 0 : 4279 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4280 4281 if (bp->b_flags & B_MALLOC) 4282 panic("allocbuf: VMIO buffer can't be malloced"); 4283 /* 4284 * Set B_CACHE initially if buffer is 0 length or will become 4285 * 0-length. 4286 */ 4287 if (size == 0 || bp->b_bufsize == 0) 4288 bp->b_flags |= B_CACHE; 4289 4290 if (newbsize < bp->b_bufsize) 4291 vfs_vmio_truncate(bp, desiredpages); 4292 /* XXX This looks as if it should be newbsize > b_bufsize */ 4293 else if (size > bp->b_bcount) 4294 vfs_vmio_extend(bp, desiredpages, size); 4295 bufspace_adjust(bp, newbsize); 4296 } 4297 bp->b_bcount = size; /* requested buffer size. */ 4298 return (1); 4299 } 4300 4301 extern int inflight_transient_maps; 4302 4303 static struct bio_queue nondump_bios; 4304 4305 void 4306 biodone(struct bio *bp) 4307 { 4308 struct mtx *mtxp; 4309 void (*done)(struct bio *); 4310 vm_offset_t start, end; 4311 4312 biotrack(bp, __func__); 4313 4314 /* 4315 * Avoid completing I/O when dumping after a panic since that may 4316 * result in a deadlock in the filesystem or pager code. Note that 4317 * this doesn't affect dumps that were started manually since we aim 4318 * to keep the system usable after it has been resumed. 4319 */ 4320 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4321 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4322 return; 4323 } 4324 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4325 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4326 bp->bio_flags |= BIO_UNMAPPED; 4327 start = trunc_page((vm_offset_t)bp->bio_data); 4328 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4329 bp->bio_data = unmapped_buf; 4330 pmap_qremove(start, atop(end - start)); 4331 vmem_free(transient_arena, start, end - start); 4332 atomic_add_int(&inflight_transient_maps, -1); 4333 } 4334 done = bp->bio_done; 4335 if (done == NULL) { 4336 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4337 mtx_lock(mtxp); 4338 bp->bio_flags |= BIO_DONE; 4339 wakeup(bp); 4340 mtx_unlock(mtxp); 4341 } else 4342 done(bp); 4343 } 4344 4345 /* 4346 * Wait for a BIO to finish. 4347 */ 4348 int 4349 biowait(struct bio *bp, const char *wchan) 4350 { 4351 struct mtx *mtxp; 4352 4353 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4354 mtx_lock(mtxp); 4355 while ((bp->bio_flags & BIO_DONE) == 0) 4356 msleep(bp, mtxp, PRIBIO, wchan, 0); 4357 mtx_unlock(mtxp); 4358 if (bp->bio_error != 0) 4359 return (bp->bio_error); 4360 if (!(bp->bio_flags & BIO_ERROR)) 4361 return (0); 4362 return (EIO); 4363 } 4364 4365 void 4366 biofinish(struct bio *bp, struct devstat *stat, int error) 4367 { 4368 4369 if (error) { 4370 bp->bio_error = error; 4371 bp->bio_flags |= BIO_ERROR; 4372 } 4373 if (stat != NULL) 4374 devstat_end_transaction_bio(stat, bp); 4375 biodone(bp); 4376 } 4377 4378 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4379 void 4380 biotrack_buf(struct bio *bp, const char *location) 4381 { 4382 4383 buf_track(bp->bio_track_bp, location); 4384 } 4385 #endif 4386 4387 /* 4388 * bufwait: 4389 * 4390 * Wait for buffer I/O completion, returning error status. The buffer 4391 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4392 * error and cleared. 4393 */ 4394 int 4395 bufwait(struct buf *bp) 4396 { 4397 if (bp->b_iocmd == BIO_READ) 4398 bwait(bp, PRIBIO, "biord"); 4399 else 4400 bwait(bp, PRIBIO, "biowr"); 4401 if (bp->b_flags & B_EINTR) { 4402 bp->b_flags &= ~B_EINTR; 4403 return (EINTR); 4404 } 4405 if (bp->b_ioflags & BIO_ERROR) { 4406 return (bp->b_error ? bp->b_error : EIO); 4407 } else { 4408 return (0); 4409 } 4410 } 4411 4412 /* 4413 * bufdone: 4414 * 4415 * Finish I/O on a buffer, optionally calling a completion function. 4416 * This is usually called from an interrupt so process blocking is 4417 * not allowed. 4418 * 4419 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4420 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4421 * assuming B_INVAL is clear. 4422 * 4423 * For the VMIO case, we set B_CACHE if the op was a read and no 4424 * read error occurred, or if the op was a write. B_CACHE is never 4425 * set if the buffer is invalid or otherwise uncacheable. 4426 * 4427 * biodone does not mess with B_INVAL, allowing the I/O routine or the 4428 * initiator to leave B_INVAL set to brelse the buffer out of existence 4429 * in the biodone routine. 4430 */ 4431 void 4432 bufdone(struct buf *bp) 4433 { 4434 struct bufobj *dropobj; 4435 void (*biodone)(struct buf *); 4436 4437 buf_track(bp, __func__); 4438 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4439 dropobj = NULL; 4440 4441 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4442 BUF_ASSERT_HELD(bp); 4443 4444 runningbufwakeup(bp); 4445 if (bp->b_iocmd == BIO_WRITE) 4446 dropobj = bp->b_bufobj; 4447 /* call optional completion function if requested */ 4448 if (bp->b_iodone != NULL) { 4449 biodone = bp->b_iodone; 4450 bp->b_iodone = NULL; 4451 (*biodone) (bp); 4452 if (dropobj) 4453 bufobj_wdrop(dropobj); 4454 return; 4455 } 4456 if (bp->b_flags & B_VMIO) { 4457 /* 4458 * Set B_CACHE if the op was a normal read and no error 4459 * occurred. B_CACHE is set for writes in the b*write() 4460 * routines. 4461 */ 4462 if (bp->b_iocmd == BIO_READ && 4463 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4464 !(bp->b_ioflags & BIO_ERROR)) 4465 bp->b_flags |= B_CACHE; 4466 vfs_vmio_iodone(bp); 4467 } 4468 if (!LIST_EMPTY(&bp->b_dep)) 4469 buf_complete(bp); 4470 if ((bp->b_flags & B_CKHASH) != 0) { 4471 KASSERT(bp->b_iocmd == BIO_READ, 4472 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4473 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4474 (*bp->b_ckhashcalc)(bp); 4475 } 4476 /* 4477 * For asynchronous completions, release the buffer now. The brelse 4478 * will do a wakeup there if necessary - so no need to do a wakeup 4479 * here in the async case. The sync case always needs to do a wakeup. 4480 */ 4481 if (bp->b_flags & B_ASYNC) { 4482 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4483 (bp->b_ioflags & BIO_ERROR)) 4484 brelse(bp); 4485 else 4486 bqrelse(bp); 4487 } else 4488 bdone(bp); 4489 if (dropobj) 4490 bufobj_wdrop(dropobj); 4491 } 4492 4493 /* 4494 * This routine is called in lieu of iodone in the case of 4495 * incomplete I/O. This keeps the busy status for pages 4496 * consistent. 4497 */ 4498 void 4499 vfs_unbusy_pages(struct buf *bp) 4500 { 4501 int i; 4502 vm_object_t obj; 4503 vm_page_t m; 4504 4505 runningbufwakeup(bp); 4506 if (!(bp->b_flags & B_VMIO)) 4507 return; 4508 4509 obj = bp->b_bufobj->bo_object; 4510 VM_OBJECT_WLOCK(obj); 4511 for (i = 0; i < bp->b_npages; i++) { 4512 m = bp->b_pages[i]; 4513 if (m == bogus_page) { 4514 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4515 if (!m) 4516 panic("vfs_unbusy_pages: page missing\n"); 4517 bp->b_pages[i] = m; 4518 if (buf_mapped(bp)) { 4519 BUF_CHECK_MAPPED(bp); 4520 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4521 bp->b_pages, bp->b_npages); 4522 } else 4523 BUF_CHECK_UNMAPPED(bp); 4524 } 4525 vm_page_sunbusy(m); 4526 } 4527 vm_object_pip_wakeupn(obj, bp->b_npages); 4528 VM_OBJECT_WUNLOCK(obj); 4529 } 4530 4531 /* 4532 * vfs_page_set_valid: 4533 * 4534 * Set the valid bits in a page based on the supplied offset. The 4535 * range is restricted to the buffer's size. 4536 * 4537 * This routine is typically called after a read completes. 4538 */ 4539 static void 4540 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4541 { 4542 vm_ooffset_t eoff; 4543 4544 /* 4545 * Compute the end offset, eoff, such that [off, eoff) does not span a 4546 * page boundary and eoff is not greater than the end of the buffer. 4547 * The end of the buffer, in this case, is our file EOF, not the 4548 * allocation size of the buffer. 4549 */ 4550 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4551 if (eoff > bp->b_offset + bp->b_bcount) 4552 eoff = bp->b_offset + bp->b_bcount; 4553 4554 /* 4555 * Set valid range. This is typically the entire buffer and thus the 4556 * entire page. 4557 */ 4558 if (eoff > off) 4559 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4560 } 4561 4562 /* 4563 * vfs_page_set_validclean: 4564 * 4565 * Set the valid bits and clear the dirty bits in a page based on the 4566 * supplied offset. The range is restricted to the buffer's size. 4567 */ 4568 static void 4569 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4570 { 4571 vm_ooffset_t soff, eoff; 4572 4573 /* 4574 * Start and end offsets in buffer. eoff - soff may not cross a 4575 * page boundary or cross the end of the buffer. The end of the 4576 * buffer, in this case, is our file EOF, not the allocation size 4577 * of the buffer. 4578 */ 4579 soff = off; 4580 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4581 if (eoff > bp->b_offset + bp->b_bcount) 4582 eoff = bp->b_offset + bp->b_bcount; 4583 4584 /* 4585 * Set valid range. This is typically the entire buffer and thus the 4586 * entire page. 4587 */ 4588 if (eoff > soff) { 4589 vm_page_set_validclean( 4590 m, 4591 (vm_offset_t) (soff & PAGE_MASK), 4592 (vm_offset_t) (eoff - soff) 4593 ); 4594 } 4595 } 4596 4597 /* 4598 * Ensure that all buffer pages are not exclusive busied. If any page is 4599 * exclusive busy, drain it. 4600 */ 4601 void 4602 vfs_drain_busy_pages(struct buf *bp) 4603 { 4604 vm_page_t m; 4605 int i, last_busied; 4606 4607 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4608 last_busied = 0; 4609 for (i = 0; i < bp->b_npages; i++) { 4610 m = bp->b_pages[i]; 4611 if (vm_page_xbusied(m)) { 4612 for (; last_busied < i; last_busied++) 4613 vm_page_sbusy(bp->b_pages[last_busied]); 4614 while (vm_page_xbusied(m)) { 4615 vm_page_lock(m); 4616 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4617 vm_page_busy_sleep(m, "vbpage", true); 4618 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4619 } 4620 } 4621 } 4622 for (i = 0; i < last_busied; i++) 4623 vm_page_sunbusy(bp->b_pages[i]); 4624 } 4625 4626 /* 4627 * This routine is called before a device strategy routine. 4628 * It is used to tell the VM system that paging I/O is in 4629 * progress, and treat the pages associated with the buffer 4630 * almost as being exclusive busy. Also the object paging_in_progress 4631 * flag is handled to make sure that the object doesn't become 4632 * inconsistent. 4633 * 4634 * Since I/O has not been initiated yet, certain buffer flags 4635 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4636 * and should be ignored. 4637 */ 4638 void 4639 vfs_busy_pages(struct buf *bp, int clear_modify) 4640 { 4641 vm_object_t obj; 4642 vm_ooffset_t foff; 4643 vm_page_t m; 4644 int i; 4645 bool bogus; 4646 4647 if (!(bp->b_flags & B_VMIO)) 4648 return; 4649 4650 obj = bp->b_bufobj->bo_object; 4651 foff = bp->b_offset; 4652 KASSERT(bp->b_offset != NOOFFSET, 4653 ("vfs_busy_pages: no buffer offset")); 4654 VM_OBJECT_WLOCK(obj); 4655 vfs_drain_busy_pages(bp); 4656 if (bp->b_bufsize != 0) 4657 vfs_setdirty_locked_object(bp); 4658 bogus = false; 4659 for (i = 0; i < bp->b_npages; i++) { 4660 m = bp->b_pages[i]; 4661 4662 if ((bp->b_flags & B_CLUSTER) == 0) { 4663 vm_object_pip_add(obj, 1); 4664 vm_page_sbusy(m); 4665 } 4666 /* 4667 * When readying a buffer for a read ( i.e 4668 * clear_modify == 0 ), it is important to do 4669 * bogus_page replacement for valid pages in 4670 * partially instantiated buffers. Partially 4671 * instantiated buffers can, in turn, occur when 4672 * reconstituting a buffer from its VM backing store 4673 * base. We only have to do this if B_CACHE is 4674 * clear ( which causes the I/O to occur in the 4675 * first place ). The replacement prevents the read 4676 * I/O from overwriting potentially dirty VM-backed 4677 * pages. XXX bogus page replacement is, uh, bogus. 4678 * It may not work properly with small-block devices. 4679 * We need to find a better way. 4680 */ 4681 if (clear_modify) { 4682 pmap_remove_write(m); 4683 vfs_page_set_validclean(bp, foff, m); 4684 } else if (m->valid == VM_PAGE_BITS_ALL && 4685 (bp->b_flags & B_CACHE) == 0) { 4686 bp->b_pages[i] = bogus_page; 4687 bogus = true; 4688 } 4689 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4690 } 4691 VM_OBJECT_WUNLOCK(obj); 4692 if (bogus && buf_mapped(bp)) { 4693 BUF_CHECK_MAPPED(bp); 4694 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4695 bp->b_pages, bp->b_npages); 4696 } 4697 } 4698 4699 /* 4700 * vfs_bio_set_valid: 4701 * 4702 * Set the range within the buffer to valid. The range is 4703 * relative to the beginning of the buffer, b_offset. Note that 4704 * b_offset itself may be offset from the beginning of the first 4705 * page. 4706 */ 4707 void 4708 vfs_bio_set_valid(struct buf *bp, int base, int size) 4709 { 4710 int i, n; 4711 vm_page_t m; 4712 4713 if (!(bp->b_flags & B_VMIO)) 4714 return; 4715 4716 /* 4717 * Fixup base to be relative to beginning of first page. 4718 * Set initial n to be the maximum number of bytes in the 4719 * first page that can be validated. 4720 */ 4721 base += (bp->b_offset & PAGE_MASK); 4722 n = PAGE_SIZE - (base & PAGE_MASK); 4723 4724 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4725 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4726 m = bp->b_pages[i]; 4727 if (n > size) 4728 n = size; 4729 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4730 base += n; 4731 size -= n; 4732 n = PAGE_SIZE; 4733 } 4734 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4735 } 4736 4737 /* 4738 * vfs_bio_clrbuf: 4739 * 4740 * If the specified buffer is a non-VMIO buffer, clear the entire 4741 * buffer. If the specified buffer is a VMIO buffer, clear and 4742 * validate only the previously invalid portions of the buffer. 4743 * This routine essentially fakes an I/O, so we need to clear 4744 * BIO_ERROR and B_INVAL. 4745 * 4746 * Note that while we only theoretically need to clear through b_bcount, 4747 * we go ahead and clear through b_bufsize. 4748 */ 4749 void 4750 vfs_bio_clrbuf(struct buf *bp) 4751 { 4752 int i, j, mask, sa, ea, slide; 4753 4754 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4755 clrbuf(bp); 4756 return; 4757 } 4758 bp->b_flags &= ~B_INVAL; 4759 bp->b_ioflags &= ~BIO_ERROR; 4760 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4761 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4762 (bp->b_offset & PAGE_MASK) == 0) { 4763 if (bp->b_pages[0] == bogus_page) 4764 goto unlock; 4765 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4766 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4767 if ((bp->b_pages[0]->valid & mask) == mask) 4768 goto unlock; 4769 if ((bp->b_pages[0]->valid & mask) == 0) { 4770 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4771 bp->b_pages[0]->valid |= mask; 4772 goto unlock; 4773 } 4774 } 4775 sa = bp->b_offset & PAGE_MASK; 4776 slide = 0; 4777 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4778 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4779 ea = slide & PAGE_MASK; 4780 if (ea == 0) 4781 ea = PAGE_SIZE; 4782 if (bp->b_pages[i] == bogus_page) 4783 continue; 4784 j = sa / DEV_BSIZE; 4785 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4786 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4787 if ((bp->b_pages[i]->valid & mask) == mask) 4788 continue; 4789 if ((bp->b_pages[i]->valid & mask) == 0) 4790 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4791 else { 4792 for (; sa < ea; sa += DEV_BSIZE, j++) { 4793 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4794 pmap_zero_page_area(bp->b_pages[i], 4795 sa, DEV_BSIZE); 4796 } 4797 } 4798 } 4799 bp->b_pages[i]->valid |= mask; 4800 } 4801 unlock: 4802 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4803 bp->b_resid = 0; 4804 } 4805 4806 void 4807 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4808 { 4809 vm_page_t m; 4810 int i, n; 4811 4812 if (buf_mapped(bp)) { 4813 BUF_CHECK_MAPPED(bp); 4814 bzero(bp->b_data + base, size); 4815 } else { 4816 BUF_CHECK_UNMAPPED(bp); 4817 n = PAGE_SIZE - (base & PAGE_MASK); 4818 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4819 m = bp->b_pages[i]; 4820 if (n > size) 4821 n = size; 4822 pmap_zero_page_area(m, base & PAGE_MASK, n); 4823 base += n; 4824 size -= n; 4825 n = PAGE_SIZE; 4826 } 4827 } 4828 } 4829 4830 /* 4831 * Update buffer flags based on I/O request parameters, optionally releasing the 4832 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4833 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4834 * I/O). Otherwise the buffer is released to the cache. 4835 */ 4836 static void 4837 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4838 { 4839 4840 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4841 ("buf %p non-VMIO noreuse", bp)); 4842 4843 if ((ioflag & IO_DIRECT) != 0) 4844 bp->b_flags |= B_DIRECT; 4845 if ((ioflag & IO_EXT) != 0) 4846 bp->b_xflags |= BX_ALTDATA; 4847 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4848 bp->b_flags |= B_RELBUF; 4849 if ((ioflag & IO_NOREUSE) != 0) 4850 bp->b_flags |= B_NOREUSE; 4851 if (release) 4852 brelse(bp); 4853 } else if (release) 4854 bqrelse(bp); 4855 } 4856 4857 void 4858 vfs_bio_brelse(struct buf *bp, int ioflag) 4859 { 4860 4861 b_io_dismiss(bp, ioflag, true); 4862 } 4863 4864 void 4865 vfs_bio_set_flags(struct buf *bp, int ioflag) 4866 { 4867 4868 b_io_dismiss(bp, ioflag, false); 4869 } 4870 4871 /* 4872 * vm_hold_load_pages and vm_hold_free_pages get pages into 4873 * a buffers address space. The pages are anonymous and are 4874 * not associated with a file object. 4875 */ 4876 static void 4877 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4878 { 4879 vm_offset_t pg; 4880 vm_page_t p; 4881 int index; 4882 4883 BUF_CHECK_MAPPED(bp); 4884 4885 to = round_page(to); 4886 from = round_page(from); 4887 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4888 4889 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4890 /* 4891 * note: must allocate system pages since blocking here 4892 * could interfere with paging I/O, no matter which 4893 * process we are. 4894 */ 4895 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4896 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | 4897 VM_ALLOC_WAITOK); 4898 pmap_qenter(pg, &p, 1); 4899 bp->b_pages[index] = p; 4900 } 4901 bp->b_npages = index; 4902 } 4903 4904 /* Return pages associated with this buf to the vm system */ 4905 static void 4906 vm_hold_free_pages(struct buf *bp, int newbsize) 4907 { 4908 vm_offset_t from; 4909 vm_page_t p; 4910 int index, newnpages; 4911 4912 BUF_CHECK_MAPPED(bp); 4913 4914 from = round_page((vm_offset_t)bp->b_data + newbsize); 4915 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4916 if (bp->b_npages > newnpages) 4917 pmap_qremove(from, bp->b_npages - newnpages); 4918 for (index = newnpages; index < bp->b_npages; index++) { 4919 p = bp->b_pages[index]; 4920 bp->b_pages[index] = NULL; 4921 p->wire_count--; 4922 vm_page_free(p); 4923 } 4924 vm_wire_sub(bp->b_npages - newnpages); 4925 bp->b_npages = newnpages; 4926 } 4927 4928 /* 4929 * Map an IO request into kernel virtual address space. 4930 * 4931 * All requests are (re)mapped into kernel VA space. 4932 * Notice that we use b_bufsize for the size of the buffer 4933 * to be mapped. b_bcount might be modified by the driver. 4934 * 4935 * Note that even if the caller determines that the address space should 4936 * be valid, a race or a smaller-file mapped into a larger space may 4937 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4938 * check the return value. 4939 * 4940 * This function only works with pager buffers. 4941 */ 4942 int 4943 vmapbuf(struct buf *bp, int mapbuf) 4944 { 4945 vm_prot_t prot; 4946 int pidx; 4947 4948 if (bp->b_bufsize < 0) 4949 return (-1); 4950 prot = VM_PROT_READ; 4951 if (bp->b_iocmd == BIO_READ) 4952 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4953 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4954 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4955 btoc(MAXPHYS))) < 0) 4956 return (-1); 4957 bp->b_npages = pidx; 4958 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4959 if (mapbuf || !unmapped_buf_allowed) { 4960 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4961 bp->b_data = bp->b_kvabase + bp->b_offset; 4962 } else 4963 bp->b_data = unmapped_buf; 4964 return(0); 4965 } 4966 4967 /* 4968 * Free the io map PTEs associated with this IO operation. 4969 * We also invalidate the TLB entries and restore the original b_addr. 4970 * 4971 * This function only works with pager buffers. 4972 */ 4973 void 4974 vunmapbuf(struct buf *bp) 4975 { 4976 int npages; 4977 4978 npages = bp->b_npages; 4979 if (buf_mapped(bp)) 4980 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4981 vm_page_unhold_pages(bp->b_pages, npages); 4982 4983 bp->b_data = unmapped_buf; 4984 } 4985 4986 void 4987 bdone(struct buf *bp) 4988 { 4989 struct mtx *mtxp; 4990 4991 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4992 mtx_lock(mtxp); 4993 bp->b_flags |= B_DONE; 4994 wakeup(bp); 4995 mtx_unlock(mtxp); 4996 } 4997 4998 void 4999 bwait(struct buf *bp, u_char pri, const char *wchan) 5000 { 5001 struct mtx *mtxp; 5002 5003 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5004 mtx_lock(mtxp); 5005 while ((bp->b_flags & B_DONE) == 0) 5006 msleep(bp, mtxp, pri, wchan, 0); 5007 mtx_unlock(mtxp); 5008 } 5009 5010 int 5011 bufsync(struct bufobj *bo, int waitfor) 5012 { 5013 5014 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 5015 } 5016 5017 void 5018 bufstrategy(struct bufobj *bo, struct buf *bp) 5019 { 5020 int i __unused; 5021 struct vnode *vp; 5022 5023 vp = bp->b_vp; 5024 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5025 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5026 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5027 i = VOP_STRATEGY(vp, bp); 5028 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5029 } 5030 5031 /* 5032 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5033 */ 5034 void 5035 bufobj_init(struct bufobj *bo, void *private) 5036 { 5037 static volatile int bufobj_cleanq; 5038 5039 bo->bo_domain = 5040 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5041 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5042 bo->bo_private = private; 5043 TAILQ_INIT(&bo->bo_clean.bv_hd); 5044 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5045 } 5046 5047 void 5048 bufobj_wrefl(struct bufobj *bo) 5049 { 5050 5051 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5052 ASSERT_BO_WLOCKED(bo); 5053 bo->bo_numoutput++; 5054 } 5055 5056 void 5057 bufobj_wref(struct bufobj *bo) 5058 { 5059 5060 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5061 BO_LOCK(bo); 5062 bo->bo_numoutput++; 5063 BO_UNLOCK(bo); 5064 } 5065 5066 void 5067 bufobj_wdrop(struct bufobj *bo) 5068 { 5069 5070 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5071 BO_LOCK(bo); 5072 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5073 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5074 bo->bo_flag &= ~BO_WWAIT; 5075 wakeup(&bo->bo_numoutput); 5076 } 5077 BO_UNLOCK(bo); 5078 } 5079 5080 int 5081 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5082 { 5083 int error; 5084 5085 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5086 ASSERT_BO_WLOCKED(bo); 5087 error = 0; 5088 while (bo->bo_numoutput) { 5089 bo->bo_flag |= BO_WWAIT; 5090 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5091 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5092 if (error) 5093 break; 5094 } 5095 return (error); 5096 } 5097 5098 /* 5099 * Set bio_data or bio_ma for struct bio from the struct buf. 5100 */ 5101 void 5102 bdata2bio(struct buf *bp, struct bio *bip) 5103 { 5104 5105 if (!buf_mapped(bp)) { 5106 KASSERT(unmapped_buf_allowed, ("unmapped")); 5107 bip->bio_ma = bp->b_pages; 5108 bip->bio_ma_n = bp->b_npages; 5109 bip->bio_data = unmapped_buf; 5110 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5111 bip->bio_flags |= BIO_UNMAPPED; 5112 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5113 PAGE_SIZE == bp->b_npages, 5114 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5115 (long long)bip->bio_length, bip->bio_ma_n)); 5116 } else { 5117 bip->bio_data = bp->b_data; 5118 bip->bio_ma = NULL; 5119 } 5120 } 5121 5122 /* 5123 * The MIPS pmap code currently doesn't handle aliased pages. 5124 * The VIPT caches may not handle page aliasing themselves, leading 5125 * to data corruption. 5126 * 5127 * As such, this code makes a system extremely unhappy if said 5128 * system doesn't support unaliasing the above situation in hardware. 5129 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 5130 * this feature at build time, so it has to be handled in software. 5131 * 5132 * Once the MIPS pmap/cache code grows to support this function on 5133 * earlier chips, it should be flipped back off. 5134 */ 5135 #ifdef __mips__ 5136 static int buf_pager_relbuf = 1; 5137 #else 5138 static int buf_pager_relbuf = 0; 5139 #endif 5140 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5141 &buf_pager_relbuf, 0, 5142 "Make buffer pager release buffers after reading"); 5143 5144 /* 5145 * The buffer pager. It uses buffer reads to validate pages. 5146 * 5147 * In contrast to the generic local pager from vm/vnode_pager.c, this 5148 * pager correctly and easily handles volumes where the underlying 5149 * device block size is greater than the machine page size. The 5150 * buffer cache transparently extends the requested page run to be 5151 * aligned at the block boundary, and does the necessary bogus page 5152 * replacements in the addends to avoid obliterating already valid 5153 * pages. 5154 * 5155 * The only non-trivial issue is that the exclusive busy state for 5156 * pages, which is assumed by the vm_pager_getpages() interface, is 5157 * incompatible with the VMIO buffer cache's desire to share-busy the 5158 * pages. This function performs a trivial downgrade of the pages' 5159 * state before reading buffers, and a less trivial upgrade from the 5160 * shared-busy to excl-busy state after the read. 5161 */ 5162 int 5163 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5164 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5165 vbg_get_blksize_t get_blksize) 5166 { 5167 vm_page_t m; 5168 vm_object_t object; 5169 struct buf *bp; 5170 struct mount *mp; 5171 daddr_t lbn, lbnp; 5172 vm_ooffset_t la, lb, poff, poffe; 5173 long bsize; 5174 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5175 bool redo, lpart; 5176 5177 object = vp->v_object; 5178 mp = vp->v_mount; 5179 error = 0; 5180 la = IDX_TO_OFF(ma[count - 1]->pindex); 5181 if (la >= object->un_pager.vnp.vnp_size) 5182 return (VM_PAGER_BAD); 5183 5184 /* 5185 * Change the meaning of la from where the last requested page starts 5186 * to where it ends, because that's the end of the requested region 5187 * and the start of the potential read-ahead region. 5188 */ 5189 la += PAGE_SIZE; 5190 lpart = la > object->un_pager.vnp.vnp_size; 5191 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 5192 5193 /* 5194 * Calculate read-ahead, behind and total pages. 5195 */ 5196 pgsin = count; 5197 lb = IDX_TO_OFF(ma[0]->pindex); 5198 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5199 pgsin += pgsin_b; 5200 if (rbehind != NULL) 5201 *rbehind = pgsin_b; 5202 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5203 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5204 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5205 PAGE_SIZE) - la); 5206 pgsin += pgsin_a; 5207 if (rahead != NULL) 5208 *rahead = pgsin_a; 5209 VM_CNT_INC(v_vnodein); 5210 VM_CNT_ADD(v_vnodepgsin, pgsin); 5211 5212 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5213 != 0) ? GB_UNMAPPED : 0; 5214 VM_OBJECT_WLOCK(object); 5215 again: 5216 for (i = 0; i < count; i++) 5217 vm_page_busy_downgrade(ma[i]); 5218 VM_OBJECT_WUNLOCK(object); 5219 5220 lbnp = -1; 5221 for (i = 0; i < count; i++) { 5222 m = ma[i]; 5223 5224 /* 5225 * Pages are shared busy and the object lock is not 5226 * owned, which together allow for the pages' 5227 * invalidation. The racy test for validity avoids 5228 * useless creation of the buffer for the most typical 5229 * case when invalidation is not used in redo or for 5230 * parallel read. The shared->excl upgrade loop at 5231 * the end of the function catches the race in a 5232 * reliable way (protected by the object lock). 5233 */ 5234 if (m->valid == VM_PAGE_BITS_ALL) 5235 continue; 5236 5237 poff = IDX_TO_OFF(m->pindex); 5238 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5239 for (; poff < poffe; poff += bsize) { 5240 lbn = get_lblkno(vp, poff); 5241 if (lbn == lbnp) 5242 goto next_page; 5243 lbnp = lbn; 5244 5245 bsize = get_blksize(vp, lbn); 5246 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 5247 br_flags, &bp); 5248 if (error != 0) 5249 goto end_pages; 5250 if (LIST_EMPTY(&bp->b_dep)) { 5251 /* 5252 * Invalidation clears m->valid, but 5253 * may leave B_CACHE flag if the 5254 * buffer existed at the invalidation 5255 * time. In this case, recycle the 5256 * buffer to do real read on next 5257 * bread() after redo. 5258 * 5259 * Otherwise B_RELBUF is not strictly 5260 * necessary, enable to reduce buf 5261 * cache pressure. 5262 */ 5263 if (buf_pager_relbuf || 5264 m->valid != VM_PAGE_BITS_ALL) 5265 bp->b_flags |= B_RELBUF; 5266 5267 bp->b_flags &= ~B_NOCACHE; 5268 brelse(bp); 5269 } else { 5270 bqrelse(bp); 5271 } 5272 } 5273 KASSERT(1 /* racy, enable for debugging */ || 5274 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 5275 ("buf %d %p invalid", i, m)); 5276 if (i == count - 1 && lpart) { 5277 VM_OBJECT_WLOCK(object); 5278 if (m->valid != 0 && 5279 m->valid != VM_PAGE_BITS_ALL) 5280 vm_page_zero_invalid(m, TRUE); 5281 VM_OBJECT_WUNLOCK(object); 5282 } 5283 next_page:; 5284 } 5285 end_pages: 5286 5287 VM_OBJECT_WLOCK(object); 5288 redo = false; 5289 for (i = 0; i < count; i++) { 5290 vm_page_sunbusy(ma[i]); 5291 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 5292 5293 /* 5294 * Since the pages were only sbusy while neither the 5295 * buffer nor the object lock was held by us, or 5296 * reallocated while vm_page_grab() slept for busy 5297 * relinguish, they could have been invalidated. 5298 * Recheck the valid bits and re-read as needed. 5299 * 5300 * Note that the last page is made fully valid in the 5301 * read loop, and partial validity for the page at 5302 * index count - 1 could mean that the page was 5303 * invalidated or removed, so we must restart for 5304 * safety as well. 5305 */ 5306 if (ma[i]->valid != VM_PAGE_BITS_ALL) 5307 redo = true; 5308 } 5309 if (redo && error == 0) 5310 goto again; 5311 VM_OBJECT_WUNLOCK(object); 5312 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5313 } 5314 5315 #include "opt_ddb.h" 5316 #ifdef DDB 5317 #include <ddb/ddb.h> 5318 5319 /* DDB command to show buffer data */ 5320 DB_SHOW_COMMAND(buffer, db_show_buffer) 5321 { 5322 /* get args */ 5323 struct buf *bp = (struct buf *)addr; 5324 #ifdef FULL_BUF_TRACKING 5325 uint32_t i, j; 5326 #endif 5327 5328 if (!have_addr) { 5329 db_printf("usage: show buffer <addr>\n"); 5330 return; 5331 } 5332 5333 db_printf("buf at %p\n", bp); 5334 db_printf("b_flags = 0x%b, b_xflags=0x%b\n", 5335 (u_int)bp->b_flags, PRINT_BUF_FLAGS, 5336 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS); 5337 db_printf("b_vflags=0x%b b_ioflags0x%b\n", 5338 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS, 5339 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS); 5340 db_printf( 5341 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5342 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, " 5343 "b_vp = %p, b_dep = %p\n", 5344 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5345 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5346 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first); 5347 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5348 bp->b_kvabase, bp->b_kvasize); 5349 if (bp->b_npages) { 5350 int i; 5351 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5352 for (i = 0; i < bp->b_npages; i++) { 5353 vm_page_t m; 5354 m = bp->b_pages[i]; 5355 if (m != NULL) 5356 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5357 (u_long)m->pindex, 5358 (u_long)VM_PAGE_TO_PHYS(m)); 5359 else 5360 db_printf("( ??? )"); 5361 if ((i + 1) < bp->b_npages) 5362 db_printf(","); 5363 } 5364 db_printf("\n"); 5365 } 5366 BUF_LOCKPRINTINFO(bp); 5367 #if defined(FULL_BUF_TRACKING) 5368 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5369 5370 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5371 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5372 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5373 continue; 5374 db_printf(" %2u: %s\n", j, 5375 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5376 } 5377 #elif defined(BUF_TRACKING) 5378 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5379 #endif 5380 db_printf(" "); 5381 } 5382 5383 DB_SHOW_COMMAND(bufqueues, bufqueues) 5384 { 5385 struct bufdomain *bd; 5386 struct buf *bp; 5387 long total; 5388 int i, j, cnt; 5389 5390 db_printf("bqempty: %d\n", bqempty.bq_len); 5391 5392 for (i = 0; i < buf_domains; i++) { 5393 bd = &bdomain[i]; 5394 db_printf("Buf domain %d\n", i); 5395 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5396 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5397 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5398 db_printf("\n"); 5399 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5400 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5401 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5402 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5403 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5404 db_printf("\n"); 5405 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5406 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5407 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5408 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5409 db_printf("\n"); 5410 total = 0; 5411 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5412 total += bp->b_bufsize; 5413 db_printf("\tcleanq count\t%d (%ld)\n", 5414 bd->bd_cleanq->bq_len, total); 5415 total = 0; 5416 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5417 total += bp->b_bufsize; 5418 db_printf("\tdirtyq count\t%d (%ld)\n", 5419 bd->bd_dirtyq.bq_len, total); 5420 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5421 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5422 db_printf("\tCPU "); 5423 for (j = 0; j <= mp_maxid; j++) 5424 db_printf("%d, ", bd->bd_subq[j].bq_len); 5425 db_printf("\n"); 5426 cnt = 0; 5427 total = 0; 5428 for (j = 0; j < nbuf; j++) 5429 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) { 5430 cnt++; 5431 total += buf[j].b_bufsize; 5432 } 5433 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5434 cnt = 0; 5435 total = 0; 5436 for (j = 0; j < nbuf; j++) 5437 if (buf[j].b_domain == i) { 5438 cnt++; 5439 total += buf[j].b_bufsize; 5440 } 5441 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5442 } 5443 } 5444 5445 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 5446 { 5447 struct buf *bp; 5448 int i; 5449 5450 for (i = 0; i < nbuf; i++) { 5451 bp = &buf[i]; 5452 if (BUF_ISLOCKED(bp)) { 5453 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5454 db_printf("\n"); 5455 if (db_pager_quit) 5456 break; 5457 } 5458 } 5459 } 5460 5461 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5462 { 5463 struct vnode *vp; 5464 struct buf *bp; 5465 5466 if (!have_addr) { 5467 db_printf("usage: show vnodebufs <addr>\n"); 5468 return; 5469 } 5470 vp = (struct vnode *)addr; 5471 db_printf("Clean buffers:\n"); 5472 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5473 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5474 db_printf("\n"); 5475 } 5476 db_printf("Dirty buffers:\n"); 5477 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5478 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5479 db_printf("\n"); 5480 } 5481 } 5482 5483 DB_COMMAND(countfreebufs, db_coundfreebufs) 5484 { 5485 struct buf *bp; 5486 int i, used = 0, nfree = 0; 5487 5488 if (have_addr) { 5489 db_printf("usage: countfreebufs\n"); 5490 return; 5491 } 5492 5493 for (i = 0; i < nbuf; i++) { 5494 bp = &buf[i]; 5495 if (bp->b_qindex == QUEUE_EMPTY) 5496 nfree++; 5497 else 5498 used++; 5499 } 5500 5501 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5502 nfree + used); 5503 db_printf("numfreebuffers is %d\n", numfreebuffers); 5504 } 5505 #endif /* DDB */ 5506