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 struct thread *td; 2077 int i; 2078 2079 td = curthread; 2080 2081 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 2082 if (inmem(vp, *rablkno)) 2083 continue; 2084 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 2085 if ((rabp->b_flags & B_CACHE) != 0) { 2086 brelse(rabp); 2087 continue; 2088 } 2089 #ifdef RACCT 2090 if (racct_enable) { 2091 PROC_LOCK(curproc); 2092 racct_add_buf(curproc, rabp, 0); 2093 PROC_UNLOCK(curproc); 2094 } 2095 #endif /* RACCT */ 2096 td->td_ru.ru_inblock++; 2097 rabp->b_flags |= B_ASYNC; 2098 rabp->b_flags &= ~B_INVAL; 2099 if ((flags & GB_CKHASH) != 0) { 2100 rabp->b_flags |= B_CKHASH; 2101 rabp->b_ckhashcalc = ckhashfunc; 2102 } 2103 rabp->b_ioflags &= ~BIO_ERROR; 2104 rabp->b_iocmd = BIO_READ; 2105 if (rabp->b_rcred == NOCRED && cred != NOCRED) 2106 rabp->b_rcred = crhold(cred); 2107 vfs_busy_pages(rabp, 0); 2108 BUF_KERNPROC(rabp); 2109 rabp->b_iooffset = dbtob(rabp->b_blkno); 2110 bstrategy(rabp); 2111 } 2112 } 2113 2114 /* 2115 * Entry point for bread() and breadn() via #defines in sys/buf.h. 2116 * 2117 * Get a buffer with the specified data. Look in the cache first. We 2118 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 2119 * is set, the buffer is valid and we do not have to do anything, see 2120 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 2121 * 2122 * Always return a NULL buffer pointer (in bpp) when returning an error. 2123 */ 2124 int 2125 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 2126 int *rabsize, int cnt, struct ucred *cred, int flags, 2127 void (*ckhashfunc)(struct buf *), struct buf **bpp) 2128 { 2129 struct buf *bp; 2130 struct thread *td; 2131 int error, readwait, rv; 2132 2133 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 2134 td = curthread; 2135 /* 2136 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags 2137 * are specified. 2138 */ 2139 error = getblkx(vp, blkno, size, 0, 0, flags, &bp); 2140 if (error != 0) { 2141 *bpp = NULL; 2142 return (error); 2143 } 2144 flags &= ~GB_NOSPARSE; 2145 *bpp = bp; 2146 2147 /* 2148 * If not found in cache, do some I/O 2149 */ 2150 readwait = 0; 2151 if ((bp->b_flags & B_CACHE) == 0) { 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 bp->b_iocmd = BIO_READ; 2161 bp->b_flags &= ~B_INVAL; 2162 if ((flags & GB_CKHASH) != 0) { 2163 bp->b_flags |= B_CKHASH; 2164 bp->b_ckhashcalc = ckhashfunc; 2165 } 2166 bp->b_ioflags &= ~BIO_ERROR; 2167 if (bp->b_rcred == NOCRED && cred != NOCRED) 2168 bp->b_rcred = crhold(cred); 2169 vfs_busy_pages(bp, 0); 2170 bp->b_iooffset = dbtob(bp->b_blkno); 2171 bstrategy(bp); 2172 ++readwait; 2173 } 2174 2175 /* 2176 * Attempt to initiate asynchronous I/O on read-ahead blocks. 2177 */ 2178 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 2179 2180 rv = 0; 2181 if (readwait) { 2182 rv = bufwait(bp); 2183 if (rv != 0) { 2184 brelse(bp); 2185 *bpp = NULL; 2186 } 2187 } 2188 return (rv); 2189 } 2190 2191 /* 2192 * Write, release buffer on completion. (Done by iodone 2193 * if async). Do not bother writing anything if the buffer 2194 * is invalid. 2195 * 2196 * Note that we set B_CACHE here, indicating that buffer is 2197 * fully valid and thus cacheable. This is true even of NFS 2198 * now so we set it generally. This could be set either here 2199 * or in biodone() since the I/O is synchronous. We put it 2200 * here. 2201 */ 2202 int 2203 bufwrite(struct buf *bp) 2204 { 2205 int oldflags; 2206 struct vnode *vp; 2207 long space; 2208 int vp_md; 2209 2210 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2211 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 2212 bp->b_flags |= B_INVAL | B_RELBUF; 2213 bp->b_flags &= ~B_CACHE; 2214 brelse(bp); 2215 return (ENXIO); 2216 } 2217 if (bp->b_flags & B_INVAL) { 2218 brelse(bp); 2219 return (0); 2220 } 2221 2222 if (bp->b_flags & B_BARRIER) 2223 atomic_add_long(&barrierwrites, 1); 2224 2225 oldflags = bp->b_flags; 2226 2227 BUF_ASSERT_HELD(bp); 2228 2229 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 2230 ("FFS background buffer should not get here %p", bp)); 2231 2232 vp = bp->b_vp; 2233 if (vp) 2234 vp_md = vp->v_vflag & VV_MD; 2235 else 2236 vp_md = 0; 2237 2238 /* 2239 * Mark the buffer clean. Increment the bufobj write count 2240 * before bundirty() call, to prevent other thread from seeing 2241 * empty dirty list and zero counter for writes in progress, 2242 * falsely indicating that the bufobj is clean. 2243 */ 2244 bufobj_wref(bp->b_bufobj); 2245 bundirty(bp); 2246 2247 bp->b_flags &= ~B_DONE; 2248 bp->b_ioflags &= ~BIO_ERROR; 2249 bp->b_flags |= B_CACHE; 2250 bp->b_iocmd = BIO_WRITE; 2251 2252 vfs_busy_pages(bp, 1); 2253 2254 /* 2255 * Normal bwrites pipeline writes 2256 */ 2257 bp->b_runningbufspace = bp->b_bufsize; 2258 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 2259 2260 #ifdef RACCT 2261 if (racct_enable) { 2262 PROC_LOCK(curproc); 2263 racct_add_buf(curproc, bp, 1); 2264 PROC_UNLOCK(curproc); 2265 } 2266 #endif /* RACCT */ 2267 curthread->td_ru.ru_oublock++; 2268 if (oldflags & B_ASYNC) 2269 BUF_KERNPROC(bp); 2270 bp->b_iooffset = dbtob(bp->b_blkno); 2271 buf_track(bp, __func__); 2272 bstrategy(bp); 2273 2274 if ((oldflags & B_ASYNC) == 0) { 2275 int rtval = bufwait(bp); 2276 brelse(bp); 2277 return (rtval); 2278 } else if (space > hirunningspace) { 2279 /* 2280 * don't allow the async write to saturate the I/O 2281 * system. We will not deadlock here because 2282 * we are blocking waiting for I/O that is already in-progress 2283 * to complete. We do not block here if it is the update 2284 * or syncer daemon trying to clean up as that can lead 2285 * to deadlock. 2286 */ 2287 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2288 waitrunningbufspace(); 2289 } 2290 2291 return (0); 2292 } 2293 2294 void 2295 bufbdflush(struct bufobj *bo, struct buf *bp) 2296 { 2297 struct buf *nbp; 2298 2299 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 2300 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2301 altbufferflushes++; 2302 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 2303 BO_LOCK(bo); 2304 /* 2305 * Try to find a buffer to flush. 2306 */ 2307 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2308 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2309 BUF_LOCK(nbp, 2310 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2311 continue; 2312 if (bp == nbp) 2313 panic("bdwrite: found ourselves"); 2314 BO_UNLOCK(bo); 2315 /* Don't countdeps with the bo lock held. */ 2316 if (buf_countdeps(nbp, 0)) { 2317 BO_LOCK(bo); 2318 BUF_UNLOCK(nbp); 2319 continue; 2320 } 2321 if (nbp->b_flags & B_CLUSTEROK) { 2322 vfs_bio_awrite(nbp); 2323 } else { 2324 bremfree(nbp); 2325 bawrite(nbp); 2326 } 2327 dirtybufferflushes++; 2328 break; 2329 } 2330 if (nbp == NULL) 2331 BO_UNLOCK(bo); 2332 } 2333 } 2334 2335 /* 2336 * Delayed write. (Buffer is marked dirty). Do not bother writing 2337 * anything if the buffer is marked invalid. 2338 * 2339 * Note that since the buffer must be completely valid, we can safely 2340 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2341 * biodone() in order to prevent getblk from writing the buffer 2342 * out synchronously. 2343 */ 2344 void 2345 bdwrite(struct buf *bp) 2346 { 2347 struct thread *td = curthread; 2348 struct vnode *vp; 2349 struct bufobj *bo; 2350 2351 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2352 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2353 KASSERT((bp->b_flags & B_BARRIER) == 0, 2354 ("Barrier request in delayed write %p", bp)); 2355 BUF_ASSERT_HELD(bp); 2356 2357 if (bp->b_flags & B_INVAL) { 2358 brelse(bp); 2359 return; 2360 } 2361 2362 /* 2363 * If we have too many dirty buffers, don't create any more. 2364 * If we are wildly over our limit, then force a complete 2365 * cleanup. Otherwise, just keep the situation from getting 2366 * out of control. Note that we have to avoid a recursive 2367 * disaster and not try to clean up after our own cleanup! 2368 */ 2369 vp = bp->b_vp; 2370 bo = bp->b_bufobj; 2371 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2372 td->td_pflags |= TDP_INBDFLUSH; 2373 BO_BDFLUSH(bo, bp); 2374 td->td_pflags &= ~TDP_INBDFLUSH; 2375 } else 2376 recursiveflushes++; 2377 2378 bdirty(bp); 2379 /* 2380 * Set B_CACHE, indicating that the buffer is fully valid. This is 2381 * true even of NFS now. 2382 */ 2383 bp->b_flags |= B_CACHE; 2384 2385 /* 2386 * This bmap keeps the system from needing to do the bmap later, 2387 * perhaps when the system is attempting to do a sync. Since it 2388 * is likely that the indirect block -- or whatever other datastructure 2389 * that the filesystem needs is still in memory now, it is a good 2390 * thing to do this. Note also, that if the pageout daemon is 2391 * requesting a sync -- there might not be enough memory to do 2392 * the bmap then... So, this is important to do. 2393 */ 2394 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2395 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2396 } 2397 2398 buf_track(bp, __func__); 2399 2400 /* 2401 * Set the *dirty* buffer range based upon the VM system dirty 2402 * pages. 2403 * 2404 * Mark the buffer pages as clean. We need to do this here to 2405 * satisfy the vnode_pager and the pageout daemon, so that it 2406 * thinks that the pages have been "cleaned". Note that since 2407 * the pages are in a delayed write buffer -- the VFS layer 2408 * "will" see that the pages get written out on the next sync, 2409 * or perhaps the cluster will be completed. 2410 */ 2411 vfs_clean_pages_dirty_buf(bp); 2412 bqrelse(bp); 2413 2414 /* 2415 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2416 * due to the softdep code. 2417 */ 2418 } 2419 2420 /* 2421 * bdirty: 2422 * 2423 * Turn buffer into delayed write request. We must clear BIO_READ and 2424 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2425 * itself to properly update it in the dirty/clean lists. We mark it 2426 * B_DONE to ensure that any asynchronization of the buffer properly 2427 * clears B_DONE ( else a panic will occur later ). 2428 * 2429 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2430 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2431 * should only be called if the buffer is known-good. 2432 * 2433 * Since the buffer is not on a queue, we do not update the numfreebuffers 2434 * count. 2435 * 2436 * The buffer must be on QUEUE_NONE. 2437 */ 2438 void 2439 bdirty(struct buf *bp) 2440 { 2441 2442 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2443 bp, bp->b_vp, bp->b_flags); 2444 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2445 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2446 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2447 BUF_ASSERT_HELD(bp); 2448 bp->b_flags &= ~(B_RELBUF); 2449 bp->b_iocmd = BIO_WRITE; 2450 2451 if ((bp->b_flags & B_DELWRI) == 0) { 2452 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2453 reassignbuf(bp); 2454 bdirtyadd(bp); 2455 } 2456 } 2457 2458 /* 2459 * bundirty: 2460 * 2461 * Clear B_DELWRI for buffer. 2462 * 2463 * Since the buffer is not on a queue, we do not update the numfreebuffers 2464 * count. 2465 * 2466 * The buffer must be on QUEUE_NONE. 2467 */ 2468 2469 void 2470 bundirty(struct buf *bp) 2471 { 2472 2473 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2474 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2475 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2476 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2477 BUF_ASSERT_HELD(bp); 2478 2479 if (bp->b_flags & B_DELWRI) { 2480 bp->b_flags &= ~B_DELWRI; 2481 reassignbuf(bp); 2482 bdirtysub(bp); 2483 } 2484 /* 2485 * Since it is now being written, we can clear its deferred write flag. 2486 */ 2487 bp->b_flags &= ~B_DEFERRED; 2488 } 2489 2490 /* 2491 * bawrite: 2492 * 2493 * Asynchronous write. Start output on a buffer, but do not wait for 2494 * it to complete. The buffer is released when the output completes. 2495 * 2496 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2497 * B_INVAL buffers. Not us. 2498 */ 2499 void 2500 bawrite(struct buf *bp) 2501 { 2502 2503 bp->b_flags |= B_ASYNC; 2504 (void) bwrite(bp); 2505 } 2506 2507 /* 2508 * babarrierwrite: 2509 * 2510 * Asynchronous barrier write. Start output on a buffer, but do not 2511 * wait for it to complete. Place a write barrier after this write so 2512 * that this buffer and all buffers written before it are committed to 2513 * the disk before any buffers written after this write are committed 2514 * to the disk. The buffer is released when the output completes. 2515 */ 2516 void 2517 babarrierwrite(struct buf *bp) 2518 { 2519 2520 bp->b_flags |= B_ASYNC | B_BARRIER; 2521 (void) bwrite(bp); 2522 } 2523 2524 /* 2525 * bbarrierwrite: 2526 * 2527 * Synchronous barrier write. Start output on a buffer and wait for 2528 * it to complete. Place a write barrier after this write so that 2529 * this buffer and all buffers written before it are committed to 2530 * the disk before any buffers written after this write are committed 2531 * to the disk. The buffer is released when the output completes. 2532 */ 2533 int 2534 bbarrierwrite(struct buf *bp) 2535 { 2536 2537 bp->b_flags |= B_BARRIER; 2538 return (bwrite(bp)); 2539 } 2540 2541 /* 2542 * bwillwrite: 2543 * 2544 * Called prior to the locking of any vnodes when we are expecting to 2545 * write. We do not want to starve the buffer cache with too many 2546 * dirty buffers so we block here. By blocking prior to the locking 2547 * of any vnodes we attempt to avoid the situation where a locked vnode 2548 * prevents the various system daemons from flushing related buffers. 2549 */ 2550 void 2551 bwillwrite(void) 2552 { 2553 2554 if (buf_dirty_count_severe()) { 2555 mtx_lock(&bdirtylock); 2556 while (buf_dirty_count_severe()) { 2557 bdirtywait = 1; 2558 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2559 "flswai", 0); 2560 } 2561 mtx_unlock(&bdirtylock); 2562 } 2563 } 2564 2565 /* 2566 * Return true if we have too many dirty buffers. 2567 */ 2568 int 2569 buf_dirty_count_severe(void) 2570 { 2571 2572 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty)); 2573 } 2574 2575 /* 2576 * brelse: 2577 * 2578 * Release a busy buffer and, if requested, free its resources. The 2579 * buffer will be stashed in the appropriate bufqueue[] allowing it 2580 * to be accessed later as a cache entity or reused for other purposes. 2581 */ 2582 void 2583 brelse(struct buf *bp) 2584 { 2585 struct mount *v_mnt; 2586 int qindex; 2587 2588 /* 2589 * Many functions erroneously call brelse with a NULL bp under rare 2590 * error conditions. Simply return when called with a NULL bp. 2591 */ 2592 if (bp == NULL) 2593 return; 2594 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2595 bp, bp->b_vp, bp->b_flags); 2596 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2597 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2598 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2599 ("brelse: non-VMIO buffer marked NOREUSE")); 2600 2601 if (BUF_LOCKRECURSED(bp)) { 2602 /* 2603 * Do not process, in particular, do not handle the 2604 * B_INVAL/B_RELBUF and do not release to free list. 2605 */ 2606 BUF_UNLOCK(bp); 2607 return; 2608 } 2609 2610 if (bp->b_flags & B_MANAGED) { 2611 bqrelse(bp); 2612 return; 2613 } 2614 2615 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2616 BO_LOCK(bp->b_bufobj); 2617 bp->b_vflags &= ~BV_BKGRDERR; 2618 BO_UNLOCK(bp->b_bufobj); 2619 bdirty(bp); 2620 } 2621 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2622 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2623 !(bp->b_flags & B_INVAL)) { 2624 /* 2625 * Failed write, redirty. All errors except ENXIO (which 2626 * means the device is gone) are treated as being 2627 * transient. 2628 * 2629 * XXX Treating EIO as transient is not correct; the 2630 * contract with the local storage device drivers is that 2631 * they will only return EIO once the I/O is no longer 2632 * retriable. Network I/O also respects this through the 2633 * guarantees of TCP and/or the internal retries of NFS. 2634 * ENOMEM might be transient, but we also have no way of 2635 * knowing when its ok to retry/reschedule. In general, 2636 * this entire case should be made obsolete through better 2637 * error handling/recovery and resource scheduling. 2638 * 2639 * Do this also for buffers that failed with ENXIO, but have 2640 * non-empty dependencies - the soft updates code might need 2641 * to access the buffer to untangle them. 2642 * 2643 * Must clear BIO_ERROR to prevent pages from being scrapped. 2644 */ 2645 bp->b_ioflags &= ~BIO_ERROR; 2646 bdirty(bp); 2647 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2648 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2649 /* 2650 * Either a failed read I/O, or we were asked to free or not 2651 * cache the buffer, or we failed to write to a device that's 2652 * no longer present. 2653 */ 2654 bp->b_flags |= B_INVAL; 2655 if (!LIST_EMPTY(&bp->b_dep)) 2656 buf_deallocate(bp); 2657 if (bp->b_flags & B_DELWRI) 2658 bdirtysub(bp); 2659 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2660 if ((bp->b_flags & B_VMIO) == 0) { 2661 allocbuf(bp, 0); 2662 if (bp->b_vp) 2663 brelvp(bp); 2664 } 2665 } 2666 2667 /* 2668 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2669 * is called with B_DELWRI set, the underlying pages may wind up 2670 * getting freed causing a previous write (bdwrite()) to get 'lost' 2671 * because pages associated with a B_DELWRI bp are marked clean. 2672 * 2673 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2674 * if B_DELWRI is set. 2675 */ 2676 if (bp->b_flags & B_DELWRI) 2677 bp->b_flags &= ~B_RELBUF; 2678 2679 /* 2680 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2681 * constituted, not even NFS buffers now. Two flags effect this. If 2682 * B_INVAL, the struct buf is invalidated but the VM object is kept 2683 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2684 * 2685 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2686 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2687 * buffer is also B_INVAL because it hits the re-dirtying code above. 2688 * 2689 * Normally we can do this whether a buffer is B_DELWRI or not. If 2690 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2691 * the commit state and we cannot afford to lose the buffer. If the 2692 * buffer has a background write in progress, we need to keep it 2693 * around to prevent it from being reconstituted and starting a second 2694 * background write. 2695 */ 2696 2697 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL; 2698 2699 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2700 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2701 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 || 2702 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) { 2703 vfs_vmio_invalidate(bp); 2704 allocbuf(bp, 0); 2705 } 2706 2707 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2708 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2709 allocbuf(bp, 0); 2710 bp->b_flags &= ~B_NOREUSE; 2711 if (bp->b_vp != NULL) 2712 brelvp(bp); 2713 } 2714 2715 /* 2716 * If the buffer has junk contents signal it and eventually 2717 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2718 * doesn't find it. 2719 */ 2720 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2721 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2722 bp->b_flags |= B_INVAL; 2723 if (bp->b_flags & B_INVAL) { 2724 if (bp->b_flags & B_DELWRI) 2725 bundirty(bp); 2726 if (bp->b_vp) 2727 brelvp(bp); 2728 } 2729 2730 buf_track(bp, __func__); 2731 2732 /* buffers with no memory */ 2733 if (bp->b_bufsize == 0) { 2734 buf_free(bp); 2735 return; 2736 } 2737 /* buffers with junk contents */ 2738 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2739 (bp->b_ioflags & BIO_ERROR)) { 2740 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2741 if (bp->b_vflags & BV_BKGRDINPROG) 2742 panic("losing buffer 2"); 2743 qindex = QUEUE_CLEAN; 2744 bp->b_flags |= B_AGE; 2745 /* remaining buffers */ 2746 } else if (bp->b_flags & B_DELWRI) 2747 qindex = QUEUE_DIRTY; 2748 else 2749 qindex = QUEUE_CLEAN; 2750 2751 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2752 panic("brelse: not dirty"); 2753 2754 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT); 2755 /* binsfree unlocks bp. */ 2756 binsfree(bp, qindex); 2757 } 2758 2759 /* 2760 * Release a buffer back to the appropriate queue but do not try to free 2761 * it. The buffer is expected to be used again soon. 2762 * 2763 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2764 * biodone() to requeue an async I/O on completion. It is also used when 2765 * known good buffers need to be requeued but we think we may need the data 2766 * again soon. 2767 * 2768 * XXX we should be able to leave the B_RELBUF hint set on completion. 2769 */ 2770 void 2771 bqrelse(struct buf *bp) 2772 { 2773 int qindex; 2774 2775 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2776 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2777 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2778 2779 qindex = QUEUE_NONE; 2780 if (BUF_LOCKRECURSED(bp)) { 2781 /* do not release to free list */ 2782 BUF_UNLOCK(bp); 2783 return; 2784 } 2785 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2786 2787 if (bp->b_flags & B_MANAGED) { 2788 if (bp->b_flags & B_REMFREE) 2789 bremfreef(bp); 2790 goto out; 2791 } 2792 2793 /* buffers with stale but valid contents */ 2794 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2795 BV_BKGRDERR)) == BV_BKGRDERR) { 2796 BO_LOCK(bp->b_bufobj); 2797 bp->b_vflags &= ~BV_BKGRDERR; 2798 BO_UNLOCK(bp->b_bufobj); 2799 qindex = QUEUE_DIRTY; 2800 } else { 2801 if ((bp->b_flags & B_DELWRI) == 0 && 2802 (bp->b_xflags & BX_VNDIRTY)) 2803 panic("bqrelse: not dirty"); 2804 if ((bp->b_flags & B_NOREUSE) != 0) { 2805 brelse(bp); 2806 return; 2807 } 2808 qindex = QUEUE_CLEAN; 2809 } 2810 buf_track(bp, __func__); 2811 /* binsfree unlocks bp. */ 2812 binsfree(bp, qindex); 2813 return; 2814 2815 out: 2816 buf_track(bp, __func__); 2817 /* unlock */ 2818 BUF_UNLOCK(bp); 2819 } 2820 2821 /* 2822 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2823 * restore bogus pages. 2824 */ 2825 static void 2826 vfs_vmio_iodone(struct buf *bp) 2827 { 2828 vm_ooffset_t foff; 2829 vm_page_t m; 2830 vm_object_t obj; 2831 struct vnode *vp __unused; 2832 int i, iosize, resid; 2833 bool bogus; 2834 2835 obj = bp->b_bufobj->bo_object; 2836 KASSERT(obj->paging_in_progress >= bp->b_npages, 2837 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2838 obj->paging_in_progress, bp->b_npages)); 2839 2840 vp = bp->b_vp; 2841 KASSERT(vp->v_holdcnt > 0, 2842 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2843 KASSERT(vp->v_object != NULL, 2844 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2845 2846 foff = bp->b_offset; 2847 KASSERT(bp->b_offset != NOOFFSET, 2848 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2849 2850 bogus = false; 2851 iosize = bp->b_bcount - bp->b_resid; 2852 VM_OBJECT_WLOCK(obj); 2853 for (i = 0; i < bp->b_npages; i++) { 2854 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2855 if (resid > iosize) 2856 resid = iosize; 2857 2858 /* 2859 * cleanup bogus pages, restoring the originals 2860 */ 2861 m = bp->b_pages[i]; 2862 if (m == bogus_page) { 2863 bogus = true; 2864 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2865 if (m == NULL) 2866 panic("biodone: page disappeared!"); 2867 bp->b_pages[i] = m; 2868 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2869 /* 2870 * In the write case, the valid and clean bits are 2871 * already changed correctly ( see bdwrite() ), so we 2872 * only need to do this here in the read case. 2873 */ 2874 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2875 resid)) == 0, ("vfs_vmio_iodone: page %p " 2876 "has unexpected dirty bits", m)); 2877 vfs_page_set_valid(bp, foff, m); 2878 } 2879 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2880 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2881 (intmax_t)foff, (uintmax_t)m->pindex)); 2882 2883 vm_page_sunbusy(m); 2884 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2885 iosize -= resid; 2886 } 2887 vm_object_pip_wakeupn(obj, bp->b_npages); 2888 VM_OBJECT_WUNLOCK(obj); 2889 if (bogus && buf_mapped(bp)) { 2890 BUF_CHECK_MAPPED(bp); 2891 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2892 bp->b_pages, bp->b_npages); 2893 } 2894 } 2895 2896 /* 2897 * Unwire a page held by a buf and either free it or update the page queues to 2898 * reflect its recent use. 2899 */ 2900 static void 2901 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2902 { 2903 bool freed; 2904 2905 vm_page_lock(m); 2906 if (vm_page_unwire_noq(m)) { 2907 if ((bp->b_flags & B_DIRECT) != 0) 2908 freed = vm_page_try_to_free(m); 2909 else 2910 freed = false; 2911 if (!freed) { 2912 /* 2913 * Use a racy check of the valid bits to determine 2914 * whether we can accelerate reclamation of the page. 2915 * The valid bits will be stable unless the page is 2916 * being mapped or is referenced by multiple buffers, 2917 * and in those cases we expect races to be rare. At 2918 * worst we will either accelerate reclamation of a 2919 * valid page and violate LRU, or unnecessarily defer 2920 * reclamation of an invalid page. 2921 * 2922 * The B_NOREUSE flag marks data that is not expected to 2923 * be reused, so accelerate reclamation in that case 2924 * too. Otherwise, maintain LRU. 2925 */ 2926 if (m->valid == 0 || (bp->b_flags & B_NOREUSE) != 0) 2927 vm_page_deactivate_noreuse(m); 2928 else if (vm_page_active(m)) 2929 vm_page_reference(m); 2930 else 2931 vm_page_deactivate(m); 2932 } 2933 } 2934 vm_page_unlock(m); 2935 } 2936 2937 /* 2938 * Perform page invalidation when a buffer is released. The fully invalid 2939 * pages will be reclaimed later in vfs_vmio_truncate(). 2940 */ 2941 static void 2942 vfs_vmio_invalidate(struct buf *bp) 2943 { 2944 vm_object_t obj; 2945 vm_page_t m; 2946 int i, resid, poffset, presid; 2947 2948 if (buf_mapped(bp)) { 2949 BUF_CHECK_MAPPED(bp); 2950 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2951 } else 2952 BUF_CHECK_UNMAPPED(bp); 2953 /* 2954 * Get the base offset and length of the buffer. Note that 2955 * in the VMIO case if the buffer block size is not 2956 * page-aligned then b_data pointer may not be page-aligned. 2957 * But our b_pages[] array *IS* page aligned. 2958 * 2959 * block sizes less then DEV_BSIZE (usually 512) are not 2960 * supported due to the page granularity bits (m->valid, 2961 * m->dirty, etc...). 2962 * 2963 * See man buf(9) for more information 2964 */ 2965 obj = bp->b_bufobj->bo_object; 2966 resid = bp->b_bufsize; 2967 poffset = bp->b_offset & PAGE_MASK; 2968 VM_OBJECT_WLOCK(obj); 2969 for (i = 0; i < bp->b_npages; i++) { 2970 m = bp->b_pages[i]; 2971 if (m == bogus_page) 2972 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2973 bp->b_pages[i] = NULL; 2974 2975 presid = resid > (PAGE_SIZE - poffset) ? 2976 (PAGE_SIZE - poffset) : resid; 2977 KASSERT(presid >= 0, ("brelse: extra page")); 2978 while (vm_page_xbusied(m)) { 2979 vm_page_lock(m); 2980 VM_OBJECT_WUNLOCK(obj); 2981 vm_page_busy_sleep(m, "mbncsh", true); 2982 VM_OBJECT_WLOCK(obj); 2983 } 2984 if (pmap_page_wired_mappings(m) == 0) 2985 vm_page_set_invalid(m, poffset, presid); 2986 vfs_vmio_unwire(bp, m); 2987 resid -= presid; 2988 poffset = 0; 2989 } 2990 VM_OBJECT_WUNLOCK(obj); 2991 bp->b_npages = 0; 2992 } 2993 2994 /* 2995 * Page-granular truncation of an existing VMIO buffer. 2996 */ 2997 static void 2998 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2999 { 3000 vm_object_t obj; 3001 vm_page_t m; 3002 int i; 3003 3004 if (bp->b_npages == desiredpages) 3005 return; 3006 3007 if (buf_mapped(bp)) { 3008 BUF_CHECK_MAPPED(bp); 3009 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 3010 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 3011 } else 3012 BUF_CHECK_UNMAPPED(bp); 3013 3014 /* 3015 * The object lock is needed only if we will attempt to free pages. 3016 */ 3017 obj = (bp->b_flags & B_DIRECT) != 0 ? bp->b_bufobj->bo_object : NULL; 3018 if (obj != NULL) 3019 VM_OBJECT_WLOCK(obj); 3020 for (i = desiredpages; i < bp->b_npages; i++) { 3021 m = bp->b_pages[i]; 3022 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3023 bp->b_pages[i] = NULL; 3024 vfs_vmio_unwire(bp, m); 3025 } 3026 if (obj != NULL) 3027 VM_OBJECT_WUNLOCK(obj); 3028 bp->b_npages = desiredpages; 3029 } 3030 3031 /* 3032 * Byte granular extension of VMIO buffers. 3033 */ 3034 static void 3035 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3036 { 3037 /* 3038 * We are growing the buffer, possibly in a 3039 * byte-granular fashion. 3040 */ 3041 vm_object_t obj; 3042 vm_offset_t toff; 3043 vm_offset_t tinc; 3044 vm_page_t m; 3045 3046 /* 3047 * Step 1, bring in the VM pages from the object, allocating 3048 * them if necessary. We must clear B_CACHE if these pages 3049 * are not valid for the range covered by the buffer. 3050 */ 3051 obj = bp->b_bufobj->bo_object; 3052 VM_OBJECT_WLOCK(obj); 3053 if (bp->b_npages < desiredpages) { 3054 /* 3055 * We must allocate system pages since blocking 3056 * here could interfere with paging I/O, no 3057 * matter which process we are. 3058 * 3059 * Only exclusive busy can be tested here. 3060 * Blocking on shared busy might lead to 3061 * deadlocks once allocbuf() is called after 3062 * pages are vfs_busy_pages(). 3063 */ 3064 (void)vm_page_grab_pages(obj, 3065 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3066 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3067 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3068 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3069 bp->b_npages = desiredpages; 3070 } 3071 3072 /* 3073 * Step 2. We've loaded the pages into the buffer, 3074 * we have to figure out if we can still have B_CACHE 3075 * set. Note that B_CACHE is set according to the 3076 * byte-granular range ( bcount and size ), not the 3077 * aligned range ( newbsize ). 3078 * 3079 * The VM test is against m->valid, which is DEV_BSIZE 3080 * aligned. Needless to say, the validity of the data 3081 * needs to also be DEV_BSIZE aligned. Note that this 3082 * fails with NFS if the server or some other client 3083 * extends the file's EOF. If our buffer is resized, 3084 * B_CACHE may remain set! XXX 3085 */ 3086 toff = bp->b_bcount; 3087 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3088 while ((bp->b_flags & B_CACHE) && toff < size) { 3089 vm_pindex_t pi; 3090 3091 if (tinc > (size - toff)) 3092 tinc = size - toff; 3093 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3094 m = bp->b_pages[pi]; 3095 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3096 toff += tinc; 3097 tinc = PAGE_SIZE; 3098 } 3099 VM_OBJECT_WUNLOCK(obj); 3100 3101 /* 3102 * Step 3, fixup the KVA pmap. 3103 */ 3104 if (buf_mapped(bp)) 3105 bpmap_qenter(bp); 3106 else 3107 BUF_CHECK_UNMAPPED(bp); 3108 } 3109 3110 /* 3111 * Check to see if a block at a particular lbn is available for a clustered 3112 * write. 3113 */ 3114 static int 3115 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3116 { 3117 struct buf *bpa; 3118 int match; 3119 3120 match = 0; 3121 3122 /* If the buf isn't in core skip it */ 3123 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3124 return (0); 3125 3126 /* If the buf is busy we don't want to wait for it */ 3127 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3128 return (0); 3129 3130 /* Only cluster with valid clusterable delayed write buffers */ 3131 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3132 (B_DELWRI | B_CLUSTEROK)) 3133 goto done; 3134 3135 if (bpa->b_bufsize != size) 3136 goto done; 3137 3138 /* 3139 * Check to see if it is in the expected place on disk and that the 3140 * block has been mapped. 3141 */ 3142 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3143 match = 1; 3144 done: 3145 BUF_UNLOCK(bpa); 3146 return (match); 3147 } 3148 3149 /* 3150 * vfs_bio_awrite: 3151 * 3152 * Implement clustered async writes for clearing out B_DELWRI buffers. 3153 * This is much better then the old way of writing only one buffer at 3154 * a time. Note that we may not be presented with the buffers in the 3155 * correct order, so we search for the cluster in both directions. 3156 */ 3157 int 3158 vfs_bio_awrite(struct buf *bp) 3159 { 3160 struct bufobj *bo; 3161 int i; 3162 int j; 3163 daddr_t lblkno = bp->b_lblkno; 3164 struct vnode *vp = bp->b_vp; 3165 int ncl; 3166 int nwritten; 3167 int size; 3168 int maxcl; 3169 int gbflags; 3170 3171 bo = &vp->v_bufobj; 3172 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3173 /* 3174 * right now we support clustered writing only to regular files. If 3175 * we find a clusterable block we could be in the middle of a cluster 3176 * rather then at the beginning. 3177 */ 3178 if ((vp->v_type == VREG) && 3179 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3180 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3181 3182 size = vp->v_mount->mnt_stat.f_iosize; 3183 maxcl = MAXPHYS / size; 3184 3185 BO_RLOCK(bo); 3186 for (i = 1; i < maxcl; i++) 3187 if (vfs_bio_clcheck(vp, size, lblkno + i, 3188 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3189 break; 3190 3191 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3192 if (vfs_bio_clcheck(vp, size, lblkno - j, 3193 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3194 break; 3195 BO_RUNLOCK(bo); 3196 --j; 3197 ncl = i + j; 3198 /* 3199 * this is a possible cluster write 3200 */ 3201 if (ncl != 1) { 3202 BUF_UNLOCK(bp); 3203 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3204 gbflags); 3205 return (nwritten); 3206 } 3207 } 3208 bremfree(bp); 3209 bp->b_flags |= B_ASYNC; 3210 /* 3211 * default (old) behavior, writing out only one block 3212 * 3213 * XXX returns b_bufsize instead of b_bcount for nwritten? 3214 */ 3215 nwritten = bp->b_bufsize; 3216 (void) bwrite(bp); 3217 3218 return (nwritten); 3219 } 3220 3221 /* 3222 * getnewbuf_kva: 3223 * 3224 * Allocate KVA for an empty buf header according to gbflags. 3225 */ 3226 static int 3227 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3228 { 3229 3230 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3231 /* 3232 * In order to keep fragmentation sane we only allocate kva 3233 * in BKVASIZE chunks. XXX with vmem we can do page size. 3234 */ 3235 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3236 3237 if (maxsize != bp->b_kvasize && 3238 bufkva_alloc(bp, maxsize, gbflags)) 3239 return (ENOSPC); 3240 } 3241 return (0); 3242 } 3243 3244 /* 3245 * getnewbuf: 3246 * 3247 * Find and initialize a new buffer header, freeing up existing buffers 3248 * in the bufqueues as necessary. The new buffer is returned locked. 3249 * 3250 * We block if: 3251 * We have insufficient buffer headers 3252 * We have insufficient buffer space 3253 * buffer_arena is too fragmented ( space reservation fails ) 3254 * If we have to flush dirty buffers ( but we try to avoid this ) 3255 * 3256 * The caller is responsible for releasing the reserved bufspace after 3257 * allocbuf() is called. 3258 */ 3259 static struct buf * 3260 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3261 { 3262 struct bufdomain *bd; 3263 struct buf *bp; 3264 bool metadata, reserved; 3265 3266 bp = NULL; 3267 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3268 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3269 if (!unmapped_buf_allowed) 3270 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3271 3272 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3273 vp->v_type == VCHR) 3274 metadata = true; 3275 else 3276 metadata = false; 3277 if (vp == NULL) 3278 bd = &bdomain[0]; 3279 else 3280 bd = &bdomain[vp->v_bufobj.bo_domain]; 3281 3282 counter_u64_add(getnewbufcalls, 1); 3283 reserved = false; 3284 do { 3285 if (reserved == false && 3286 bufspace_reserve(bd, maxsize, metadata) != 0) { 3287 counter_u64_add(getnewbufrestarts, 1); 3288 continue; 3289 } 3290 reserved = true; 3291 if ((bp = buf_alloc(bd)) == NULL) { 3292 counter_u64_add(getnewbufrestarts, 1); 3293 continue; 3294 } 3295 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3296 return (bp); 3297 break; 3298 } while (buf_recycle(bd, false) == 0); 3299 3300 if (reserved) 3301 bufspace_release(bd, maxsize); 3302 if (bp != NULL) { 3303 bp->b_flags |= B_INVAL; 3304 brelse(bp); 3305 } 3306 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3307 3308 return (NULL); 3309 } 3310 3311 /* 3312 * buf_daemon: 3313 * 3314 * buffer flushing daemon. Buffers are normally flushed by the 3315 * update daemon but if it cannot keep up this process starts to 3316 * take the load in an attempt to prevent getnewbuf() from blocking. 3317 */ 3318 static struct kproc_desc buf_kp = { 3319 "bufdaemon", 3320 buf_daemon, 3321 &bufdaemonproc 3322 }; 3323 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3324 3325 static int 3326 buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3327 { 3328 int flushed; 3329 3330 flushed = flushbufqueues(vp, bd, target, 0); 3331 if (flushed == 0) { 3332 /* 3333 * Could not find any buffers without rollback 3334 * dependencies, so just write the first one 3335 * in the hopes of eventually making progress. 3336 */ 3337 if (vp != NULL && target > 2) 3338 target /= 2; 3339 flushbufqueues(vp, bd, target, 1); 3340 } 3341 return (flushed); 3342 } 3343 3344 static void 3345 buf_daemon() 3346 { 3347 struct bufdomain *bd; 3348 int speedupreq; 3349 int lodirty; 3350 int i; 3351 3352 /* 3353 * This process needs to be suspended prior to shutdown sync. 3354 */ 3355 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 3356 SHUTDOWN_PRI_LAST + 100); 3357 3358 /* 3359 * Start the buf clean daemons as children threads. 3360 */ 3361 for (i = 0 ; i < buf_domains; i++) { 3362 int error; 3363 3364 error = kthread_add((void (*)(void *))bufspace_daemon, 3365 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3366 if (error) 3367 panic("error %d spawning bufspace daemon", error); 3368 } 3369 3370 /* 3371 * This process is allowed to take the buffer cache to the limit 3372 */ 3373 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3374 mtx_lock(&bdlock); 3375 for (;;) { 3376 bd_request = 0; 3377 mtx_unlock(&bdlock); 3378 3379 kthread_suspend_check(); 3380 3381 /* 3382 * Save speedupreq for this pass and reset to capture new 3383 * requests. 3384 */ 3385 speedupreq = bd_speedupreq; 3386 bd_speedupreq = 0; 3387 3388 /* 3389 * Flush each domain sequentially according to its level and 3390 * the speedup request. 3391 */ 3392 for (i = 0; i < buf_domains; i++) { 3393 bd = &bdomain[i]; 3394 if (speedupreq) 3395 lodirty = bd->bd_numdirtybuffers / 2; 3396 else 3397 lodirty = bd->bd_lodirtybuffers; 3398 while (bd->bd_numdirtybuffers > lodirty) { 3399 if (buf_flush(NULL, bd, 3400 bd->bd_numdirtybuffers - lodirty) == 0) 3401 break; 3402 kern_yield(PRI_USER); 3403 } 3404 } 3405 3406 /* 3407 * Only clear bd_request if we have reached our low water 3408 * mark. The buf_daemon normally waits 1 second and 3409 * then incrementally flushes any dirty buffers that have 3410 * built up, within reason. 3411 * 3412 * If we were unable to hit our low water mark and couldn't 3413 * find any flushable buffers, we sleep for a short period 3414 * to avoid endless loops on unlockable buffers. 3415 */ 3416 mtx_lock(&bdlock); 3417 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3418 /* 3419 * We reached our low water mark, reset the 3420 * request and sleep until we are needed again. 3421 * The sleep is just so the suspend code works. 3422 */ 3423 bd_request = 0; 3424 /* 3425 * Do an extra wakeup in case dirty threshold 3426 * changed via sysctl and the explicit transition 3427 * out of shortfall was missed. 3428 */ 3429 bdirtywakeup(); 3430 if (runningbufspace <= lorunningspace) 3431 runningwakeup(); 3432 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3433 } else { 3434 /* 3435 * We couldn't find any flushable dirty buffers but 3436 * still have too many dirty buffers, we 3437 * have to sleep and try again. (rare) 3438 */ 3439 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3440 } 3441 } 3442 } 3443 3444 /* 3445 * flushbufqueues: 3446 * 3447 * Try to flush a buffer in the dirty queue. We must be careful to 3448 * free up B_INVAL buffers instead of write them, which NFS is 3449 * particularly sensitive to. 3450 */ 3451 static int flushwithdeps = 0; 3452 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3453 0, "Number of buffers flushed with dependecies that require rollbacks"); 3454 3455 static int 3456 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3457 int flushdeps) 3458 { 3459 struct bufqueue *bq; 3460 struct buf *sentinel; 3461 struct vnode *vp; 3462 struct mount *mp; 3463 struct buf *bp; 3464 int hasdeps; 3465 int flushed; 3466 int error; 3467 bool unlock; 3468 3469 flushed = 0; 3470 bq = &bd->bd_dirtyq; 3471 bp = NULL; 3472 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3473 sentinel->b_qindex = QUEUE_SENTINEL; 3474 BQ_LOCK(bq); 3475 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3476 BQ_UNLOCK(bq); 3477 while (flushed != target) { 3478 maybe_yield(); 3479 BQ_LOCK(bq); 3480 bp = TAILQ_NEXT(sentinel, b_freelist); 3481 if (bp != NULL) { 3482 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3483 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3484 b_freelist); 3485 } else { 3486 BQ_UNLOCK(bq); 3487 break; 3488 } 3489 /* 3490 * Skip sentinels inserted by other invocations of the 3491 * flushbufqueues(), taking care to not reorder them. 3492 * 3493 * Only flush the buffers that belong to the 3494 * vnode locked by the curthread. 3495 */ 3496 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3497 bp->b_vp != lvp)) { 3498 BQ_UNLOCK(bq); 3499 continue; 3500 } 3501 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3502 BQ_UNLOCK(bq); 3503 if (error != 0) 3504 continue; 3505 3506 /* 3507 * BKGRDINPROG can only be set with the buf and bufobj 3508 * locks both held. We tolerate a race to clear it here. 3509 */ 3510 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3511 (bp->b_flags & B_DELWRI) == 0) { 3512 BUF_UNLOCK(bp); 3513 continue; 3514 } 3515 if (bp->b_flags & B_INVAL) { 3516 bremfreef(bp); 3517 brelse(bp); 3518 flushed++; 3519 continue; 3520 } 3521 3522 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3523 if (flushdeps == 0) { 3524 BUF_UNLOCK(bp); 3525 continue; 3526 } 3527 hasdeps = 1; 3528 } else 3529 hasdeps = 0; 3530 /* 3531 * We must hold the lock on a vnode before writing 3532 * one of its buffers. Otherwise we may confuse, or 3533 * in the case of a snapshot vnode, deadlock the 3534 * system. 3535 * 3536 * The lock order here is the reverse of the normal 3537 * of vnode followed by buf lock. This is ok because 3538 * the NOWAIT will prevent deadlock. 3539 */ 3540 vp = bp->b_vp; 3541 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3542 BUF_UNLOCK(bp); 3543 continue; 3544 } 3545 if (lvp == NULL) { 3546 unlock = true; 3547 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3548 } else { 3549 ASSERT_VOP_LOCKED(vp, "getbuf"); 3550 unlock = false; 3551 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3552 vn_lock(vp, LK_TRYUPGRADE); 3553 } 3554 if (error == 0) { 3555 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3556 bp, bp->b_vp, bp->b_flags); 3557 if (curproc == bufdaemonproc) { 3558 vfs_bio_awrite(bp); 3559 } else { 3560 bremfree(bp); 3561 bwrite(bp); 3562 counter_u64_add(notbufdflushes, 1); 3563 } 3564 vn_finished_write(mp); 3565 if (unlock) 3566 VOP_UNLOCK(vp, 0); 3567 flushwithdeps += hasdeps; 3568 flushed++; 3569 3570 /* 3571 * Sleeping on runningbufspace while holding 3572 * vnode lock leads to deadlock. 3573 */ 3574 if (curproc == bufdaemonproc && 3575 runningbufspace > hirunningspace) 3576 waitrunningbufspace(); 3577 continue; 3578 } 3579 vn_finished_write(mp); 3580 BUF_UNLOCK(bp); 3581 } 3582 BQ_LOCK(bq); 3583 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3584 BQ_UNLOCK(bq); 3585 free(sentinel, M_TEMP); 3586 return (flushed); 3587 } 3588 3589 /* 3590 * Check to see if a block is currently memory resident. 3591 */ 3592 struct buf * 3593 incore(struct bufobj *bo, daddr_t blkno) 3594 { 3595 struct buf *bp; 3596 3597 BO_RLOCK(bo); 3598 bp = gbincore(bo, blkno); 3599 BO_RUNLOCK(bo); 3600 return (bp); 3601 } 3602 3603 /* 3604 * Returns true if no I/O is needed to access the 3605 * associated VM object. This is like incore except 3606 * it also hunts around in the VM system for the data. 3607 */ 3608 3609 static int 3610 inmem(struct vnode * vp, daddr_t blkno) 3611 { 3612 vm_object_t obj; 3613 vm_offset_t toff, tinc, size; 3614 vm_page_t m; 3615 vm_ooffset_t off; 3616 3617 ASSERT_VOP_LOCKED(vp, "inmem"); 3618 3619 if (incore(&vp->v_bufobj, blkno)) 3620 return 1; 3621 if (vp->v_mount == NULL) 3622 return 0; 3623 obj = vp->v_object; 3624 if (obj == NULL) 3625 return (0); 3626 3627 size = PAGE_SIZE; 3628 if (size > vp->v_mount->mnt_stat.f_iosize) 3629 size = vp->v_mount->mnt_stat.f_iosize; 3630 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3631 3632 VM_OBJECT_RLOCK(obj); 3633 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3634 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3635 if (!m) 3636 goto notinmem; 3637 tinc = size; 3638 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3639 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3640 if (vm_page_is_valid(m, 3641 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3642 goto notinmem; 3643 } 3644 VM_OBJECT_RUNLOCK(obj); 3645 return 1; 3646 3647 notinmem: 3648 VM_OBJECT_RUNLOCK(obj); 3649 return (0); 3650 } 3651 3652 /* 3653 * Set the dirty range for a buffer based on the status of the dirty 3654 * bits in the pages comprising the buffer. The range is limited 3655 * to the size of the buffer. 3656 * 3657 * Tell the VM system that the pages associated with this buffer 3658 * are clean. This is used for delayed writes where the data is 3659 * going to go to disk eventually without additional VM intevention. 3660 * 3661 * Note that while we only really need to clean through to b_bcount, we 3662 * just go ahead and clean through to b_bufsize. 3663 */ 3664 static void 3665 vfs_clean_pages_dirty_buf(struct buf *bp) 3666 { 3667 vm_ooffset_t foff, noff, eoff; 3668 vm_page_t m; 3669 int i; 3670 3671 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3672 return; 3673 3674 foff = bp->b_offset; 3675 KASSERT(bp->b_offset != NOOFFSET, 3676 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3677 3678 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3679 vfs_drain_busy_pages(bp); 3680 vfs_setdirty_locked_object(bp); 3681 for (i = 0; i < bp->b_npages; i++) { 3682 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3683 eoff = noff; 3684 if (eoff > bp->b_offset + bp->b_bufsize) 3685 eoff = bp->b_offset + bp->b_bufsize; 3686 m = bp->b_pages[i]; 3687 vfs_page_set_validclean(bp, foff, m); 3688 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3689 foff = noff; 3690 } 3691 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3692 } 3693 3694 static void 3695 vfs_setdirty_locked_object(struct buf *bp) 3696 { 3697 vm_object_t object; 3698 int i; 3699 3700 object = bp->b_bufobj->bo_object; 3701 VM_OBJECT_ASSERT_WLOCKED(object); 3702 3703 /* 3704 * We qualify the scan for modified pages on whether the 3705 * object has been flushed yet. 3706 */ 3707 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3708 vm_offset_t boffset; 3709 vm_offset_t eoffset; 3710 3711 /* 3712 * test the pages to see if they have been modified directly 3713 * by users through the VM system. 3714 */ 3715 for (i = 0; i < bp->b_npages; i++) 3716 vm_page_test_dirty(bp->b_pages[i]); 3717 3718 /* 3719 * Calculate the encompassing dirty range, boffset and eoffset, 3720 * (eoffset - boffset) bytes. 3721 */ 3722 3723 for (i = 0; i < bp->b_npages; i++) { 3724 if (bp->b_pages[i]->dirty) 3725 break; 3726 } 3727 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3728 3729 for (i = bp->b_npages - 1; i >= 0; --i) { 3730 if (bp->b_pages[i]->dirty) { 3731 break; 3732 } 3733 } 3734 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3735 3736 /* 3737 * Fit it to the buffer. 3738 */ 3739 3740 if (eoffset > bp->b_bcount) 3741 eoffset = bp->b_bcount; 3742 3743 /* 3744 * If we have a good dirty range, merge with the existing 3745 * dirty range. 3746 */ 3747 3748 if (boffset < eoffset) { 3749 if (bp->b_dirtyoff > boffset) 3750 bp->b_dirtyoff = boffset; 3751 if (bp->b_dirtyend < eoffset) 3752 bp->b_dirtyend = eoffset; 3753 } 3754 } 3755 } 3756 3757 /* 3758 * Allocate the KVA mapping for an existing buffer. 3759 * If an unmapped buffer is provided but a mapped buffer is requested, take 3760 * also care to properly setup mappings between pages and KVA. 3761 */ 3762 static void 3763 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3764 { 3765 int bsize, maxsize, need_mapping, need_kva; 3766 off_t offset; 3767 3768 need_mapping = bp->b_data == unmapped_buf && 3769 (gbflags & GB_UNMAPPED) == 0; 3770 need_kva = bp->b_kvabase == unmapped_buf && 3771 bp->b_data == unmapped_buf && 3772 (gbflags & GB_KVAALLOC) != 0; 3773 if (!need_mapping && !need_kva) 3774 return; 3775 3776 BUF_CHECK_UNMAPPED(bp); 3777 3778 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3779 /* 3780 * Buffer is not mapped, but the KVA was already 3781 * reserved at the time of the instantiation. Use the 3782 * allocated space. 3783 */ 3784 goto has_addr; 3785 } 3786 3787 /* 3788 * Calculate the amount of the address space we would reserve 3789 * if the buffer was mapped. 3790 */ 3791 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3792 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3793 offset = blkno * bsize; 3794 maxsize = size + (offset & PAGE_MASK); 3795 maxsize = imax(maxsize, bsize); 3796 3797 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3798 if ((gbflags & GB_NOWAIT_BD) != 0) { 3799 /* 3800 * XXXKIB: defragmentation cannot 3801 * succeed, not sure what else to do. 3802 */ 3803 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3804 } 3805 counter_u64_add(mappingrestarts, 1); 3806 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3807 } 3808 has_addr: 3809 if (need_mapping) { 3810 /* b_offset is handled by bpmap_qenter. */ 3811 bp->b_data = bp->b_kvabase; 3812 BUF_CHECK_MAPPED(bp); 3813 bpmap_qenter(bp); 3814 } 3815 } 3816 3817 struct buf * 3818 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3819 int flags) 3820 { 3821 struct buf *bp; 3822 int error; 3823 3824 error = getblkx(vp, blkno, size, slpflag, slptimeo, flags, &bp); 3825 if (error != 0) 3826 return (NULL); 3827 return (bp); 3828 } 3829 3830 /* 3831 * getblkx: 3832 * 3833 * Get a block given a specified block and offset into a file/device. 3834 * The buffers B_DONE bit will be cleared on return, making it almost 3835 * ready for an I/O initiation. B_INVAL may or may not be set on 3836 * return. The caller should clear B_INVAL prior to initiating a 3837 * READ. 3838 * 3839 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3840 * an existing buffer. 3841 * 3842 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3843 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3844 * and then cleared based on the backing VM. If the previous buffer is 3845 * non-0-sized but invalid, B_CACHE will be cleared. 3846 * 3847 * If getblk() must create a new buffer, the new buffer is returned with 3848 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3849 * case it is returned with B_INVAL clear and B_CACHE set based on the 3850 * backing VM. 3851 * 3852 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3853 * B_CACHE bit is clear. 3854 * 3855 * What this means, basically, is that the caller should use B_CACHE to 3856 * determine whether the buffer is fully valid or not and should clear 3857 * B_INVAL prior to issuing a read. If the caller intends to validate 3858 * the buffer by loading its data area with something, the caller needs 3859 * to clear B_INVAL. If the caller does this without issuing an I/O, 3860 * the caller should set B_CACHE ( as an optimization ), else the caller 3861 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3862 * a write attempt or if it was a successful read. If the caller 3863 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3864 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3865 */ 3866 int 3867 getblkx(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3868 int flags, struct buf **bpp) 3869 { 3870 struct buf *bp; 3871 struct bufobj *bo; 3872 daddr_t d_blkno; 3873 int bsize, error, maxsize, vmio; 3874 off_t offset; 3875 3876 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3877 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3878 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3879 ASSERT_VOP_LOCKED(vp, "getblk"); 3880 if (size > maxbcachebuf) 3881 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3882 maxbcachebuf); 3883 if (!unmapped_buf_allowed) 3884 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3885 3886 bo = &vp->v_bufobj; 3887 d_blkno = blkno; 3888 loop: 3889 BO_RLOCK(bo); 3890 bp = gbincore(bo, blkno); 3891 if (bp != NULL) { 3892 int lockflags; 3893 /* 3894 * Buffer is in-core. If the buffer is not busy nor managed, 3895 * it must be on a queue. 3896 */ 3897 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3898 3899 if ((flags & GB_LOCK_NOWAIT) != 0) 3900 lockflags |= LK_NOWAIT; 3901 3902 error = BUF_TIMELOCK(bp, lockflags, 3903 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3904 3905 /* 3906 * If we slept and got the lock we have to restart in case 3907 * the buffer changed identities. 3908 */ 3909 if (error == ENOLCK) 3910 goto loop; 3911 /* We timed out or were interrupted. */ 3912 else if (error != 0) 3913 return (error); 3914 /* If recursed, assume caller knows the rules. */ 3915 else if (BUF_LOCKRECURSED(bp)) 3916 goto end; 3917 3918 /* 3919 * The buffer is locked. B_CACHE is cleared if the buffer is 3920 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3921 * and for a VMIO buffer B_CACHE is adjusted according to the 3922 * backing VM cache. 3923 */ 3924 if (bp->b_flags & B_INVAL) 3925 bp->b_flags &= ~B_CACHE; 3926 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3927 bp->b_flags |= B_CACHE; 3928 if (bp->b_flags & B_MANAGED) 3929 MPASS(bp->b_qindex == QUEUE_NONE); 3930 else 3931 bremfree(bp); 3932 3933 /* 3934 * check for size inconsistencies for non-VMIO case. 3935 */ 3936 if (bp->b_bcount != size) { 3937 if ((bp->b_flags & B_VMIO) == 0 || 3938 (size > bp->b_kvasize)) { 3939 if (bp->b_flags & B_DELWRI) { 3940 bp->b_flags |= B_NOCACHE; 3941 bwrite(bp); 3942 } else { 3943 if (LIST_EMPTY(&bp->b_dep)) { 3944 bp->b_flags |= B_RELBUF; 3945 brelse(bp); 3946 } else { 3947 bp->b_flags |= B_NOCACHE; 3948 bwrite(bp); 3949 } 3950 } 3951 goto loop; 3952 } 3953 } 3954 3955 /* 3956 * Handle the case of unmapped buffer which should 3957 * become mapped, or the buffer for which KVA 3958 * reservation is requested. 3959 */ 3960 bp_unmapped_get_kva(bp, blkno, size, flags); 3961 3962 /* 3963 * If the size is inconsistent in the VMIO case, we can resize 3964 * the buffer. This might lead to B_CACHE getting set or 3965 * cleared. If the size has not changed, B_CACHE remains 3966 * unchanged from its previous state. 3967 */ 3968 allocbuf(bp, size); 3969 3970 KASSERT(bp->b_offset != NOOFFSET, 3971 ("getblk: no buffer offset")); 3972 3973 /* 3974 * A buffer with B_DELWRI set and B_CACHE clear must 3975 * be committed before we can return the buffer in 3976 * order to prevent the caller from issuing a read 3977 * ( due to B_CACHE not being set ) and overwriting 3978 * it. 3979 * 3980 * Most callers, including NFS and FFS, need this to 3981 * operate properly either because they assume they 3982 * can issue a read if B_CACHE is not set, or because 3983 * ( for example ) an uncached B_DELWRI might loop due 3984 * to softupdates re-dirtying the buffer. In the latter 3985 * case, B_CACHE is set after the first write completes, 3986 * preventing further loops. 3987 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3988 * above while extending the buffer, we cannot allow the 3989 * buffer to remain with B_CACHE set after the write 3990 * completes or it will represent a corrupt state. To 3991 * deal with this we set B_NOCACHE to scrap the buffer 3992 * after the write. 3993 * 3994 * We might be able to do something fancy, like setting 3995 * B_CACHE in bwrite() except if B_DELWRI is already set, 3996 * so the below call doesn't set B_CACHE, but that gets real 3997 * confusing. This is much easier. 3998 */ 3999 4000 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 4001 bp->b_flags |= B_NOCACHE; 4002 bwrite(bp); 4003 goto loop; 4004 } 4005 bp->b_flags &= ~B_DONE; 4006 } else { 4007 /* 4008 * Buffer is not in-core, create new buffer. The buffer 4009 * returned by getnewbuf() is locked. Note that the returned 4010 * buffer is also considered valid (not marked B_INVAL). 4011 */ 4012 BO_RUNLOCK(bo); 4013 /* 4014 * If the user does not want us to create the buffer, bail out 4015 * here. 4016 */ 4017 if (flags & GB_NOCREAT) 4018 return (EEXIST); 4019 4020 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 4021 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4022 offset = blkno * bsize; 4023 vmio = vp->v_object != NULL; 4024 if (vmio) { 4025 maxsize = size + (offset & PAGE_MASK); 4026 } else { 4027 maxsize = size; 4028 /* Do not allow non-VMIO notmapped buffers. */ 4029 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4030 } 4031 maxsize = imax(maxsize, bsize); 4032 if ((flags & GB_NOSPARSE) != 0 && vmio && 4033 !vn_isdisk(vp, NULL)) { 4034 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4035 KASSERT(error != EOPNOTSUPP, 4036 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4037 vp)); 4038 if (error != 0) 4039 return (error); 4040 if (d_blkno == -1) 4041 return (EJUSTRETURN); 4042 } 4043 4044 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4045 if (bp == NULL) { 4046 if (slpflag || slptimeo) 4047 return (ETIMEDOUT); 4048 /* 4049 * XXX This is here until the sleep path is diagnosed 4050 * enough to work under very low memory conditions. 4051 * 4052 * There's an issue on low memory, 4BSD+non-preempt 4053 * systems (eg MIPS routers with 32MB RAM) where buffer 4054 * exhaustion occurs without sleeping for buffer 4055 * reclaimation. This just sticks in a loop and 4056 * constantly attempts to allocate a buffer, which 4057 * hits exhaustion and tries to wakeup bufdaemon. 4058 * This never happens because we never yield. 4059 * 4060 * The real solution is to identify and fix these cases 4061 * so we aren't effectively busy-waiting in a loop 4062 * until the reclaimation path has cycles to run. 4063 */ 4064 kern_yield(PRI_USER); 4065 goto loop; 4066 } 4067 4068 /* 4069 * This code is used to make sure that a buffer is not 4070 * created while the getnewbuf routine is blocked. 4071 * This can be a problem whether the vnode is locked or not. 4072 * If the buffer is created out from under us, we have to 4073 * throw away the one we just created. 4074 * 4075 * Note: this must occur before we associate the buffer 4076 * with the vp especially considering limitations in 4077 * the splay tree implementation when dealing with duplicate 4078 * lblkno's. 4079 */ 4080 BO_LOCK(bo); 4081 if (gbincore(bo, blkno)) { 4082 BO_UNLOCK(bo); 4083 bp->b_flags |= B_INVAL; 4084 bufspace_release(bufdomain(bp), maxsize); 4085 brelse(bp); 4086 goto loop; 4087 } 4088 4089 /* 4090 * Insert the buffer into the hash, so that it can 4091 * be found by incore. 4092 */ 4093 bp->b_lblkno = blkno; 4094 bp->b_blkno = d_blkno; 4095 bp->b_offset = offset; 4096 bgetvp(vp, bp); 4097 BO_UNLOCK(bo); 4098 4099 /* 4100 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4101 * buffer size starts out as 0, B_CACHE will be set by 4102 * allocbuf() for the VMIO case prior to it testing the 4103 * backing store for validity. 4104 */ 4105 4106 if (vmio) { 4107 bp->b_flags |= B_VMIO; 4108 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4109 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4110 bp, vp->v_object, bp->b_bufobj->bo_object)); 4111 } else { 4112 bp->b_flags &= ~B_VMIO; 4113 KASSERT(bp->b_bufobj->bo_object == NULL, 4114 ("ARGH! has b_bufobj->bo_object %p %p\n", 4115 bp, bp->b_bufobj->bo_object)); 4116 BUF_CHECK_MAPPED(bp); 4117 } 4118 4119 allocbuf(bp, size); 4120 bufspace_release(bufdomain(bp), maxsize); 4121 bp->b_flags &= ~B_DONE; 4122 } 4123 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4124 BUF_ASSERT_HELD(bp); 4125 end: 4126 buf_track(bp, __func__); 4127 KASSERT(bp->b_bufobj == bo, 4128 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4129 *bpp = bp; 4130 return (0); 4131 } 4132 4133 /* 4134 * Get an empty, disassociated buffer of given size. The buffer is initially 4135 * set to B_INVAL. 4136 */ 4137 struct buf * 4138 geteblk(int size, int flags) 4139 { 4140 struct buf *bp; 4141 int maxsize; 4142 4143 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4144 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4145 if ((flags & GB_NOWAIT_BD) && 4146 (curthread->td_pflags & TDP_BUFNEED) != 0) 4147 return (NULL); 4148 } 4149 allocbuf(bp, size); 4150 bufspace_release(bufdomain(bp), maxsize); 4151 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4152 BUF_ASSERT_HELD(bp); 4153 return (bp); 4154 } 4155 4156 /* 4157 * Truncate the backing store for a non-vmio buffer. 4158 */ 4159 static void 4160 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4161 { 4162 4163 if (bp->b_flags & B_MALLOC) { 4164 /* 4165 * malloced buffers are not shrunk 4166 */ 4167 if (newbsize == 0) { 4168 bufmallocadjust(bp, 0); 4169 free(bp->b_data, M_BIOBUF); 4170 bp->b_data = bp->b_kvabase; 4171 bp->b_flags &= ~B_MALLOC; 4172 } 4173 return; 4174 } 4175 vm_hold_free_pages(bp, newbsize); 4176 bufspace_adjust(bp, newbsize); 4177 } 4178 4179 /* 4180 * Extend the backing for a non-VMIO buffer. 4181 */ 4182 static void 4183 vfs_nonvmio_extend(struct buf *bp, int newbsize) 4184 { 4185 caddr_t origbuf; 4186 int origbufsize; 4187 4188 /* 4189 * We only use malloced memory on the first allocation. 4190 * and revert to page-allocated memory when the buffer 4191 * grows. 4192 * 4193 * There is a potential smp race here that could lead 4194 * to bufmallocspace slightly passing the max. It 4195 * is probably extremely rare and not worth worrying 4196 * over. 4197 */ 4198 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4199 bufmallocspace < maxbufmallocspace) { 4200 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4201 bp->b_flags |= B_MALLOC; 4202 bufmallocadjust(bp, newbsize); 4203 return; 4204 } 4205 4206 /* 4207 * If the buffer is growing on its other-than-first 4208 * allocation then we revert to the page-allocation 4209 * scheme. 4210 */ 4211 origbuf = NULL; 4212 origbufsize = 0; 4213 if (bp->b_flags & B_MALLOC) { 4214 origbuf = bp->b_data; 4215 origbufsize = bp->b_bufsize; 4216 bp->b_data = bp->b_kvabase; 4217 bufmallocadjust(bp, 0); 4218 bp->b_flags &= ~B_MALLOC; 4219 newbsize = round_page(newbsize); 4220 } 4221 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4222 (vm_offset_t) bp->b_data + newbsize); 4223 if (origbuf != NULL) { 4224 bcopy(origbuf, bp->b_data, origbufsize); 4225 free(origbuf, M_BIOBUF); 4226 } 4227 bufspace_adjust(bp, newbsize); 4228 } 4229 4230 /* 4231 * This code constitutes the buffer memory from either anonymous system 4232 * memory (in the case of non-VMIO operations) or from an associated 4233 * VM object (in the case of VMIO operations). This code is able to 4234 * resize a buffer up or down. 4235 * 4236 * Note that this code is tricky, and has many complications to resolve 4237 * deadlock or inconsistent data situations. Tread lightly!!! 4238 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4239 * the caller. Calling this code willy nilly can result in the loss of data. 4240 * 4241 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4242 * B_CACHE for the non-VMIO case. 4243 */ 4244 int 4245 allocbuf(struct buf *bp, int size) 4246 { 4247 int newbsize; 4248 4249 BUF_ASSERT_HELD(bp); 4250 4251 if (bp->b_bcount == size) 4252 return (1); 4253 4254 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 4255 panic("allocbuf: buffer too small"); 4256 4257 newbsize = roundup2(size, DEV_BSIZE); 4258 if ((bp->b_flags & B_VMIO) == 0) { 4259 if ((bp->b_flags & B_MALLOC) == 0) 4260 newbsize = round_page(newbsize); 4261 /* 4262 * Just get anonymous memory from the kernel. Don't 4263 * mess with B_CACHE. 4264 */ 4265 if (newbsize < bp->b_bufsize) 4266 vfs_nonvmio_truncate(bp, newbsize); 4267 else if (newbsize > bp->b_bufsize) 4268 vfs_nonvmio_extend(bp, newbsize); 4269 } else { 4270 int desiredpages; 4271 4272 desiredpages = (size == 0) ? 0 : 4273 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4274 4275 if (bp->b_flags & B_MALLOC) 4276 panic("allocbuf: VMIO buffer can't be malloced"); 4277 /* 4278 * Set B_CACHE initially if buffer is 0 length or will become 4279 * 0-length. 4280 */ 4281 if (size == 0 || bp->b_bufsize == 0) 4282 bp->b_flags |= B_CACHE; 4283 4284 if (newbsize < bp->b_bufsize) 4285 vfs_vmio_truncate(bp, desiredpages); 4286 /* XXX This looks as if it should be newbsize > b_bufsize */ 4287 else if (size > bp->b_bcount) 4288 vfs_vmio_extend(bp, desiredpages, size); 4289 bufspace_adjust(bp, newbsize); 4290 } 4291 bp->b_bcount = size; /* requested buffer size. */ 4292 return (1); 4293 } 4294 4295 extern int inflight_transient_maps; 4296 4297 static struct bio_queue nondump_bios; 4298 4299 void 4300 biodone(struct bio *bp) 4301 { 4302 struct mtx *mtxp; 4303 void (*done)(struct bio *); 4304 vm_offset_t start, end; 4305 4306 biotrack(bp, __func__); 4307 4308 /* 4309 * Avoid completing I/O when dumping after a panic since that may 4310 * result in a deadlock in the filesystem or pager code. Note that 4311 * this doesn't affect dumps that were started manually since we aim 4312 * to keep the system usable after it has been resumed. 4313 */ 4314 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4315 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4316 return; 4317 } 4318 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4319 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4320 bp->bio_flags |= BIO_UNMAPPED; 4321 start = trunc_page((vm_offset_t)bp->bio_data); 4322 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4323 bp->bio_data = unmapped_buf; 4324 pmap_qremove(start, atop(end - start)); 4325 vmem_free(transient_arena, start, end - start); 4326 atomic_add_int(&inflight_transient_maps, -1); 4327 } 4328 done = bp->bio_done; 4329 if (done == NULL) { 4330 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4331 mtx_lock(mtxp); 4332 bp->bio_flags |= BIO_DONE; 4333 wakeup(bp); 4334 mtx_unlock(mtxp); 4335 } else 4336 done(bp); 4337 } 4338 4339 /* 4340 * Wait for a BIO to finish. 4341 */ 4342 int 4343 biowait(struct bio *bp, const char *wchan) 4344 { 4345 struct mtx *mtxp; 4346 4347 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4348 mtx_lock(mtxp); 4349 while ((bp->bio_flags & BIO_DONE) == 0) 4350 msleep(bp, mtxp, PRIBIO, wchan, 0); 4351 mtx_unlock(mtxp); 4352 if (bp->bio_error != 0) 4353 return (bp->bio_error); 4354 if (!(bp->bio_flags & BIO_ERROR)) 4355 return (0); 4356 return (EIO); 4357 } 4358 4359 void 4360 biofinish(struct bio *bp, struct devstat *stat, int error) 4361 { 4362 4363 if (error) { 4364 bp->bio_error = error; 4365 bp->bio_flags |= BIO_ERROR; 4366 } 4367 if (stat != NULL) 4368 devstat_end_transaction_bio(stat, bp); 4369 biodone(bp); 4370 } 4371 4372 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4373 void 4374 biotrack_buf(struct bio *bp, const char *location) 4375 { 4376 4377 buf_track(bp->bio_track_bp, location); 4378 } 4379 #endif 4380 4381 /* 4382 * bufwait: 4383 * 4384 * Wait for buffer I/O completion, returning error status. The buffer 4385 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4386 * error and cleared. 4387 */ 4388 int 4389 bufwait(struct buf *bp) 4390 { 4391 if (bp->b_iocmd == BIO_READ) 4392 bwait(bp, PRIBIO, "biord"); 4393 else 4394 bwait(bp, PRIBIO, "biowr"); 4395 if (bp->b_flags & B_EINTR) { 4396 bp->b_flags &= ~B_EINTR; 4397 return (EINTR); 4398 } 4399 if (bp->b_ioflags & BIO_ERROR) { 4400 return (bp->b_error ? bp->b_error : EIO); 4401 } else { 4402 return (0); 4403 } 4404 } 4405 4406 /* 4407 * bufdone: 4408 * 4409 * Finish I/O on a buffer, optionally calling a completion function. 4410 * This is usually called from an interrupt so process blocking is 4411 * not allowed. 4412 * 4413 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4414 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4415 * assuming B_INVAL is clear. 4416 * 4417 * For the VMIO case, we set B_CACHE if the op was a read and no 4418 * read error occurred, or if the op was a write. B_CACHE is never 4419 * set if the buffer is invalid or otherwise uncacheable. 4420 * 4421 * bufdone does not mess with B_INVAL, allowing the I/O routine or the 4422 * initiator to leave B_INVAL set to brelse the buffer out of existence 4423 * in the biodone routine. 4424 */ 4425 void 4426 bufdone(struct buf *bp) 4427 { 4428 struct bufobj *dropobj; 4429 void (*biodone)(struct buf *); 4430 4431 buf_track(bp, __func__); 4432 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4433 dropobj = NULL; 4434 4435 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4436 BUF_ASSERT_HELD(bp); 4437 4438 runningbufwakeup(bp); 4439 if (bp->b_iocmd == BIO_WRITE) 4440 dropobj = bp->b_bufobj; 4441 /* call optional completion function if requested */ 4442 if (bp->b_iodone != NULL) { 4443 biodone = bp->b_iodone; 4444 bp->b_iodone = NULL; 4445 (*biodone) (bp); 4446 if (dropobj) 4447 bufobj_wdrop(dropobj); 4448 return; 4449 } 4450 if (bp->b_flags & B_VMIO) { 4451 /* 4452 * Set B_CACHE if the op was a normal read and no error 4453 * occurred. B_CACHE is set for writes in the b*write() 4454 * routines. 4455 */ 4456 if (bp->b_iocmd == BIO_READ && 4457 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4458 !(bp->b_ioflags & BIO_ERROR)) 4459 bp->b_flags |= B_CACHE; 4460 vfs_vmio_iodone(bp); 4461 } 4462 if (!LIST_EMPTY(&bp->b_dep)) 4463 buf_complete(bp); 4464 if ((bp->b_flags & B_CKHASH) != 0) { 4465 KASSERT(bp->b_iocmd == BIO_READ, 4466 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4467 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4468 (*bp->b_ckhashcalc)(bp); 4469 } 4470 /* 4471 * For asynchronous completions, release the buffer now. The brelse 4472 * will do a wakeup there if necessary - so no need to do a wakeup 4473 * here in the async case. The sync case always needs to do a wakeup. 4474 */ 4475 if (bp->b_flags & B_ASYNC) { 4476 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4477 (bp->b_ioflags & BIO_ERROR)) 4478 brelse(bp); 4479 else 4480 bqrelse(bp); 4481 } else 4482 bdone(bp); 4483 if (dropobj) 4484 bufobj_wdrop(dropobj); 4485 } 4486 4487 /* 4488 * This routine is called in lieu of iodone in the case of 4489 * incomplete I/O. This keeps the busy status for pages 4490 * consistent. 4491 */ 4492 void 4493 vfs_unbusy_pages(struct buf *bp) 4494 { 4495 int i; 4496 vm_object_t obj; 4497 vm_page_t m; 4498 4499 runningbufwakeup(bp); 4500 if (!(bp->b_flags & B_VMIO)) 4501 return; 4502 4503 obj = bp->b_bufobj->bo_object; 4504 VM_OBJECT_WLOCK(obj); 4505 for (i = 0; i < bp->b_npages; i++) { 4506 m = bp->b_pages[i]; 4507 if (m == bogus_page) { 4508 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4509 if (!m) 4510 panic("vfs_unbusy_pages: page missing\n"); 4511 bp->b_pages[i] = m; 4512 if (buf_mapped(bp)) { 4513 BUF_CHECK_MAPPED(bp); 4514 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4515 bp->b_pages, bp->b_npages); 4516 } else 4517 BUF_CHECK_UNMAPPED(bp); 4518 } 4519 vm_page_sunbusy(m); 4520 } 4521 vm_object_pip_wakeupn(obj, bp->b_npages); 4522 VM_OBJECT_WUNLOCK(obj); 4523 } 4524 4525 /* 4526 * vfs_page_set_valid: 4527 * 4528 * Set the valid bits in a page based on the supplied offset. The 4529 * range is restricted to the buffer's size. 4530 * 4531 * This routine is typically called after a read completes. 4532 */ 4533 static void 4534 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4535 { 4536 vm_ooffset_t eoff; 4537 4538 /* 4539 * Compute the end offset, eoff, such that [off, eoff) does not span a 4540 * page boundary and eoff is not greater than the end of the buffer. 4541 * The end of the buffer, in this case, is our file EOF, not the 4542 * allocation size of the buffer. 4543 */ 4544 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4545 if (eoff > bp->b_offset + bp->b_bcount) 4546 eoff = bp->b_offset + bp->b_bcount; 4547 4548 /* 4549 * Set valid range. This is typically the entire buffer and thus the 4550 * entire page. 4551 */ 4552 if (eoff > off) 4553 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4554 } 4555 4556 /* 4557 * vfs_page_set_validclean: 4558 * 4559 * Set the valid bits and clear the dirty bits in a page based on the 4560 * supplied offset. The range is restricted to the buffer's size. 4561 */ 4562 static void 4563 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4564 { 4565 vm_ooffset_t soff, eoff; 4566 4567 /* 4568 * Start and end offsets in buffer. eoff - soff may not cross a 4569 * page boundary or cross the end of the buffer. The end of the 4570 * buffer, in this case, is our file EOF, not the allocation size 4571 * of the buffer. 4572 */ 4573 soff = off; 4574 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4575 if (eoff > bp->b_offset + bp->b_bcount) 4576 eoff = bp->b_offset + bp->b_bcount; 4577 4578 /* 4579 * Set valid range. This is typically the entire buffer and thus the 4580 * entire page. 4581 */ 4582 if (eoff > soff) { 4583 vm_page_set_validclean( 4584 m, 4585 (vm_offset_t) (soff & PAGE_MASK), 4586 (vm_offset_t) (eoff - soff) 4587 ); 4588 } 4589 } 4590 4591 /* 4592 * Ensure that all buffer pages are not exclusive busied. If any page is 4593 * exclusive busy, drain it. 4594 */ 4595 void 4596 vfs_drain_busy_pages(struct buf *bp) 4597 { 4598 vm_page_t m; 4599 int i, last_busied; 4600 4601 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4602 last_busied = 0; 4603 for (i = 0; i < bp->b_npages; i++) { 4604 m = bp->b_pages[i]; 4605 if (vm_page_xbusied(m)) { 4606 for (; last_busied < i; last_busied++) 4607 vm_page_sbusy(bp->b_pages[last_busied]); 4608 while (vm_page_xbusied(m)) { 4609 vm_page_lock(m); 4610 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4611 vm_page_busy_sleep(m, "vbpage", true); 4612 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4613 } 4614 } 4615 } 4616 for (i = 0; i < last_busied; i++) 4617 vm_page_sunbusy(bp->b_pages[i]); 4618 } 4619 4620 /* 4621 * This routine is called before a device strategy routine. 4622 * It is used to tell the VM system that paging I/O is in 4623 * progress, and treat the pages associated with the buffer 4624 * almost as being exclusive busy. Also the object paging_in_progress 4625 * flag is handled to make sure that the object doesn't become 4626 * inconsistent. 4627 * 4628 * Since I/O has not been initiated yet, certain buffer flags 4629 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4630 * and should be ignored. 4631 */ 4632 void 4633 vfs_busy_pages(struct buf *bp, int clear_modify) 4634 { 4635 vm_object_t obj; 4636 vm_ooffset_t foff; 4637 vm_page_t m; 4638 int i; 4639 bool bogus; 4640 4641 if (!(bp->b_flags & B_VMIO)) 4642 return; 4643 4644 obj = bp->b_bufobj->bo_object; 4645 foff = bp->b_offset; 4646 KASSERT(bp->b_offset != NOOFFSET, 4647 ("vfs_busy_pages: no buffer offset")); 4648 VM_OBJECT_WLOCK(obj); 4649 vfs_drain_busy_pages(bp); 4650 if (bp->b_bufsize != 0) 4651 vfs_setdirty_locked_object(bp); 4652 bogus = false; 4653 for (i = 0; i < bp->b_npages; i++) { 4654 m = bp->b_pages[i]; 4655 4656 if ((bp->b_flags & B_CLUSTER) == 0) { 4657 vm_object_pip_add(obj, 1); 4658 vm_page_sbusy(m); 4659 } 4660 /* 4661 * When readying a buffer for a read ( i.e 4662 * clear_modify == 0 ), it is important to do 4663 * bogus_page replacement for valid pages in 4664 * partially instantiated buffers. Partially 4665 * instantiated buffers can, in turn, occur when 4666 * reconstituting a buffer from its VM backing store 4667 * base. We only have to do this if B_CACHE is 4668 * clear ( which causes the I/O to occur in the 4669 * first place ). The replacement prevents the read 4670 * I/O from overwriting potentially dirty VM-backed 4671 * pages. XXX bogus page replacement is, uh, bogus. 4672 * It may not work properly with small-block devices. 4673 * We need to find a better way. 4674 */ 4675 if (clear_modify) { 4676 pmap_remove_write(m); 4677 vfs_page_set_validclean(bp, foff, m); 4678 } else if (m->valid == VM_PAGE_BITS_ALL && 4679 (bp->b_flags & B_CACHE) == 0) { 4680 bp->b_pages[i] = bogus_page; 4681 bogus = true; 4682 } 4683 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4684 } 4685 VM_OBJECT_WUNLOCK(obj); 4686 if (bogus && buf_mapped(bp)) { 4687 BUF_CHECK_MAPPED(bp); 4688 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4689 bp->b_pages, bp->b_npages); 4690 } 4691 } 4692 4693 /* 4694 * vfs_bio_set_valid: 4695 * 4696 * Set the range within the buffer to valid. The range is 4697 * relative to the beginning of the buffer, b_offset. Note that 4698 * b_offset itself may be offset from the beginning of the first 4699 * page. 4700 */ 4701 void 4702 vfs_bio_set_valid(struct buf *bp, int base, int size) 4703 { 4704 int i, n; 4705 vm_page_t m; 4706 4707 if (!(bp->b_flags & B_VMIO)) 4708 return; 4709 4710 /* 4711 * Fixup base to be relative to beginning of first page. 4712 * Set initial n to be the maximum number of bytes in the 4713 * first page that can be validated. 4714 */ 4715 base += (bp->b_offset & PAGE_MASK); 4716 n = PAGE_SIZE - (base & PAGE_MASK); 4717 4718 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4719 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4720 m = bp->b_pages[i]; 4721 if (n > size) 4722 n = size; 4723 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4724 base += n; 4725 size -= n; 4726 n = PAGE_SIZE; 4727 } 4728 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4729 } 4730 4731 /* 4732 * vfs_bio_clrbuf: 4733 * 4734 * If the specified buffer is a non-VMIO buffer, clear the entire 4735 * buffer. If the specified buffer is a VMIO buffer, clear and 4736 * validate only the previously invalid portions of the buffer. 4737 * This routine essentially fakes an I/O, so we need to clear 4738 * BIO_ERROR and B_INVAL. 4739 * 4740 * Note that while we only theoretically need to clear through b_bcount, 4741 * we go ahead and clear through b_bufsize. 4742 */ 4743 void 4744 vfs_bio_clrbuf(struct buf *bp) 4745 { 4746 int i, j, mask, sa, ea, slide; 4747 4748 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4749 clrbuf(bp); 4750 return; 4751 } 4752 bp->b_flags &= ~B_INVAL; 4753 bp->b_ioflags &= ~BIO_ERROR; 4754 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4755 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4756 (bp->b_offset & PAGE_MASK) == 0) { 4757 if (bp->b_pages[0] == bogus_page) 4758 goto unlock; 4759 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4760 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4761 if ((bp->b_pages[0]->valid & mask) == mask) 4762 goto unlock; 4763 if ((bp->b_pages[0]->valid & mask) == 0) { 4764 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4765 bp->b_pages[0]->valid |= mask; 4766 goto unlock; 4767 } 4768 } 4769 sa = bp->b_offset & PAGE_MASK; 4770 slide = 0; 4771 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4772 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4773 ea = slide & PAGE_MASK; 4774 if (ea == 0) 4775 ea = PAGE_SIZE; 4776 if (bp->b_pages[i] == bogus_page) 4777 continue; 4778 j = sa / DEV_BSIZE; 4779 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4780 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4781 if ((bp->b_pages[i]->valid & mask) == mask) 4782 continue; 4783 if ((bp->b_pages[i]->valid & mask) == 0) 4784 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4785 else { 4786 for (; sa < ea; sa += DEV_BSIZE, j++) { 4787 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4788 pmap_zero_page_area(bp->b_pages[i], 4789 sa, DEV_BSIZE); 4790 } 4791 } 4792 } 4793 bp->b_pages[i]->valid |= mask; 4794 } 4795 unlock: 4796 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4797 bp->b_resid = 0; 4798 } 4799 4800 void 4801 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4802 { 4803 vm_page_t m; 4804 int i, n; 4805 4806 if (buf_mapped(bp)) { 4807 BUF_CHECK_MAPPED(bp); 4808 bzero(bp->b_data + base, size); 4809 } else { 4810 BUF_CHECK_UNMAPPED(bp); 4811 n = PAGE_SIZE - (base & PAGE_MASK); 4812 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4813 m = bp->b_pages[i]; 4814 if (n > size) 4815 n = size; 4816 pmap_zero_page_area(m, base & PAGE_MASK, n); 4817 base += n; 4818 size -= n; 4819 n = PAGE_SIZE; 4820 } 4821 } 4822 } 4823 4824 /* 4825 * Update buffer flags based on I/O request parameters, optionally releasing the 4826 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4827 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4828 * I/O). Otherwise the buffer is released to the cache. 4829 */ 4830 static void 4831 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4832 { 4833 4834 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4835 ("buf %p non-VMIO noreuse", bp)); 4836 4837 if ((ioflag & IO_DIRECT) != 0) 4838 bp->b_flags |= B_DIRECT; 4839 if ((ioflag & IO_EXT) != 0) 4840 bp->b_xflags |= BX_ALTDATA; 4841 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4842 bp->b_flags |= B_RELBUF; 4843 if ((ioflag & IO_NOREUSE) != 0) 4844 bp->b_flags |= B_NOREUSE; 4845 if (release) 4846 brelse(bp); 4847 } else if (release) 4848 bqrelse(bp); 4849 } 4850 4851 void 4852 vfs_bio_brelse(struct buf *bp, int ioflag) 4853 { 4854 4855 b_io_dismiss(bp, ioflag, true); 4856 } 4857 4858 void 4859 vfs_bio_set_flags(struct buf *bp, int ioflag) 4860 { 4861 4862 b_io_dismiss(bp, ioflag, false); 4863 } 4864 4865 /* 4866 * vm_hold_load_pages and vm_hold_free_pages get pages into 4867 * a buffers address space. The pages are anonymous and are 4868 * not associated with a file object. 4869 */ 4870 static void 4871 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4872 { 4873 vm_offset_t pg; 4874 vm_page_t p; 4875 int index; 4876 4877 BUF_CHECK_MAPPED(bp); 4878 4879 to = round_page(to); 4880 from = round_page(from); 4881 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4882 4883 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4884 /* 4885 * note: must allocate system pages since blocking here 4886 * could interfere with paging I/O, no matter which 4887 * process we are. 4888 */ 4889 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4890 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | 4891 VM_ALLOC_WAITOK); 4892 pmap_qenter(pg, &p, 1); 4893 bp->b_pages[index] = p; 4894 } 4895 bp->b_npages = index; 4896 } 4897 4898 /* Return pages associated with this buf to the vm system */ 4899 static void 4900 vm_hold_free_pages(struct buf *bp, int newbsize) 4901 { 4902 vm_offset_t from; 4903 vm_page_t p; 4904 int index, newnpages; 4905 4906 BUF_CHECK_MAPPED(bp); 4907 4908 from = round_page((vm_offset_t)bp->b_data + newbsize); 4909 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4910 if (bp->b_npages > newnpages) 4911 pmap_qremove(from, bp->b_npages - newnpages); 4912 for (index = newnpages; index < bp->b_npages; index++) { 4913 p = bp->b_pages[index]; 4914 bp->b_pages[index] = NULL; 4915 p->wire_count--; 4916 vm_page_free(p); 4917 } 4918 vm_wire_sub(bp->b_npages - newnpages); 4919 bp->b_npages = newnpages; 4920 } 4921 4922 /* 4923 * Map an IO request into kernel virtual address space. 4924 * 4925 * All requests are (re)mapped into kernel VA space. 4926 * Notice that we use b_bufsize for the size of the buffer 4927 * to be mapped. b_bcount might be modified by the driver. 4928 * 4929 * Note that even if the caller determines that the address space should 4930 * be valid, a race or a smaller-file mapped into a larger space may 4931 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4932 * check the return value. 4933 * 4934 * This function only works with pager buffers. 4935 */ 4936 int 4937 vmapbuf(struct buf *bp, int mapbuf) 4938 { 4939 vm_prot_t prot; 4940 int pidx; 4941 4942 if (bp->b_bufsize < 0) 4943 return (-1); 4944 prot = VM_PROT_READ; 4945 if (bp->b_iocmd == BIO_READ) 4946 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4947 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4948 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4949 btoc(MAXPHYS))) < 0) 4950 return (-1); 4951 bp->b_npages = pidx; 4952 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4953 if (mapbuf || !unmapped_buf_allowed) { 4954 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4955 bp->b_data = bp->b_kvabase + bp->b_offset; 4956 } else 4957 bp->b_data = unmapped_buf; 4958 return(0); 4959 } 4960 4961 /* 4962 * Free the io map PTEs associated with this IO operation. 4963 * We also invalidate the TLB entries and restore the original b_addr. 4964 * 4965 * This function only works with pager buffers. 4966 */ 4967 void 4968 vunmapbuf(struct buf *bp) 4969 { 4970 int npages; 4971 4972 npages = bp->b_npages; 4973 if (buf_mapped(bp)) 4974 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4975 vm_page_unhold_pages(bp->b_pages, npages); 4976 4977 bp->b_data = unmapped_buf; 4978 } 4979 4980 void 4981 bdone(struct buf *bp) 4982 { 4983 struct mtx *mtxp; 4984 4985 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4986 mtx_lock(mtxp); 4987 bp->b_flags |= B_DONE; 4988 wakeup(bp); 4989 mtx_unlock(mtxp); 4990 } 4991 4992 void 4993 bwait(struct buf *bp, u_char pri, const char *wchan) 4994 { 4995 struct mtx *mtxp; 4996 4997 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4998 mtx_lock(mtxp); 4999 while ((bp->b_flags & B_DONE) == 0) 5000 msleep(bp, mtxp, pri, wchan, 0); 5001 mtx_unlock(mtxp); 5002 } 5003 5004 int 5005 bufsync(struct bufobj *bo, int waitfor) 5006 { 5007 5008 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 5009 } 5010 5011 void 5012 bufstrategy(struct bufobj *bo, struct buf *bp) 5013 { 5014 int i __unused; 5015 struct vnode *vp; 5016 5017 vp = bp->b_vp; 5018 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5019 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5020 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5021 i = VOP_STRATEGY(vp, bp); 5022 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5023 } 5024 5025 /* 5026 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5027 */ 5028 void 5029 bufobj_init(struct bufobj *bo, void *private) 5030 { 5031 static volatile int bufobj_cleanq; 5032 5033 bo->bo_domain = 5034 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5035 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5036 bo->bo_private = private; 5037 TAILQ_INIT(&bo->bo_clean.bv_hd); 5038 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5039 } 5040 5041 void 5042 bufobj_wrefl(struct bufobj *bo) 5043 { 5044 5045 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5046 ASSERT_BO_WLOCKED(bo); 5047 bo->bo_numoutput++; 5048 } 5049 5050 void 5051 bufobj_wref(struct bufobj *bo) 5052 { 5053 5054 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5055 BO_LOCK(bo); 5056 bo->bo_numoutput++; 5057 BO_UNLOCK(bo); 5058 } 5059 5060 void 5061 bufobj_wdrop(struct bufobj *bo) 5062 { 5063 5064 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5065 BO_LOCK(bo); 5066 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5067 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5068 bo->bo_flag &= ~BO_WWAIT; 5069 wakeup(&bo->bo_numoutput); 5070 } 5071 BO_UNLOCK(bo); 5072 } 5073 5074 int 5075 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5076 { 5077 int error; 5078 5079 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5080 ASSERT_BO_WLOCKED(bo); 5081 error = 0; 5082 while (bo->bo_numoutput) { 5083 bo->bo_flag |= BO_WWAIT; 5084 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5085 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5086 if (error) 5087 break; 5088 } 5089 return (error); 5090 } 5091 5092 /* 5093 * Set bio_data or bio_ma for struct bio from the struct buf. 5094 */ 5095 void 5096 bdata2bio(struct buf *bp, struct bio *bip) 5097 { 5098 5099 if (!buf_mapped(bp)) { 5100 KASSERT(unmapped_buf_allowed, ("unmapped")); 5101 bip->bio_ma = bp->b_pages; 5102 bip->bio_ma_n = bp->b_npages; 5103 bip->bio_data = unmapped_buf; 5104 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5105 bip->bio_flags |= BIO_UNMAPPED; 5106 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5107 PAGE_SIZE == bp->b_npages, 5108 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5109 (long long)bip->bio_length, bip->bio_ma_n)); 5110 } else { 5111 bip->bio_data = bp->b_data; 5112 bip->bio_ma = NULL; 5113 } 5114 } 5115 5116 /* 5117 * The MIPS pmap code currently doesn't handle aliased pages. 5118 * The VIPT caches may not handle page aliasing themselves, leading 5119 * to data corruption. 5120 * 5121 * As such, this code makes a system extremely unhappy if said 5122 * system doesn't support unaliasing the above situation in hardware. 5123 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 5124 * this feature at build time, so it has to be handled in software. 5125 * 5126 * Once the MIPS pmap/cache code grows to support this function on 5127 * earlier chips, it should be flipped back off. 5128 */ 5129 #ifdef __mips__ 5130 static int buf_pager_relbuf = 1; 5131 #else 5132 static int buf_pager_relbuf = 0; 5133 #endif 5134 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5135 &buf_pager_relbuf, 0, 5136 "Make buffer pager release buffers after reading"); 5137 5138 /* 5139 * The buffer pager. It uses buffer reads to validate pages. 5140 * 5141 * In contrast to the generic local pager from vm/vnode_pager.c, this 5142 * pager correctly and easily handles volumes where the underlying 5143 * device block size is greater than the machine page size. The 5144 * buffer cache transparently extends the requested page run to be 5145 * aligned at the block boundary, and does the necessary bogus page 5146 * replacements in the addends to avoid obliterating already valid 5147 * pages. 5148 * 5149 * The only non-trivial issue is that the exclusive busy state for 5150 * pages, which is assumed by the vm_pager_getpages() interface, is 5151 * incompatible with the VMIO buffer cache's desire to share-busy the 5152 * pages. This function performs a trivial downgrade of the pages' 5153 * state before reading buffers, and a less trivial upgrade from the 5154 * shared-busy to excl-busy state after the read. 5155 */ 5156 int 5157 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5158 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5159 vbg_get_blksize_t get_blksize) 5160 { 5161 vm_page_t m; 5162 vm_object_t object; 5163 struct buf *bp; 5164 struct mount *mp; 5165 daddr_t lbn, lbnp; 5166 vm_ooffset_t la, lb, poff, poffe; 5167 long bsize; 5168 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5169 bool redo, lpart; 5170 5171 object = vp->v_object; 5172 mp = vp->v_mount; 5173 error = 0; 5174 la = IDX_TO_OFF(ma[count - 1]->pindex); 5175 if (la >= object->un_pager.vnp.vnp_size) 5176 return (VM_PAGER_BAD); 5177 5178 /* 5179 * Change the meaning of la from where the last requested page starts 5180 * to where it ends, because that's the end of the requested region 5181 * and the start of the potential read-ahead region. 5182 */ 5183 la += PAGE_SIZE; 5184 lpart = la > object->un_pager.vnp.vnp_size; 5185 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 5186 5187 /* 5188 * Calculate read-ahead, behind and total pages. 5189 */ 5190 pgsin = count; 5191 lb = IDX_TO_OFF(ma[0]->pindex); 5192 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5193 pgsin += pgsin_b; 5194 if (rbehind != NULL) 5195 *rbehind = pgsin_b; 5196 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5197 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5198 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5199 PAGE_SIZE) - la); 5200 pgsin += pgsin_a; 5201 if (rahead != NULL) 5202 *rahead = pgsin_a; 5203 VM_CNT_INC(v_vnodein); 5204 VM_CNT_ADD(v_vnodepgsin, pgsin); 5205 5206 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5207 != 0) ? GB_UNMAPPED : 0; 5208 VM_OBJECT_WLOCK(object); 5209 again: 5210 for (i = 0; i < count; i++) 5211 vm_page_busy_downgrade(ma[i]); 5212 VM_OBJECT_WUNLOCK(object); 5213 5214 lbnp = -1; 5215 for (i = 0; i < count; i++) { 5216 m = ma[i]; 5217 5218 /* 5219 * Pages are shared busy and the object lock is not 5220 * owned, which together allow for the pages' 5221 * invalidation. The racy test for validity avoids 5222 * useless creation of the buffer for the most typical 5223 * case when invalidation is not used in redo or for 5224 * parallel read. The shared->excl upgrade loop at 5225 * the end of the function catches the race in a 5226 * reliable way (protected by the object lock). 5227 */ 5228 if (m->valid == VM_PAGE_BITS_ALL) 5229 continue; 5230 5231 poff = IDX_TO_OFF(m->pindex); 5232 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5233 for (; poff < poffe; poff += bsize) { 5234 lbn = get_lblkno(vp, poff); 5235 if (lbn == lbnp) 5236 goto next_page; 5237 lbnp = lbn; 5238 5239 bsize = get_blksize(vp, lbn); 5240 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 5241 br_flags, &bp); 5242 if (error != 0) 5243 goto end_pages; 5244 if (LIST_EMPTY(&bp->b_dep)) { 5245 /* 5246 * Invalidation clears m->valid, but 5247 * may leave B_CACHE flag if the 5248 * buffer existed at the invalidation 5249 * time. In this case, recycle the 5250 * buffer to do real read on next 5251 * bread() after redo. 5252 * 5253 * Otherwise B_RELBUF is not strictly 5254 * necessary, enable to reduce buf 5255 * cache pressure. 5256 */ 5257 if (buf_pager_relbuf || 5258 m->valid != VM_PAGE_BITS_ALL) 5259 bp->b_flags |= B_RELBUF; 5260 5261 bp->b_flags &= ~B_NOCACHE; 5262 brelse(bp); 5263 } else { 5264 bqrelse(bp); 5265 } 5266 } 5267 KASSERT(1 /* racy, enable for debugging */ || 5268 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 5269 ("buf %d %p invalid", i, m)); 5270 if (i == count - 1 && lpart) { 5271 VM_OBJECT_WLOCK(object); 5272 if (m->valid != 0 && 5273 m->valid != VM_PAGE_BITS_ALL) 5274 vm_page_zero_invalid(m, TRUE); 5275 VM_OBJECT_WUNLOCK(object); 5276 } 5277 next_page:; 5278 } 5279 end_pages: 5280 5281 VM_OBJECT_WLOCK(object); 5282 redo = false; 5283 for (i = 0; i < count; i++) { 5284 vm_page_sunbusy(ma[i]); 5285 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 5286 5287 /* 5288 * Since the pages were only sbusy while neither the 5289 * buffer nor the object lock was held by us, or 5290 * reallocated while vm_page_grab() slept for busy 5291 * relinguish, they could have been invalidated. 5292 * Recheck the valid bits and re-read as needed. 5293 * 5294 * Note that the last page is made fully valid in the 5295 * read loop, and partial validity for the page at 5296 * index count - 1 could mean that the page was 5297 * invalidated or removed, so we must restart for 5298 * safety as well. 5299 */ 5300 if (ma[i]->valid != VM_PAGE_BITS_ALL) 5301 redo = true; 5302 } 5303 if (redo && error == 0) 5304 goto again; 5305 VM_OBJECT_WUNLOCK(object); 5306 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5307 } 5308 5309 #include "opt_ddb.h" 5310 #ifdef DDB 5311 #include <ddb/ddb.h> 5312 5313 /* DDB command to show buffer data */ 5314 DB_SHOW_COMMAND(buffer, db_show_buffer) 5315 { 5316 /* get args */ 5317 struct buf *bp = (struct buf *)addr; 5318 #ifdef FULL_BUF_TRACKING 5319 uint32_t i, j; 5320 #endif 5321 5322 if (!have_addr) { 5323 db_printf("usage: show buffer <addr>\n"); 5324 return; 5325 } 5326 5327 db_printf("buf at %p\n", bp); 5328 db_printf("b_flags = 0x%b, b_xflags=0x%b\n", 5329 (u_int)bp->b_flags, PRINT_BUF_FLAGS, 5330 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS); 5331 db_printf("b_vflags=0x%b b_ioflags0x%b\n", 5332 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS, 5333 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS); 5334 db_printf( 5335 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5336 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, " 5337 "b_vp = %p, b_dep = %p\n", 5338 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5339 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5340 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first); 5341 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5342 bp->b_kvabase, bp->b_kvasize); 5343 if (bp->b_npages) { 5344 int i; 5345 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5346 for (i = 0; i < bp->b_npages; i++) { 5347 vm_page_t m; 5348 m = bp->b_pages[i]; 5349 if (m != NULL) 5350 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5351 (u_long)m->pindex, 5352 (u_long)VM_PAGE_TO_PHYS(m)); 5353 else 5354 db_printf("( ??? )"); 5355 if ((i + 1) < bp->b_npages) 5356 db_printf(","); 5357 } 5358 db_printf("\n"); 5359 } 5360 BUF_LOCKPRINTINFO(bp); 5361 #if defined(FULL_BUF_TRACKING) 5362 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5363 5364 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5365 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5366 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5367 continue; 5368 db_printf(" %2u: %s\n", j, 5369 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5370 } 5371 #elif defined(BUF_TRACKING) 5372 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5373 #endif 5374 db_printf(" "); 5375 } 5376 5377 DB_SHOW_COMMAND(bufqueues, bufqueues) 5378 { 5379 struct bufdomain *bd; 5380 struct buf *bp; 5381 long total; 5382 int i, j, cnt; 5383 5384 db_printf("bqempty: %d\n", bqempty.bq_len); 5385 5386 for (i = 0; i < buf_domains; i++) { 5387 bd = &bdomain[i]; 5388 db_printf("Buf domain %d\n", i); 5389 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5390 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5391 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5392 db_printf("\n"); 5393 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5394 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5395 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5396 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5397 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5398 db_printf("\n"); 5399 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5400 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5401 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5402 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5403 db_printf("\n"); 5404 total = 0; 5405 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5406 total += bp->b_bufsize; 5407 db_printf("\tcleanq count\t%d (%ld)\n", 5408 bd->bd_cleanq->bq_len, total); 5409 total = 0; 5410 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5411 total += bp->b_bufsize; 5412 db_printf("\tdirtyq count\t%d (%ld)\n", 5413 bd->bd_dirtyq.bq_len, total); 5414 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5415 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5416 db_printf("\tCPU "); 5417 for (j = 0; j <= mp_maxid; j++) 5418 db_printf("%d, ", bd->bd_subq[j].bq_len); 5419 db_printf("\n"); 5420 cnt = 0; 5421 total = 0; 5422 for (j = 0; j < nbuf; j++) 5423 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) { 5424 cnt++; 5425 total += buf[j].b_bufsize; 5426 } 5427 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5428 cnt = 0; 5429 total = 0; 5430 for (j = 0; j < nbuf; j++) 5431 if (buf[j].b_domain == i) { 5432 cnt++; 5433 total += buf[j].b_bufsize; 5434 } 5435 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5436 } 5437 } 5438 5439 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 5440 { 5441 struct buf *bp; 5442 int i; 5443 5444 for (i = 0; i < nbuf; i++) { 5445 bp = &buf[i]; 5446 if (BUF_ISLOCKED(bp)) { 5447 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5448 db_printf("\n"); 5449 if (db_pager_quit) 5450 break; 5451 } 5452 } 5453 } 5454 5455 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5456 { 5457 struct vnode *vp; 5458 struct buf *bp; 5459 5460 if (!have_addr) { 5461 db_printf("usage: show vnodebufs <addr>\n"); 5462 return; 5463 } 5464 vp = (struct vnode *)addr; 5465 db_printf("Clean buffers:\n"); 5466 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5467 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5468 db_printf("\n"); 5469 } 5470 db_printf("Dirty buffers:\n"); 5471 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5472 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5473 db_printf("\n"); 5474 } 5475 } 5476 5477 DB_COMMAND(countfreebufs, db_coundfreebufs) 5478 { 5479 struct buf *bp; 5480 int i, used = 0, nfree = 0; 5481 5482 if (have_addr) { 5483 db_printf("usage: countfreebufs\n"); 5484 return; 5485 } 5486 5487 for (i = 0; i < nbuf; i++) { 5488 bp = &buf[i]; 5489 if (bp->b_qindex == QUEUE_EMPTY) 5490 nfree++; 5491 else 5492 used++; 5493 } 5494 5495 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5496 nfree + used); 5497 db_printf("numfreebuffers is %d\n", numfreebuffers); 5498 } 5499 #endif /* DDB */ 5500