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