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 * Unwire a page held by a buf and either free it or update the page queues to 2899 * reflect its recent use. 2900 */ 2901 static void 2902 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2903 { 2904 bool freed; 2905 2906 vm_page_lock(m); 2907 if (vm_page_unwire_noq(m)) { 2908 if ((bp->b_flags & B_DIRECT) != 0) 2909 freed = vm_page_try_to_free(m); 2910 else 2911 freed = false; 2912 if (!freed) { 2913 /* 2914 * Use a racy check of the valid bits to determine 2915 * whether we can accelerate reclamation of the page. 2916 * The valid bits will be stable unless the page is 2917 * being mapped or is referenced by multiple buffers, 2918 * and in those cases we expect races to be rare. At 2919 * worst we will either accelerate reclamation of a 2920 * valid page and violate LRU, or unnecessarily defer 2921 * reclamation of an invalid page. 2922 * 2923 * The B_NOREUSE flag marks data that is not expected to 2924 * be reused, so accelerate reclamation in that case 2925 * too. Otherwise, maintain LRU. 2926 */ 2927 if (m->valid == 0 || (bp->b_flags & B_NOREUSE) != 0) 2928 vm_page_deactivate_noreuse(m); 2929 else if (vm_page_active(m)) 2930 vm_page_reference(m); 2931 else 2932 vm_page_deactivate(m); 2933 } 2934 } 2935 vm_page_unlock(m); 2936 } 2937 2938 /* 2939 * Perform page invalidation when a buffer is released. The fully invalid 2940 * pages will be reclaimed later in vfs_vmio_truncate(). 2941 */ 2942 static void 2943 vfs_vmio_invalidate(struct buf *bp) 2944 { 2945 vm_object_t obj; 2946 vm_page_t m; 2947 int i, resid, poffset, presid; 2948 2949 if (buf_mapped(bp)) { 2950 BUF_CHECK_MAPPED(bp); 2951 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2952 } else 2953 BUF_CHECK_UNMAPPED(bp); 2954 /* 2955 * Get the base offset and length of the buffer. Note that 2956 * in the VMIO case if the buffer block size is not 2957 * page-aligned then b_data pointer may not be page-aligned. 2958 * But our b_pages[] array *IS* page aligned. 2959 * 2960 * block sizes less then DEV_BSIZE (usually 512) are not 2961 * supported due to the page granularity bits (m->valid, 2962 * m->dirty, etc...). 2963 * 2964 * See man buf(9) for more information 2965 */ 2966 obj = bp->b_bufobj->bo_object; 2967 resid = bp->b_bufsize; 2968 poffset = bp->b_offset & PAGE_MASK; 2969 VM_OBJECT_WLOCK(obj); 2970 for (i = 0; i < bp->b_npages; i++) { 2971 m = bp->b_pages[i]; 2972 if (m == bogus_page) 2973 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2974 bp->b_pages[i] = NULL; 2975 2976 presid = resid > (PAGE_SIZE - poffset) ? 2977 (PAGE_SIZE - poffset) : resid; 2978 KASSERT(presid >= 0, ("brelse: extra page")); 2979 while (vm_page_xbusied(m)) { 2980 vm_page_lock(m); 2981 VM_OBJECT_WUNLOCK(obj); 2982 vm_page_busy_sleep(m, "mbncsh", true); 2983 VM_OBJECT_WLOCK(obj); 2984 } 2985 if (pmap_page_wired_mappings(m) == 0) 2986 vm_page_set_invalid(m, poffset, presid); 2987 vfs_vmio_unwire(bp, m); 2988 resid -= presid; 2989 poffset = 0; 2990 } 2991 VM_OBJECT_WUNLOCK(obj); 2992 bp->b_npages = 0; 2993 } 2994 2995 /* 2996 * Page-granular truncation of an existing VMIO buffer. 2997 */ 2998 static void 2999 vfs_vmio_truncate(struct buf *bp, int desiredpages) 3000 { 3001 vm_object_t obj; 3002 vm_page_t m; 3003 int i; 3004 3005 if (bp->b_npages == desiredpages) 3006 return; 3007 3008 if (buf_mapped(bp)) { 3009 BUF_CHECK_MAPPED(bp); 3010 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 3011 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 3012 } else 3013 BUF_CHECK_UNMAPPED(bp); 3014 3015 /* 3016 * The object lock is needed only if we will attempt to free pages. 3017 */ 3018 obj = (bp->b_flags & B_DIRECT) != 0 ? bp->b_bufobj->bo_object : NULL; 3019 if (obj != NULL) 3020 VM_OBJECT_WLOCK(obj); 3021 for (i = desiredpages; i < bp->b_npages; i++) { 3022 m = bp->b_pages[i]; 3023 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3024 bp->b_pages[i] = NULL; 3025 vfs_vmio_unwire(bp, m); 3026 } 3027 if (obj != NULL) 3028 VM_OBJECT_WUNLOCK(obj); 3029 bp->b_npages = desiredpages; 3030 } 3031 3032 /* 3033 * Byte granular extension of VMIO buffers. 3034 */ 3035 static void 3036 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3037 { 3038 /* 3039 * We are growing the buffer, possibly in a 3040 * byte-granular fashion. 3041 */ 3042 vm_object_t obj; 3043 vm_offset_t toff; 3044 vm_offset_t tinc; 3045 vm_page_t m; 3046 3047 /* 3048 * Step 1, bring in the VM pages from the object, allocating 3049 * them if necessary. We must clear B_CACHE if these pages 3050 * are not valid for the range covered by the buffer. 3051 */ 3052 obj = bp->b_bufobj->bo_object; 3053 VM_OBJECT_WLOCK(obj); 3054 if (bp->b_npages < desiredpages) { 3055 /* 3056 * We must allocate system pages since blocking 3057 * here could interfere with paging I/O, no 3058 * matter which process we are. 3059 * 3060 * Only exclusive busy can be tested here. 3061 * Blocking on shared busy might lead to 3062 * deadlocks once allocbuf() is called after 3063 * pages are vfs_busy_pages(). 3064 */ 3065 (void)vm_page_grab_pages(obj, 3066 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3067 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3068 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3069 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3070 bp->b_npages = desiredpages; 3071 } 3072 3073 /* 3074 * Step 2. We've loaded the pages into the buffer, 3075 * we have to figure out if we can still have B_CACHE 3076 * set. Note that B_CACHE is set according to the 3077 * byte-granular range ( bcount and size ), not the 3078 * aligned range ( newbsize ). 3079 * 3080 * The VM test is against m->valid, which is DEV_BSIZE 3081 * aligned. Needless to say, the validity of the data 3082 * needs to also be DEV_BSIZE aligned. Note that this 3083 * fails with NFS if the server or some other client 3084 * extends the file's EOF. If our buffer is resized, 3085 * B_CACHE may remain set! XXX 3086 */ 3087 toff = bp->b_bcount; 3088 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3089 while ((bp->b_flags & B_CACHE) && toff < size) { 3090 vm_pindex_t pi; 3091 3092 if (tinc > (size - toff)) 3093 tinc = size - toff; 3094 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3095 m = bp->b_pages[pi]; 3096 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3097 toff += tinc; 3098 tinc = PAGE_SIZE; 3099 } 3100 VM_OBJECT_WUNLOCK(obj); 3101 3102 /* 3103 * Step 3, fixup the KVA pmap. 3104 */ 3105 if (buf_mapped(bp)) 3106 bpmap_qenter(bp); 3107 else 3108 BUF_CHECK_UNMAPPED(bp); 3109 } 3110 3111 /* 3112 * Check to see if a block at a particular lbn is available for a clustered 3113 * write. 3114 */ 3115 static int 3116 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3117 { 3118 struct buf *bpa; 3119 int match; 3120 3121 match = 0; 3122 3123 /* If the buf isn't in core skip it */ 3124 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3125 return (0); 3126 3127 /* If the buf is busy we don't want to wait for it */ 3128 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3129 return (0); 3130 3131 /* Only cluster with valid clusterable delayed write buffers */ 3132 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3133 (B_DELWRI | B_CLUSTEROK)) 3134 goto done; 3135 3136 if (bpa->b_bufsize != size) 3137 goto done; 3138 3139 /* 3140 * Check to see if it is in the expected place on disk and that the 3141 * block has been mapped. 3142 */ 3143 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3144 match = 1; 3145 done: 3146 BUF_UNLOCK(bpa); 3147 return (match); 3148 } 3149 3150 /* 3151 * vfs_bio_awrite: 3152 * 3153 * Implement clustered async writes for clearing out B_DELWRI buffers. 3154 * This is much better then the old way of writing only one buffer at 3155 * a time. Note that we may not be presented with the buffers in the 3156 * correct order, so we search for the cluster in both directions. 3157 */ 3158 int 3159 vfs_bio_awrite(struct buf *bp) 3160 { 3161 struct bufobj *bo; 3162 int i; 3163 int j; 3164 daddr_t lblkno = bp->b_lblkno; 3165 struct vnode *vp = bp->b_vp; 3166 int ncl; 3167 int nwritten; 3168 int size; 3169 int maxcl; 3170 int gbflags; 3171 3172 bo = &vp->v_bufobj; 3173 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3174 /* 3175 * right now we support clustered writing only to regular files. If 3176 * we find a clusterable block we could be in the middle of a cluster 3177 * rather then at the beginning. 3178 */ 3179 if ((vp->v_type == VREG) && 3180 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3181 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3182 3183 size = vp->v_mount->mnt_stat.f_iosize; 3184 maxcl = MAXPHYS / size; 3185 3186 BO_RLOCK(bo); 3187 for (i = 1; i < maxcl; i++) 3188 if (vfs_bio_clcheck(vp, size, lblkno + i, 3189 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3190 break; 3191 3192 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3193 if (vfs_bio_clcheck(vp, size, lblkno - j, 3194 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3195 break; 3196 BO_RUNLOCK(bo); 3197 --j; 3198 ncl = i + j; 3199 /* 3200 * this is a possible cluster write 3201 */ 3202 if (ncl != 1) { 3203 BUF_UNLOCK(bp); 3204 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3205 gbflags); 3206 return (nwritten); 3207 } 3208 } 3209 bremfree(bp); 3210 bp->b_flags |= B_ASYNC; 3211 /* 3212 * default (old) behavior, writing out only one block 3213 * 3214 * XXX returns b_bufsize instead of b_bcount for nwritten? 3215 */ 3216 nwritten = bp->b_bufsize; 3217 (void) bwrite(bp); 3218 3219 return (nwritten); 3220 } 3221 3222 /* 3223 * getnewbuf_kva: 3224 * 3225 * Allocate KVA for an empty buf header according to gbflags. 3226 */ 3227 static int 3228 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3229 { 3230 3231 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3232 /* 3233 * In order to keep fragmentation sane we only allocate kva 3234 * in BKVASIZE chunks. XXX with vmem we can do page size. 3235 */ 3236 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3237 3238 if (maxsize != bp->b_kvasize && 3239 bufkva_alloc(bp, maxsize, gbflags)) 3240 return (ENOSPC); 3241 } 3242 return (0); 3243 } 3244 3245 /* 3246 * getnewbuf: 3247 * 3248 * Find and initialize a new buffer header, freeing up existing buffers 3249 * in the bufqueues as necessary. The new buffer is returned locked. 3250 * 3251 * We block if: 3252 * We have insufficient buffer headers 3253 * We have insufficient buffer space 3254 * buffer_arena is too fragmented ( space reservation fails ) 3255 * If we have to flush dirty buffers ( but we try to avoid this ) 3256 * 3257 * The caller is responsible for releasing the reserved bufspace after 3258 * allocbuf() is called. 3259 */ 3260 static struct buf * 3261 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3262 { 3263 struct bufdomain *bd; 3264 struct buf *bp; 3265 bool metadata, reserved; 3266 3267 bp = NULL; 3268 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3269 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3270 if (!unmapped_buf_allowed) 3271 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3272 3273 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3274 vp->v_type == VCHR) 3275 metadata = true; 3276 else 3277 metadata = false; 3278 if (vp == NULL) 3279 bd = &bdomain[0]; 3280 else 3281 bd = &bdomain[vp->v_bufobj.bo_domain]; 3282 3283 counter_u64_add(getnewbufcalls, 1); 3284 reserved = false; 3285 do { 3286 if (reserved == false && 3287 bufspace_reserve(bd, maxsize, metadata) != 0) { 3288 counter_u64_add(getnewbufrestarts, 1); 3289 continue; 3290 } 3291 reserved = true; 3292 if ((bp = buf_alloc(bd)) == NULL) { 3293 counter_u64_add(getnewbufrestarts, 1); 3294 continue; 3295 } 3296 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3297 return (bp); 3298 break; 3299 } while (buf_recycle(bd, false) == 0); 3300 3301 if (reserved) 3302 bufspace_release(bd, maxsize); 3303 if (bp != NULL) { 3304 bp->b_flags |= B_INVAL; 3305 brelse(bp); 3306 } 3307 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3308 3309 return (NULL); 3310 } 3311 3312 /* 3313 * buf_daemon: 3314 * 3315 * buffer flushing daemon. Buffers are normally flushed by the 3316 * update daemon but if it cannot keep up this process starts to 3317 * take the load in an attempt to prevent getnewbuf() from blocking. 3318 */ 3319 static struct kproc_desc buf_kp = { 3320 "bufdaemon", 3321 buf_daemon, 3322 &bufdaemonproc 3323 }; 3324 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3325 3326 static int 3327 buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3328 { 3329 int flushed; 3330 3331 flushed = flushbufqueues(vp, bd, target, 0); 3332 if (flushed == 0) { 3333 /* 3334 * Could not find any buffers without rollback 3335 * dependencies, so just write the first one 3336 * in the hopes of eventually making progress. 3337 */ 3338 if (vp != NULL && target > 2) 3339 target /= 2; 3340 flushbufqueues(vp, bd, target, 1); 3341 } 3342 return (flushed); 3343 } 3344 3345 static void 3346 buf_daemon() 3347 { 3348 struct bufdomain *bd; 3349 int speedupreq; 3350 int lodirty; 3351 int i; 3352 3353 /* 3354 * This process needs to be suspended prior to shutdown sync. 3355 */ 3356 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 3357 SHUTDOWN_PRI_LAST + 100); 3358 3359 /* 3360 * Start the buf clean daemons as children threads. 3361 */ 3362 for (i = 0 ; i < buf_domains; i++) { 3363 int error; 3364 3365 error = kthread_add((void (*)(void *))bufspace_daemon, 3366 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3367 if (error) 3368 panic("error %d spawning bufspace daemon", error); 3369 } 3370 3371 /* 3372 * This process is allowed to take the buffer cache to the limit 3373 */ 3374 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3375 mtx_lock(&bdlock); 3376 for (;;) { 3377 bd_request = 0; 3378 mtx_unlock(&bdlock); 3379 3380 kthread_suspend_check(); 3381 3382 /* 3383 * Save speedupreq for this pass and reset to capture new 3384 * requests. 3385 */ 3386 speedupreq = bd_speedupreq; 3387 bd_speedupreq = 0; 3388 3389 /* 3390 * Flush each domain sequentially according to its level and 3391 * the speedup request. 3392 */ 3393 for (i = 0; i < buf_domains; i++) { 3394 bd = &bdomain[i]; 3395 if (speedupreq) 3396 lodirty = bd->bd_numdirtybuffers / 2; 3397 else 3398 lodirty = bd->bd_lodirtybuffers; 3399 while (bd->bd_numdirtybuffers > lodirty) { 3400 if (buf_flush(NULL, bd, 3401 bd->bd_numdirtybuffers - lodirty) == 0) 3402 break; 3403 kern_yield(PRI_USER); 3404 } 3405 } 3406 3407 /* 3408 * Only clear bd_request if we have reached our low water 3409 * mark. The buf_daemon normally waits 1 second and 3410 * then incrementally flushes any dirty buffers that have 3411 * built up, within reason. 3412 * 3413 * If we were unable to hit our low water mark and couldn't 3414 * find any flushable buffers, we sleep for a short period 3415 * to avoid endless loops on unlockable buffers. 3416 */ 3417 mtx_lock(&bdlock); 3418 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3419 /* 3420 * We reached our low water mark, reset the 3421 * request and sleep until we are needed again. 3422 * The sleep is just so the suspend code works. 3423 */ 3424 bd_request = 0; 3425 /* 3426 * Do an extra wakeup in case dirty threshold 3427 * changed via sysctl and the explicit transition 3428 * out of shortfall was missed. 3429 */ 3430 bdirtywakeup(); 3431 if (runningbufspace <= lorunningspace) 3432 runningwakeup(); 3433 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3434 } else { 3435 /* 3436 * We couldn't find any flushable dirty buffers but 3437 * still have too many dirty buffers, we 3438 * have to sleep and try again. (rare) 3439 */ 3440 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3441 } 3442 } 3443 } 3444 3445 /* 3446 * flushbufqueues: 3447 * 3448 * Try to flush a buffer in the dirty queue. We must be careful to 3449 * free up B_INVAL buffers instead of write them, which NFS is 3450 * particularly sensitive to. 3451 */ 3452 static int flushwithdeps = 0; 3453 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3454 0, "Number of buffers flushed with dependecies that require rollbacks"); 3455 3456 static int 3457 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3458 int flushdeps) 3459 { 3460 struct bufqueue *bq; 3461 struct buf *sentinel; 3462 struct vnode *vp; 3463 struct mount *mp; 3464 struct buf *bp; 3465 int hasdeps; 3466 int flushed; 3467 int error; 3468 bool unlock; 3469 3470 flushed = 0; 3471 bq = &bd->bd_dirtyq; 3472 bp = NULL; 3473 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3474 sentinel->b_qindex = QUEUE_SENTINEL; 3475 BQ_LOCK(bq); 3476 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3477 BQ_UNLOCK(bq); 3478 while (flushed != target) { 3479 maybe_yield(); 3480 BQ_LOCK(bq); 3481 bp = TAILQ_NEXT(sentinel, b_freelist); 3482 if (bp != NULL) { 3483 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3484 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3485 b_freelist); 3486 } else { 3487 BQ_UNLOCK(bq); 3488 break; 3489 } 3490 /* 3491 * Skip sentinels inserted by other invocations of the 3492 * flushbufqueues(), taking care to not reorder them. 3493 * 3494 * Only flush the buffers that belong to the 3495 * vnode locked by the curthread. 3496 */ 3497 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3498 bp->b_vp != lvp)) { 3499 BQ_UNLOCK(bq); 3500 continue; 3501 } 3502 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3503 BQ_UNLOCK(bq); 3504 if (error != 0) 3505 continue; 3506 3507 /* 3508 * BKGRDINPROG can only be set with the buf and bufobj 3509 * locks both held. We tolerate a race to clear it here. 3510 */ 3511 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3512 (bp->b_flags & B_DELWRI) == 0) { 3513 BUF_UNLOCK(bp); 3514 continue; 3515 } 3516 if (bp->b_flags & B_INVAL) { 3517 bremfreef(bp); 3518 brelse(bp); 3519 flushed++; 3520 continue; 3521 } 3522 3523 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3524 if (flushdeps == 0) { 3525 BUF_UNLOCK(bp); 3526 continue; 3527 } 3528 hasdeps = 1; 3529 } else 3530 hasdeps = 0; 3531 /* 3532 * We must hold the lock on a vnode before writing 3533 * one of its buffers. Otherwise we may confuse, or 3534 * in the case of a snapshot vnode, deadlock the 3535 * system. 3536 * 3537 * The lock order here is the reverse of the normal 3538 * of vnode followed by buf lock. This is ok because 3539 * the NOWAIT will prevent deadlock. 3540 */ 3541 vp = bp->b_vp; 3542 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3543 BUF_UNLOCK(bp); 3544 continue; 3545 } 3546 if (lvp == NULL) { 3547 unlock = true; 3548 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3549 } else { 3550 ASSERT_VOP_LOCKED(vp, "getbuf"); 3551 unlock = false; 3552 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3553 vn_lock(vp, LK_TRYUPGRADE); 3554 } 3555 if (error == 0) { 3556 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3557 bp, bp->b_vp, bp->b_flags); 3558 if (curproc == bufdaemonproc) { 3559 vfs_bio_awrite(bp); 3560 } else { 3561 bremfree(bp); 3562 bwrite(bp); 3563 counter_u64_add(notbufdflushes, 1); 3564 } 3565 vn_finished_write(mp); 3566 if (unlock) 3567 VOP_UNLOCK(vp, 0); 3568 flushwithdeps += hasdeps; 3569 flushed++; 3570 3571 /* 3572 * Sleeping on runningbufspace while holding 3573 * vnode lock leads to deadlock. 3574 */ 3575 if (curproc == bufdaemonproc && 3576 runningbufspace > hirunningspace) 3577 waitrunningbufspace(); 3578 continue; 3579 } 3580 vn_finished_write(mp); 3581 BUF_UNLOCK(bp); 3582 } 3583 BQ_LOCK(bq); 3584 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3585 BQ_UNLOCK(bq); 3586 free(sentinel, M_TEMP); 3587 return (flushed); 3588 } 3589 3590 /* 3591 * Check to see if a block is currently memory resident. 3592 */ 3593 struct buf * 3594 incore(struct bufobj *bo, daddr_t blkno) 3595 { 3596 struct buf *bp; 3597 3598 BO_RLOCK(bo); 3599 bp = gbincore(bo, blkno); 3600 BO_RUNLOCK(bo); 3601 return (bp); 3602 } 3603 3604 /* 3605 * Returns true if no I/O is needed to access the 3606 * associated VM object. This is like incore except 3607 * it also hunts around in the VM system for the data. 3608 */ 3609 3610 static int 3611 inmem(struct vnode * vp, daddr_t blkno) 3612 { 3613 vm_object_t obj; 3614 vm_offset_t toff, tinc, size; 3615 vm_page_t m; 3616 vm_ooffset_t off; 3617 3618 ASSERT_VOP_LOCKED(vp, "inmem"); 3619 3620 if (incore(&vp->v_bufobj, blkno)) 3621 return 1; 3622 if (vp->v_mount == NULL) 3623 return 0; 3624 obj = vp->v_object; 3625 if (obj == NULL) 3626 return (0); 3627 3628 size = PAGE_SIZE; 3629 if (size > vp->v_mount->mnt_stat.f_iosize) 3630 size = vp->v_mount->mnt_stat.f_iosize; 3631 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3632 3633 VM_OBJECT_RLOCK(obj); 3634 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3635 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3636 if (!m) 3637 goto notinmem; 3638 tinc = size; 3639 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3640 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3641 if (vm_page_is_valid(m, 3642 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3643 goto notinmem; 3644 } 3645 VM_OBJECT_RUNLOCK(obj); 3646 return 1; 3647 3648 notinmem: 3649 VM_OBJECT_RUNLOCK(obj); 3650 return (0); 3651 } 3652 3653 /* 3654 * Set the dirty range for a buffer based on the status of the dirty 3655 * bits in the pages comprising the buffer. The range is limited 3656 * to the size of the buffer. 3657 * 3658 * Tell the VM system that the pages associated with this buffer 3659 * are clean. This is used for delayed writes where the data is 3660 * going to go to disk eventually without additional VM intevention. 3661 * 3662 * Note that while we only really need to clean through to b_bcount, we 3663 * just go ahead and clean through to b_bufsize. 3664 */ 3665 static void 3666 vfs_clean_pages_dirty_buf(struct buf *bp) 3667 { 3668 vm_ooffset_t foff, noff, eoff; 3669 vm_page_t m; 3670 int i; 3671 3672 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3673 return; 3674 3675 foff = bp->b_offset; 3676 KASSERT(bp->b_offset != NOOFFSET, 3677 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3678 3679 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3680 vfs_drain_busy_pages(bp); 3681 vfs_setdirty_locked_object(bp); 3682 for (i = 0; i < bp->b_npages; i++) { 3683 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3684 eoff = noff; 3685 if (eoff > bp->b_offset + bp->b_bufsize) 3686 eoff = bp->b_offset + bp->b_bufsize; 3687 m = bp->b_pages[i]; 3688 vfs_page_set_validclean(bp, foff, m); 3689 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3690 foff = noff; 3691 } 3692 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3693 } 3694 3695 static void 3696 vfs_setdirty_locked_object(struct buf *bp) 3697 { 3698 vm_object_t object; 3699 int i; 3700 3701 object = bp->b_bufobj->bo_object; 3702 VM_OBJECT_ASSERT_WLOCKED(object); 3703 3704 /* 3705 * We qualify the scan for modified pages on whether the 3706 * object has been flushed yet. 3707 */ 3708 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3709 vm_offset_t boffset; 3710 vm_offset_t eoffset; 3711 3712 /* 3713 * test the pages to see if they have been modified directly 3714 * by users through the VM system. 3715 */ 3716 for (i = 0; i < bp->b_npages; i++) 3717 vm_page_test_dirty(bp->b_pages[i]); 3718 3719 /* 3720 * Calculate the encompassing dirty range, boffset and eoffset, 3721 * (eoffset - boffset) bytes. 3722 */ 3723 3724 for (i = 0; i < bp->b_npages; i++) { 3725 if (bp->b_pages[i]->dirty) 3726 break; 3727 } 3728 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3729 3730 for (i = bp->b_npages - 1; i >= 0; --i) { 3731 if (bp->b_pages[i]->dirty) { 3732 break; 3733 } 3734 } 3735 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3736 3737 /* 3738 * Fit it to the buffer. 3739 */ 3740 3741 if (eoffset > bp->b_bcount) 3742 eoffset = bp->b_bcount; 3743 3744 /* 3745 * If we have a good dirty range, merge with the existing 3746 * dirty range. 3747 */ 3748 3749 if (boffset < eoffset) { 3750 if (bp->b_dirtyoff > boffset) 3751 bp->b_dirtyoff = boffset; 3752 if (bp->b_dirtyend < eoffset) 3753 bp->b_dirtyend = eoffset; 3754 } 3755 } 3756 } 3757 3758 /* 3759 * Allocate the KVA mapping for an existing buffer. 3760 * If an unmapped buffer is provided but a mapped buffer is requested, take 3761 * also care to properly setup mappings between pages and KVA. 3762 */ 3763 static void 3764 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3765 { 3766 int bsize, maxsize, need_mapping, need_kva; 3767 off_t offset; 3768 3769 need_mapping = bp->b_data == unmapped_buf && 3770 (gbflags & GB_UNMAPPED) == 0; 3771 need_kva = bp->b_kvabase == unmapped_buf && 3772 bp->b_data == unmapped_buf && 3773 (gbflags & GB_KVAALLOC) != 0; 3774 if (!need_mapping && !need_kva) 3775 return; 3776 3777 BUF_CHECK_UNMAPPED(bp); 3778 3779 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3780 /* 3781 * Buffer is not mapped, but the KVA was already 3782 * reserved at the time of the instantiation. Use the 3783 * allocated space. 3784 */ 3785 goto has_addr; 3786 } 3787 3788 /* 3789 * Calculate the amount of the address space we would reserve 3790 * if the buffer was mapped. 3791 */ 3792 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3793 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3794 offset = blkno * bsize; 3795 maxsize = size + (offset & PAGE_MASK); 3796 maxsize = imax(maxsize, bsize); 3797 3798 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3799 if ((gbflags & GB_NOWAIT_BD) != 0) { 3800 /* 3801 * XXXKIB: defragmentation cannot 3802 * succeed, not sure what else to do. 3803 */ 3804 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3805 } 3806 counter_u64_add(mappingrestarts, 1); 3807 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3808 } 3809 has_addr: 3810 if (need_mapping) { 3811 /* b_offset is handled by bpmap_qenter. */ 3812 bp->b_data = bp->b_kvabase; 3813 BUF_CHECK_MAPPED(bp); 3814 bpmap_qenter(bp); 3815 } 3816 } 3817 3818 struct buf * 3819 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3820 int flags) 3821 { 3822 struct buf *bp; 3823 int error; 3824 3825 error = getblkx(vp, blkno, size, slpflag, slptimeo, flags, &bp); 3826 if (error != 0) 3827 return (NULL); 3828 return (bp); 3829 } 3830 3831 /* 3832 * getblkx: 3833 * 3834 * Get a block given a specified block and offset into a file/device. 3835 * The buffers B_DONE bit will be cleared on return, making it almost 3836 * ready for an I/O initiation. B_INVAL may or may not be set on 3837 * return. The caller should clear B_INVAL prior to initiating a 3838 * READ. 3839 * 3840 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3841 * an existing buffer. 3842 * 3843 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3844 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3845 * and then cleared based on the backing VM. If the previous buffer is 3846 * non-0-sized but invalid, B_CACHE will be cleared. 3847 * 3848 * If getblk() must create a new buffer, the new buffer is returned with 3849 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3850 * case it is returned with B_INVAL clear and B_CACHE set based on the 3851 * backing VM. 3852 * 3853 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3854 * B_CACHE bit is clear. 3855 * 3856 * What this means, basically, is that the caller should use B_CACHE to 3857 * determine whether the buffer is fully valid or not and should clear 3858 * B_INVAL prior to issuing a read. If the caller intends to validate 3859 * the buffer by loading its data area with something, the caller needs 3860 * to clear B_INVAL. If the caller does this without issuing an I/O, 3861 * the caller should set B_CACHE ( as an optimization ), else the caller 3862 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3863 * a write attempt or if it was a successful read. If the caller 3864 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3865 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3866 */ 3867 int 3868 getblkx(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3869 int flags, struct buf **bpp) 3870 { 3871 struct buf *bp; 3872 struct bufobj *bo; 3873 daddr_t d_blkno; 3874 int bsize, error, maxsize, vmio; 3875 off_t offset; 3876 3877 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3878 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3879 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3880 ASSERT_VOP_LOCKED(vp, "getblk"); 3881 if (size > maxbcachebuf) 3882 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3883 maxbcachebuf); 3884 if (!unmapped_buf_allowed) 3885 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3886 3887 bo = &vp->v_bufobj; 3888 d_blkno = blkno; 3889 loop: 3890 BO_RLOCK(bo); 3891 bp = gbincore(bo, blkno); 3892 if (bp != NULL) { 3893 int lockflags; 3894 /* 3895 * Buffer is in-core. If the buffer is not busy nor managed, 3896 * it must be on a queue. 3897 */ 3898 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3899 3900 if ((flags & GB_LOCK_NOWAIT) != 0) 3901 lockflags |= LK_NOWAIT; 3902 3903 error = BUF_TIMELOCK(bp, lockflags, 3904 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3905 3906 /* 3907 * If we slept and got the lock we have to restart in case 3908 * the buffer changed identities. 3909 */ 3910 if (error == ENOLCK) 3911 goto loop; 3912 /* We timed out or were interrupted. */ 3913 else if (error != 0) 3914 return (error); 3915 /* If recursed, assume caller knows the rules. */ 3916 else if (BUF_LOCKRECURSED(bp)) 3917 goto end; 3918 3919 /* 3920 * The buffer is locked. B_CACHE is cleared if the buffer is 3921 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3922 * and for a VMIO buffer B_CACHE is adjusted according to the 3923 * backing VM cache. 3924 */ 3925 if (bp->b_flags & B_INVAL) 3926 bp->b_flags &= ~B_CACHE; 3927 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3928 bp->b_flags |= B_CACHE; 3929 if (bp->b_flags & B_MANAGED) 3930 MPASS(bp->b_qindex == QUEUE_NONE); 3931 else 3932 bremfree(bp); 3933 3934 /* 3935 * check for size inconsistencies for non-VMIO case. 3936 */ 3937 if (bp->b_bcount != size) { 3938 if ((bp->b_flags & B_VMIO) == 0 || 3939 (size > bp->b_kvasize)) { 3940 if (bp->b_flags & B_DELWRI) { 3941 bp->b_flags |= B_NOCACHE; 3942 bwrite(bp); 3943 } else { 3944 if (LIST_EMPTY(&bp->b_dep)) { 3945 bp->b_flags |= B_RELBUF; 3946 brelse(bp); 3947 } else { 3948 bp->b_flags |= B_NOCACHE; 3949 bwrite(bp); 3950 } 3951 } 3952 goto loop; 3953 } 3954 } 3955 3956 /* 3957 * Handle the case of unmapped buffer which should 3958 * become mapped, or the buffer for which KVA 3959 * reservation is requested. 3960 */ 3961 bp_unmapped_get_kva(bp, blkno, size, flags); 3962 3963 /* 3964 * If the size is inconsistent in the VMIO case, we can resize 3965 * the buffer. This might lead to B_CACHE getting set or 3966 * cleared. If the size has not changed, B_CACHE remains 3967 * unchanged from its previous state. 3968 */ 3969 allocbuf(bp, size); 3970 3971 KASSERT(bp->b_offset != NOOFFSET, 3972 ("getblk: no buffer offset")); 3973 3974 /* 3975 * A buffer with B_DELWRI set and B_CACHE clear must 3976 * be committed before we can return the buffer in 3977 * order to prevent the caller from issuing a read 3978 * ( due to B_CACHE not being set ) and overwriting 3979 * it. 3980 * 3981 * Most callers, including NFS and FFS, need this to 3982 * operate properly either because they assume they 3983 * can issue a read if B_CACHE is not set, or because 3984 * ( for example ) an uncached B_DELWRI might loop due 3985 * to softupdates re-dirtying the buffer. In the latter 3986 * case, B_CACHE is set after the first write completes, 3987 * preventing further loops. 3988 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3989 * above while extending the buffer, we cannot allow the 3990 * buffer to remain with B_CACHE set after the write 3991 * completes or it will represent a corrupt state. To 3992 * deal with this we set B_NOCACHE to scrap the buffer 3993 * after the write. 3994 * 3995 * We might be able to do something fancy, like setting 3996 * B_CACHE in bwrite() except if B_DELWRI is already set, 3997 * so the below call doesn't set B_CACHE, but that gets real 3998 * confusing. This is much easier. 3999 */ 4000 4001 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 4002 bp->b_flags |= B_NOCACHE; 4003 bwrite(bp); 4004 goto loop; 4005 } 4006 bp->b_flags &= ~B_DONE; 4007 } else { 4008 /* 4009 * Buffer is not in-core, create new buffer. The buffer 4010 * returned by getnewbuf() is locked. Note that the returned 4011 * buffer is also considered valid (not marked B_INVAL). 4012 */ 4013 BO_RUNLOCK(bo); 4014 /* 4015 * If the user does not want us to create the buffer, bail out 4016 * here. 4017 */ 4018 if (flags & GB_NOCREAT) 4019 return (EEXIST); 4020 4021 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 4022 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4023 offset = blkno * bsize; 4024 vmio = vp->v_object != NULL; 4025 if (vmio) { 4026 maxsize = size + (offset & PAGE_MASK); 4027 } else { 4028 maxsize = size; 4029 /* Do not allow non-VMIO notmapped buffers. */ 4030 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4031 } 4032 maxsize = imax(maxsize, bsize); 4033 if ((flags & GB_NOSPARSE) != 0 && vmio && 4034 !vn_isdisk(vp, NULL)) { 4035 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4036 KASSERT(error != EOPNOTSUPP, 4037 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4038 vp)); 4039 if (error != 0) 4040 return (error); 4041 if (d_blkno == -1) 4042 return (EJUSTRETURN); 4043 } 4044 4045 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4046 if (bp == NULL) { 4047 if (slpflag || slptimeo) 4048 return (ETIMEDOUT); 4049 /* 4050 * XXX This is here until the sleep path is diagnosed 4051 * enough to work under very low memory conditions. 4052 * 4053 * There's an issue on low memory, 4BSD+non-preempt 4054 * systems (eg MIPS routers with 32MB RAM) where buffer 4055 * exhaustion occurs without sleeping for buffer 4056 * reclaimation. This just sticks in a loop and 4057 * constantly attempts to allocate a buffer, which 4058 * hits exhaustion and tries to wakeup bufdaemon. 4059 * This never happens because we never yield. 4060 * 4061 * The real solution is to identify and fix these cases 4062 * so we aren't effectively busy-waiting in a loop 4063 * until the reclaimation path has cycles to run. 4064 */ 4065 kern_yield(PRI_USER); 4066 goto loop; 4067 } 4068 4069 /* 4070 * This code is used to make sure that a buffer is not 4071 * created while the getnewbuf routine is blocked. 4072 * This can be a problem whether the vnode is locked or not. 4073 * If the buffer is created out from under us, we have to 4074 * throw away the one we just created. 4075 * 4076 * Note: this must occur before we associate the buffer 4077 * with the vp especially considering limitations in 4078 * the splay tree implementation when dealing with duplicate 4079 * lblkno's. 4080 */ 4081 BO_LOCK(bo); 4082 if (gbincore(bo, blkno)) { 4083 BO_UNLOCK(bo); 4084 bp->b_flags |= B_INVAL; 4085 bufspace_release(bufdomain(bp), maxsize); 4086 brelse(bp); 4087 goto loop; 4088 } 4089 4090 /* 4091 * Insert the buffer into the hash, so that it can 4092 * be found by incore. 4093 */ 4094 bp->b_lblkno = blkno; 4095 bp->b_blkno = d_blkno; 4096 bp->b_offset = offset; 4097 bgetvp(vp, bp); 4098 BO_UNLOCK(bo); 4099 4100 /* 4101 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4102 * buffer size starts out as 0, B_CACHE will be set by 4103 * allocbuf() for the VMIO case prior to it testing the 4104 * backing store for validity. 4105 */ 4106 4107 if (vmio) { 4108 bp->b_flags |= B_VMIO; 4109 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4110 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4111 bp, vp->v_object, bp->b_bufobj->bo_object)); 4112 } else { 4113 bp->b_flags &= ~B_VMIO; 4114 KASSERT(bp->b_bufobj->bo_object == NULL, 4115 ("ARGH! has b_bufobj->bo_object %p %p\n", 4116 bp, bp->b_bufobj->bo_object)); 4117 BUF_CHECK_MAPPED(bp); 4118 } 4119 4120 allocbuf(bp, size); 4121 bufspace_release(bufdomain(bp), maxsize); 4122 bp->b_flags &= ~B_DONE; 4123 } 4124 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4125 BUF_ASSERT_HELD(bp); 4126 end: 4127 buf_track(bp, __func__); 4128 KASSERT(bp->b_bufobj == bo, 4129 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4130 *bpp = bp; 4131 return (0); 4132 } 4133 4134 /* 4135 * Get an empty, disassociated buffer of given size. The buffer is initially 4136 * set to B_INVAL. 4137 */ 4138 struct buf * 4139 geteblk(int size, int flags) 4140 { 4141 struct buf *bp; 4142 int maxsize; 4143 4144 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4145 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4146 if ((flags & GB_NOWAIT_BD) && 4147 (curthread->td_pflags & TDP_BUFNEED) != 0) 4148 return (NULL); 4149 } 4150 allocbuf(bp, size); 4151 bufspace_release(bufdomain(bp), maxsize); 4152 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4153 BUF_ASSERT_HELD(bp); 4154 return (bp); 4155 } 4156 4157 /* 4158 * Truncate the backing store for a non-vmio buffer. 4159 */ 4160 static void 4161 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4162 { 4163 4164 if (bp->b_flags & B_MALLOC) { 4165 /* 4166 * malloced buffers are not shrunk 4167 */ 4168 if (newbsize == 0) { 4169 bufmallocadjust(bp, 0); 4170 free(bp->b_data, M_BIOBUF); 4171 bp->b_data = bp->b_kvabase; 4172 bp->b_flags &= ~B_MALLOC; 4173 } 4174 return; 4175 } 4176 vm_hold_free_pages(bp, newbsize); 4177 bufspace_adjust(bp, newbsize); 4178 } 4179 4180 /* 4181 * Extend the backing for a non-VMIO buffer. 4182 */ 4183 static void 4184 vfs_nonvmio_extend(struct buf *bp, int newbsize) 4185 { 4186 caddr_t origbuf; 4187 int origbufsize; 4188 4189 /* 4190 * We only use malloced memory on the first allocation. 4191 * and revert to page-allocated memory when the buffer 4192 * grows. 4193 * 4194 * There is a potential smp race here that could lead 4195 * to bufmallocspace slightly passing the max. It 4196 * is probably extremely rare and not worth worrying 4197 * over. 4198 */ 4199 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4200 bufmallocspace < maxbufmallocspace) { 4201 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4202 bp->b_flags |= B_MALLOC; 4203 bufmallocadjust(bp, newbsize); 4204 return; 4205 } 4206 4207 /* 4208 * If the buffer is growing on its other-than-first 4209 * allocation then we revert to the page-allocation 4210 * scheme. 4211 */ 4212 origbuf = NULL; 4213 origbufsize = 0; 4214 if (bp->b_flags & B_MALLOC) { 4215 origbuf = bp->b_data; 4216 origbufsize = bp->b_bufsize; 4217 bp->b_data = bp->b_kvabase; 4218 bufmallocadjust(bp, 0); 4219 bp->b_flags &= ~B_MALLOC; 4220 newbsize = round_page(newbsize); 4221 } 4222 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4223 (vm_offset_t) bp->b_data + newbsize); 4224 if (origbuf != NULL) { 4225 bcopy(origbuf, bp->b_data, origbufsize); 4226 free(origbuf, M_BIOBUF); 4227 } 4228 bufspace_adjust(bp, newbsize); 4229 } 4230 4231 /* 4232 * This code constitutes the buffer memory from either anonymous system 4233 * memory (in the case of non-VMIO operations) or from an associated 4234 * VM object (in the case of VMIO operations). This code is able to 4235 * resize a buffer up or down. 4236 * 4237 * Note that this code is tricky, and has many complications to resolve 4238 * deadlock or inconsistent data situations. Tread lightly!!! 4239 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4240 * the caller. Calling this code willy nilly can result in the loss of data. 4241 * 4242 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4243 * B_CACHE for the non-VMIO case. 4244 */ 4245 int 4246 allocbuf(struct buf *bp, int size) 4247 { 4248 int newbsize; 4249 4250 BUF_ASSERT_HELD(bp); 4251 4252 if (bp->b_bcount == size) 4253 return (1); 4254 4255 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 4256 panic("allocbuf: buffer too small"); 4257 4258 newbsize = roundup2(size, DEV_BSIZE); 4259 if ((bp->b_flags & B_VMIO) == 0) { 4260 if ((bp->b_flags & B_MALLOC) == 0) 4261 newbsize = round_page(newbsize); 4262 /* 4263 * Just get anonymous memory from the kernel. Don't 4264 * mess with B_CACHE. 4265 */ 4266 if (newbsize < bp->b_bufsize) 4267 vfs_nonvmio_truncate(bp, newbsize); 4268 else if (newbsize > bp->b_bufsize) 4269 vfs_nonvmio_extend(bp, newbsize); 4270 } else { 4271 int desiredpages; 4272 4273 desiredpages = (size == 0) ? 0 : 4274 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4275 4276 if (bp->b_flags & B_MALLOC) 4277 panic("allocbuf: VMIO buffer can't be malloced"); 4278 /* 4279 * Set B_CACHE initially if buffer is 0 length or will become 4280 * 0-length. 4281 */ 4282 if (size == 0 || bp->b_bufsize == 0) 4283 bp->b_flags |= B_CACHE; 4284 4285 if (newbsize < bp->b_bufsize) 4286 vfs_vmio_truncate(bp, desiredpages); 4287 /* XXX This looks as if it should be newbsize > b_bufsize */ 4288 else if (size > bp->b_bcount) 4289 vfs_vmio_extend(bp, desiredpages, size); 4290 bufspace_adjust(bp, newbsize); 4291 } 4292 bp->b_bcount = size; /* requested buffer size. */ 4293 return (1); 4294 } 4295 4296 extern int inflight_transient_maps; 4297 4298 static struct bio_queue nondump_bios; 4299 4300 void 4301 biodone(struct bio *bp) 4302 { 4303 struct mtx *mtxp; 4304 void (*done)(struct bio *); 4305 vm_offset_t start, end; 4306 4307 biotrack(bp, __func__); 4308 4309 /* 4310 * Avoid completing I/O when dumping after a panic since that may 4311 * result in a deadlock in the filesystem or pager code. Note that 4312 * this doesn't affect dumps that were started manually since we aim 4313 * to keep the system usable after it has been resumed. 4314 */ 4315 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4316 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4317 return; 4318 } 4319 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4320 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4321 bp->bio_flags |= BIO_UNMAPPED; 4322 start = trunc_page((vm_offset_t)bp->bio_data); 4323 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4324 bp->bio_data = unmapped_buf; 4325 pmap_qremove(start, atop(end - start)); 4326 vmem_free(transient_arena, start, end - start); 4327 atomic_add_int(&inflight_transient_maps, -1); 4328 } 4329 done = bp->bio_done; 4330 if (done == NULL) { 4331 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4332 mtx_lock(mtxp); 4333 bp->bio_flags |= BIO_DONE; 4334 wakeup(bp); 4335 mtx_unlock(mtxp); 4336 } else 4337 done(bp); 4338 } 4339 4340 /* 4341 * Wait for a BIO to finish. 4342 */ 4343 int 4344 biowait(struct bio *bp, const char *wchan) 4345 { 4346 struct mtx *mtxp; 4347 4348 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4349 mtx_lock(mtxp); 4350 while ((bp->bio_flags & BIO_DONE) == 0) 4351 msleep(bp, mtxp, PRIBIO, wchan, 0); 4352 mtx_unlock(mtxp); 4353 if (bp->bio_error != 0) 4354 return (bp->bio_error); 4355 if (!(bp->bio_flags & BIO_ERROR)) 4356 return (0); 4357 return (EIO); 4358 } 4359 4360 void 4361 biofinish(struct bio *bp, struct devstat *stat, int error) 4362 { 4363 4364 if (error) { 4365 bp->bio_error = error; 4366 bp->bio_flags |= BIO_ERROR; 4367 } 4368 if (stat != NULL) 4369 devstat_end_transaction_bio(stat, bp); 4370 biodone(bp); 4371 } 4372 4373 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4374 void 4375 biotrack_buf(struct bio *bp, const char *location) 4376 { 4377 4378 buf_track(bp->bio_track_bp, location); 4379 } 4380 #endif 4381 4382 /* 4383 * bufwait: 4384 * 4385 * Wait for buffer I/O completion, returning error status. The buffer 4386 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4387 * error and cleared. 4388 */ 4389 int 4390 bufwait(struct buf *bp) 4391 { 4392 if (bp->b_iocmd == BIO_READ) 4393 bwait(bp, PRIBIO, "biord"); 4394 else 4395 bwait(bp, PRIBIO, "biowr"); 4396 if (bp->b_flags & B_EINTR) { 4397 bp->b_flags &= ~B_EINTR; 4398 return (EINTR); 4399 } 4400 if (bp->b_ioflags & BIO_ERROR) { 4401 return (bp->b_error ? bp->b_error : EIO); 4402 } else { 4403 return (0); 4404 } 4405 } 4406 4407 /* 4408 * bufdone: 4409 * 4410 * Finish I/O on a buffer, optionally calling a completion function. 4411 * This is usually called from an interrupt so process blocking is 4412 * not allowed. 4413 * 4414 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4415 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4416 * assuming B_INVAL is clear. 4417 * 4418 * For the VMIO case, we set B_CACHE if the op was a read and no 4419 * read error occurred, or if the op was a write. B_CACHE is never 4420 * set if the buffer is invalid or otherwise uncacheable. 4421 * 4422 * bufdone does not mess with B_INVAL, allowing the I/O routine or the 4423 * initiator to leave B_INVAL set to brelse the buffer out of existence 4424 * in the biodone routine. 4425 */ 4426 void 4427 bufdone(struct buf *bp) 4428 { 4429 struct bufobj *dropobj; 4430 void (*biodone)(struct buf *); 4431 4432 buf_track(bp, __func__); 4433 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4434 dropobj = NULL; 4435 4436 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4437 BUF_ASSERT_HELD(bp); 4438 4439 runningbufwakeup(bp); 4440 if (bp->b_iocmd == BIO_WRITE) 4441 dropobj = bp->b_bufobj; 4442 /* call optional completion function if requested */ 4443 if (bp->b_iodone != NULL) { 4444 biodone = bp->b_iodone; 4445 bp->b_iodone = NULL; 4446 (*biodone) (bp); 4447 if (dropobj) 4448 bufobj_wdrop(dropobj); 4449 return; 4450 } 4451 if (bp->b_flags & B_VMIO) { 4452 /* 4453 * Set B_CACHE if the op was a normal read and no error 4454 * occurred. B_CACHE is set for writes in the b*write() 4455 * routines. 4456 */ 4457 if (bp->b_iocmd == BIO_READ && 4458 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4459 !(bp->b_ioflags & BIO_ERROR)) 4460 bp->b_flags |= B_CACHE; 4461 vfs_vmio_iodone(bp); 4462 } 4463 if (!LIST_EMPTY(&bp->b_dep)) 4464 buf_complete(bp); 4465 if ((bp->b_flags & B_CKHASH) != 0) { 4466 KASSERT(bp->b_iocmd == BIO_READ, 4467 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4468 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4469 (*bp->b_ckhashcalc)(bp); 4470 } 4471 /* 4472 * For asynchronous completions, release the buffer now. The brelse 4473 * will do a wakeup there if necessary - so no need to do a wakeup 4474 * here in the async case. The sync case always needs to do a wakeup. 4475 */ 4476 if (bp->b_flags & B_ASYNC) { 4477 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4478 (bp->b_ioflags & BIO_ERROR)) 4479 brelse(bp); 4480 else 4481 bqrelse(bp); 4482 } else 4483 bdone(bp); 4484 if (dropobj) 4485 bufobj_wdrop(dropobj); 4486 } 4487 4488 /* 4489 * This routine is called in lieu of iodone in the case of 4490 * incomplete I/O. This keeps the busy status for pages 4491 * consistent. 4492 */ 4493 void 4494 vfs_unbusy_pages(struct buf *bp) 4495 { 4496 int i; 4497 vm_object_t obj; 4498 vm_page_t m; 4499 4500 runningbufwakeup(bp); 4501 if (!(bp->b_flags & B_VMIO)) 4502 return; 4503 4504 obj = bp->b_bufobj->bo_object; 4505 VM_OBJECT_WLOCK(obj); 4506 for (i = 0; i < bp->b_npages; i++) { 4507 m = bp->b_pages[i]; 4508 if (m == bogus_page) { 4509 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4510 if (!m) 4511 panic("vfs_unbusy_pages: page missing\n"); 4512 bp->b_pages[i] = m; 4513 if (buf_mapped(bp)) { 4514 BUF_CHECK_MAPPED(bp); 4515 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4516 bp->b_pages, bp->b_npages); 4517 } else 4518 BUF_CHECK_UNMAPPED(bp); 4519 } 4520 vm_page_sunbusy(m); 4521 } 4522 vm_object_pip_wakeupn(obj, bp->b_npages); 4523 VM_OBJECT_WUNLOCK(obj); 4524 } 4525 4526 /* 4527 * vfs_page_set_valid: 4528 * 4529 * Set the valid bits in a page based on the supplied offset. The 4530 * range is restricted to the buffer's size. 4531 * 4532 * This routine is typically called after a read completes. 4533 */ 4534 static void 4535 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4536 { 4537 vm_ooffset_t eoff; 4538 4539 /* 4540 * Compute the end offset, eoff, such that [off, eoff) does not span a 4541 * page boundary and eoff is not greater than the end of the buffer. 4542 * The end of the buffer, in this case, is our file EOF, not the 4543 * allocation size of the buffer. 4544 */ 4545 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4546 if (eoff > bp->b_offset + bp->b_bcount) 4547 eoff = bp->b_offset + bp->b_bcount; 4548 4549 /* 4550 * Set valid range. This is typically the entire buffer and thus the 4551 * entire page. 4552 */ 4553 if (eoff > off) 4554 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4555 } 4556 4557 /* 4558 * vfs_page_set_validclean: 4559 * 4560 * Set the valid bits and clear the dirty bits in a page based on the 4561 * supplied offset. The range is restricted to the buffer's size. 4562 */ 4563 static void 4564 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4565 { 4566 vm_ooffset_t soff, eoff; 4567 4568 /* 4569 * Start and end offsets in buffer. eoff - soff may not cross a 4570 * page boundary or cross the end of the buffer. The end of the 4571 * buffer, in this case, is our file EOF, not the allocation size 4572 * of the buffer. 4573 */ 4574 soff = off; 4575 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4576 if (eoff > bp->b_offset + bp->b_bcount) 4577 eoff = bp->b_offset + bp->b_bcount; 4578 4579 /* 4580 * Set valid range. This is typically the entire buffer and thus the 4581 * entire page. 4582 */ 4583 if (eoff > soff) { 4584 vm_page_set_validclean( 4585 m, 4586 (vm_offset_t) (soff & PAGE_MASK), 4587 (vm_offset_t) (eoff - soff) 4588 ); 4589 } 4590 } 4591 4592 /* 4593 * Ensure that all buffer pages are not exclusive busied. If any page is 4594 * exclusive busy, drain it. 4595 */ 4596 void 4597 vfs_drain_busy_pages(struct buf *bp) 4598 { 4599 vm_page_t m; 4600 int i, last_busied; 4601 4602 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4603 last_busied = 0; 4604 for (i = 0; i < bp->b_npages; i++) { 4605 m = bp->b_pages[i]; 4606 if (vm_page_xbusied(m)) { 4607 for (; last_busied < i; last_busied++) 4608 vm_page_sbusy(bp->b_pages[last_busied]); 4609 while (vm_page_xbusied(m)) { 4610 vm_page_lock(m); 4611 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4612 vm_page_busy_sleep(m, "vbpage", true); 4613 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4614 } 4615 } 4616 } 4617 for (i = 0; i < last_busied; i++) 4618 vm_page_sunbusy(bp->b_pages[i]); 4619 } 4620 4621 /* 4622 * This routine is called before a device strategy routine. 4623 * It is used to tell the VM system that paging I/O is in 4624 * progress, and treat the pages associated with the buffer 4625 * almost as being exclusive busy. Also the object paging_in_progress 4626 * flag is handled to make sure that the object doesn't become 4627 * inconsistent. 4628 * 4629 * Since I/O has not been initiated yet, certain buffer flags 4630 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4631 * and should be ignored. 4632 */ 4633 void 4634 vfs_busy_pages(struct buf *bp, int clear_modify) 4635 { 4636 vm_object_t obj; 4637 vm_ooffset_t foff; 4638 vm_page_t m; 4639 int i; 4640 bool bogus; 4641 4642 if (!(bp->b_flags & B_VMIO)) 4643 return; 4644 4645 obj = bp->b_bufobj->bo_object; 4646 foff = bp->b_offset; 4647 KASSERT(bp->b_offset != NOOFFSET, 4648 ("vfs_busy_pages: no buffer offset")); 4649 VM_OBJECT_WLOCK(obj); 4650 vfs_drain_busy_pages(bp); 4651 if (bp->b_bufsize != 0) 4652 vfs_setdirty_locked_object(bp); 4653 bogus = false; 4654 for (i = 0; i < bp->b_npages; i++) { 4655 m = bp->b_pages[i]; 4656 4657 if ((bp->b_flags & B_CLUSTER) == 0) { 4658 vm_object_pip_add(obj, 1); 4659 vm_page_sbusy(m); 4660 } 4661 /* 4662 * When readying a buffer for a read ( i.e 4663 * clear_modify == 0 ), it is important to do 4664 * bogus_page replacement for valid pages in 4665 * partially instantiated buffers. Partially 4666 * instantiated buffers can, in turn, occur when 4667 * reconstituting a buffer from its VM backing store 4668 * base. We only have to do this if B_CACHE is 4669 * clear ( which causes the I/O to occur in the 4670 * first place ). The replacement prevents the read 4671 * I/O from overwriting potentially dirty VM-backed 4672 * pages. XXX bogus page replacement is, uh, bogus. 4673 * It may not work properly with small-block devices. 4674 * We need to find a better way. 4675 */ 4676 if (clear_modify) { 4677 pmap_remove_write(m); 4678 vfs_page_set_validclean(bp, foff, m); 4679 } else if (m->valid == VM_PAGE_BITS_ALL && 4680 (bp->b_flags & B_CACHE) == 0) { 4681 bp->b_pages[i] = bogus_page; 4682 bogus = true; 4683 } 4684 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4685 } 4686 VM_OBJECT_WUNLOCK(obj); 4687 if (bogus && buf_mapped(bp)) { 4688 BUF_CHECK_MAPPED(bp); 4689 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4690 bp->b_pages, bp->b_npages); 4691 } 4692 } 4693 4694 /* 4695 * vfs_bio_set_valid: 4696 * 4697 * Set the range within the buffer to valid. The range is 4698 * relative to the beginning of the buffer, b_offset. Note that 4699 * b_offset itself may be offset from the beginning of the first 4700 * page. 4701 */ 4702 void 4703 vfs_bio_set_valid(struct buf *bp, int base, int size) 4704 { 4705 int i, n; 4706 vm_page_t m; 4707 4708 if (!(bp->b_flags & B_VMIO)) 4709 return; 4710 4711 /* 4712 * Fixup base to be relative to beginning of first page. 4713 * Set initial n to be the maximum number of bytes in the 4714 * first page that can be validated. 4715 */ 4716 base += (bp->b_offset & PAGE_MASK); 4717 n = PAGE_SIZE - (base & PAGE_MASK); 4718 4719 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4720 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4721 m = bp->b_pages[i]; 4722 if (n > size) 4723 n = size; 4724 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4725 base += n; 4726 size -= n; 4727 n = PAGE_SIZE; 4728 } 4729 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4730 } 4731 4732 /* 4733 * vfs_bio_clrbuf: 4734 * 4735 * If the specified buffer is a non-VMIO buffer, clear the entire 4736 * buffer. If the specified buffer is a VMIO buffer, clear and 4737 * validate only the previously invalid portions of the buffer. 4738 * This routine essentially fakes an I/O, so we need to clear 4739 * BIO_ERROR and B_INVAL. 4740 * 4741 * Note that while we only theoretically need to clear through b_bcount, 4742 * we go ahead and clear through b_bufsize. 4743 */ 4744 void 4745 vfs_bio_clrbuf(struct buf *bp) 4746 { 4747 int i, j, mask, sa, ea, slide; 4748 4749 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4750 clrbuf(bp); 4751 return; 4752 } 4753 bp->b_flags &= ~B_INVAL; 4754 bp->b_ioflags &= ~BIO_ERROR; 4755 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4756 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4757 (bp->b_offset & PAGE_MASK) == 0) { 4758 if (bp->b_pages[0] == bogus_page) 4759 goto unlock; 4760 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4761 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4762 if ((bp->b_pages[0]->valid & mask) == mask) 4763 goto unlock; 4764 if ((bp->b_pages[0]->valid & mask) == 0) { 4765 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4766 bp->b_pages[0]->valid |= mask; 4767 goto unlock; 4768 } 4769 } 4770 sa = bp->b_offset & PAGE_MASK; 4771 slide = 0; 4772 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4773 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4774 ea = slide & PAGE_MASK; 4775 if (ea == 0) 4776 ea = PAGE_SIZE; 4777 if (bp->b_pages[i] == bogus_page) 4778 continue; 4779 j = sa / DEV_BSIZE; 4780 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4781 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4782 if ((bp->b_pages[i]->valid & mask) == mask) 4783 continue; 4784 if ((bp->b_pages[i]->valid & mask) == 0) 4785 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4786 else { 4787 for (; sa < ea; sa += DEV_BSIZE, j++) { 4788 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4789 pmap_zero_page_area(bp->b_pages[i], 4790 sa, DEV_BSIZE); 4791 } 4792 } 4793 } 4794 bp->b_pages[i]->valid |= mask; 4795 } 4796 unlock: 4797 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4798 bp->b_resid = 0; 4799 } 4800 4801 void 4802 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4803 { 4804 vm_page_t m; 4805 int i, n; 4806 4807 if (buf_mapped(bp)) { 4808 BUF_CHECK_MAPPED(bp); 4809 bzero(bp->b_data + base, size); 4810 } else { 4811 BUF_CHECK_UNMAPPED(bp); 4812 n = PAGE_SIZE - (base & PAGE_MASK); 4813 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4814 m = bp->b_pages[i]; 4815 if (n > size) 4816 n = size; 4817 pmap_zero_page_area(m, base & PAGE_MASK, n); 4818 base += n; 4819 size -= n; 4820 n = PAGE_SIZE; 4821 } 4822 } 4823 } 4824 4825 /* 4826 * Update buffer flags based on I/O request parameters, optionally releasing the 4827 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4828 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4829 * I/O). Otherwise the buffer is released to the cache. 4830 */ 4831 static void 4832 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4833 { 4834 4835 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4836 ("buf %p non-VMIO noreuse", bp)); 4837 4838 if ((ioflag & IO_DIRECT) != 0) 4839 bp->b_flags |= B_DIRECT; 4840 if ((ioflag & IO_EXT) != 0) 4841 bp->b_xflags |= BX_ALTDATA; 4842 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4843 bp->b_flags |= B_RELBUF; 4844 if ((ioflag & IO_NOREUSE) != 0) 4845 bp->b_flags |= B_NOREUSE; 4846 if (release) 4847 brelse(bp); 4848 } else if (release) 4849 bqrelse(bp); 4850 } 4851 4852 void 4853 vfs_bio_brelse(struct buf *bp, int ioflag) 4854 { 4855 4856 b_io_dismiss(bp, ioflag, true); 4857 } 4858 4859 void 4860 vfs_bio_set_flags(struct buf *bp, int ioflag) 4861 { 4862 4863 b_io_dismiss(bp, ioflag, false); 4864 } 4865 4866 /* 4867 * vm_hold_load_pages and vm_hold_free_pages get pages into 4868 * a buffers address space. The pages are anonymous and are 4869 * not associated with a file object. 4870 */ 4871 static void 4872 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4873 { 4874 vm_offset_t pg; 4875 vm_page_t p; 4876 int index; 4877 4878 BUF_CHECK_MAPPED(bp); 4879 4880 to = round_page(to); 4881 from = round_page(from); 4882 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4883 4884 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4885 /* 4886 * note: must allocate system pages since blocking here 4887 * could interfere with paging I/O, no matter which 4888 * process we are. 4889 */ 4890 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4891 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | 4892 VM_ALLOC_WAITOK); 4893 pmap_qenter(pg, &p, 1); 4894 bp->b_pages[index] = p; 4895 } 4896 bp->b_npages = index; 4897 } 4898 4899 /* Return pages associated with this buf to the vm system */ 4900 static void 4901 vm_hold_free_pages(struct buf *bp, int newbsize) 4902 { 4903 vm_offset_t from; 4904 vm_page_t p; 4905 int index, newnpages; 4906 4907 BUF_CHECK_MAPPED(bp); 4908 4909 from = round_page((vm_offset_t)bp->b_data + newbsize); 4910 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4911 if (bp->b_npages > newnpages) 4912 pmap_qremove(from, bp->b_npages - newnpages); 4913 for (index = newnpages; index < bp->b_npages; index++) { 4914 p = bp->b_pages[index]; 4915 bp->b_pages[index] = NULL; 4916 p->wire_count--; 4917 vm_page_free(p); 4918 } 4919 vm_wire_sub(bp->b_npages - newnpages); 4920 bp->b_npages = newnpages; 4921 } 4922 4923 /* 4924 * Map an IO request into kernel virtual address space. 4925 * 4926 * All requests are (re)mapped into kernel VA space. 4927 * Notice that we use b_bufsize for the size of the buffer 4928 * to be mapped. b_bcount might be modified by the driver. 4929 * 4930 * Note that even if the caller determines that the address space should 4931 * be valid, a race or a smaller-file mapped into a larger space may 4932 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4933 * check the return value. 4934 * 4935 * This function only works with pager buffers. 4936 */ 4937 int 4938 vmapbuf(struct buf *bp, int mapbuf) 4939 { 4940 vm_prot_t prot; 4941 int pidx; 4942 4943 if (bp->b_bufsize < 0) 4944 return (-1); 4945 prot = VM_PROT_READ; 4946 if (bp->b_iocmd == BIO_READ) 4947 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4948 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4949 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4950 btoc(MAXPHYS))) < 0) 4951 return (-1); 4952 bp->b_npages = pidx; 4953 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4954 if (mapbuf || !unmapped_buf_allowed) { 4955 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4956 bp->b_data = bp->b_kvabase + bp->b_offset; 4957 } else 4958 bp->b_data = unmapped_buf; 4959 return(0); 4960 } 4961 4962 /* 4963 * Free the io map PTEs associated with this IO operation. 4964 * We also invalidate the TLB entries and restore the original b_addr. 4965 * 4966 * This function only works with pager buffers. 4967 */ 4968 void 4969 vunmapbuf(struct buf *bp) 4970 { 4971 int npages; 4972 4973 npages = bp->b_npages; 4974 if (buf_mapped(bp)) 4975 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4976 vm_page_unhold_pages(bp->b_pages, npages); 4977 4978 bp->b_data = unmapped_buf; 4979 } 4980 4981 void 4982 bdone(struct buf *bp) 4983 { 4984 struct mtx *mtxp; 4985 4986 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4987 mtx_lock(mtxp); 4988 bp->b_flags |= B_DONE; 4989 wakeup(bp); 4990 mtx_unlock(mtxp); 4991 } 4992 4993 void 4994 bwait(struct buf *bp, u_char pri, const char *wchan) 4995 { 4996 struct mtx *mtxp; 4997 4998 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4999 mtx_lock(mtxp); 5000 while ((bp->b_flags & B_DONE) == 0) 5001 msleep(bp, mtxp, pri, wchan, 0); 5002 mtx_unlock(mtxp); 5003 } 5004 5005 int 5006 bufsync(struct bufobj *bo, int waitfor) 5007 { 5008 5009 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 5010 } 5011 5012 void 5013 bufstrategy(struct bufobj *bo, struct buf *bp) 5014 { 5015 int i __unused; 5016 struct vnode *vp; 5017 5018 vp = bp->b_vp; 5019 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5020 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5021 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5022 i = VOP_STRATEGY(vp, bp); 5023 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5024 } 5025 5026 /* 5027 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5028 */ 5029 void 5030 bufobj_init(struct bufobj *bo, void *private) 5031 { 5032 static volatile int bufobj_cleanq; 5033 5034 bo->bo_domain = 5035 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5036 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5037 bo->bo_private = private; 5038 TAILQ_INIT(&bo->bo_clean.bv_hd); 5039 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5040 } 5041 5042 void 5043 bufobj_wrefl(struct bufobj *bo) 5044 { 5045 5046 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5047 ASSERT_BO_WLOCKED(bo); 5048 bo->bo_numoutput++; 5049 } 5050 5051 void 5052 bufobj_wref(struct bufobj *bo) 5053 { 5054 5055 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5056 BO_LOCK(bo); 5057 bo->bo_numoutput++; 5058 BO_UNLOCK(bo); 5059 } 5060 5061 void 5062 bufobj_wdrop(struct bufobj *bo) 5063 { 5064 5065 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5066 BO_LOCK(bo); 5067 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5068 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5069 bo->bo_flag &= ~BO_WWAIT; 5070 wakeup(&bo->bo_numoutput); 5071 } 5072 BO_UNLOCK(bo); 5073 } 5074 5075 int 5076 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5077 { 5078 int error; 5079 5080 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5081 ASSERT_BO_WLOCKED(bo); 5082 error = 0; 5083 while (bo->bo_numoutput) { 5084 bo->bo_flag |= BO_WWAIT; 5085 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5086 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5087 if (error) 5088 break; 5089 } 5090 return (error); 5091 } 5092 5093 /* 5094 * Set bio_data or bio_ma for struct bio from the struct buf. 5095 */ 5096 void 5097 bdata2bio(struct buf *bp, struct bio *bip) 5098 { 5099 5100 if (!buf_mapped(bp)) { 5101 KASSERT(unmapped_buf_allowed, ("unmapped")); 5102 bip->bio_ma = bp->b_pages; 5103 bip->bio_ma_n = bp->b_npages; 5104 bip->bio_data = unmapped_buf; 5105 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5106 bip->bio_flags |= BIO_UNMAPPED; 5107 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5108 PAGE_SIZE == bp->b_npages, 5109 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5110 (long long)bip->bio_length, bip->bio_ma_n)); 5111 } else { 5112 bip->bio_data = bp->b_data; 5113 bip->bio_ma = NULL; 5114 } 5115 } 5116 5117 /* 5118 * The MIPS pmap code currently doesn't handle aliased pages. 5119 * The VIPT caches may not handle page aliasing themselves, leading 5120 * to data corruption. 5121 * 5122 * As such, this code makes a system extremely unhappy if said 5123 * system doesn't support unaliasing the above situation in hardware. 5124 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 5125 * this feature at build time, so it has to be handled in software. 5126 * 5127 * Once the MIPS pmap/cache code grows to support this function on 5128 * earlier chips, it should be flipped back off. 5129 */ 5130 #ifdef __mips__ 5131 static int buf_pager_relbuf = 1; 5132 #else 5133 static int buf_pager_relbuf = 0; 5134 #endif 5135 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5136 &buf_pager_relbuf, 0, 5137 "Make buffer pager release buffers after reading"); 5138 5139 /* 5140 * The buffer pager. It uses buffer reads to validate pages. 5141 * 5142 * In contrast to the generic local pager from vm/vnode_pager.c, this 5143 * pager correctly and easily handles volumes where the underlying 5144 * device block size is greater than the machine page size. The 5145 * buffer cache transparently extends the requested page run to be 5146 * aligned at the block boundary, and does the necessary bogus page 5147 * replacements in the addends to avoid obliterating already valid 5148 * pages. 5149 * 5150 * The only non-trivial issue is that the exclusive busy state for 5151 * pages, which is assumed by the vm_pager_getpages() interface, is 5152 * incompatible with the VMIO buffer cache's desire to share-busy the 5153 * pages. This function performs a trivial downgrade of the pages' 5154 * state before reading buffers, and a less trivial upgrade from the 5155 * shared-busy to excl-busy state after the read. 5156 */ 5157 int 5158 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5159 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5160 vbg_get_blksize_t get_blksize) 5161 { 5162 vm_page_t m; 5163 vm_object_t object; 5164 struct buf *bp; 5165 struct mount *mp; 5166 daddr_t lbn, lbnp; 5167 vm_ooffset_t la, lb, poff, poffe; 5168 long bsize; 5169 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5170 bool redo, lpart; 5171 5172 object = vp->v_object; 5173 mp = vp->v_mount; 5174 error = 0; 5175 la = IDX_TO_OFF(ma[count - 1]->pindex); 5176 if (la >= object->un_pager.vnp.vnp_size) 5177 return (VM_PAGER_BAD); 5178 5179 /* 5180 * Change the meaning of la from where the last requested page starts 5181 * to where it ends, because that's the end of the requested region 5182 * and the start of the potential read-ahead region. 5183 */ 5184 la += PAGE_SIZE; 5185 lpart = la > object->un_pager.vnp.vnp_size; 5186 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 5187 5188 /* 5189 * Calculate read-ahead, behind and total pages. 5190 */ 5191 pgsin = count; 5192 lb = IDX_TO_OFF(ma[0]->pindex); 5193 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5194 pgsin += pgsin_b; 5195 if (rbehind != NULL) 5196 *rbehind = pgsin_b; 5197 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5198 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5199 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5200 PAGE_SIZE) - la); 5201 pgsin += pgsin_a; 5202 if (rahead != NULL) 5203 *rahead = pgsin_a; 5204 VM_CNT_INC(v_vnodein); 5205 VM_CNT_ADD(v_vnodepgsin, pgsin); 5206 5207 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5208 != 0) ? GB_UNMAPPED : 0; 5209 VM_OBJECT_WLOCK(object); 5210 again: 5211 for (i = 0; i < count; i++) 5212 vm_page_busy_downgrade(ma[i]); 5213 VM_OBJECT_WUNLOCK(object); 5214 5215 lbnp = -1; 5216 for (i = 0; i < count; i++) { 5217 m = ma[i]; 5218 5219 /* 5220 * Pages are shared busy and the object lock is not 5221 * owned, which together allow for the pages' 5222 * invalidation. The racy test for validity avoids 5223 * useless creation of the buffer for the most typical 5224 * case when invalidation is not used in redo or for 5225 * parallel read. The shared->excl upgrade loop at 5226 * the end of the function catches the race in a 5227 * reliable way (protected by the object lock). 5228 */ 5229 if (m->valid == VM_PAGE_BITS_ALL) 5230 continue; 5231 5232 poff = IDX_TO_OFF(m->pindex); 5233 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5234 for (; poff < poffe; poff += bsize) { 5235 lbn = get_lblkno(vp, poff); 5236 if (lbn == lbnp) 5237 goto next_page; 5238 lbnp = lbn; 5239 5240 bsize = get_blksize(vp, lbn); 5241 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 5242 br_flags, &bp); 5243 if (error != 0) 5244 goto end_pages; 5245 if (LIST_EMPTY(&bp->b_dep)) { 5246 /* 5247 * Invalidation clears m->valid, but 5248 * may leave B_CACHE flag if the 5249 * buffer existed at the invalidation 5250 * time. In this case, recycle the 5251 * buffer to do real read on next 5252 * bread() after redo. 5253 * 5254 * Otherwise B_RELBUF is not strictly 5255 * necessary, enable to reduce buf 5256 * cache pressure. 5257 */ 5258 if (buf_pager_relbuf || 5259 m->valid != VM_PAGE_BITS_ALL) 5260 bp->b_flags |= B_RELBUF; 5261 5262 bp->b_flags &= ~B_NOCACHE; 5263 brelse(bp); 5264 } else { 5265 bqrelse(bp); 5266 } 5267 } 5268 KASSERT(1 /* racy, enable for debugging */ || 5269 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 5270 ("buf %d %p invalid", i, m)); 5271 if (i == count - 1 && lpart) { 5272 VM_OBJECT_WLOCK(object); 5273 if (m->valid != 0 && 5274 m->valid != VM_PAGE_BITS_ALL) 5275 vm_page_zero_invalid(m, TRUE); 5276 VM_OBJECT_WUNLOCK(object); 5277 } 5278 next_page:; 5279 } 5280 end_pages: 5281 5282 VM_OBJECT_WLOCK(object); 5283 redo = false; 5284 for (i = 0; i < count; i++) { 5285 vm_page_sunbusy(ma[i]); 5286 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 5287 5288 /* 5289 * Since the pages were only sbusy while neither the 5290 * buffer nor the object lock was held by us, or 5291 * reallocated while vm_page_grab() slept for busy 5292 * relinguish, they could have been invalidated. 5293 * Recheck the valid bits and re-read as needed. 5294 * 5295 * Note that the last page is made fully valid in the 5296 * read loop, and partial validity for the page at 5297 * index count - 1 could mean that the page was 5298 * invalidated or removed, so we must restart for 5299 * safety as well. 5300 */ 5301 if (ma[i]->valid != VM_PAGE_BITS_ALL) 5302 redo = true; 5303 } 5304 if (redo && error == 0) 5305 goto again; 5306 VM_OBJECT_WUNLOCK(object); 5307 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5308 } 5309 5310 #include "opt_ddb.h" 5311 #ifdef DDB 5312 #include <ddb/ddb.h> 5313 5314 /* DDB command to show buffer data */ 5315 DB_SHOW_COMMAND(buffer, db_show_buffer) 5316 { 5317 /* get args */ 5318 struct buf *bp = (struct buf *)addr; 5319 #ifdef FULL_BUF_TRACKING 5320 uint32_t i, j; 5321 #endif 5322 5323 if (!have_addr) { 5324 db_printf("usage: show buffer <addr>\n"); 5325 return; 5326 } 5327 5328 db_printf("buf at %p\n", bp); 5329 db_printf("b_flags = 0x%b, b_xflags=0x%b\n", 5330 (u_int)bp->b_flags, PRINT_BUF_FLAGS, 5331 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS); 5332 db_printf("b_vflags=0x%b b_ioflags0x%b\n", 5333 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS, 5334 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS); 5335 db_printf( 5336 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5337 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, " 5338 "b_vp = %p, b_dep = %p\n", 5339 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5340 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5341 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first); 5342 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5343 bp->b_kvabase, bp->b_kvasize); 5344 if (bp->b_npages) { 5345 int i; 5346 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5347 for (i = 0; i < bp->b_npages; i++) { 5348 vm_page_t m; 5349 m = bp->b_pages[i]; 5350 if (m != NULL) 5351 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5352 (u_long)m->pindex, 5353 (u_long)VM_PAGE_TO_PHYS(m)); 5354 else 5355 db_printf("( ??? )"); 5356 if ((i + 1) < bp->b_npages) 5357 db_printf(","); 5358 } 5359 db_printf("\n"); 5360 } 5361 BUF_LOCKPRINTINFO(bp); 5362 #if defined(FULL_BUF_TRACKING) 5363 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5364 5365 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5366 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5367 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5368 continue; 5369 db_printf(" %2u: %s\n", j, 5370 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5371 } 5372 #elif defined(BUF_TRACKING) 5373 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5374 #endif 5375 db_printf(" "); 5376 } 5377 5378 DB_SHOW_COMMAND(bufqueues, bufqueues) 5379 { 5380 struct bufdomain *bd; 5381 struct buf *bp; 5382 long total; 5383 int i, j, cnt; 5384 5385 db_printf("bqempty: %d\n", bqempty.bq_len); 5386 5387 for (i = 0; i < buf_domains; i++) { 5388 bd = &bdomain[i]; 5389 db_printf("Buf domain %d\n", i); 5390 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5391 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5392 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5393 db_printf("\n"); 5394 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5395 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5396 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5397 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5398 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5399 db_printf("\n"); 5400 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5401 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5402 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5403 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5404 db_printf("\n"); 5405 total = 0; 5406 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5407 total += bp->b_bufsize; 5408 db_printf("\tcleanq count\t%d (%ld)\n", 5409 bd->bd_cleanq->bq_len, total); 5410 total = 0; 5411 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5412 total += bp->b_bufsize; 5413 db_printf("\tdirtyq count\t%d (%ld)\n", 5414 bd->bd_dirtyq.bq_len, total); 5415 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5416 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5417 db_printf("\tCPU "); 5418 for (j = 0; j <= mp_maxid; j++) 5419 db_printf("%d, ", bd->bd_subq[j].bq_len); 5420 db_printf("\n"); 5421 cnt = 0; 5422 total = 0; 5423 for (j = 0; j < nbuf; j++) 5424 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) { 5425 cnt++; 5426 total += buf[j].b_bufsize; 5427 } 5428 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5429 cnt = 0; 5430 total = 0; 5431 for (j = 0; j < nbuf; j++) 5432 if (buf[j].b_domain == i) { 5433 cnt++; 5434 total += buf[j].b_bufsize; 5435 } 5436 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5437 } 5438 } 5439 5440 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 5441 { 5442 struct buf *bp; 5443 int i; 5444 5445 for (i = 0; i < nbuf; i++) { 5446 bp = &buf[i]; 5447 if (BUF_ISLOCKED(bp)) { 5448 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5449 db_printf("\n"); 5450 if (db_pager_quit) 5451 break; 5452 } 5453 } 5454 } 5455 5456 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5457 { 5458 struct vnode *vp; 5459 struct buf *bp; 5460 5461 if (!have_addr) { 5462 db_printf("usage: show vnodebufs <addr>\n"); 5463 return; 5464 } 5465 vp = (struct vnode *)addr; 5466 db_printf("Clean buffers:\n"); 5467 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5468 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5469 db_printf("\n"); 5470 } 5471 db_printf("Dirty buffers:\n"); 5472 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5473 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5474 db_printf("\n"); 5475 } 5476 } 5477 5478 DB_COMMAND(countfreebufs, db_coundfreebufs) 5479 { 5480 struct buf *bp; 5481 int i, used = 0, nfree = 0; 5482 5483 if (have_addr) { 5484 db_printf("usage: countfreebufs\n"); 5485 return; 5486 } 5487 5488 for (i = 0; i < nbuf; i++) { 5489 bp = &buf[i]; 5490 if (bp->b_qindex == QUEUE_EMPTY) 5491 nfree++; 5492 else 5493 used++; 5494 } 5495 5496 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5497 nfree + used); 5498 db_printf("numfreebuffers is %d\n", numfreebuffers); 5499 } 5500 #endif /* DDB */ 5501