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