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/syscallsubr.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 char *buf; /* buffer header pool */ 151 static struct buf * 152 nbufp(unsigned i) 153 { 154 return ((struct buf *)(buf + (sizeof(struct buf) + 155 sizeof(vm_page_t) * atop(maxbcachebuf)) * i)); 156 } 157 158 caddr_t __read_mostly unmapped_buf; 159 160 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 161 struct proc *bufdaemonproc; 162 163 static void vm_hold_free_pages(struct buf *bp, int newbsize); 164 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 165 vm_offset_t to); 166 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 167 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 168 vm_page_t m); 169 static void vfs_clean_pages_dirty_buf(struct buf *bp); 170 static void vfs_setdirty_range(struct buf *bp); 171 static void vfs_vmio_invalidate(struct buf *bp); 172 static void vfs_vmio_truncate(struct buf *bp, int npages); 173 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 174 static int vfs_bio_clcheck(struct vnode *vp, int size, 175 daddr_t lblkno, daddr_t blkno); 176 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int, 177 void (*)(struct buf *)); 178 static int buf_flush(struct vnode *vp, struct bufdomain *, int); 179 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int); 180 static void buf_daemon(void); 181 static __inline void bd_wakeup(void); 182 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 183 static void bufkva_reclaim(vmem_t *, int); 184 static void bufkva_free(struct buf *); 185 static int buf_import(void *, void **, int, int, int); 186 static void buf_release(void *, void **, int); 187 static void maxbcachebuf_adjust(void); 188 static inline struct bufdomain *bufdomain(struct buf *); 189 static void bq_remove(struct bufqueue *bq, struct buf *bp); 190 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock); 191 static int buf_recycle(struct bufdomain *, bool kva); 192 static void bq_init(struct bufqueue *bq, int qindex, int cpu, 193 const char *lockname); 194 static void bd_init(struct bufdomain *bd); 195 static int bd_flushall(struct bufdomain *bd); 196 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS); 197 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS); 198 199 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 200 int vmiodirenable = TRUE; 201 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 202 "Use the VM system for directory writes"); 203 long runningbufspace; 204 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 205 "Amount of presently outstanding async buffer io"); 206 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 207 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers"); 208 static counter_u64_t bufkvaspace; 209 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 210 "Kernel virtual memory used for buffers"); 211 static long maxbufspace; 212 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace, 213 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace, 214 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L", 215 "Maximum allowed value of bufspace (including metadata)"); 216 static long bufmallocspace; 217 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 218 "Amount of malloced memory for buffers"); 219 static long maxbufmallocspace; 220 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 221 0, "Maximum amount of malloced memory for buffers"); 222 static long lobufspace; 223 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace, 224 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace, 225 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L", 226 "Minimum amount of buffers we want to have"); 227 long hibufspace; 228 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace, 229 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace, 230 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L", 231 "Maximum allowed value of bufspace (excluding metadata)"); 232 long bufspacethresh; 233 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh, 234 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh, 235 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L", 236 "Bufspace consumed before waking the daemon to free some"); 237 static counter_u64_t buffreekvacnt; 238 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 239 "Number of times we have freed the KVA space from some buffer"); 240 static counter_u64_t bufdefragcnt; 241 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 242 "Number of times we have had to repeat buffer allocation to defragment"); 243 static long lorunningspace; 244 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 245 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 246 "Minimum preferred space used for in-progress I/O"); 247 static long hirunningspace; 248 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 249 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 250 "Maximum amount of space to use for in-progress I/O"); 251 int dirtybufferflushes; 252 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 253 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 254 int bdwriteskip; 255 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 256 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 257 int altbufferflushes; 258 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW | CTLFLAG_STATS, 259 &altbufferflushes, 0, "Number of fsync flushes to limit dirty buffers"); 260 static int recursiveflushes; 261 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW | CTLFLAG_STATS, 262 &recursiveflushes, 0, "Number of flushes skipped due to being recursive"); 263 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS); 264 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers, 265 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I", 266 "Number of buffers that are dirty (has unwritten changes) at the moment"); 267 static int lodirtybuffers; 268 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers, 269 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers, 270 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I", 271 "How many buffers we want to have free before bufdaemon can sleep"); 272 static int hidirtybuffers; 273 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers, 274 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers, 275 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I", 276 "When the number of dirty buffers is considered severe"); 277 int dirtybufthresh; 278 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh, 279 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh, 280 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I", 281 "Number of bdwrite to bawrite conversions to clear dirty buffers"); 282 static int numfreebuffers; 283 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 284 "Number of free buffers"); 285 static int lofreebuffers; 286 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers, 287 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers, 288 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I", 289 "Target number of free buffers"); 290 static int hifreebuffers; 291 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers, 292 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers, 293 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I", 294 "Threshold for clean buffer recycling"); 295 static counter_u64_t getnewbufcalls; 296 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, 297 &getnewbufcalls, "Number of calls to getnewbuf"); 298 static counter_u64_t getnewbufrestarts; 299 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, 300 &getnewbufrestarts, 301 "Number of times getnewbuf has had to restart a buffer acquisition"); 302 static counter_u64_t mappingrestarts; 303 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD, 304 &mappingrestarts, 305 "Number of times getblk has had to restart a buffer mapping for " 306 "unmapped buffer"); 307 static counter_u64_t numbufallocfails; 308 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, 309 &numbufallocfails, "Number of times buffer allocations failed"); 310 static int flushbufqtarget = 100; 311 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 312 "Amount of work to do in flushbufqueues when helping bufdaemon"); 313 static counter_u64_t notbufdflushes; 314 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 315 "Number of dirty buffer flushes done by the bufdaemon helpers"); 316 static long barrierwrites; 317 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW | CTLFLAG_STATS, 318 &barrierwrites, 0, "Number of barrier writes"); 319 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 320 &unmapped_buf_allowed, 0, 321 "Permit the use of the unmapped i/o"); 322 int maxbcachebuf = MAXBCACHEBUF; 323 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0, 324 "Maximum size of a buffer cache block"); 325 326 /* 327 * This lock synchronizes access to bd_request. 328 */ 329 static struct mtx_padalign __exclusive_cache_line bdlock; 330 331 /* 332 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 333 * waitrunningbufspace(). 334 */ 335 static struct mtx_padalign __exclusive_cache_line rbreqlock; 336 337 /* 338 * Lock that protects bdirtywait. 339 */ 340 static struct mtx_padalign __exclusive_cache_line bdirtylock; 341 342 /* 343 * Wakeup point for bufdaemon, as well as indicator of whether it is already 344 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 345 * is idling. 346 */ 347 static int bd_request; 348 349 /* 350 * Request for the buf daemon to write more buffers than is indicated by 351 * lodirtybuf. This may be necessary to push out excess dependencies or 352 * defragment the address space where a simple count of the number of dirty 353 * buffers is insufficient to characterize the demand for flushing them. 354 */ 355 static int bd_speedupreq; 356 357 /* 358 * Synchronization (sleep/wakeup) variable for active buffer space requests. 359 * Set when wait starts, cleared prior to wakeup(). 360 * Used in runningbufwakeup() and waitrunningbufspace(). 361 */ 362 static int runningbufreq; 363 364 /* 365 * Synchronization for bwillwrite() waiters. 366 */ 367 static int bdirtywait; 368 369 /* 370 * Definitions for the buffer free lists. 371 */ 372 #define QUEUE_NONE 0 /* on no queue */ 373 #define QUEUE_EMPTY 1 /* empty buffer headers */ 374 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 375 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 376 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */ 377 378 /* Maximum number of buffer domains. */ 379 #define BUF_DOMAINS 8 380 381 struct bufdomainset bdlodirty; /* Domains > lodirty */ 382 struct bufdomainset bdhidirty; /* Domains > hidirty */ 383 384 /* Configured number of clean queues. */ 385 static int __read_mostly buf_domains; 386 387 BITSET_DEFINE(bufdomainset, BUF_DOMAINS); 388 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS]; 389 struct bufqueue __exclusive_cache_line bqempty; 390 391 /* 392 * per-cpu empty buffer cache. 393 */ 394 uma_zone_t buf_zone; 395 396 /* 397 * Single global constant for BUF_WMESG, to avoid getting multiple references. 398 * buf_wmesg is referred from macros. 399 */ 400 const char *buf_wmesg = BUF_WMESG; 401 402 static int 403 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 404 { 405 long value; 406 int error; 407 408 value = *(long *)arg1; 409 error = sysctl_handle_long(oidp, &value, 0, req); 410 if (error != 0 || req->newptr == NULL) 411 return (error); 412 mtx_lock(&rbreqlock); 413 if (arg1 == &hirunningspace) { 414 if (value < lorunningspace) 415 error = EINVAL; 416 else 417 hirunningspace = value; 418 } else { 419 KASSERT(arg1 == &lorunningspace, 420 ("%s: unknown arg1", __func__)); 421 if (value > hirunningspace) 422 error = EINVAL; 423 else 424 lorunningspace = value; 425 } 426 mtx_unlock(&rbreqlock); 427 return (error); 428 } 429 430 static int 431 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS) 432 { 433 int error; 434 int value; 435 int i; 436 437 value = *(int *)arg1; 438 error = sysctl_handle_int(oidp, &value, 0, req); 439 if (error != 0 || req->newptr == NULL) 440 return (error); 441 *(int *)arg1 = value; 442 for (i = 0; i < buf_domains; i++) 443 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 444 value / buf_domains; 445 446 return (error); 447 } 448 449 static int 450 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS) 451 { 452 long value; 453 int error; 454 int i; 455 456 value = *(long *)arg1; 457 error = sysctl_handle_long(oidp, &value, 0, req); 458 if (error != 0 || req->newptr == NULL) 459 return (error); 460 *(long *)arg1 = value; 461 for (i = 0; i < buf_domains; i++) 462 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 463 value / buf_domains; 464 465 return (error); 466 } 467 468 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 469 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 470 static int 471 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 472 { 473 long lvalue; 474 int ivalue; 475 int i; 476 477 lvalue = 0; 478 for (i = 0; i < buf_domains; i++) 479 lvalue += bdomain[i].bd_bufspace; 480 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 481 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 482 if (lvalue > INT_MAX) 483 /* On overflow, still write out a long to trigger ENOMEM. */ 484 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 485 ivalue = lvalue; 486 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 487 } 488 #else 489 static int 490 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 491 { 492 long lvalue; 493 int i; 494 495 lvalue = 0; 496 for (i = 0; i < buf_domains; i++) 497 lvalue += bdomain[i].bd_bufspace; 498 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 499 } 500 #endif 501 502 static int 503 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS) 504 { 505 int value; 506 int i; 507 508 value = 0; 509 for (i = 0; i < buf_domains; i++) 510 value += bdomain[i].bd_numdirtybuffers; 511 return (sysctl_handle_int(oidp, &value, 0, req)); 512 } 513 514 /* 515 * bdirtywakeup: 516 * 517 * Wakeup any bwillwrite() waiters. 518 */ 519 static void 520 bdirtywakeup(void) 521 { 522 mtx_lock(&bdirtylock); 523 if (bdirtywait) { 524 bdirtywait = 0; 525 wakeup(&bdirtywait); 526 } 527 mtx_unlock(&bdirtylock); 528 } 529 530 /* 531 * bd_clear: 532 * 533 * Clear a domain from the appropriate bitsets when dirtybuffers 534 * is decremented. 535 */ 536 static void 537 bd_clear(struct bufdomain *bd) 538 { 539 540 mtx_lock(&bdirtylock); 541 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers) 542 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 543 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers) 544 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 545 mtx_unlock(&bdirtylock); 546 } 547 548 /* 549 * bd_set: 550 * 551 * Set a domain in the appropriate bitsets when dirtybuffers 552 * is incremented. 553 */ 554 static void 555 bd_set(struct bufdomain *bd) 556 { 557 558 mtx_lock(&bdirtylock); 559 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers) 560 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 561 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers) 562 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 563 mtx_unlock(&bdirtylock); 564 } 565 566 /* 567 * bdirtysub: 568 * 569 * Decrement the numdirtybuffers count by one and wakeup any 570 * threads blocked in bwillwrite(). 571 */ 572 static void 573 bdirtysub(struct buf *bp) 574 { 575 struct bufdomain *bd; 576 int num; 577 578 bd = bufdomain(bp); 579 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1); 580 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 581 bdirtywakeup(); 582 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 583 bd_clear(bd); 584 } 585 586 /* 587 * bdirtyadd: 588 * 589 * Increment the numdirtybuffers count by one and wakeup the buf 590 * daemon if needed. 591 */ 592 static void 593 bdirtyadd(struct buf *bp) 594 { 595 struct bufdomain *bd; 596 int num; 597 598 /* 599 * Only do the wakeup once as we cross the boundary. The 600 * buf daemon will keep running until the condition clears. 601 */ 602 bd = bufdomain(bp); 603 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1); 604 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 605 bd_wakeup(); 606 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 607 bd_set(bd); 608 } 609 610 /* 611 * bufspace_daemon_wakeup: 612 * 613 * Wakeup the daemons responsible for freeing clean bufs. 614 */ 615 static void 616 bufspace_daemon_wakeup(struct bufdomain *bd) 617 { 618 619 /* 620 * avoid the lock if the daemon is running. 621 */ 622 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) { 623 BD_RUN_LOCK(bd); 624 atomic_store_int(&bd->bd_running, 1); 625 wakeup(&bd->bd_running); 626 BD_RUN_UNLOCK(bd); 627 } 628 } 629 630 /* 631 * bufspace_daemon_wait: 632 * 633 * Sleep until the domain falls below a limit or one second passes. 634 */ 635 static void 636 bufspace_daemon_wait(struct bufdomain *bd) 637 { 638 /* 639 * Re-check our limits and sleep. bd_running must be 640 * cleared prior to checking the limits to avoid missed 641 * wakeups. The waker will adjust one of bufspace or 642 * freebuffers prior to checking bd_running. 643 */ 644 BD_RUN_LOCK(bd); 645 atomic_store_int(&bd->bd_running, 0); 646 if (bd->bd_bufspace < bd->bd_bufspacethresh && 647 bd->bd_freebuffers > bd->bd_lofreebuffers) { 648 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP, 649 "-", hz); 650 } else { 651 /* Avoid spurious wakeups while running. */ 652 atomic_store_int(&bd->bd_running, 1); 653 BD_RUN_UNLOCK(bd); 654 } 655 } 656 657 /* 658 * bufspace_adjust: 659 * 660 * Adjust the reported bufspace for a KVA managed buffer, possibly 661 * waking any waiters. 662 */ 663 static void 664 bufspace_adjust(struct buf *bp, int bufsize) 665 { 666 struct bufdomain *bd; 667 long space; 668 int diff; 669 670 KASSERT((bp->b_flags & B_MALLOC) == 0, 671 ("bufspace_adjust: malloc buf %p", bp)); 672 bd = bufdomain(bp); 673 diff = bufsize - bp->b_bufsize; 674 if (diff < 0) { 675 atomic_subtract_long(&bd->bd_bufspace, -diff); 676 } else if (diff > 0) { 677 space = atomic_fetchadd_long(&bd->bd_bufspace, diff); 678 /* Wake up the daemon on the transition. */ 679 if (space < bd->bd_bufspacethresh && 680 space + diff >= bd->bd_bufspacethresh) 681 bufspace_daemon_wakeup(bd); 682 } 683 bp->b_bufsize = bufsize; 684 } 685 686 /* 687 * bufspace_reserve: 688 * 689 * Reserve bufspace before calling allocbuf(). metadata has a 690 * different space limit than data. 691 */ 692 static int 693 bufspace_reserve(struct bufdomain *bd, int size, bool metadata) 694 { 695 long limit, new; 696 long space; 697 698 if (metadata) 699 limit = bd->bd_maxbufspace; 700 else 701 limit = bd->bd_hibufspace; 702 space = atomic_fetchadd_long(&bd->bd_bufspace, size); 703 new = space + size; 704 if (new > limit) { 705 atomic_subtract_long(&bd->bd_bufspace, size); 706 return (ENOSPC); 707 } 708 709 /* Wake up the daemon on the transition. */ 710 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh) 711 bufspace_daemon_wakeup(bd); 712 713 return (0); 714 } 715 716 /* 717 * bufspace_release: 718 * 719 * Release reserved bufspace after bufspace_adjust() has consumed it. 720 */ 721 static void 722 bufspace_release(struct bufdomain *bd, int size) 723 { 724 725 atomic_subtract_long(&bd->bd_bufspace, size); 726 } 727 728 /* 729 * bufspace_wait: 730 * 731 * Wait for bufspace, acting as the buf daemon if a locked vnode is 732 * supplied. bd_wanted must be set prior to polling for space. The 733 * operation must be re-tried on return. 734 */ 735 static void 736 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags, 737 int slpflag, int slptimeo) 738 { 739 struct thread *td; 740 int error, fl, norunbuf; 741 742 if ((gbflags & GB_NOWAIT_BD) != 0) 743 return; 744 745 td = curthread; 746 BD_LOCK(bd); 747 while (bd->bd_wanted) { 748 if (vp != NULL && vp->v_type != VCHR && 749 (td->td_pflags & TDP_BUFNEED) == 0) { 750 BD_UNLOCK(bd); 751 /* 752 * getblk() is called with a vnode locked, and 753 * some majority of the dirty buffers may as 754 * well belong to the vnode. Flushing the 755 * buffers there would make a progress that 756 * cannot be achieved by the buf_daemon, that 757 * cannot lock the vnode. 758 */ 759 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 760 (td->td_pflags & TDP_NORUNNINGBUF); 761 762 /* 763 * Play bufdaemon. The getnewbuf() function 764 * may be called while the thread owns lock 765 * for another dirty buffer for the same 766 * vnode, which makes it impossible to use 767 * VOP_FSYNC() there, due to the buffer lock 768 * recursion. 769 */ 770 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 771 fl = buf_flush(vp, bd, flushbufqtarget); 772 td->td_pflags &= norunbuf; 773 BD_LOCK(bd); 774 if (fl != 0) 775 continue; 776 if (bd->bd_wanted == 0) 777 break; 778 } 779 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 780 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 781 if (error != 0) 782 break; 783 } 784 BD_UNLOCK(bd); 785 } 786 787 /* 788 * bufspace_daemon: 789 * 790 * buffer space management daemon. Tries to maintain some marginal 791 * amount of free buffer space so that requesting processes neither 792 * block nor work to reclaim buffers. 793 */ 794 static void 795 bufspace_daemon(void *arg) 796 { 797 struct bufdomain *bd; 798 799 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 800 SHUTDOWN_PRI_LAST + 100); 801 802 bd = arg; 803 for (;;) { 804 kthread_suspend_check(); 805 806 /* 807 * Free buffers from the clean queue until we meet our 808 * targets. 809 * 810 * Theory of operation: The buffer cache is most efficient 811 * when some free buffer headers and space are always 812 * available to getnewbuf(). This daemon attempts to prevent 813 * the excessive blocking and synchronization associated 814 * with shortfall. It goes through three phases according 815 * demand: 816 * 817 * 1) The daemon wakes up voluntarily once per-second 818 * during idle periods when the counters are below 819 * the wakeup thresholds (bufspacethresh, lofreebuffers). 820 * 821 * 2) The daemon wakes up as we cross the thresholds 822 * ahead of any potential blocking. This may bounce 823 * slightly according to the rate of consumption and 824 * release. 825 * 826 * 3) The daemon and consumers are starved for working 827 * clean buffers. This is the 'bufspace' sleep below 828 * which will inefficiently trade bufs with bqrelse 829 * until we return to condition 2. 830 */ 831 while (bd->bd_bufspace > bd->bd_lobufspace || 832 bd->bd_freebuffers < bd->bd_hifreebuffers) { 833 if (buf_recycle(bd, false) != 0) { 834 if (bd_flushall(bd)) 835 continue; 836 /* 837 * Speedup dirty if we've run out of clean 838 * buffers. This is possible in particular 839 * because softdep may held many bufs locked 840 * pending writes to other bufs which are 841 * marked for delayed write, exhausting 842 * clean space until they are written. 843 */ 844 bd_speedup(); 845 BD_LOCK(bd); 846 if (bd->bd_wanted) { 847 msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 848 PRIBIO|PDROP, "bufspace", hz/10); 849 } else 850 BD_UNLOCK(bd); 851 } 852 maybe_yield(); 853 } 854 bufspace_daemon_wait(bd); 855 } 856 } 857 858 /* 859 * bufmallocadjust: 860 * 861 * Adjust the reported bufspace for a malloc managed buffer, possibly 862 * waking any waiters. 863 */ 864 static void 865 bufmallocadjust(struct buf *bp, int bufsize) 866 { 867 int diff; 868 869 KASSERT((bp->b_flags & B_MALLOC) != 0, 870 ("bufmallocadjust: non-malloc buf %p", bp)); 871 diff = bufsize - bp->b_bufsize; 872 if (diff < 0) 873 atomic_subtract_long(&bufmallocspace, -diff); 874 else 875 atomic_add_long(&bufmallocspace, diff); 876 bp->b_bufsize = bufsize; 877 } 878 879 /* 880 * runningwakeup: 881 * 882 * Wake up processes that are waiting on asynchronous writes to fall 883 * below lorunningspace. 884 */ 885 static void 886 runningwakeup(void) 887 { 888 889 mtx_lock(&rbreqlock); 890 if (runningbufreq) { 891 runningbufreq = 0; 892 wakeup(&runningbufreq); 893 } 894 mtx_unlock(&rbreqlock); 895 } 896 897 /* 898 * runningbufwakeup: 899 * 900 * Decrement the outstanding write count according. 901 */ 902 void 903 runningbufwakeup(struct buf *bp) 904 { 905 long space, bspace; 906 907 bspace = bp->b_runningbufspace; 908 if (bspace == 0) 909 return; 910 space = atomic_fetchadd_long(&runningbufspace, -bspace); 911 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 912 space, bspace)); 913 bp->b_runningbufspace = 0; 914 /* 915 * Only acquire the lock and wakeup on the transition from exceeding 916 * the threshold to falling below it. 917 */ 918 if (space < lorunningspace) 919 return; 920 if (space - bspace > lorunningspace) 921 return; 922 runningwakeup(); 923 } 924 925 /* 926 * waitrunningbufspace() 927 * 928 * runningbufspace is a measure of the amount of I/O currently 929 * running. This routine is used in async-write situations to 930 * prevent creating huge backups of pending writes to a device. 931 * Only asynchronous writes are governed by this function. 932 * 933 * This does NOT turn an async write into a sync write. It waits 934 * for earlier writes to complete and generally returns before the 935 * caller's write has reached the device. 936 */ 937 void 938 waitrunningbufspace(void) 939 { 940 941 mtx_lock(&rbreqlock); 942 while (runningbufspace > hirunningspace) { 943 runningbufreq = 1; 944 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 945 } 946 mtx_unlock(&rbreqlock); 947 } 948 949 /* 950 * vfs_buf_test_cache: 951 * 952 * Called when a buffer is extended. This function clears the B_CACHE 953 * bit if the newly extended portion of the buffer does not contain 954 * valid data. 955 */ 956 static __inline void 957 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 958 vm_offset_t size, vm_page_t m) 959 { 960 961 /* 962 * This function and its results are protected by higher level 963 * synchronization requiring vnode and buf locks to page in and 964 * validate pages. 965 */ 966 if (bp->b_flags & B_CACHE) { 967 int base = (foff + off) & PAGE_MASK; 968 if (vm_page_is_valid(m, base, size) == 0) 969 bp->b_flags &= ~B_CACHE; 970 } 971 } 972 973 /* Wake up the buffer daemon if necessary */ 974 static void 975 bd_wakeup(void) 976 { 977 978 mtx_lock(&bdlock); 979 if (bd_request == 0) { 980 bd_request = 1; 981 wakeup(&bd_request); 982 } 983 mtx_unlock(&bdlock); 984 } 985 986 /* 987 * Adjust the maxbcachbuf tunable. 988 */ 989 static void 990 maxbcachebuf_adjust(void) 991 { 992 int i; 993 994 /* 995 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 996 */ 997 i = 2; 998 while (i * 2 <= maxbcachebuf) 999 i *= 2; 1000 maxbcachebuf = i; 1001 if (maxbcachebuf < MAXBSIZE) 1002 maxbcachebuf = MAXBSIZE; 1003 if (maxbcachebuf > maxphys) 1004 maxbcachebuf = maxphys; 1005 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 1006 printf("maxbcachebuf=%d\n", maxbcachebuf); 1007 } 1008 1009 /* 1010 * bd_speedup - speedup the buffer cache flushing code 1011 */ 1012 void 1013 bd_speedup(void) 1014 { 1015 int needwake; 1016 1017 mtx_lock(&bdlock); 1018 needwake = 0; 1019 if (bd_speedupreq == 0 || bd_request == 0) 1020 needwake = 1; 1021 bd_speedupreq = 1; 1022 bd_request = 1; 1023 if (needwake) 1024 wakeup(&bd_request); 1025 mtx_unlock(&bdlock); 1026 } 1027 1028 #ifdef __i386__ 1029 #define TRANSIENT_DENOM 5 1030 #else 1031 #define TRANSIENT_DENOM 10 1032 #endif 1033 1034 /* 1035 * Calculating buffer cache scaling values and reserve space for buffer 1036 * headers. This is called during low level kernel initialization and 1037 * may be called more then once. We CANNOT write to the memory area 1038 * being reserved at this time. 1039 */ 1040 caddr_t 1041 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 1042 { 1043 int tuned_nbuf; 1044 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 1045 1046 /* 1047 * physmem_est is in pages. Convert it to kilobytes (assumes 1048 * PAGE_SIZE is >= 1K) 1049 */ 1050 physmem_est = physmem_est * (PAGE_SIZE / 1024); 1051 1052 maxbcachebuf_adjust(); 1053 /* 1054 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 1055 * For the first 64MB of ram nominally allocate sufficient buffers to 1056 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 1057 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 1058 * the buffer cache we limit the eventual kva reservation to 1059 * maxbcache bytes. 1060 * 1061 * factor represents the 1/4 x ram conversion. 1062 */ 1063 if (nbuf == 0) { 1064 int factor = 4 * BKVASIZE / 1024; 1065 1066 nbuf = 50; 1067 if (physmem_est > 4096) 1068 nbuf += min((physmem_est - 4096) / factor, 1069 65536 / factor); 1070 if (physmem_est > 65536) 1071 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 1072 32 * 1024 * 1024 / (factor * 5)); 1073 1074 if (maxbcache && nbuf > maxbcache / BKVASIZE) 1075 nbuf = maxbcache / BKVASIZE; 1076 tuned_nbuf = 1; 1077 } else 1078 tuned_nbuf = 0; 1079 1080 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 1081 maxbuf = (LONG_MAX / 3) / BKVASIZE; 1082 if (nbuf > maxbuf) { 1083 if (!tuned_nbuf) 1084 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 1085 maxbuf); 1086 nbuf = maxbuf; 1087 } 1088 1089 /* 1090 * Ideal allocation size for the transient bio submap is 10% 1091 * of the maximal space buffer map. This roughly corresponds 1092 * to the amount of the buffer mapped for typical UFS load. 1093 * 1094 * Clip the buffer map to reserve space for the transient 1095 * BIOs, if its extent is bigger than 90% (80% on i386) of the 1096 * maximum buffer map extent on the platform. 1097 * 1098 * The fall-back to the maxbuf in case of maxbcache unset, 1099 * allows to not trim the buffer KVA for the architectures 1100 * with ample KVA space. 1101 */ 1102 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 1103 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 1104 buf_sz = (long)nbuf * BKVASIZE; 1105 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 1106 (TRANSIENT_DENOM - 1)) { 1107 /* 1108 * There is more KVA than memory. Do not 1109 * adjust buffer map size, and assign the rest 1110 * of maxbuf to transient map. 1111 */ 1112 biotmap_sz = maxbuf_sz - buf_sz; 1113 } else { 1114 /* 1115 * Buffer map spans all KVA we could afford on 1116 * this platform. Give 10% (20% on i386) of 1117 * the buffer map to the transient bio map. 1118 */ 1119 biotmap_sz = buf_sz / TRANSIENT_DENOM; 1120 buf_sz -= biotmap_sz; 1121 } 1122 if (biotmap_sz / INT_MAX > maxphys) 1123 bio_transient_maxcnt = INT_MAX; 1124 else 1125 bio_transient_maxcnt = biotmap_sz / maxphys; 1126 /* 1127 * Artificially limit to 1024 simultaneous in-flight I/Os 1128 * using the transient mapping. 1129 */ 1130 if (bio_transient_maxcnt > 1024) 1131 bio_transient_maxcnt = 1024; 1132 if (tuned_nbuf) 1133 nbuf = buf_sz / BKVASIZE; 1134 } 1135 1136 if (nswbuf == 0) { 1137 nswbuf = min(nbuf / 4, 256); 1138 if (nswbuf < NSWBUF_MIN) 1139 nswbuf = NSWBUF_MIN; 1140 } 1141 1142 /* 1143 * Reserve space for the buffer cache buffers 1144 */ 1145 buf = (char *)v; 1146 v = (caddr_t)buf + (sizeof(struct buf) + sizeof(vm_page_t) * 1147 atop(maxbcachebuf)) * nbuf; 1148 1149 return (v); 1150 } 1151 1152 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1153 void 1154 bufinit(void) 1155 { 1156 struct buf *bp; 1157 int i; 1158 1159 KASSERT(maxbcachebuf >= MAXBSIZE, 1160 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1161 MAXBSIZE)); 1162 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock"); 1163 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1164 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1165 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1166 1167 unmapped_buf = (caddr_t)kva_alloc(maxphys); 1168 1169 /* finally, initialize each buffer header and stick on empty q */ 1170 for (i = 0; i < nbuf; i++) { 1171 bp = nbufp(i); 1172 bzero(bp, sizeof(*bp) + sizeof(vm_page_t) * atop(maxbcachebuf)); 1173 bp->b_flags = B_INVAL; 1174 bp->b_rcred = NOCRED; 1175 bp->b_wcred = NOCRED; 1176 bp->b_qindex = QUEUE_NONE; 1177 bp->b_domain = -1; 1178 bp->b_subqueue = mp_maxid + 1; 1179 bp->b_xflags = 0; 1180 bp->b_data = bp->b_kvabase = unmapped_buf; 1181 LIST_INIT(&bp->b_dep); 1182 BUF_LOCKINIT(bp); 1183 bq_insert(&bqempty, bp, false); 1184 } 1185 1186 /* 1187 * maxbufspace is the absolute maximum amount of buffer space we are 1188 * allowed to reserve in KVM and in real terms. The absolute maximum 1189 * is nominally used by metadata. hibufspace is the nominal maximum 1190 * used by most other requests. The differential is required to 1191 * ensure that metadata deadlocks don't occur. 1192 * 1193 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1194 * this may result in KVM fragmentation which is not handled optimally 1195 * by the system. XXX This is less true with vmem. We could use 1196 * PAGE_SIZE. 1197 */ 1198 maxbufspace = (long)nbuf * BKVASIZE; 1199 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1200 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1201 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1202 1203 /* 1204 * Note: The 16 MiB upper limit for hirunningspace was chosen 1205 * arbitrarily and may need further tuning. It corresponds to 1206 * 128 outstanding write IO requests (if IO size is 128 KiB), 1207 * which fits with many RAID controllers' tagged queuing limits. 1208 * The lower 1 MiB limit is the historical upper limit for 1209 * hirunningspace. 1210 */ 1211 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1212 16 * 1024 * 1024), 1024 * 1024); 1213 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1214 1215 /* 1216 * Limit the amount of malloc memory since it is wired permanently into 1217 * the kernel space. Even though this is accounted for in the buffer 1218 * allocation, we don't want the malloced region to grow uncontrolled. 1219 * The malloc scheme improves memory utilization significantly on 1220 * average (small) directories. 1221 */ 1222 maxbufmallocspace = hibufspace / 20; 1223 1224 /* 1225 * Reduce the chance of a deadlock occurring by limiting the number 1226 * of delayed-write dirty buffers we allow to stack up. 1227 */ 1228 hidirtybuffers = nbuf / 4 + 20; 1229 dirtybufthresh = hidirtybuffers * 9 / 10; 1230 /* 1231 * To support extreme low-memory systems, make sure hidirtybuffers 1232 * cannot eat up all available buffer space. This occurs when our 1233 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1234 * buffer space assuming BKVASIZE'd buffers. 1235 */ 1236 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1237 hidirtybuffers >>= 1; 1238 } 1239 lodirtybuffers = hidirtybuffers / 2; 1240 1241 /* 1242 * lofreebuffers should be sufficient to avoid stalling waiting on 1243 * buf headers under heavy utilization. The bufs in per-cpu caches 1244 * are counted as free but will be unavailable to threads executing 1245 * on other cpus. 1246 * 1247 * hifreebuffers is the free target for the bufspace daemon. This 1248 * should be set appropriately to limit work per-iteration. 1249 */ 1250 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1251 hifreebuffers = (3 * lofreebuffers) / 2; 1252 numfreebuffers = nbuf; 1253 1254 /* Setup the kva and free list allocators. */ 1255 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1256 buf_zone = uma_zcache_create("buf free cache", 1257 sizeof(struct buf) + sizeof(vm_page_t) * atop(maxbcachebuf), 1258 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1259 1260 /* 1261 * Size the clean queue according to the amount of buffer space. 1262 * One queue per-256mb up to the max. More queues gives better 1263 * concurrency but less accurate LRU. 1264 */ 1265 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS); 1266 for (i = 0 ; i < buf_domains; i++) { 1267 struct bufdomain *bd; 1268 1269 bd = &bdomain[i]; 1270 bd_init(bd); 1271 bd->bd_freebuffers = nbuf / buf_domains; 1272 bd->bd_hifreebuffers = hifreebuffers / buf_domains; 1273 bd->bd_lofreebuffers = lofreebuffers / buf_domains; 1274 bd->bd_bufspace = 0; 1275 bd->bd_maxbufspace = maxbufspace / buf_domains; 1276 bd->bd_hibufspace = hibufspace / buf_domains; 1277 bd->bd_lobufspace = lobufspace / buf_domains; 1278 bd->bd_bufspacethresh = bufspacethresh / buf_domains; 1279 bd->bd_numdirtybuffers = 0; 1280 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains; 1281 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains; 1282 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains; 1283 /* Don't allow more than 2% of bufs in the per-cpu caches. */ 1284 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus; 1285 } 1286 getnewbufcalls = counter_u64_alloc(M_WAITOK); 1287 getnewbufrestarts = counter_u64_alloc(M_WAITOK); 1288 mappingrestarts = counter_u64_alloc(M_WAITOK); 1289 numbufallocfails = counter_u64_alloc(M_WAITOK); 1290 notbufdflushes = counter_u64_alloc(M_WAITOK); 1291 buffreekvacnt = counter_u64_alloc(M_WAITOK); 1292 bufdefragcnt = counter_u64_alloc(M_WAITOK); 1293 bufkvaspace = counter_u64_alloc(M_WAITOK); 1294 } 1295 1296 #ifdef INVARIANTS 1297 static inline void 1298 vfs_buf_check_mapped(struct buf *bp) 1299 { 1300 1301 KASSERT(bp->b_kvabase != unmapped_buf, 1302 ("mapped buf: b_kvabase was not updated %p", bp)); 1303 KASSERT(bp->b_data != unmapped_buf, 1304 ("mapped buf: b_data was not updated %p", bp)); 1305 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1306 maxphys, ("b_data + b_offset unmapped %p", bp)); 1307 } 1308 1309 static inline void 1310 vfs_buf_check_unmapped(struct buf *bp) 1311 { 1312 1313 KASSERT(bp->b_data == unmapped_buf, 1314 ("unmapped buf: corrupted b_data %p", bp)); 1315 } 1316 1317 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1318 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1319 #else 1320 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1321 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1322 #endif 1323 1324 static int 1325 isbufbusy(struct buf *bp) 1326 { 1327 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1328 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1329 return (1); 1330 return (0); 1331 } 1332 1333 /* 1334 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1335 */ 1336 void 1337 bufshutdown(int show_busybufs) 1338 { 1339 static int first_buf_printf = 1; 1340 struct buf *bp; 1341 int i, iter, nbusy, pbusy; 1342 #ifndef PREEMPTION 1343 int subiter; 1344 #endif 1345 1346 /* 1347 * Sync filesystems for shutdown 1348 */ 1349 wdog_kern_pat(WD_LASTVAL); 1350 kern_sync(curthread); 1351 1352 /* 1353 * With soft updates, some buffers that are 1354 * written will be remarked as dirty until other 1355 * buffers are written. 1356 */ 1357 for (iter = pbusy = 0; iter < 20; iter++) { 1358 nbusy = 0; 1359 for (i = nbuf - 1; i >= 0; i--) { 1360 bp = nbufp(i); 1361 if (isbufbusy(bp)) 1362 nbusy++; 1363 } 1364 if (nbusy == 0) { 1365 if (first_buf_printf) 1366 printf("All buffers synced."); 1367 break; 1368 } 1369 if (first_buf_printf) { 1370 printf("Syncing disks, buffers remaining... "); 1371 first_buf_printf = 0; 1372 } 1373 printf("%d ", nbusy); 1374 if (nbusy < pbusy) 1375 iter = 0; 1376 pbusy = nbusy; 1377 1378 wdog_kern_pat(WD_LASTVAL); 1379 kern_sync(curthread); 1380 1381 #ifdef PREEMPTION 1382 /* 1383 * Spin for a while to allow interrupt threads to run. 1384 */ 1385 DELAY(50000 * iter); 1386 #else 1387 /* 1388 * Context switch several times to allow interrupt 1389 * threads to run. 1390 */ 1391 for (subiter = 0; subiter < 50 * iter; subiter++) { 1392 thread_lock(curthread); 1393 mi_switch(SW_VOL); 1394 DELAY(1000); 1395 } 1396 #endif 1397 } 1398 printf("\n"); 1399 /* 1400 * Count only busy local buffers to prevent forcing 1401 * a fsck if we're just a client of a wedged NFS server 1402 */ 1403 nbusy = 0; 1404 for (i = nbuf - 1; i >= 0; i--) { 1405 bp = nbufp(i); 1406 if (isbufbusy(bp)) { 1407 #if 0 1408 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1409 if (bp->b_dev == NULL) { 1410 TAILQ_REMOVE(&mountlist, 1411 bp->b_vp->v_mount, mnt_list); 1412 continue; 1413 } 1414 #endif 1415 nbusy++; 1416 if (show_busybufs > 0) { 1417 printf( 1418 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1419 nbusy, bp, bp->b_vp, bp->b_flags, 1420 (intmax_t)bp->b_blkno, 1421 (intmax_t)bp->b_lblkno); 1422 BUF_LOCKPRINTINFO(bp); 1423 if (show_busybufs > 1) 1424 vn_printf(bp->b_vp, 1425 "vnode content: "); 1426 } 1427 } 1428 } 1429 if (nbusy) { 1430 /* 1431 * Failed to sync all blocks. Indicate this and don't 1432 * unmount filesystems (thus forcing an fsck on reboot). 1433 */ 1434 printf("Giving up on %d buffers\n", nbusy); 1435 DELAY(5000000); /* 5 seconds */ 1436 } else { 1437 if (!first_buf_printf) 1438 printf("Final sync complete\n"); 1439 /* 1440 * Unmount filesystems 1441 */ 1442 if (!KERNEL_PANICKED()) 1443 vfs_unmountall(); 1444 } 1445 swapoff_all(); 1446 DELAY(100000); /* wait for console output to finish */ 1447 } 1448 1449 static void 1450 bpmap_qenter(struct buf *bp) 1451 { 1452 1453 BUF_CHECK_MAPPED(bp); 1454 1455 /* 1456 * bp->b_data is relative to bp->b_offset, but 1457 * bp->b_offset may be offset into the first page. 1458 */ 1459 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1460 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1461 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1462 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1463 } 1464 1465 static inline struct bufdomain * 1466 bufdomain(struct buf *bp) 1467 { 1468 1469 return (&bdomain[bp->b_domain]); 1470 } 1471 1472 static struct bufqueue * 1473 bufqueue(struct buf *bp) 1474 { 1475 1476 switch (bp->b_qindex) { 1477 case QUEUE_NONE: 1478 /* FALLTHROUGH */ 1479 case QUEUE_SENTINEL: 1480 return (NULL); 1481 case QUEUE_EMPTY: 1482 return (&bqempty); 1483 case QUEUE_DIRTY: 1484 return (&bufdomain(bp)->bd_dirtyq); 1485 case QUEUE_CLEAN: 1486 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]); 1487 default: 1488 break; 1489 } 1490 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex); 1491 } 1492 1493 /* 1494 * Return the locked bufqueue that bp is a member of. 1495 */ 1496 static struct bufqueue * 1497 bufqueue_acquire(struct buf *bp) 1498 { 1499 struct bufqueue *bq, *nbq; 1500 1501 /* 1502 * bp can be pushed from a per-cpu queue to the 1503 * cleanq while we're waiting on the lock. Retry 1504 * if the queues don't match. 1505 */ 1506 bq = bufqueue(bp); 1507 BQ_LOCK(bq); 1508 for (;;) { 1509 nbq = bufqueue(bp); 1510 if (bq == nbq) 1511 break; 1512 BQ_UNLOCK(bq); 1513 BQ_LOCK(nbq); 1514 bq = nbq; 1515 } 1516 return (bq); 1517 } 1518 1519 /* 1520 * binsfree: 1521 * 1522 * Insert the buffer into the appropriate free list. Requires a 1523 * locked buffer on entry and buffer is unlocked before return. 1524 */ 1525 static void 1526 binsfree(struct buf *bp, int qindex) 1527 { 1528 struct bufdomain *bd; 1529 struct bufqueue *bq; 1530 1531 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY, 1532 ("binsfree: Invalid qindex %d", qindex)); 1533 BUF_ASSERT_XLOCKED(bp); 1534 1535 /* 1536 * Handle delayed bremfree() processing. 1537 */ 1538 if (bp->b_flags & B_REMFREE) { 1539 if (bp->b_qindex == qindex) { 1540 bp->b_flags |= B_REUSE; 1541 bp->b_flags &= ~B_REMFREE; 1542 BUF_UNLOCK(bp); 1543 return; 1544 } 1545 bq = bufqueue_acquire(bp); 1546 bq_remove(bq, bp); 1547 BQ_UNLOCK(bq); 1548 } 1549 bd = bufdomain(bp); 1550 if (qindex == QUEUE_CLEAN) { 1551 if (bd->bd_lim != 0) 1552 bq = &bd->bd_subq[PCPU_GET(cpuid)]; 1553 else 1554 bq = bd->bd_cleanq; 1555 } else 1556 bq = &bd->bd_dirtyq; 1557 bq_insert(bq, bp, true); 1558 } 1559 1560 /* 1561 * buf_free: 1562 * 1563 * Free a buffer to the buf zone once it no longer has valid contents. 1564 */ 1565 static void 1566 buf_free(struct buf *bp) 1567 { 1568 1569 if (bp->b_flags & B_REMFREE) 1570 bremfreef(bp); 1571 if (bp->b_vflags & BV_BKGRDINPROG) 1572 panic("losing buffer 1"); 1573 if (bp->b_rcred != NOCRED) { 1574 crfree(bp->b_rcred); 1575 bp->b_rcred = NOCRED; 1576 } 1577 if (bp->b_wcred != NOCRED) { 1578 crfree(bp->b_wcred); 1579 bp->b_wcred = NOCRED; 1580 } 1581 if (!LIST_EMPTY(&bp->b_dep)) 1582 buf_deallocate(bp); 1583 bufkva_free(bp); 1584 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1); 1585 MPASS((bp->b_flags & B_MAXPHYS) == 0); 1586 BUF_UNLOCK(bp); 1587 uma_zfree(buf_zone, bp); 1588 } 1589 1590 /* 1591 * buf_import: 1592 * 1593 * Import bufs into the uma cache from the buf list. The system still 1594 * expects a static array of bufs and much of the synchronization 1595 * around bufs assumes type stable storage. As a result, UMA is used 1596 * only as a per-cpu cache of bufs still maintained on a global list. 1597 */ 1598 static int 1599 buf_import(void *arg, void **store, int cnt, int domain, int flags) 1600 { 1601 struct buf *bp; 1602 int i; 1603 1604 BQ_LOCK(&bqempty); 1605 for (i = 0; i < cnt; i++) { 1606 bp = TAILQ_FIRST(&bqempty.bq_queue); 1607 if (bp == NULL) 1608 break; 1609 bq_remove(&bqempty, bp); 1610 store[i] = bp; 1611 } 1612 BQ_UNLOCK(&bqempty); 1613 1614 return (i); 1615 } 1616 1617 /* 1618 * buf_release: 1619 * 1620 * Release bufs from the uma cache back to the buffer queues. 1621 */ 1622 static void 1623 buf_release(void *arg, void **store, int cnt) 1624 { 1625 struct bufqueue *bq; 1626 struct buf *bp; 1627 int i; 1628 1629 bq = &bqempty; 1630 BQ_LOCK(bq); 1631 for (i = 0; i < cnt; i++) { 1632 bp = store[i]; 1633 /* Inline bq_insert() to batch locking. */ 1634 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1635 bp->b_flags &= ~(B_AGE | B_REUSE); 1636 bq->bq_len++; 1637 bp->b_qindex = bq->bq_index; 1638 } 1639 BQ_UNLOCK(bq); 1640 } 1641 1642 /* 1643 * buf_alloc: 1644 * 1645 * Allocate an empty buffer header. 1646 */ 1647 static struct buf * 1648 buf_alloc(struct bufdomain *bd) 1649 { 1650 struct buf *bp; 1651 int freebufs, error; 1652 1653 /* 1654 * We can only run out of bufs in the buf zone if the average buf 1655 * is less than BKVASIZE. In this case the actual wait/block will 1656 * come from buf_reycle() failing to flush one of these small bufs. 1657 */ 1658 bp = NULL; 1659 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1); 1660 if (freebufs > 0) 1661 bp = uma_zalloc(buf_zone, M_NOWAIT); 1662 if (bp == NULL) { 1663 atomic_add_int(&bd->bd_freebuffers, 1); 1664 bufspace_daemon_wakeup(bd); 1665 counter_u64_add(numbufallocfails, 1); 1666 return (NULL); 1667 } 1668 /* 1669 * Wake-up the bufspace daemon on transition below threshold. 1670 */ 1671 if (freebufs == bd->bd_lofreebuffers) 1672 bufspace_daemon_wakeup(bd); 1673 1674 error = BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 1675 KASSERT(error == 0, ("%s: BUF_LOCK on free buf %p: %d.", __func__, bp, 1676 error)); 1677 (void)error; 1678 1679 KASSERT(bp->b_vp == NULL, 1680 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1681 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1682 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1683 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1684 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1685 KASSERT(bp->b_npages == 0, 1686 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1687 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1688 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1689 MPASS((bp->b_flags & B_MAXPHYS) == 0); 1690 1691 bp->b_domain = BD_DOMAIN(bd); 1692 bp->b_flags = 0; 1693 bp->b_ioflags = 0; 1694 bp->b_xflags = 0; 1695 bp->b_vflags = 0; 1696 bp->b_vp = NULL; 1697 bp->b_blkno = bp->b_lblkno = 0; 1698 bp->b_offset = NOOFFSET; 1699 bp->b_iodone = 0; 1700 bp->b_error = 0; 1701 bp->b_resid = 0; 1702 bp->b_bcount = 0; 1703 bp->b_npages = 0; 1704 bp->b_dirtyoff = bp->b_dirtyend = 0; 1705 bp->b_bufobj = NULL; 1706 bp->b_data = bp->b_kvabase = unmapped_buf; 1707 bp->b_fsprivate1 = NULL; 1708 bp->b_fsprivate2 = NULL; 1709 bp->b_fsprivate3 = NULL; 1710 LIST_INIT(&bp->b_dep); 1711 1712 return (bp); 1713 } 1714 1715 /* 1716 * buf_recycle: 1717 * 1718 * Free a buffer from the given bufqueue. kva controls whether the 1719 * freed buf must own some kva resources. This is used for 1720 * defragmenting. 1721 */ 1722 static int 1723 buf_recycle(struct bufdomain *bd, bool kva) 1724 { 1725 struct bufqueue *bq; 1726 struct buf *bp, *nbp; 1727 1728 if (kva) 1729 counter_u64_add(bufdefragcnt, 1); 1730 nbp = NULL; 1731 bq = bd->bd_cleanq; 1732 BQ_LOCK(bq); 1733 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd), 1734 ("buf_recycle: Locks don't match")); 1735 nbp = TAILQ_FIRST(&bq->bq_queue); 1736 1737 /* 1738 * Run scan, possibly freeing data and/or kva mappings on the fly 1739 * depending. 1740 */ 1741 while ((bp = nbp) != NULL) { 1742 /* 1743 * Calculate next bp (we can only use it if we do not 1744 * release the bqlock). 1745 */ 1746 nbp = TAILQ_NEXT(bp, b_freelist); 1747 1748 /* 1749 * If we are defragging then we need a buffer with 1750 * some kva to reclaim. 1751 */ 1752 if (kva && bp->b_kvasize == 0) 1753 continue; 1754 1755 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1756 continue; 1757 1758 /* 1759 * Implement a second chance algorithm for frequently 1760 * accessed buffers. 1761 */ 1762 if ((bp->b_flags & B_REUSE) != 0) { 1763 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1764 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1765 bp->b_flags &= ~B_REUSE; 1766 BUF_UNLOCK(bp); 1767 continue; 1768 } 1769 1770 /* 1771 * Skip buffers with background writes in progress. 1772 */ 1773 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1774 BUF_UNLOCK(bp); 1775 continue; 1776 } 1777 1778 KASSERT(bp->b_qindex == QUEUE_CLEAN, 1779 ("buf_recycle: inconsistent queue %d bp %p", 1780 bp->b_qindex, bp)); 1781 KASSERT(bp->b_domain == BD_DOMAIN(bd), 1782 ("getnewbuf: queue domain %d doesn't match request %d", 1783 bp->b_domain, (int)BD_DOMAIN(bd))); 1784 /* 1785 * NOTE: nbp is now entirely invalid. We can only restart 1786 * the scan from this point on. 1787 */ 1788 bq_remove(bq, bp); 1789 BQ_UNLOCK(bq); 1790 1791 /* 1792 * Requeue the background write buffer with error and 1793 * restart the scan. 1794 */ 1795 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1796 bqrelse(bp); 1797 BQ_LOCK(bq); 1798 nbp = TAILQ_FIRST(&bq->bq_queue); 1799 continue; 1800 } 1801 bp->b_flags |= B_INVAL; 1802 brelse(bp); 1803 return (0); 1804 } 1805 bd->bd_wanted = 1; 1806 BQ_UNLOCK(bq); 1807 1808 return (ENOBUFS); 1809 } 1810 1811 /* 1812 * bremfree: 1813 * 1814 * Mark the buffer for removal from the appropriate free list. 1815 * 1816 */ 1817 void 1818 bremfree(struct buf *bp) 1819 { 1820 1821 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1822 KASSERT((bp->b_flags & B_REMFREE) == 0, 1823 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1824 KASSERT(bp->b_qindex != QUEUE_NONE, 1825 ("bremfree: buffer %p not on a queue.", bp)); 1826 BUF_ASSERT_XLOCKED(bp); 1827 1828 bp->b_flags |= B_REMFREE; 1829 } 1830 1831 /* 1832 * bremfreef: 1833 * 1834 * Force an immediate removal from a free list. Used only in nfs when 1835 * it abuses the b_freelist pointer. 1836 */ 1837 void 1838 bremfreef(struct buf *bp) 1839 { 1840 struct bufqueue *bq; 1841 1842 bq = bufqueue_acquire(bp); 1843 bq_remove(bq, bp); 1844 BQ_UNLOCK(bq); 1845 } 1846 1847 static void 1848 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname) 1849 { 1850 1851 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF); 1852 TAILQ_INIT(&bq->bq_queue); 1853 bq->bq_len = 0; 1854 bq->bq_index = qindex; 1855 bq->bq_subqueue = subqueue; 1856 } 1857 1858 static void 1859 bd_init(struct bufdomain *bd) 1860 { 1861 int i; 1862 1863 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1]; 1864 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock"); 1865 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock"); 1866 for (i = 0; i <= mp_maxid; i++) 1867 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i, 1868 "bufq clean subqueue lock"); 1869 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF); 1870 } 1871 1872 /* 1873 * bq_remove: 1874 * 1875 * Removes a buffer from the free list, must be called with the 1876 * correct qlock held. 1877 */ 1878 static void 1879 bq_remove(struct bufqueue *bq, struct buf *bp) 1880 { 1881 1882 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X", 1883 bp, bp->b_vp, bp->b_flags); 1884 KASSERT(bp->b_qindex != QUEUE_NONE, 1885 ("bq_remove: buffer %p not on a queue.", bp)); 1886 KASSERT(bufqueue(bp) == bq, 1887 ("bq_remove: Remove buffer %p from wrong queue.", bp)); 1888 1889 BQ_ASSERT_LOCKED(bq); 1890 if (bp->b_qindex != QUEUE_EMPTY) { 1891 BUF_ASSERT_XLOCKED(bp); 1892 } 1893 KASSERT(bq->bq_len >= 1, 1894 ("queue %d underflow", bp->b_qindex)); 1895 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1896 bq->bq_len--; 1897 bp->b_qindex = QUEUE_NONE; 1898 bp->b_flags &= ~(B_REMFREE | B_REUSE); 1899 } 1900 1901 static void 1902 bd_flush(struct bufdomain *bd, struct bufqueue *bq) 1903 { 1904 struct buf *bp; 1905 1906 BQ_ASSERT_LOCKED(bq); 1907 if (bq != bd->bd_cleanq) { 1908 BD_LOCK(bd); 1909 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) { 1910 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1911 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp, 1912 b_freelist); 1913 bp->b_subqueue = bd->bd_cleanq->bq_subqueue; 1914 } 1915 bd->bd_cleanq->bq_len += bq->bq_len; 1916 bq->bq_len = 0; 1917 } 1918 if (bd->bd_wanted) { 1919 bd->bd_wanted = 0; 1920 wakeup(&bd->bd_wanted); 1921 } 1922 if (bq != bd->bd_cleanq) 1923 BD_UNLOCK(bd); 1924 } 1925 1926 static int 1927 bd_flushall(struct bufdomain *bd) 1928 { 1929 struct bufqueue *bq; 1930 int flushed; 1931 int i; 1932 1933 if (bd->bd_lim == 0) 1934 return (0); 1935 flushed = 0; 1936 for (i = 0; i <= mp_maxid; i++) { 1937 bq = &bd->bd_subq[i]; 1938 if (bq->bq_len == 0) 1939 continue; 1940 BQ_LOCK(bq); 1941 bd_flush(bd, bq); 1942 BQ_UNLOCK(bq); 1943 flushed++; 1944 } 1945 1946 return (flushed); 1947 } 1948 1949 static void 1950 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock) 1951 { 1952 struct bufdomain *bd; 1953 1954 if (bp->b_qindex != QUEUE_NONE) 1955 panic("bq_insert: free buffer %p onto another queue?", bp); 1956 1957 bd = bufdomain(bp); 1958 if (bp->b_flags & B_AGE) { 1959 /* Place this buf directly on the real queue. */ 1960 if (bq->bq_index == QUEUE_CLEAN) 1961 bq = bd->bd_cleanq; 1962 BQ_LOCK(bq); 1963 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist); 1964 } else { 1965 BQ_LOCK(bq); 1966 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1967 } 1968 bp->b_flags &= ~(B_AGE | B_REUSE); 1969 bq->bq_len++; 1970 bp->b_qindex = bq->bq_index; 1971 bp->b_subqueue = bq->bq_subqueue; 1972 1973 /* 1974 * Unlock before we notify so that we don't wakeup a waiter that 1975 * fails a trylock on the buf and sleeps again. 1976 */ 1977 if (unlock) 1978 BUF_UNLOCK(bp); 1979 1980 if (bp->b_qindex == QUEUE_CLEAN) { 1981 /* 1982 * Flush the per-cpu queue and notify any waiters. 1983 */ 1984 if (bd->bd_wanted || (bq != bd->bd_cleanq && 1985 bq->bq_len >= bd->bd_lim)) 1986 bd_flush(bd, bq); 1987 } 1988 BQ_UNLOCK(bq); 1989 } 1990 1991 /* 1992 * bufkva_free: 1993 * 1994 * Free the kva allocation for a buffer. 1995 * 1996 */ 1997 static void 1998 bufkva_free(struct buf *bp) 1999 { 2000 2001 #ifdef INVARIANTS 2002 if (bp->b_kvasize == 0) { 2003 KASSERT(bp->b_kvabase == unmapped_buf && 2004 bp->b_data == unmapped_buf, 2005 ("Leaked KVA space on %p", bp)); 2006 } else if (buf_mapped(bp)) 2007 BUF_CHECK_MAPPED(bp); 2008 else 2009 BUF_CHECK_UNMAPPED(bp); 2010 #endif 2011 if (bp->b_kvasize == 0) 2012 return; 2013 2014 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 2015 counter_u64_add(bufkvaspace, -bp->b_kvasize); 2016 counter_u64_add(buffreekvacnt, 1); 2017 bp->b_data = bp->b_kvabase = unmapped_buf; 2018 bp->b_kvasize = 0; 2019 } 2020 2021 /* 2022 * bufkva_alloc: 2023 * 2024 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 2025 */ 2026 static int 2027 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 2028 { 2029 vm_offset_t addr; 2030 int error; 2031 2032 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 2033 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 2034 MPASS((bp->b_flags & B_MAXPHYS) == 0); 2035 KASSERT(maxsize <= maxbcachebuf, 2036 ("bufkva_alloc kva too large %d %u", maxsize, maxbcachebuf)); 2037 2038 bufkva_free(bp); 2039 2040 addr = 0; 2041 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 2042 if (error != 0) { 2043 /* 2044 * Buffer map is too fragmented. Request the caller 2045 * to defragment the map. 2046 */ 2047 return (error); 2048 } 2049 bp->b_kvabase = (caddr_t)addr; 2050 bp->b_kvasize = maxsize; 2051 counter_u64_add(bufkvaspace, bp->b_kvasize); 2052 if ((gbflags & GB_UNMAPPED) != 0) { 2053 bp->b_data = unmapped_buf; 2054 BUF_CHECK_UNMAPPED(bp); 2055 } else { 2056 bp->b_data = bp->b_kvabase; 2057 BUF_CHECK_MAPPED(bp); 2058 } 2059 return (0); 2060 } 2061 2062 /* 2063 * bufkva_reclaim: 2064 * 2065 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 2066 * callback that fires to avoid returning failure. 2067 */ 2068 static void 2069 bufkva_reclaim(vmem_t *vmem, int flags) 2070 { 2071 bool done; 2072 int q; 2073 int i; 2074 2075 done = false; 2076 for (i = 0; i < 5; i++) { 2077 for (q = 0; q < buf_domains; q++) 2078 if (buf_recycle(&bdomain[q], true) != 0) 2079 done = true; 2080 if (done) 2081 break; 2082 } 2083 return; 2084 } 2085 2086 /* 2087 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 2088 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 2089 * the buffer is valid and we do not have to do anything. 2090 */ 2091 static void 2092 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt, 2093 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *)) 2094 { 2095 struct buf *rabp; 2096 struct thread *td; 2097 int i; 2098 2099 td = curthread; 2100 2101 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 2102 if (inmem(vp, *rablkno)) 2103 continue; 2104 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 2105 if ((rabp->b_flags & B_CACHE) != 0) { 2106 brelse(rabp); 2107 continue; 2108 } 2109 #ifdef RACCT 2110 if (racct_enable) { 2111 PROC_LOCK(curproc); 2112 racct_add_buf(curproc, rabp, 0); 2113 PROC_UNLOCK(curproc); 2114 } 2115 #endif /* RACCT */ 2116 td->td_ru.ru_inblock++; 2117 rabp->b_flags |= B_ASYNC; 2118 rabp->b_flags &= ~B_INVAL; 2119 if ((flags & GB_CKHASH) != 0) { 2120 rabp->b_flags |= B_CKHASH; 2121 rabp->b_ckhashcalc = ckhashfunc; 2122 } 2123 rabp->b_ioflags &= ~BIO_ERROR; 2124 rabp->b_iocmd = BIO_READ; 2125 if (rabp->b_rcred == NOCRED && cred != NOCRED) 2126 rabp->b_rcred = crhold(cred); 2127 vfs_busy_pages(rabp, 0); 2128 BUF_KERNPROC(rabp); 2129 rabp->b_iooffset = dbtob(rabp->b_blkno); 2130 bstrategy(rabp); 2131 } 2132 } 2133 2134 /* 2135 * Entry point for bread() and breadn() via #defines in sys/buf.h. 2136 * 2137 * Get a buffer with the specified data. Look in the cache first. We 2138 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 2139 * is set, the buffer is valid and we do not have to do anything, see 2140 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 2141 * 2142 * Always return a NULL buffer pointer (in bpp) when returning an error. 2143 * 2144 * The blkno parameter is the logical block being requested. Normally 2145 * the mapping of logical block number to disk block address is done 2146 * by calling VOP_BMAP(). However, if the mapping is already known, the 2147 * disk block address can be passed using the dblkno parameter. If the 2148 * disk block address is not known, then the same value should be passed 2149 * for blkno and dblkno. 2150 */ 2151 int 2152 breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, 2153 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags, 2154 void (*ckhashfunc)(struct buf *), struct buf **bpp) 2155 { 2156 struct buf *bp; 2157 struct thread *td; 2158 int error, readwait, rv; 2159 2160 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 2161 td = curthread; 2162 /* 2163 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags 2164 * are specified. 2165 */ 2166 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp); 2167 if (error != 0) { 2168 *bpp = NULL; 2169 return (error); 2170 } 2171 KASSERT(blkno == bp->b_lblkno, 2172 ("getblkx returned buffer for blkno %jd instead of blkno %jd", 2173 (intmax_t)bp->b_lblkno, (intmax_t)blkno)); 2174 flags &= ~GB_NOSPARSE; 2175 *bpp = bp; 2176 2177 /* 2178 * If not found in cache, do some I/O 2179 */ 2180 readwait = 0; 2181 if ((bp->b_flags & B_CACHE) == 0) { 2182 #ifdef RACCT 2183 if (racct_enable) { 2184 PROC_LOCK(td->td_proc); 2185 racct_add_buf(td->td_proc, bp, 0); 2186 PROC_UNLOCK(td->td_proc); 2187 } 2188 #endif /* RACCT */ 2189 td->td_ru.ru_inblock++; 2190 bp->b_iocmd = BIO_READ; 2191 bp->b_flags &= ~B_INVAL; 2192 if ((flags & GB_CKHASH) != 0) { 2193 bp->b_flags |= B_CKHASH; 2194 bp->b_ckhashcalc = ckhashfunc; 2195 } 2196 if ((flags & GB_CVTENXIO) != 0) 2197 bp->b_xflags |= BX_CVTENXIO; 2198 bp->b_ioflags &= ~BIO_ERROR; 2199 if (bp->b_rcred == NOCRED && cred != NOCRED) 2200 bp->b_rcred = crhold(cred); 2201 vfs_busy_pages(bp, 0); 2202 bp->b_iooffset = dbtob(bp->b_blkno); 2203 bstrategy(bp); 2204 ++readwait; 2205 } 2206 2207 /* 2208 * Attempt to initiate asynchronous I/O on read-ahead blocks. 2209 */ 2210 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 2211 2212 rv = 0; 2213 if (readwait) { 2214 rv = bufwait(bp); 2215 if (rv != 0) { 2216 brelse(bp); 2217 *bpp = NULL; 2218 } 2219 } 2220 return (rv); 2221 } 2222 2223 /* 2224 * Write, release buffer on completion. (Done by iodone 2225 * if async). Do not bother writing anything if the buffer 2226 * is invalid. 2227 * 2228 * Note that we set B_CACHE here, indicating that buffer is 2229 * fully valid and thus cacheable. This is true even of NFS 2230 * now so we set it generally. This could be set either here 2231 * or in biodone() since the I/O is synchronous. We put it 2232 * here. 2233 */ 2234 int 2235 bufwrite(struct buf *bp) 2236 { 2237 int oldflags; 2238 struct vnode *vp; 2239 long space; 2240 int vp_md; 2241 2242 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2243 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 2244 bp->b_flags |= B_INVAL | B_RELBUF; 2245 bp->b_flags &= ~B_CACHE; 2246 brelse(bp); 2247 return (ENXIO); 2248 } 2249 if (bp->b_flags & B_INVAL) { 2250 brelse(bp); 2251 return (0); 2252 } 2253 2254 if (bp->b_flags & B_BARRIER) 2255 atomic_add_long(&barrierwrites, 1); 2256 2257 oldflags = bp->b_flags; 2258 2259 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 2260 ("FFS background buffer should not get here %p", bp)); 2261 2262 vp = bp->b_vp; 2263 if (vp) 2264 vp_md = vp->v_vflag & VV_MD; 2265 else 2266 vp_md = 0; 2267 2268 /* 2269 * Mark the buffer clean. Increment the bufobj write count 2270 * before bundirty() call, to prevent other thread from seeing 2271 * empty dirty list and zero counter for writes in progress, 2272 * falsely indicating that the bufobj is clean. 2273 */ 2274 bufobj_wref(bp->b_bufobj); 2275 bundirty(bp); 2276 2277 bp->b_flags &= ~B_DONE; 2278 bp->b_ioflags &= ~BIO_ERROR; 2279 bp->b_flags |= B_CACHE; 2280 bp->b_iocmd = BIO_WRITE; 2281 2282 vfs_busy_pages(bp, 1); 2283 2284 /* 2285 * Normal bwrites pipeline writes 2286 */ 2287 bp->b_runningbufspace = bp->b_bufsize; 2288 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 2289 2290 #ifdef RACCT 2291 if (racct_enable) { 2292 PROC_LOCK(curproc); 2293 racct_add_buf(curproc, bp, 1); 2294 PROC_UNLOCK(curproc); 2295 } 2296 #endif /* RACCT */ 2297 curthread->td_ru.ru_oublock++; 2298 if (oldflags & B_ASYNC) 2299 BUF_KERNPROC(bp); 2300 bp->b_iooffset = dbtob(bp->b_blkno); 2301 buf_track(bp, __func__); 2302 bstrategy(bp); 2303 2304 if ((oldflags & B_ASYNC) == 0) { 2305 int rtval = bufwait(bp); 2306 brelse(bp); 2307 return (rtval); 2308 } else if (space > hirunningspace) { 2309 /* 2310 * don't allow the async write to saturate the I/O 2311 * system. We will not deadlock here because 2312 * we are blocking waiting for I/O that is already in-progress 2313 * to complete. We do not block here if it is the update 2314 * or syncer daemon trying to clean up as that can lead 2315 * to deadlock. 2316 */ 2317 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2318 waitrunningbufspace(); 2319 } 2320 2321 return (0); 2322 } 2323 2324 void 2325 bufbdflush(struct bufobj *bo, struct buf *bp) 2326 { 2327 struct buf *nbp; 2328 struct bufdomain *bd; 2329 2330 bd = &bdomain[bo->bo_domain]; 2331 if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh + 10) { 2332 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2333 altbufferflushes++; 2334 } else if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh) { 2335 BO_LOCK(bo); 2336 /* 2337 * Try to find a buffer to flush. 2338 */ 2339 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2340 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2341 BUF_LOCK(nbp, 2342 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2343 continue; 2344 if (bp == nbp) 2345 panic("bdwrite: found ourselves"); 2346 BO_UNLOCK(bo); 2347 /* Don't countdeps with the bo lock held. */ 2348 if (buf_countdeps(nbp, 0)) { 2349 BO_LOCK(bo); 2350 BUF_UNLOCK(nbp); 2351 continue; 2352 } 2353 if (nbp->b_flags & B_CLUSTEROK) { 2354 vfs_bio_awrite(nbp); 2355 } else { 2356 bremfree(nbp); 2357 bawrite(nbp); 2358 } 2359 dirtybufferflushes++; 2360 break; 2361 } 2362 if (nbp == NULL) 2363 BO_UNLOCK(bo); 2364 } 2365 } 2366 2367 /* 2368 * Delayed write. (Buffer is marked dirty). Do not bother writing 2369 * anything if the buffer is marked invalid. 2370 * 2371 * Note that since the buffer must be completely valid, we can safely 2372 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2373 * biodone() in order to prevent getblk from writing the buffer 2374 * out synchronously. 2375 */ 2376 void 2377 bdwrite(struct buf *bp) 2378 { 2379 struct thread *td = curthread; 2380 struct vnode *vp; 2381 struct bufobj *bo; 2382 2383 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2384 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2385 KASSERT((bp->b_flags & B_BARRIER) == 0, 2386 ("Barrier request in delayed write %p", bp)); 2387 2388 if (bp->b_flags & B_INVAL) { 2389 brelse(bp); 2390 return; 2391 } 2392 2393 /* 2394 * If we have too many dirty buffers, don't create any more. 2395 * If we are wildly over our limit, then force a complete 2396 * cleanup. Otherwise, just keep the situation from getting 2397 * out of control. Note that we have to avoid a recursive 2398 * disaster and not try to clean up after our own cleanup! 2399 */ 2400 vp = bp->b_vp; 2401 bo = bp->b_bufobj; 2402 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2403 td->td_pflags |= TDP_INBDFLUSH; 2404 BO_BDFLUSH(bo, bp); 2405 td->td_pflags &= ~TDP_INBDFLUSH; 2406 } else 2407 recursiveflushes++; 2408 2409 bdirty(bp); 2410 /* 2411 * Set B_CACHE, indicating that the buffer is fully valid. This is 2412 * true even of NFS now. 2413 */ 2414 bp->b_flags |= B_CACHE; 2415 2416 /* 2417 * This bmap keeps the system from needing to do the bmap later, 2418 * perhaps when the system is attempting to do a sync. Since it 2419 * is likely that the indirect block -- or whatever other datastructure 2420 * that the filesystem needs is still in memory now, it is a good 2421 * thing to do this. Note also, that if the pageout daemon is 2422 * requesting a sync -- there might not be enough memory to do 2423 * the bmap then... So, this is important to do. 2424 */ 2425 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2426 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2427 } 2428 2429 buf_track(bp, __func__); 2430 2431 /* 2432 * Set the *dirty* buffer range based upon the VM system dirty 2433 * pages. 2434 * 2435 * Mark the buffer pages as clean. We need to do this here to 2436 * satisfy the vnode_pager and the pageout daemon, so that it 2437 * thinks that the pages have been "cleaned". Note that since 2438 * the pages are in a delayed write buffer -- the VFS layer 2439 * "will" see that the pages get written out on the next sync, 2440 * or perhaps the cluster will be completed. 2441 */ 2442 vfs_clean_pages_dirty_buf(bp); 2443 bqrelse(bp); 2444 2445 /* 2446 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2447 * due to the softdep code. 2448 */ 2449 } 2450 2451 /* 2452 * bdirty: 2453 * 2454 * Turn buffer into delayed write request. We must clear BIO_READ and 2455 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2456 * itself to properly update it in the dirty/clean lists. We mark it 2457 * B_DONE to ensure that any asynchronization of the buffer properly 2458 * clears B_DONE ( else a panic will occur later ). 2459 * 2460 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2461 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2462 * should only be called if the buffer is known-good. 2463 * 2464 * Since the buffer is not on a queue, we do not update the numfreebuffers 2465 * count. 2466 * 2467 * The buffer must be on QUEUE_NONE. 2468 */ 2469 void 2470 bdirty(struct buf *bp) 2471 { 2472 2473 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2474 bp, bp->b_vp, bp->b_flags); 2475 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2476 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2477 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2478 bp->b_flags &= ~(B_RELBUF); 2479 bp->b_iocmd = BIO_WRITE; 2480 2481 if ((bp->b_flags & B_DELWRI) == 0) { 2482 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2483 reassignbuf(bp); 2484 bdirtyadd(bp); 2485 } 2486 } 2487 2488 /* 2489 * bundirty: 2490 * 2491 * Clear B_DELWRI for buffer. 2492 * 2493 * Since the buffer is not on a queue, we do not update the numfreebuffers 2494 * count. 2495 * 2496 * The buffer must be on QUEUE_NONE. 2497 */ 2498 2499 void 2500 bundirty(struct buf *bp) 2501 { 2502 2503 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2504 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2505 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2506 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2507 2508 if (bp->b_flags & B_DELWRI) { 2509 bp->b_flags &= ~B_DELWRI; 2510 reassignbuf(bp); 2511 bdirtysub(bp); 2512 } 2513 /* 2514 * Since it is now being written, we can clear its deferred write flag. 2515 */ 2516 bp->b_flags &= ~B_DEFERRED; 2517 } 2518 2519 /* 2520 * bawrite: 2521 * 2522 * Asynchronous write. Start output on a buffer, but do not wait for 2523 * it to complete. The buffer is released when the output completes. 2524 * 2525 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2526 * B_INVAL buffers. Not us. 2527 */ 2528 void 2529 bawrite(struct buf *bp) 2530 { 2531 2532 bp->b_flags |= B_ASYNC; 2533 (void) bwrite(bp); 2534 } 2535 2536 /* 2537 * babarrierwrite: 2538 * 2539 * Asynchronous barrier write. Start output on a buffer, but do not 2540 * wait for it to complete. Place a write barrier after this write so 2541 * that this buffer and all buffers written before it are committed to 2542 * the disk before any buffers written after this write are committed 2543 * to the disk. The buffer is released when the output completes. 2544 */ 2545 void 2546 babarrierwrite(struct buf *bp) 2547 { 2548 2549 bp->b_flags |= B_ASYNC | B_BARRIER; 2550 (void) bwrite(bp); 2551 } 2552 2553 /* 2554 * bbarrierwrite: 2555 * 2556 * Synchronous barrier write. Start output on a buffer and wait for 2557 * it to complete. Place a write barrier after this write so that 2558 * this buffer and all buffers written before it are committed to 2559 * the disk before any buffers written after this write are committed 2560 * to the disk. The buffer is released when the output completes. 2561 */ 2562 int 2563 bbarrierwrite(struct buf *bp) 2564 { 2565 2566 bp->b_flags |= B_BARRIER; 2567 return (bwrite(bp)); 2568 } 2569 2570 /* 2571 * bwillwrite: 2572 * 2573 * Called prior to the locking of any vnodes when we are expecting to 2574 * write. We do not want to starve the buffer cache with too many 2575 * dirty buffers so we block here. By blocking prior to the locking 2576 * of any vnodes we attempt to avoid the situation where a locked vnode 2577 * prevents the various system daemons from flushing related buffers. 2578 */ 2579 void 2580 bwillwrite(void) 2581 { 2582 2583 if (buf_dirty_count_severe()) { 2584 mtx_lock(&bdirtylock); 2585 while (buf_dirty_count_severe()) { 2586 bdirtywait = 1; 2587 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2588 "flswai", 0); 2589 } 2590 mtx_unlock(&bdirtylock); 2591 } 2592 } 2593 2594 /* 2595 * Return true if we have too many dirty buffers. 2596 */ 2597 int 2598 buf_dirty_count_severe(void) 2599 { 2600 2601 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty)); 2602 } 2603 2604 /* 2605 * brelse: 2606 * 2607 * Release a busy buffer and, if requested, free its resources. The 2608 * buffer will be stashed in the appropriate bufqueue[] allowing it 2609 * to be accessed later as a cache entity or reused for other purposes. 2610 */ 2611 void 2612 brelse(struct buf *bp) 2613 { 2614 struct mount *v_mnt; 2615 int qindex; 2616 2617 /* 2618 * Many functions erroneously call brelse with a NULL bp under rare 2619 * error conditions. Simply return when called with a NULL bp. 2620 */ 2621 if (bp == NULL) 2622 return; 2623 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2624 bp, bp->b_vp, bp->b_flags); 2625 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2626 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2627 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2628 ("brelse: non-VMIO buffer marked NOREUSE")); 2629 2630 if (BUF_LOCKRECURSED(bp)) { 2631 /* 2632 * Do not process, in particular, do not handle the 2633 * B_INVAL/B_RELBUF and do not release to free list. 2634 */ 2635 BUF_UNLOCK(bp); 2636 return; 2637 } 2638 2639 if (bp->b_flags & B_MANAGED) { 2640 bqrelse(bp); 2641 return; 2642 } 2643 2644 if (LIST_EMPTY(&bp->b_dep)) { 2645 bp->b_flags &= ~B_IOSTARTED; 2646 } else { 2647 KASSERT((bp->b_flags & B_IOSTARTED) == 0, 2648 ("brelse: SU io not finished bp %p", bp)); 2649 } 2650 2651 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2652 BO_LOCK(bp->b_bufobj); 2653 bp->b_vflags &= ~BV_BKGRDERR; 2654 BO_UNLOCK(bp->b_bufobj); 2655 bdirty(bp); 2656 } 2657 2658 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2659 (bp->b_flags & B_INVALONERR)) { 2660 /* 2661 * Forced invalidation of dirty buffer contents, to be used 2662 * after a failed write in the rare case that the loss of the 2663 * contents is acceptable. The buffer is invalidated and 2664 * freed. 2665 */ 2666 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE; 2667 bp->b_flags &= ~(B_ASYNC | B_CACHE); 2668 } 2669 2670 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2671 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2672 !(bp->b_flags & B_INVAL)) { 2673 /* 2674 * Failed write, redirty. All errors except ENXIO (which 2675 * means the device is gone) are treated as being 2676 * transient. 2677 * 2678 * XXX Treating EIO as transient is not correct; the 2679 * contract with the local storage device drivers is that 2680 * they will only return EIO once the I/O is no longer 2681 * retriable. Network I/O also respects this through the 2682 * guarantees of TCP and/or the internal retries of NFS. 2683 * ENOMEM might be transient, but we also have no way of 2684 * knowing when its ok to retry/reschedule. In general, 2685 * this entire case should be made obsolete through better 2686 * error handling/recovery and resource scheduling. 2687 * 2688 * Do this also for buffers that failed with ENXIO, but have 2689 * non-empty dependencies - the soft updates code might need 2690 * to access the buffer to untangle them. 2691 * 2692 * Must clear BIO_ERROR to prevent pages from being scrapped. 2693 */ 2694 bp->b_ioflags &= ~BIO_ERROR; 2695 bdirty(bp); 2696 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2697 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2698 /* 2699 * Either a failed read I/O, or we were asked to free or not 2700 * cache the buffer, or we failed to write to a device that's 2701 * no longer present. 2702 */ 2703 bp->b_flags |= B_INVAL; 2704 if (!LIST_EMPTY(&bp->b_dep)) 2705 buf_deallocate(bp); 2706 if (bp->b_flags & B_DELWRI) 2707 bdirtysub(bp); 2708 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2709 if ((bp->b_flags & B_VMIO) == 0) { 2710 allocbuf(bp, 0); 2711 if (bp->b_vp) 2712 brelvp(bp); 2713 } 2714 } 2715 2716 /* 2717 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2718 * is called with B_DELWRI set, the underlying pages may wind up 2719 * getting freed causing a previous write (bdwrite()) to get 'lost' 2720 * because pages associated with a B_DELWRI bp are marked clean. 2721 * 2722 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2723 * if B_DELWRI is set. 2724 */ 2725 if (bp->b_flags & B_DELWRI) 2726 bp->b_flags &= ~B_RELBUF; 2727 2728 /* 2729 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2730 * constituted, not even NFS buffers now. Two flags effect this. If 2731 * B_INVAL, the struct buf is invalidated but the VM object is kept 2732 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2733 * 2734 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2735 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2736 * buffer is also B_INVAL because it hits the re-dirtying code above. 2737 * 2738 * Normally we can do this whether a buffer is B_DELWRI or not. If 2739 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2740 * the commit state and we cannot afford to lose the buffer. If the 2741 * buffer has a background write in progress, we need to keep it 2742 * around to prevent it from being reconstituted and starting a second 2743 * background write. 2744 */ 2745 2746 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL; 2747 2748 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2749 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2750 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 || 2751 vn_isdisk(bp->b_vp) || (bp->b_flags & B_DELWRI) == 0)) { 2752 vfs_vmio_invalidate(bp); 2753 allocbuf(bp, 0); 2754 } 2755 2756 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2757 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2758 allocbuf(bp, 0); 2759 bp->b_flags &= ~B_NOREUSE; 2760 if (bp->b_vp != NULL) 2761 brelvp(bp); 2762 } 2763 2764 /* 2765 * If the buffer has junk contents signal it and eventually 2766 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2767 * doesn't find it. 2768 */ 2769 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2770 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2771 bp->b_flags |= B_INVAL; 2772 if (bp->b_flags & B_INVAL) { 2773 if (bp->b_flags & B_DELWRI) 2774 bundirty(bp); 2775 if (bp->b_vp) 2776 brelvp(bp); 2777 } 2778 2779 buf_track(bp, __func__); 2780 2781 /* buffers with no memory */ 2782 if (bp->b_bufsize == 0) { 2783 buf_free(bp); 2784 return; 2785 } 2786 /* buffers with junk contents */ 2787 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2788 (bp->b_ioflags & BIO_ERROR)) { 2789 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2790 if (bp->b_vflags & BV_BKGRDINPROG) 2791 panic("losing buffer 2"); 2792 qindex = QUEUE_CLEAN; 2793 bp->b_flags |= B_AGE; 2794 /* remaining buffers */ 2795 } else if (bp->b_flags & B_DELWRI) 2796 qindex = QUEUE_DIRTY; 2797 else 2798 qindex = QUEUE_CLEAN; 2799 2800 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2801 panic("brelse: not dirty"); 2802 2803 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT); 2804 bp->b_xflags &= ~(BX_CVTENXIO); 2805 /* binsfree unlocks bp. */ 2806 binsfree(bp, qindex); 2807 } 2808 2809 /* 2810 * Release a buffer back to the appropriate queue but do not try to free 2811 * it. The buffer is expected to be used again soon. 2812 * 2813 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2814 * biodone() to requeue an async I/O on completion. It is also used when 2815 * known good buffers need to be requeued but we think we may need the data 2816 * again soon. 2817 * 2818 * XXX we should be able to leave the B_RELBUF hint set on completion. 2819 */ 2820 void 2821 bqrelse(struct buf *bp) 2822 { 2823 int qindex; 2824 2825 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2826 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2827 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2828 2829 qindex = QUEUE_NONE; 2830 if (BUF_LOCKRECURSED(bp)) { 2831 /* do not release to free list */ 2832 BUF_UNLOCK(bp); 2833 return; 2834 } 2835 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2836 bp->b_xflags &= ~(BX_CVTENXIO); 2837 2838 if (LIST_EMPTY(&bp->b_dep)) { 2839 bp->b_flags &= ~B_IOSTARTED; 2840 } else { 2841 KASSERT((bp->b_flags & B_IOSTARTED) == 0, 2842 ("bqrelse: SU io not finished bp %p", bp)); 2843 } 2844 2845 if (bp->b_flags & B_MANAGED) { 2846 if (bp->b_flags & B_REMFREE) 2847 bremfreef(bp); 2848 goto out; 2849 } 2850 2851 /* buffers with stale but valid contents */ 2852 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2853 BV_BKGRDERR)) == BV_BKGRDERR) { 2854 BO_LOCK(bp->b_bufobj); 2855 bp->b_vflags &= ~BV_BKGRDERR; 2856 BO_UNLOCK(bp->b_bufobj); 2857 qindex = QUEUE_DIRTY; 2858 } else { 2859 if ((bp->b_flags & B_DELWRI) == 0 && 2860 (bp->b_xflags & BX_VNDIRTY)) 2861 panic("bqrelse: not dirty"); 2862 if ((bp->b_flags & B_NOREUSE) != 0) { 2863 brelse(bp); 2864 return; 2865 } 2866 qindex = QUEUE_CLEAN; 2867 } 2868 buf_track(bp, __func__); 2869 /* binsfree unlocks bp. */ 2870 binsfree(bp, qindex); 2871 return; 2872 2873 out: 2874 buf_track(bp, __func__); 2875 /* unlock */ 2876 BUF_UNLOCK(bp); 2877 } 2878 2879 /* 2880 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2881 * restore bogus pages. 2882 */ 2883 static void 2884 vfs_vmio_iodone(struct buf *bp) 2885 { 2886 vm_ooffset_t foff; 2887 vm_page_t m; 2888 vm_object_t obj; 2889 struct vnode *vp __unused; 2890 int i, iosize, resid; 2891 bool bogus; 2892 2893 obj = bp->b_bufobj->bo_object; 2894 KASSERT(blockcount_read(&obj->paging_in_progress) >= bp->b_npages, 2895 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2896 blockcount_read(&obj->paging_in_progress), bp->b_npages)); 2897 2898 vp = bp->b_vp; 2899 VNPASS(vp->v_holdcnt > 0, vp); 2900 VNPASS(vp->v_object != NULL, vp); 2901 2902 foff = bp->b_offset; 2903 KASSERT(bp->b_offset != NOOFFSET, 2904 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2905 2906 bogus = false; 2907 iosize = bp->b_bcount - bp->b_resid; 2908 for (i = 0; i < bp->b_npages; i++) { 2909 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2910 if (resid > iosize) 2911 resid = iosize; 2912 2913 /* 2914 * cleanup bogus pages, restoring the originals 2915 */ 2916 m = bp->b_pages[i]; 2917 if (m == bogus_page) { 2918 bogus = true; 2919 m = vm_page_relookup(obj, OFF_TO_IDX(foff)); 2920 if (m == NULL) 2921 panic("biodone: page disappeared!"); 2922 bp->b_pages[i] = m; 2923 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2924 /* 2925 * In the write case, the valid and clean bits are 2926 * already changed correctly ( see bdwrite() ), so we 2927 * only need to do this here in the read case. 2928 */ 2929 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2930 resid)) == 0, ("vfs_vmio_iodone: page %p " 2931 "has unexpected dirty bits", m)); 2932 vfs_page_set_valid(bp, foff, m); 2933 } 2934 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2935 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2936 (intmax_t)foff, (uintmax_t)m->pindex)); 2937 2938 vm_page_sunbusy(m); 2939 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2940 iosize -= resid; 2941 } 2942 vm_object_pip_wakeupn(obj, bp->b_npages); 2943 if (bogus && buf_mapped(bp)) { 2944 BUF_CHECK_MAPPED(bp); 2945 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2946 bp->b_pages, bp->b_npages); 2947 } 2948 } 2949 2950 /* 2951 * Perform page invalidation when a buffer is released. The fully invalid 2952 * pages will be reclaimed later in vfs_vmio_truncate(). 2953 */ 2954 static void 2955 vfs_vmio_invalidate(struct buf *bp) 2956 { 2957 vm_object_t obj; 2958 vm_page_t m; 2959 int flags, i, resid, poffset, presid; 2960 2961 if (buf_mapped(bp)) { 2962 BUF_CHECK_MAPPED(bp); 2963 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2964 } else 2965 BUF_CHECK_UNMAPPED(bp); 2966 /* 2967 * Get the base offset and length of the buffer. Note that 2968 * in the VMIO case if the buffer block size is not 2969 * page-aligned then b_data pointer may not be page-aligned. 2970 * But our b_pages[] array *IS* page aligned. 2971 * 2972 * block sizes less then DEV_BSIZE (usually 512) are not 2973 * supported due to the page granularity bits (m->valid, 2974 * m->dirty, etc...). 2975 * 2976 * See man buf(9) for more information 2977 */ 2978 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 2979 obj = bp->b_bufobj->bo_object; 2980 resid = bp->b_bufsize; 2981 poffset = bp->b_offset & PAGE_MASK; 2982 VM_OBJECT_WLOCK(obj); 2983 for (i = 0; i < bp->b_npages; i++) { 2984 m = bp->b_pages[i]; 2985 if (m == bogus_page) 2986 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2987 bp->b_pages[i] = NULL; 2988 2989 presid = resid > (PAGE_SIZE - poffset) ? 2990 (PAGE_SIZE - poffset) : resid; 2991 KASSERT(presid >= 0, ("brelse: extra page")); 2992 vm_page_busy_acquire(m, VM_ALLOC_SBUSY); 2993 if (pmap_page_wired_mappings(m) == 0) 2994 vm_page_set_invalid(m, poffset, presid); 2995 vm_page_sunbusy(m); 2996 vm_page_release_locked(m, flags); 2997 resid -= presid; 2998 poffset = 0; 2999 } 3000 VM_OBJECT_WUNLOCK(obj); 3001 bp->b_npages = 0; 3002 } 3003 3004 /* 3005 * Page-granular truncation of an existing VMIO buffer. 3006 */ 3007 static void 3008 vfs_vmio_truncate(struct buf *bp, int desiredpages) 3009 { 3010 vm_object_t obj; 3011 vm_page_t m; 3012 int flags, i; 3013 3014 if (bp->b_npages == desiredpages) 3015 return; 3016 3017 if (buf_mapped(bp)) { 3018 BUF_CHECK_MAPPED(bp); 3019 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 3020 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 3021 } else 3022 BUF_CHECK_UNMAPPED(bp); 3023 3024 /* 3025 * The object lock is needed only if we will attempt to free pages. 3026 */ 3027 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 3028 if ((bp->b_flags & B_DIRECT) != 0) { 3029 flags |= VPR_TRYFREE; 3030 obj = bp->b_bufobj->bo_object; 3031 VM_OBJECT_WLOCK(obj); 3032 } else { 3033 obj = NULL; 3034 } 3035 for (i = desiredpages; i < bp->b_npages; i++) { 3036 m = bp->b_pages[i]; 3037 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3038 bp->b_pages[i] = NULL; 3039 if (obj != NULL) 3040 vm_page_release_locked(m, flags); 3041 else 3042 vm_page_release(m, flags); 3043 } 3044 if (obj != NULL) 3045 VM_OBJECT_WUNLOCK(obj); 3046 bp->b_npages = desiredpages; 3047 } 3048 3049 /* 3050 * Byte granular extension of VMIO buffers. 3051 */ 3052 static void 3053 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3054 { 3055 /* 3056 * We are growing the buffer, possibly in a 3057 * byte-granular fashion. 3058 */ 3059 vm_object_t obj; 3060 vm_offset_t toff; 3061 vm_offset_t tinc; 3062 vm_page_t m; 3063 3064 /* 3065 * Step 1, bring in the VM pages from the object, allocating 3066 * them if necessary. We must clear B_CACHE if these pages 3067 * are not valid for the range covered by the buffer. 3068 */ 3069 obj = bp->b_bufobj->bo_object; 3070 if (bp->b_npages < desiredpages) { 3071 KASSERT(desiredpages <= atop(maxbcachebuf), 3072 ("vfs_vmio_extend past maxbcachebuf %p %d %u", 3073 bp, desiredpages, maxbcachebuf)); 3074 3075 /* 3076 * We must allocate system pages since blocking 3077 * here could interfere with paging I/O, no 3078 * matter which process we are. 3079 * 3080 * Only exclusive busy can be tested here. 3081 * Blocking on shared busy might lead to 3082 * deadlocks once allocbuf() is called after 3083 * pages are vfs_busy_pages(). 3084 */ 3085 (void)vm_page_grab_pages_unlocked(obj, 3086 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3087 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3088 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3089 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3090 bp->b_npages = desiredpages; 3091 } 3092 3093 /* 3094 * Step 2. We've loaded the pages into the buffer, 3095 * we have to figure out if we can still have B_CACHE 3096 * set. Note that B_CACHE is set according to the 3097 * byte-granular range ( bcount and size ), not the 3098 * aligned range ( newbsize ). 3099 * 3100 * The VM test is against m->valid, which is DEV_BSIZE 3101 * aligned. Needless to say, the validity of the data 3102 * needs to also be DEV_BSIZE aligned. Note that this 3103 * fails with NFS if the server or some other client 3104 * extends the file's EOF. If our buffer is resized, 3105 * B_CACHE may remain set! XXX 3106 */ 3107 toff = bp->b_bcount; 3108 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3109 while ((bp->b_flags & B_CACHE) && toff < size) { 3110 vm_pindex_t pi; 3111 3112 if (tinc > (size - toff)) 3113 tinc = size - toff; 3114 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3115 m = bp->b_pages[pi]; 3116 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3117 toff += tinc; 3118 tinc = PAGE_SIZE; 3119 } 3120 3121 /* 3122 * Step 3, fixup the KVA pmap. 3123 */ 3124 if (buf_mapped(bp)) 3125 bpmap_qenter(bp); 3126 else 3127 BUF_CHECK_UNMAPPED(bp); 3128 } 3129 3130 /* 3131 * Check to see if a block at a particular lbn is available for a clustered 3132 * write. 3133 */ 3134 static int 3135 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3136 { 3137 struct buf *bpa; 3138 int match; 3139 3140 match = 0; 3141 3142 /* If the buf isn't in core skip it */ 3143 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3144 return (0); 3145 3146 /* If the buf is busy we don't want to wait for it */ 3147 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3148 return (0); 3149 3150 /* Only cluster with valid clusterable delayed write buffers */ 3151 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3152 (B_DELWRI | B_CLUSTEROK)) 3153 goto done; 3154 3155 if (bpa->b_bufsize != size) 3156 goto done; 3157 3158 /* 3159 * Check to see if it is in the expected place on disk and that the 3160 * block has been mapped. 3161 */ 3162 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3163 match = 1; 3164 done: 3165 BUF_UNLOCK(bpa); 3166 return (match); 3167 } 3168 3169 /* 3170 * vfs_bio_awrite: 3171 * 3172 * Implement clustered async writes for clearing out B_DELWRI buffers. 3173 * This is much better then the old way of writing only one buffer at 3174 * a time. Note that we may not be presented with the buffers in the 3175 * correct order, so we search for the cluster in both directions. 3176 */ 3177 int 3178 vfs_bio_awrite(struct buf *bp) 3179 { 3180 struct bufobj *bo; 3181 int i; 3182 int j; 3183 daddr_t lblkno = bp->b_lblkno; 3184 struct vnode *vp = bp->b_vp; 3185 int ncl; 3186 int nwritten; 3187 int size; 3188 int maxcl; 3189 int gbflags; 3190 3191 bo = &vp->v_bufobj; 3192 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3193 /* 3194 * right now we support clustered writing only to regular files. If 3195 * we find a clusterable block we could be in the middle of a cluster 3196 * rather then at the beginning. 3197 */ 3198 if ((vp->v_type == VREG) && 3199 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3200 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3201 size = vp->v_mount->mnt_stat.f_iosize; 3202 maxcl = maxphys / size; 3203 3204 BO_RLOCK(bo); 3205 for (i = 1; i < maxcl; i++) 3206 if (vfs_bio_clcheck(vp, size, lblkno + i, 3207 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3208 break; 3209 3210 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3211 if (vfs_bio_clcheck(vp, size, lblkno - j, 3212 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3213 break; 3214 BO_RUNLOCK(bo); 3215 --j; 3216 ncl = i + j; 3217 /* 3218 * this is a possible cluster write 3219 */ 3220 if (ncl != 1) { 3221 BUF_UNLOCK(bp); 3222 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3223 gbflags); 3224 return (nwritten); 3225 } 3226 } 3227 bremfree(bp); 3228 bp->b_flags |= B_ASYNC; 3229 /* 3230 * default (old) behavior, writing out only one block 3231 * 3232 * XXX returns b_bufsize instead of b_bcount for nwritten? 3233 */ 3234 nwritten = bp->b_bufsize; 3235 (void) bwrite(bp); 3236 3237 return (nwritten); 3238 } 3239 3240 /* 3241 * getnewbuf_kva: 3242 * 3243 * Allocate KVA for an empty buf header according to gbflags. 3244 */ 3245 static int 3246 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3247 { 3248 3249 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3250 /* 3251 * In order to keep fragmentation sane we only allocate kva 3252 * in BKVASIZE chunks. XXX with vmem we can do page size. 3253 */ 3254 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3255 3256 if (maxsize != bp->b_kvasize && 3257 bufkva_alloc(bp, maxsize, gbflags)) 3258 return (ENOSPC); 3259 } 3260 return (0); 3261 } 3262 3263 /* 3264 * getnewbuf: 3265 * 3266 * Find and initialize a new buffer header, freeing up existing buffers 3267 * in the bufqueues as necessary. The new buffer is returned locked. 3268 * 3269 * We block if: 3270 * We have insufficient buffer headers 3271 * We have insufficient buffer space 3272 * buffer_arena is too fragmented ( space reservation fails ) 3273 * If we have to flush dirty buffers ( but we try to avoid this ) 3274 * 3275 * The caller is responsible for releasing the reserved bufspace after 3276 * allocbuf() is called. 3277 */ 3278 static struct buf * 3279 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3280 { 3281 struct bufdomain *bd; 3282 struct buf *bp; 3283 bool metadata, reserved; 3284 3285 bp = NULL; 3286 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3287 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3288 if (!unmapped_buf_allowed) 3289 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3290 3291 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3292 vp->v_type == VCHR) 3293 metadata = true; 3294 else 3295 metadata = false; 3296 if (vp == NULL) 3297 bd = &bdomain[0]; 3298 else 3299 bd = &bdomain[vp->v_bufobj.bo_domain]; 3300 3301 counter_u64_add(getnewbufcalls, 1); 3302 reserved = false; 3303 do { 3304 if (reserved == false && 3305 bufspace_reserve(bd, maxsize, metadata) != 0) { 3306 counter_u64_add(getnewbufrestarts, 1); 3307 continue; 3308 } 3309 reserved = true; 3310 if ((bp = buf_alloc(bd)) == NULL) { 3311 counter_u64_add(getnewbufrestarts, 1); 3312 continue; 3313 } 3314 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3315 return (bp); 3316 break; 3317 } while (buf_recycle(bd, false) == 0); 3318 3319 if (reserved) 3320 bufspace_release(bd, maxsize); 3321 if (bp != NULL) { 3322 bp->b_flags |= B_INVAL; 3323 brelse(bp); 3324 } 3325 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3326 3327 return (NULL); 3328 } 3329 3330 /* 3331 * buf_daemon: 3332 * 3333 * buffer flushing daemon. Buffers are normally flushed by the 3334 * update daemon but if it cannot keep up this process starts to 3335 * take the load in an attempt to prevent getnewbuf() from blocking. 3336 */ 3337 static struct kproc_desc buf_kp = { 3338 "bufdaemon", 3339 buf_daemon, 3340 &bufdaemonproc 3341 }; 3342 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3343 3344 static int 3345 buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3346 { 3347 int flushed; 3348 3349 flushed = flushbufqueues(vp, bd, target, 0); 3350 if (flushed == 0) { 3351 /* 3352 * Could not find any buffers without rollback 3353 * dependencies, so just write the first one 3354 * in the hopes of eventually making progress. 3355 */ 3356 if (vp != NULL && target > 2) 3357 target /= 2; 3358 flushbufqueues(vp, bd, target, 1); 3359 } 3360 return (flushed); 3361 } 3362 3363 static void 3364 buf_daemon() 3365 { 3366 struct bufdomain *bd; 3367 int speedupreq; 3368 int lodirty; 3369 int i; 3370 3371 /* 3372 * This process needs to be suspended prior to shutdown sync. 3373 */ 3374 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 3375 SHUTDOWN_PRI_LAST + 100); 3376 3377 /* 3378 * Start the buf clean daemons as children threads. 3379 */ 3380 for (i = 0 ; i < buf_domains; i++) { 3381 int error; 3382 3383 error = kthread_add((void (*)(void *))bufspace_daemon, 3384 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3385 if (error) 3386 panic("error %d spawning bufspace daemon", error); 3387 } 3388 3389 /* 3390 * This process is allowed to take the buffer cache to the limit 3391 */ 3392 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3393 mtx_lock(&bdlock); 3394 for (;;) { 3395 bd_request = 0; 3396 mtx_unlock(&bdlock); 3397 3398 kthread_suspend_check(); 3399 3400 /* 3401 * Save speedupreq for this pass and reset to capture new 3402 * requests. 3403 */ 3404 speedupreq = bd_speedupreq; 3405 bd_speedupreq = 0; 3406 3407 /* 3408 * Flush each domain sequentially according to its level and 3409 * the speedup request. 3410 */ 3411 for (i = 0; i < buf_domains; i++) { 3412 bd = &bdomain[i]; 3413 if (speedupreq) 3414 lodirty = bd->bd_numdirtybuffers / 2; 3415 else 3416 lodirty = bd->bd_lodirtybuffers; 3417 while (bd->bd_numdirtybuffers > lodirty) { 3418 if (buf_flush(NULL, bd, 3419 bd->bd_numdirtybuffers - lodirty) == 0) 3420 break; 3421 kern_yield(PRI_USER); 3422 } 3423 } 3424 3425 /* 3426 * Only clear bd_request if we have reached our low water 3427 * mark. The buf_daemon normally waits 1 second and 3428 * then incrementally flushes any dirty buffers that have 3429 * built up, within reason. 3430 * 3431 * If we were unable to hit our low water mark and couldn't 3432 * find any flushable buffers, we sleep for a short period 3433 * to avoid endless loops on unlockable buffers. 3434 */ 3435 mtx_lock(&bdlock); 3436 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3437 /* 3438 * We reached our low water mark, reset the 3439 * request and sleep until we are needed again. 3440 * The sleep is just so the suspend code works. 3441 */ 3442 bd_request = 0; 3443 /* 3444 * Do an extra wakeup in case dirty threshold 3445 * changed via sysctl and the explicit transition 3446 * out of shortfall was missed. 3447 */ 3448 bdirtywakeup(); 3449 if (runningbufspace <= lorunningspace) 3450 runningwakeup(); 3451 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3452 } else { 3453 /* 3454 * We couldn't find any flushable dirty buffers but 3455 * still have too many dirty buffers, we 3456 * have to sleep and try again. (rare) 3457 */ 3458 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3459 } 3460 } 3461 } 3462 3463 /* 3464 * flushbufqueues: 3465 * 3466 * Try to flush a buffer in the dirty queue. We must be careful to 3467 * free up B_INVAL buffers instead of write them, which NFS is 3468 * particularly sensitive to. 3469 */ 3470 static int flushwithdeps = 0; 3471 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS, 3472 &flushwithdeps, 0, 3473 "Number of buffers flushed with dependecies that require rollbacks"); 3474 3475 static int 3476 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3477 int flushdeps) 3478 { 3479 struct bufqueue *bq; 3480 struct buf *sentinel; 3481 struct vnode *vp; 3482 struct mount *mp; 3483 struct buf *bp; 3484 int hasdeps; 3485 int flushed; 3486 int error; 3487 bool unlock; 3488 3489 flushed = 0; 3490 bq = &bd->bd_dirtyq; 3491 bp = NULL; 3492 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3493 sentinel->b_qindex = QUEUE_SENTINEL; 3494 BQ_LOCK(bq); 3495 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3496 BQ_UNLOCK(bq); 3497 while (flushed != target) { 3498 maybe_yield(); 3499 BQ_LOCK(bq); 3500 bp = TAILQ_NEXT(sentinel, b_freelist); 3501 if (bp != NULL) { 3502 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3503 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3504 b_freelist); 3505 } else { 3506 BQ_UNLOCK(bq); 3507 break; 3508 } 3509 /* 3510 * Skip sentinels inserted by other invocations of the 3511 * flushbufqueues(), taking care to not reorder them. 3512 * 3513 * Only flush the buffers that belong to the 3514 * vnode locked by the curthread. 3515 */ 3516 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3517 bp->b_vp != lvp)) { 3518 BQ_UNLOCK(bq); 3519 continue; 3520 } 3521 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3522 BQ_UNLOCK(bq); 3523 if (error != 0) 3524 continue; 3525 3526 /* 3527 * BKGRDINPROG can only be set with the buf and bufobj 3528 * locks both held. We tolerate a race to clear it here. 3529 */ 3530 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3531 (bp->b_flags & B_DELWRI) == 0) { 3532 BUF_UNLOCK(bp); 3533 continue; 3534 } 3535 if (bp->b_flags & B_INVAL) { 3536 bremfreef(bp); 3537 brelse(bp); 3538 flushed++; 3539 continue; 3540 } 3541 3542 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3543 if (flushdeps == 0) { 3544 BUF_UNLOCK(bp); 3545 continue; 3546 } 3547 hasdeps = 1; 3548 } else 3549 hasdeps = 0; 3550 /* 3551 * We must hold the lock on a vnode before writing 3552 * one of its buffers. Otherwise we may confuse, or 3553 * in the case of a snapshot vnode, deadlock the 3554 * system. 3555 * 3556 * The lock order here is the reverse of the normal 3557 * of vnode followed by buf lock. This is ok because 3558 * the NOWAIT will prevent deadlock. 3559 */ 3560 vp = bp->b_vp; 3561 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3562 BUF_UNLOCK(bp); 3563 continue; 3564 } 3565 if (lvp == NULL) { 3566 unlock = true; 3567 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3568 } else { 3569 ASSERT_VOP_LOCKED(vp, "getbuf"); 3570 unlock = false; 3571 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3572 vn_lock(vp, LK_TRYUPGRADE); 3573 } 3574 if (error == 0) { 3575 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3576 bp, bp->b_vp, bp->b_flags); 3577 if (curproc == bufdaemonproc) { 3578 vfs_bio_awrite(bp); 3579 } else { 3580 bremfree(bp); 3581 bwrite(bp); 3582 counter_u64_add(notbufdflushes, 1); 3583 } 3584 vn_finished_write(mp); 3585 if (unlock) 3586 VOP_UNLOCK(vp); 3587 flushwithdeps += hasdeps; 3588 flushed++; 3589 3590 /* 3591 * Sleeping on runningbufspace while holding 3592 * vnode lock leads to deadlock. 3593 */ 3594 if (curproc == bufdaemonproc && 3595 runningbufspace > hirunningspace) 3596 waitrunningbufspace(); 3597 continue; 3598 } 3599 vn_finished_write(mp); 3600 BUF_UNLOCK(bp); 3601 } 3602 BQ_LOCK(bq); 3603 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3604 BQ_UNLOCK(bq); 3605 free(sentinel, M_TEMP); 3606 return (flushed); 3607 } 3608 3609 /* 3610 * Check to see if a block is currently memory resident. 3611 */ 3612 struct buf * 3613 incore(struct bufobj *bo, daddr_t blkno) 3614 { 3615 return (gbincore_unlocked(bo, blkno)); 3616 } 3617 3618 /* 3619 * Returns true if no I/O is needed to access the 3620 * associated VM object. This is like incore except 3621 * it also hunts around in the VM system for the data. 3622 */ 3623 bool 3624 inmem(struct vnode * vp, daddr_t blkno) 3625 { 3626 vm_object_t obj; 3627 vm_offset_t toff, tinc, size; 3628 vm_page_t m, n; 3629 vm_ooffset_t off; 3630 int valid; 3631 3632 ASSERT_VOP_LOCKED(vp, "inmem"); 3633 3634 if (incore(&vp->v_bufobj, blkno)) 3635 return (true); 3636 if (vp->v_mount == NULL) 3637 return (false); 3638 obj = vp->v_object; 3639 if (obj == NULL) 3640 return (false); 3641 3642 size = PAGE_SIZE; 3643 if (size > vp->v_mount->mnt_stat.f_iosize) 3644 size = vp->v_mount->mnt_stat.f_iosize; 3645 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3646 3647 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3648 m = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff)); 3649 recheck: 3650 if (m == NULL) 3651 return (false); 3652 3653 tinc = size; 3654 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3655 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3656 /* 3657 * Consider page validity only if page mapping didn't change 3658 * during the check. 3659 */ 3660 valid = vm_page_is_valid(m, 3661 (vm_offset_t)((toff + off) & PAGE_MASK), tinc); 3662 n = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff)); 3663 if (m != n) { 3664 m = n; 3665 goto recheck; 3666 } 3667 if (!valid) 3668 return (false); 3669 } 3670 return (true); 3671 } 3672 3673 /* 3674 * Set the dirty range for a buffer based on the status of the dirty 3675 * bits in the pages comprising the buffer. The range is limited 3676 * to the size of the buffer. 3677 * 3678 * Tell the VM system that the pages associated with this buffer 3679 * are clean. This is used for delayed writes where the data is 3680 * going to go to disk eventually without additional VM intevention. 3681 * 3682 * Note that while we only really need to clean through to b_bcount, we 3683 * just go ahead and clean through to b_bufsize. 3684 */ 3685 static void 3686 vfs_clean_pages_dirty_buf(struct buf *bp) 3687 { 3688 vm_ooffset_t foff, noff, eoff; 3689 vm_page_t m; 3690 int i; 3691 3692 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3693 return; 3694 3695 foff = bp->b_offset; 3696 KASSERT(bp->b_offset != NOOFFSET, 3697 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3698 3699 vfs_busy_pages_acquire(bp); 3700 vfs_setdirty_range(bp); 3701 for (i = 0; i < bp->b_npages; i++) { 3702 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3703 eoff = noff; 3704 if (eoff > bp->b_offset + bp->b_bufsize) 3705 eoff = bp->b_offset + bp->b_bufsize; 3706 m = bp->b_pages[i]; 3707 vfs_page_set_validclean(bp, foff, m); 3708 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3709 foff = noff; 3710 } 3711 vfs_busy_pages_release(bp); 3712 } 3713 3714 static void 3715 vfs_setdirty_range(struct buf *bp) 3716 { 3717 vm_offset_t boffset; 3718 vm_offset_t eoffset; 3719 int i; 3720 3721 /* 3722 * test the pages to see if they have been modified directly 3723 * by users through the VM system. 3724 */ 3725 for (i = 0; i < bp->b_npages; i++) 3726 vm_page_test_dirty(bp->b_pages[i]); 3727 3728 /* 3729 * Calculate the encompassing dirty range, boffset and eoffset, 3730 * (eoffset - boffset) bytes. 3731 */ 3732 3733 for (i = 0; i < bp->b_npages; i++) { 3734 if (bp->b_pages[i]->dirty) 3735 break; 3736 } 3737 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3738 3739 for (i = bp->b_npages - 1; i >= 0; --i) { 3740 if (bp->b_pages[i]->dirty) { 3741 break; 3742 } 3743 } 3744 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3745 3746 /* 3747 * Fit it to the buffer. 3748 */ 3749 3750 if (eoffset > bp->b_bcount) 3751 eoffset = bp->b_bcount; 3752 3753 /* 3754 * If we have a good dirty range, merge with the existing 3755 * dirty range. 3756 */ 3757 3758 if (boffset < eoffset) { 3759 if (bp->b_dirtyoff > boffset) 3760 bp->b_dirtyoff = boffset; 3761 if (bp->b_dirtyend < eoffset) 3762 bp->b_dirtyend = eoffset; 3763 } 3764 } 3765 3766 /* 3767 * Allocate the KVA mapping for an existing buffer. 3768 * If an unmapped buffer is provided but a mapped buffer is requested, take 3769 * also care to properly setup mappings between pages and KVA. 3770 */ 3771 static void 3772 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3773 { 3774 int bsize, maxsize, need_mapping, need_kva; 3775 off_t offset; 3776 3777 need_mapping = bp->b_data == unmapped_buf && 3778 (gbflags & GB_UNMAPPED) == 0; 3779 need_kva = bp->b_kvabase == unmapped_buf && 3780 bp->b_data == unmapped_buf && 3781 (gbflags & GB_KVAALLOC) != 0; 3782 if (!need_mapping && !need_kva) 3783 return; 3784 3785 BUF_CHECK_UNMAPPED(bp); 3786 3787 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3788 /* 3789 * Buffer is not mapped, but the KVA was already 3790 * reserved at the time of the instantiation. Use the 3791 * allocated space. 3792 */ 3793 goto has_addr; 3794 } 3795 3796 /* 3797 * Calculate the amount of the address space we would reserve 3798 * if the buffer was mapped. 3799 */ 3800 bsize = vn_isdisk(bp->b_vp) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3801 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3802 offset = blkno * bsize; 3803 maxsize = size + (offset & PAGE_MASK); 3804 maxsize = imax(maxsize, bsize); 3805 3806 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3807 if ((gbflags & GB_NOWAIT_BD) != 0) { 3808 /* 3809 * XXXKIB: defragmentation cannot 3810 * succeed, not sure what else to do. 3811 */ 3812 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3813 } 3814 counter_u64_add(mappingrestarts, 1); 3815 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3816 } 3817 has_addr: 3818 if (need_mapping) { 3819 /* b_offset is handled by bpmap_qenter. */ 3820 bp->b_data = bp->b_kvabase; 3821 BUF_CHECK_MAPPED(bp); 3822 bpmap_qenter(bp); 3823 } 3824 } 3825 3826 struct buf * 3827 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3828 int flags) 3829 { 3830 struct buf *bp; 3831 int error; 3832 3833 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp); 3834 if (error != 0) 3835 return (NULL); 3836 return (bp); 3837 } 3838 3839 /* 3840 * getblkx: 3841 * 3842 * Get a block given a specified block and offset into a file/device. 3843 * The buffers B_DONE bit will be cleared on return, making it almost 3844 * ready for an I/O initiation. B_INVAL may or may not be set on 3845 * return. The caller should clear B_INVAL prior to initiating a 3846 * READ. 3847 * 3848 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3849 * an existing buffer. 3850 * 3851 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3852 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3853 * and then cleared based on the backing VM. If the previous buffer is 3854 * non-0-sized but invalid, B_CACHE will be cleared. 3855 * 3856 * If getblk() must create a new buffer, the new buffer is returned with 3857 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3858 * case it is returned with B_INVAL clear and B_CACHE set based on the 3859 * backing VM. 3860 * 3861 * getblk() also forces a bwrite() for any B_DELWRI buffer whose 3862 * B_CACHE bit is clear. 3863 * 3864 * What this means, basically, is that the caller should use B_CACHE to 3865 * determine whether the buffer is fully valid or not and should clear 3866 * B_INVAL prior to issuing a read. If the caller intends to validate 3867 * the buffer by loading its data area with something, the caller needs 3868 * to clear B_INVAL. If the caller does this without issuing an I/O, 3869 * the caller should set B_CACHE ( as an optimization ), else the caller 3870 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3871 * a write attempt or if it was a successful read. If the caller 3872 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3873 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3874 * 3875 * The blkno parameter is the logical block being requested. Normally 3876 * the mapping of logical block number to disk block address is done 3877 * by calling VOP_BMAP(). However, if the mapping is already known, the 3878 * disk block address can be passed using the dblkno parameter. If the 3879 * disk block address is not known, then the same value should be passed 3880 * for blkno and dblkno. 3881 */ 3882 int 3883 getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag, 3884 int slptimeo, int flags, struct buf **bpp) 3885 { 3886 struct buf *bp; 3887 struct bufobj *bo; 3888 daddr_t d_blkno; 3889 int bsize, error, maxsize, vmio; 3890 off_t offset; 3891 3892 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3893 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3894 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3895 ASSERT_VOP_LOCKED(vp, "getblk"); 3896 if (size > maxbcachebuf) 3897 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3898 maxbcachebuf); 3899 if (!unmapped_buf_allowed) 3900 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3901 3902 bo = &vp->v_bufobj; 3903 d_blkno = dblkno; 3904 3905 /* Attempt lockless lookup first. */ 3906 bp = gbincore_unlocked(bo, blkno); 3907 if (bp == NULL) { 3908 /* 3909 * With GB_NOCREAT we must be sure about not finding the buffer 3910 * as it may have been reassigned during unlocked lookup. 3911 */ 3912 if ((flags & GB_NOCREAT) != 0) 3913 goto loop; 3914 goto newbuf_unlocked; 3915 } 3916 3917 error = BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL, "getblku", 0, 3918 0); 3919 if (error != 0) 3920 goto loop; 3921 3922 /* Verify buf identify has not changed since lookup. */ 3923 if (bp->b_bufobj == bo && bp->b_lblkno == blkno) 3924 goto foundbuf_fastpath; 3925 3926 /* It changed, fallback to locked lookup. */ 3927 BUF_UNLOCK_RAW(bp); 3928 3929 loop: 3930 BO_RLOCK(bo); 3931 bp = gbincore(bo, blkno); 3932 if (bp != NULL) { 3933 int lockflags; 3934 3935 /* 3936 * Buffer is in-core. If the buffer is not busy nor managed, 3937 * it must be on a queue. 3938 */ 3939 lockflags = LK_EXCLUSIVE | LK_INTERLOCK | 3940 ((flags & GB_LOCK_NOWAIT) ? LK_NOWAIT : LK_SLEEPFAIL); 3941 3942 error = BUF_TIMELOCK(bp, lockflags, 3943 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3944 3945 /* 3946 * If we slept and got the lock we have to restart in case 3947 * the buffer changed identities. 3948 */ 3949 if (error == ENOLCK) 3950 goto loop; 3951 /* We timed out or were interrupted. */ 3952 else if (error != 0) 3953 return (error); 3954 3955 foundbuf_fastpath: 3956 /* If recursed, assume caller knows the rules. */ 3957 if (BUF_LOCKRECURSED(bp)) 3958 goto end; 3959 3960 /* 3961 * The buffer is locked. B_CACHE is cleared if the buffer is 3962 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3963 * and for a VMIO buffer B_CACHE is adjusted according to the 3964 * backing VM cache. 3965 */ 3966 if (bp->b_flags & B_INVAL) 3967 bp->b_flags &= ~B_CACHE; 3968 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3969 bp->b_flags |= B_CACHE; 3970 if (bp->b_flags & B_MANAGED) 3971 MPASS(bp->b_qindex == QUEUE_NONE); 3972 else 3973 bremfree(bp); 3974 3975 /* 3976 * check for size inconsistencies for non-VMIO case. 3977 */ 3978 if (bp->b_bcount != size) { 3979 if ((bp->b_flags & B_VMIO) == 0 || 3980 (size > bp->b_kvasize)) { 3981 if (bp->b_flags & B_DELWRI) { 3982 bp->b_flags |= B_NOCACHE; 3983 bwrite(bp); 3984 } else { 3985 if (LIST_EMPTY(&bp->b_dep)) { 3986 bp->b_flags |= B_RELBUF; 3987 brelse(bp); 3988 } else { 3989 bp->b_flags |= B_NOCACHE; 3990 bwrite(bp); 3991 } 3992 } 3993 goto loop; 3994 } 3995 } 3996 3997 /* 3998 * Handle the case of unmapped buffer which should 3999 * become mapped, or the buffer for which KVA 4000 * reservation is requested. 4001 */ 4002 bp_unmapped_get_kva(bp, blkno, size, flags); 4003 4004 /* 4005 * If the size is inconsistent in the VMIO case, we can resize 4006 * the buffer. This might lead to B_CACHE getting set or 4007 * cleared. If the size has not changed, B_CACHE remains 4008 * unchanged from its previous state. 4009 */ 4010 allocbuf(bp, size); 4011 4012 KASSERT(bp->b_offset != NOOFFSET, 4013 ("getblk: no buffer offset")); 4014 4015 /* 4016 * A buffer with B_DELWRI set and B_CACHE clear must 4017 * be committed before we can return the buffer in 4018 * order to prevent the caller from issuing a read 4019 * ( due to B_CACHE not being set ) and overwriting 4020 * it. 4021 * 4022 * Most callers, including NFS and FFS, need this to 4023 * operate properly either because they assume they 4024 * can issue a read if B_CACHE is not set, or because 4025 * ( for example ) an uncached B_DELWRI might loop due 4026 * to softupdates re-dirtying the buffer. In the latter 4027 * case, B_CACHE is set after the first write completes, 4028 * preventing further loops. 4029 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 4030 * above while extending the buffer, we cannot allow the 4031 * buffer to remain with B_CACHE set after the write 4032 * completes or it will represent a corrupt state. To 4033 * deal with this we set B_NOCACHE to scrap the buffer 4034 * after the write. 4035 * 4036 * We might be able to do something fancy, like setting 4037 * B_CACHE in bwrite() except if B_DELWRI is already set, 4038 * so the below call doesn't set B_CACHE, but that gets real 4039 * confusing. This is much easier. 4040 */ 4041 4042 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 4043 bp->b_flags |= B_NOCACHE; 4044 bwrite(bp); 4045 goto loop; 4046 } 4047 bp->b_flags &= ~B_DONE; 4048 } else { 4049 /* 4050 * Buffer is not in-core, create new buffer. The buffer 4051 * returned by getnewbuf() is locked. Note that the returned 4052 * buffer is also considered valid (not marked B_INVAL). 4053 */ 4054 BO_RUNLOCK(bo); 4055 newbuf_unlocked: 4056 /* 4057 * If the user does not want us to create the buffer, bail out 4058 * here. 4059 */ 4060 if (flags & GB_NOCREAT) 4061 return (EEXIST); 4062 4063 bsize = vn_isdisk(vp) ? DEV_BSIZE : bo->bo_bsize; 4064 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4065 offset = blkno * bsize; 4066 vmio = vp->v_object != NULL; 4067 if (vmio) { 4068 maxsize = size + (offset & PAGE_MASK); 4069 } else { 4070 maxsize = size; 4071 /* Do not allow non-VMIO notmapped buffers. */ 4072 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4073 } 4074 maxsize = imax(maxsize, bsize); 4075 if ((flags & GB_NOSPARSE) != 0 && vmio && 4076 !vn_isdisk(vp)) { 4077 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4078 KASSERT(error != EOPNOTSUPP, 4079 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4080 vp)); 4081 if (error != 0) 4082 return (error); 4083 if (d_blkno == -1) 4084 return (EJUSTRETURN); 4085 } 4086 4087 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4088 if (bp == NULL) { 4089 if (slpflag || slptimeo) 4090 return (ETIMEDOUT); 4091 /* 4092 * XXX This is here until the sleep path is diagnosed 4093 * enough to work under very low memory conditions. 4094 * 4095 * There's an issue on low memory, 4BSD+non-preempt 4096 * systems (eg MIPS routers with 32MB RAM) where buffer 4097 * exhaustion occurs without sleeping for buffer 4098 * reclaimation. This just sticks in a loop and 4099 * constantly attempts to allocate a buffer, which 4100 * hits exhaustion and tries to wakeup bufdaemon. 4101 * This never happens because we never yield. 4102 * 4103 * The real solution is to identify and fix these cases 4104 * so we aren't effectively busy-waiting in a loop 4105 * until the reclaimation path has cycles to run. 4106 */ 4107 kern_yield(PRI_USER); 4108 goto loop; 4109 } 4110 4111 /* 4112 * This code is used to make sure that a buffer is not 4113 * created while the getnewbuf routine is blocked. 4114 * This can be a problem whether the vnode is locked or not. 4115 * If the buffer is created out from under us, we have to 4116 * throw away the one we just created. 4117 * 4118 * Note: this must occur before we associate the buffer 4119 * with the vp especially considering limitations in 4120 * the splay tree implementation when dealing with duplicate 4121 * lblkno's. 4122 */ 4123 BO_LOCK(bo); 4124 if (gbincore(bo, blkno)) { 4125 BO_UNLOCK(bo); 4126 bp->b_flags |= B_INVAL; 4127 bufspace_release(bufdomain(bp), maxsize); 4128 brelse(bp); 4129 goto loop; 4130 } 4131 4132 /* 4133 * Insert the buffer into the hash, so that it can 4134 * be found by incore. 4135 */ 4136 bp->b_lblkno = blkno; 4137 bp->b_blkno = d_blkno; 4138 bp->b_offset = offset; 4139 bgetvp(vp, bp); 4140 BO_UNLOCK(bo); 4141 4142 /* 4143 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4144 * buffer size starts out as 0, B_CACHE will be set by 4145 * allocbuf() for the VMIO case prior to it testing the 4146 * backing store for validity. 4147 */ 4148 4149 if (vmio) { 4150 bp->b_flags |= B_VMIO; 4151 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4152 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4153 bp, vp->v_object, bp->b_bufobj->bo_object)); 4154 } else { 4155 bp->b_flags &= ~B_VMIO; 4156 KASSERT(bp->b_bufobj->bo_object == NULL, 4157 ("ARGH! has b_bufobj->bo_object %p %p\n", 4158 bp, bp->b_bufobj->bo_object)); 4159 BUF_CHECK_MAPPED(bp); 4160 } 4161 4162 allocbuf(bp, size); 4163 bufspace_release(bufdomain(bp), maxsize); 4164 bp->b_flags &= ~B_DONE; 4165 } 4166 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4167 end: 4168 buf_track(bp, __func__); 4169 KASSERT(bp->b_bufobj == bo, 4170 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4171 *bpp = bp; 4172 return (0); 4173 } 4174 4175 /* 4176 * Get an empty, disassociated buffer of given size. The buffer is initially 4177 * set to B_INVAL. 4178 */ 4179 struct buf * 4180 geteblk(int size, int flags) 4181 { 4182 struct buf *bp; 4183 int maxsize; 4184 4185 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4186 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4187 if ((flags & GB_NOWAIT_BD) && 4188 (curthread->td_pflags & TDP_BUFNEED) != 0) 4189 return (NULL); 4190 } 4191 allocbuf(bp, size); 4192 bufspace_release(bufdomain(bp), maxsize); 4193 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4194 return (bp); 4195 } 4196 4197 /* 4198 * Truncate the backing store for a non-vmio buffer. 4199 */ 4200 static void 4201 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4202 { 4203 4204 if (bp->b_flags & B_MALLOC) { 4205 /* 4206 * malloced buffers are not shrunk 4207 */ 4208 if (newbsize == 0) { 4209 bufmallocadjust(bp, 0); 4210 free(bp->b_data, M_BIOBUF); 4211 bp->b_data = bp->b_kvabase; 4212 bp->b_flags &= ~B_MALLOC; 4213 } 4214 return; 4215 } 4216 vm_hold_free_pages(bp, newbsize); 4217 bufspace_adjust(bp, newbsize); 4218 } 4219 4220 /* 4221 * Extend the backing for a non-VMIO buffer. 4222 */ 4223 static void 4224 vfs_nonvmio_extend(struct buf *bp, int newbsize) 4225 { 4226 caddr_t origbuf; 4227 int origbufsize; 4228 4229 /* 4230 * We only use malloced memory on the first allocation. 4231 * and revert to page-allocated memory when the buffer 4232 * grows. 4233 * 4234 * There is a potential smp race here that could lead 4235 * to bufmallocspace slightly passing the max. It 4236 * is probably extremely rare and not worth worrying 4237 * over. 4238 */ 4239 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4240 bufmallocspace < maxbufmallocspace) { 4241 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4242 bp->b_flags |= B_MALLOC; 4243 bufmallocadjust(bp, newbsize); 4244 return; 4245 } 4246 4247 /* 4248 * If the buffer is growing on its other-than-first 4249 * allocation then we revert to the page-allocation 4250 * scheme. 4251 */ 4252 origbuf = NULL; 4253 origbufsize = 0; 4254 if (bp->b_flags & B_MALLOC) { 4255 origbuf = bp->b_data; 4256 origbufsize = bp->b_bufsize; 4257 bp->b_data = bp->b_kvabase; 4258 bufmallocadjust(bp, 0); 4259 bp->b_flags &= ~B_MALLOC; 4260 newbsize = round_page(newbsize); 4261 } 4262 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4263 (vm_offset_t) bp->b_data + newbsize); 4264 if (origbuf != NULL) { 4265 bcopy(origbuf, bp->b_data, origbufsize); 4266 free(origbuf, M_BIOBUF); 4267 } 4268 bufspace_adjust(bp, newbsize); 4269 } 4270 4271 /* 4272 * This code constitutes the buffer memory from either anonymous system 4273 * memory (in the case of non-VMIO operations) or from an associated 4274 * VM object (in the case of VMIO operations). This code is able to 4275 * resize a buffer up or down. 4276 * 4277 * Note that this code is tricky, and has many complications to resolve 4278 * deadlock or inconsistent data situations. Tread lightly!!! 4279 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4280 * the caller. Calling this code willy nilly can result in the loss of data. 4281 * 4282 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4283 * B_CACHE for the non-VMIO case. 4284 */ 4285 int 4286 allocbuf(struct buf *bp, int size) 4287 { 4288 int newbsize; 4289 4290 if (bp->b_bcount == size) 4291 return (1); 4292 4293 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 4294 panic("allocbuf: buffer too small"); 4295 4296 newbsize = roundup2(size, DEV_BSIZE); 4297 if ((bp->b_flags & B_VMIO) == 0) { 4298 if ((bp->b_flags & B_MALLOC) == 0) 4299 newbsize = round_page(newbsize); 4300 /* 4301 * Just get anonymous memory from the kernel. Don't 4302 * mess with B_CACHE. 4303 */ 4304 if (newbsize < bp->b_bufsize) 4305 vfs_nonvmio_truncate(bp, newbsize); 4306 else if (newbsize > bp->b_bufsize) 4307 vfs_nonvmio_extend(bp, newbsize); 4308 } else { 4309 int desiredpages; 4310 4311 desiredpages = (size == 0) ? 0 : 4312 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4313 4314 if (bp->b_flags & B_MALLOC) 4315 panic("allocbuf: VMIO buffer can't be malloced"); 4316 /* 4317 * Set B_CACHE initially if buffer is 0 length or will become 4318 * 0-length. 4319 */ 4320 if (size == 0 || bp->b_bufsize == 0) 4321 bp->b_flags |= B_CACHE; 4322 4323 if (newbsize < bp->b_bufsize) 4324 vfs_vmio_truncate(bp, desiredpages); 4325 /* XXX This looks as if it should be newbsize > b_bufsize */ 4326 else if (size > bp->b_bcount) 4327 vfs_vmio_extend(bp, desiredpages, size); 4328 bufspace_adjust(bp, newbsize); 4329 } 4330 bp->b_bcount = size; /* requested buffer size. */ 4331 return (1); 4332 } 4333 4334 extern int inflight_transient_maps; 4335 4336 static struct bio_queue nondump_bios; 4337 4338 void 4339 biodone(struct bio *bp) 4340 { 4341 struct mtx *mtxp; 4342 void (*done)(struct bio *); 4343 vm_offset_t start, end; 4344 4345 biotrack(bp, __func__); 4346 4347 /* 4348 * Avoid completing I/O when dumping after a panic since that may 4349 * result in a deadlock in the filesystem or pager code. Note that 4350 * this doesn't affect dumps that were started manually since we aim 4351 * to keep the system usable after it has been resumed. 4352 */ 4353 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4354 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4355 return; 4356 } 4357 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4358 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4359 bp->bio_flags |= BIO_UNMAPPED; 4360 start = trunc_page((vm_offset_t)bp->bio_data); 4361 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4362 bp->bio_data = unmapped_buf; 4363 pmap_qremove(start, atop(end - start)); 4364 vmem_free(transient_arena, start, end - start); 4365 atomic_add_int(&inflight_transient_maps, -1); 4366 } 4367 done = bp->bio_done; 4368 if (done == NULL) { 4369 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4370 mtx_lock(mtxp); 4371 bp->bio_flags |= BIO_DONE; 4372 wakeup(bp); 4373 mtx_unlock(mtxp); 4374 } else 4375 done(bp); 4376 } 4377 4378 /* 4379 * Wait for a BIO to finish. 4380 */ 4381 int 4382 biowait(struct bio *bp, const char *wchan) 4383 { 4384 struct mtx *mtxp; 4385 4386 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4387 mtx_lock(mtxp); 4388 while ((bp->bio_flags & BIO_DONE) == 0) 4389 msleep(bp, mtxp, PRIBIO, wchan, 0); 4390 mtx_unlock(mtxp); 4391 if (bp->bio_error != 0) 4392 return (bp->bio_error); 4393 if (!(bp->bio_flags & BIO_ERROR)) 4394 return (0); 4395 return (EIO); 4396 } 4397 4398 void 4399 biofinish(struct bio *bp, struct devstat *stat, int error) 4400 { 4401 4402 if (error) { 4403 bp->bio_error = error; 4404 bp->bio_flags |= BIO_ERROR; 4405 } 4406 if (stat != NULL) 4407 devstat_end_transaction_bio(stat, bp); 4408 biodone(bp); 4409 } 4410 4411 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4412 void 4413 biotrack_buf(struct bio *bp, const char *location) 4414 { 4415 4416 buf_track(bp->bio_track_bp, location); 4417 } 4418 #endif 4419 4420 /* 4421 * bufwait: 4422 * 4423 * Wait for buffer I/O completion, returning error status. The buffer 4424 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4425 * error and cleared. 4426 */ 4427 int 4428 bufwait(struct buf *bp) 4429 { 4430 if (bp->b_iocmd == BIO_READ) 4431 bwait(bp, PRIBIO, "biord"); 4432 else 4433 bwait(bp, PRIBIO, "biowr"); 4434 if (bp->b_flags & B_EINTR) { 4435 bp->b_flags &= ~B_EINTR; 4436 return (EINTR); 4437 } 4438 if (bp->b_ioflags & BIO_ERROR) { 4439 return (bp->b_error ? bp->b_error : EIO); 4440 } else { 4441 return (0); 4442 } 4443 } 4444 4445 /* 4446 * bufdone: 4447 * 4448 * Finish I/O on a buffer, optionally calling a completion function. 4449 * This is usually called from an interrupt so process blocking is 4450 * not allowed. 4451 * 4452 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4453 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4454 * assuming B_INVAL is clear. 4455 * 4456 * For the VMIO case, we set B_CACHE if the op was a read and no 4457 * read error occurred, or if the op was a write. B_CACHE is never 4458 * set if the buffer is invalid or otherwise uncacheable. 4459 * 4460 * bufdone does not mess with B_INVAL, allowing the I/O routine or the 4461 * initiator to leave B_INVAL set to brelse the buffer out of existence 4462 * in the biodone routine. 4463 */ 4464 void 4465 bufdone(struct buf *bp) 4466 { 4467 struct bufobj *dropobj; 4468 void (*biodone)(struct buf *); 4469 4470 buf_track(bp, __func__); 4471 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4472 dropobj = NULL; 4473 4474 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4475 4476 runningbufwakeup(bp); 4477 if (bp->b_iocmd == BIO_WRITE) 4478 dropobj = bp->b_bufobj; 4479 /* call optional completion function if requested */ 4480 if (bp->b_iodone != NULL) { 4481 biodone = bp->b_iodone; 4482 bp->b_iodone = NULL; 4483 (*biodone) (bp); 4484 if (dropobj) 4485 bufobj_wdrop(dropobj); 4486 return; 4487 } 4488 if (bp->b_flags & B_VMIO) { 4489 /* 4490 * Set B_CACHE if the op was a normal read and no error 4491 * occurred. B_CACHE is set for writes in the b*write() 4492 * routines. 4493 */ 4494 if (bp->b_iocmd == BIO_READ && 4495 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4496 !(bp->b_ioflags & BIO_ERROR)) 4497 bp->b_flags |= B_CACHE; 4498 vfs_vmio_iodone(bp); 4499 } 4500 if (!LIST_EMPTY(&bp->b_dep)) 4501 buf_complete(bp); 4502 if ((bp->b_flags & B_CKHASH) != 0) { 4503 KASSERT(bp->b_iocmd == BIO_READ, 4504 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4505 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4506 (*bp->b_ckhashcalc)(bp); 4507 } 4508 /* 4509 * For asynchronous completions, release the buffer now. The brelse 4510 * will do a wakeup there if necessary - so no need to do a wakeup 4511 * here in the async case. The sync case always needs to do a wakeup. 4512 */ 4513 if (bp->b_flags & B_ASYNC) { 4514 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4515 (bp->b_ioflags & BIO_ERROR)) 4516 brelse(bp); 4517 else 4518 bqrelse(bp); 4519 } else 4520 bdone(bp); 4521 if (dropobj) 4522 bufobj_wdrop(dropobj); 4523 } 4524 4525 /* 4526 * This routine is called in lieu of iodone in the case of 4527 * incomplete I/O. This keeps the busy status for pages 4528 * consistent. 4529 */ 4530 void 4531 vfs_unbusy_pages(struct buf *bp) 4532 { 4533 int i; 4534 vm_object_t obj; 4535 vm_page_t m; 4536 4537 runningbufwakeup(bp); 4538 if (!(bp->b_flags & B_VMIO)) 4539 return; 4540 4541 obj = bp->b_bufobj->bo_object; 4542 for (i = 0; i < bp->b_npages; i++) { 4543 m = bp->b_pages[i]; 4544 if (m == bogus_page) { 4545 m = vm_page_relookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4546 if (!m) 4547 panic("vfs_unbusy_pages: page missing\n"); 4548 bp->b_pages[i] = m; 4549 if (buf_mapped(bp)) { 4550 BUF_CHECK_MAPPED(bp); 4551 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4552 bp->b_pages, bp->b_npages); 4553 } else 4554 BUF_CHECK_UNMAPPED(bp); 4555 } 4556 vm_page_sunbusy(m); 4557 } 4558 vm_object_pip_wakeupn(obj, bp->b_npages); 4559 } 4560 4561 /* 4562 * vfs_page_set_valid: 4563 * 4564 * Set the valid bits in a page based on the supplied offset. The 4565 * range is restricted to the buffer's size. 4566 * 4567 * This routine is typically called after a read completes. 4568 */ 4569 static void 4570 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4571 { 4572 vm_ooffset_t eoff; 4573 4574 /* 4575 * Compute the end offset, eoff, such that [off, eoff) does not span a 4576 * page boundary and eoff is not greater than the end of the buffer. 4577 * The end of the buffer, in this case, is our file EOF, not the 4578 * allocation size of the buffer. 4579 */ 4580 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4581 if (eoff > bp->b_offset + bp->b_bcount) 4582 eoff = bp->b_offset + bp->b_bcount; 4583 4584 /* 4585 * Set valid range. This is typically the entire buffer and thus the 4586 * entire page. 4587 */ 4588 if (eoff > off) 4589 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4590 } 4591 4592 /* 4593 * vfs_page_set_validclean: 4594 * 4595 * Set the valid bits and clear the dirty bits in a page based on the 4596 * supplied offset. The range is restricted to the buffer's size. 4597 */ 4598 static void 4599 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4600 { 4601 vm_ooffset_t soff, eoff; 4602 4603 /* 4604 * Start and end offsets in buffer. eoff - soff may not cross a 4605 * page boundary or cross the end of the buffer. The end of the 4606 * buffer, in this case, is our file EOF, not the allocation size 4607 * of the buffer. 4608 */ 4609 soff = off; 4610 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4611 if (eoff > bp->b_offset + bp->b_bcount) 4612 eoff = bp->b_offset + bp->b_bcount; 4613 4614 /* 4615 * Set valid range. This is typically the entire buffer and thus the 4616 * entire page. 4617 */ 4618 if (eoff > soff) { 4619 vm_page_set_validclean( 4620 m, 4621 (vm_offset_t) (soff & PAGE_MASK), 4622 (vm_offset_t) (eoff - soff) 4623 ); 4624 } 4625 } 4626 4627 /* 4628 * Acquire a shared busy on all pages in the buf. 4629 */ 4630 void 4631 vfs_busy_pages_acquire(struct buf *bp) 4632 { 4633 int i; 4634 4635 for (i = 0; i < bp->b_npages; i++) 4636 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY); 4637 } 4638 4639 void 4640 vfs_busy_pages_release(struct buf *bp) 4641 { 4642 int i; 4643 4644 for (i = 0; i < bp->b_npages; i++) 4645 vm_page_sunbusy(bp->b_pages[i]); 4646 } 4647 4648 /* 4649 * This routine is called before a device strategy routine. 4650 * It is used to tell the VM system that paging I/O is in 4651 * progress, and treat the pages associated with the buffer 4652 * almost as being exclusive busy. Also the object paging_in_progress 4653 * flag is handled to make sure that the object doesn't become 4654 * inconsistent. 4655 * 4656 * Since I/O has not been initiated yet, certain buffer flags 4657 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4658 * and should be ignored. 4659 */ 4660 void 4661 vfs_busy_pages(struct buf *bp, int clear_modify) 4662 { 4663 vm_object_t obj; 4664 vm_ooffset_t foff; 4665 vm_page_t m; 4666 int i; 4667 bool bogus; 4668 4669 if (!(bp->b_flags & B_VMIO)) 4670 return; 4671 4672 obj = bp->b_bufobj->bo_object; 4673 foff = bp->b_offset; 4674 KASSERT(bp->b_offset != NOOFFSET, 4675 ("vfs_busy_pages: no buffer offset")); 4676 if ((bp->b_flags & B_CLUSTER) == 0) { 4677 vm_object_pip_add(obj, bp->b_npages); 4678 vfs_busy_pages_acquire(bp); 4679 } 4680 if (bp->b_bufsize != 0) 4681 vfs_setdirty_range(bp); 4682 bogus = false; 4683 for (i = 0; i < bp->b_npages; i++) { 4684 m = bp->b_pages[i]; 4685 vm_page_assert_sbusied(m); 4686 4687 /* 4688 * When readying a buffer for a read ( i.e 4689 * clear_modify == 0 ), it is important to do 4690 * bogus_page replacement for valid pages in 4691 * partially instantiated buffers. Partially 4692 * instantiated buffers can, in turn, occur when 4693 * reconstituting a buffer from its VM backing store 4694 * base. We only have to do this if B_CACHE is 4695 * clear ( which causes the I/O to occur in the 4696 * first place ). The replacement prevents the read 4697 * I/O from overwriting potentially dirty VM-backed 4698 * pages. XXX bogus page replacement is, uh, bogus. 4699 * It may not work properly with small-block devices. 4700 * We need to find a better way. 4701 */ 4702 if (clear_modify) { 4703 pmap_remove_write(m); 4704 vfs_page_set_validclean(bp, foff, m); 4705 } else if (vm_page_all_valid(m) && 4706 (bp->b_flags & B_CACHE) == 0) { 4707 bp->b_pages[i] = bogus_page; 4708 bogus = true; 4709 } 4710 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4711 } 4712 if (bogus && buf_mapped(bp)) { 4713 BUF_CHECK_MAPPED(bp); 4714 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4715 bp->b_pages, bp->b_npages); 4716 } 4717 } 4718 4719 /* 4720 * vfs_bio_set_valid: 4721 * 4722 * Set the range within the buffer to valid. The range is 4723 * relative to the beginning of the buffer, b_offset. Note that 4724 * b_offset itself may be offset from the beginning of the first 4725 * page. 4726 */ 4727 void 4728 vfs_bio_set_valid(struct buf *bp, int base, int size) 4729 { 4730 int i, n; 4731 vm_page_t m; 4732 4733 if (!(bp->b_flags & B_VMIO)) 4734 return; 4735 4736 /* 4737 * Fixup base to be relative to beginning of first page. 4738 * Set initial n to be the maximum number of bytes in the 4739 * first page that can be validated. 4740 */ 4741 base += (bp->b_offset & PAGE_MASK); 4742 n = PAGE_SIZE - (base & PAGE_MASK); 4743 4744 /* 4745 * Busy may not be strictly necessary here because the pages are 4746 * unlikely to be fully valid and the vnode lock will synchronize 4747 * their access via getpages. It is grabbed for consistency with 4748 * other page validation. 4749 */ 4750 vfs_busy_pages_acquire(bp); 4751 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4752 m = bp->b_pages[i]; 4753 if (n > size) 4754 n = size; 4755 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4756 base += n; 4757 size -= n; 4758 n = PAGE_SIZE; 4759 } 4760 vfs_busy_pages_release(bp); 4761 } 4762 4763 /* 4764 * vfs_bio_clrbuf: 4765 * 4766 * If the specified buffer is a non-VMIO buffer, clear the entire 4767 * buffer. If the specified buffer is a VMIO buffer, clear and 4768 * validate only the previously invalid portions of the buffer. 4769 * This routine essentially fakes an I/O, so we need to clear 4770 * BIO_ERROR and B_INVAL. 4771 * 4772 * Note that while we only theoretically need to clear through b_bcount, 4773 * we go ahead and clear through b_bufsize. 4774 */ 4775 void 4776 vfs_bio_clrbuf(struct buf *bp) 4777 { 4778 int i, j, mask, sa, ea, slide; 4779 4780 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4781 clrbuf(bp); 4782 return; 4783 } 4784 bp->b_flags &= ~B_INVAL; 4785 bp->b_ioflags &= ~BIO_ERROR; 4786 vfs_busy_pages_acquire(bp); 4787 sa = bp->b_offset & PAGE_MASK; 4788 slide = 0; 4789 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4790 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4791 ea = slide & PAGE_MASK; 4792 if (ea == 0) 4793 ea = PAGE_SIZE; 4794 if (bp->b_pages[i] == bogus_page) 4795 continue; 4796 j = sa / DEV_BSIZE; 4797 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4798 if ((bp->b_pages[i]->valid & mask) == mask) 4799 continue; 4800 if ((bp->b_pages[i]->valid & mask) == 0) 4801 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4802 else { 4803 for (; sa < ea; sa += DEV_BSIZE, j++) { 4804 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4805 pmap_zero_page_area(bp->b_pages[i], 4806 sa, DEV_BSIZE); 4807 } 4808 } 4809 } 4810 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE, 4811 roundup2(ea - sa, DEV_BSIZE)); 4812 } 4813 vfs_busy_pages_release(bp); 4814 bp->b_resid = 0; 4815 } 4816 4817 void 4818 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4819 { 4820 vm_page_t m; 4821 int i, n; 4822 4823 if (buf_mapped(bp)) { 4824 BUF_CHECK_MAPPED(bp); 4825 bzero(bp->b_data + base, size); 4826 } else { 4827 BUF_CHECK_UNMAPPED(bp); 4828 n = PAGE_SIZE - (base & PAGE_MASK); 4829 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4830 m = bp->b_pages[i]; 4831 if (n > size) 4832 n = size; 4833 pmap_zero_page_area(m, base & PAGE_MASK, n); 4834 base += n; 4835 size -= n; 4836 n = PAGE_SIZE; 4837 } 4838 } 4839 } 4840 4841 /* 4842 * Update buffer flags based on I/O request parameters, optionally releasing the 4843 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4844 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4845 * I/O). Otherwise the buffer is released to the cache. 4846 */ 4847 static void 4848 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4849 { 4850 4851 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4852 ("buf %p non-VMIO noreuse", bp)); 4853 4854 if ((ioflag & IO_DIRECT) != 0) 4855 bp->b_flags |= B_DIRECT; 4856 if ((ioflag & IO_EXT) != 0) 4857 bp->b_xflags |= BX_ALTDATA; 4858 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4859 bp->b_flags |= B_RELBUF; 4860 if ((ioflag & IO_NOREUSE) != 0) 4861 bp->b_flags |= B_NOREUSE; 4862 if (release) 4863 brelse(bp); 4864 } else if (release) 4865 bqrelse(bp); 4866 } 4867 4868 void 4869 vfs_bio_brelse(struct buf *bp, int ioflag) 4870 { 4871 4872 b_io_dismiss(bp, ioflag, true); 4873 } 4874 4875 void 4876 vfs_bio_set_flags(struct buf *bp, int ioflag) 4877 { 4878 4879 b_io_dismiss(bp, ioflag, false); 4880 } 4881 4882 /* 4883 * vm_hold_load_pages and vm_hold_free_pages get pages into 4884 * a buffers address space. The pages are anonymous and are 4885 * not associated with a file object. 4886 */ 4887 static void 4888 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4889 { 4890 vm_offset_t pg; 4891 vm_page_t p; 4892 int index; 4893 4894 BUF_CHECK_MAPPED(bp); 4895 4896 to = round_page(to); 4897 from = round_page(from); 4898 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4899 MPASS((bp->b_flags & B_MAXPHYS) == 0); 4900 KASSERT(to - from <= maxbcachebuf, 4901 ("vm_hold_load_pages too large %p %#jx %#jx %u", 4902 bp, (uintmax_t)from, (uintmax_t)to, maxbcachebuf)); 4903 4904 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4905 /* 4906 * note: must allocate system pages since blocking here 4907 * could interfere with paging I/O, no matter which 4908 * process we are. 4909 */ 4910 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4911 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | 4912 VM_ALLOC_WAITOK); 4913 pmap_qenter(pg, &p, 1); 4914 bp->b_pages[index] = p; 4915 } 4916 bp->b_npages = index; 4917 } 4918 4919 /* Return pages associated with this buf to the vm system */ 4920 static void 4921 vm_hold_free_pages(struct buf *bp, int newbsize) 4922 { 4923 vm_offset_t from; 4924 vm_page_t p; 4925 int index, newnpages; 4926 4927 BUF_CHECK_MAPPED(bp); 4928 4929 from = round_page((vm_offset_t)bp->b_data + newbsize); 4930 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4931 if (bp->b_npages > newnpages) 4932 pmap_qremove(from, bp->b_npages - newnpages); 4933 for (index = newnpages; index < bp->b_npages; index++) { 4934 p = bp->b_pages[index]; 4935 bp->b_pages[index] = NULL; 4936 vm_page_unwire_noq(p); 4937 vm_page_free(p); 4938 } 4939 bp->b_npages = newnpages; 4940 } 4941 4942 /* 4943 * Map an IO request into kernel virtual address space. 4944 * 4945 * All requests are (re)mapped into kernel VA space. 4946 * Notice that we use b_bufsize for the size of the buffer 4947 * to be mapped. b_bcount might be modified by the driver. 4948 * 4949 * Note that even if the caller determines that the address space should 4950 * be valid, a race or a smaller-file mapped into a larger space may 4951 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4952 * check the return value. 4953 * 4954 * This function only works with pager buffers. 4955 */ 4956 int 4957 vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf) 4958 { 4959 vm_prot_t prot; 4960 int pidx; 4961 4962 MPASS((bp->b_flags & B_MAXPHYS) != 0); 4963 prot = VM_PROT_READ; 4964 if (bp->b_iocmd == BIO_READ) 4965 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4966 pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4967 (vm_offset_t)uaddr, len, prot, bp->b_pages, PBUF_PAGES); 4968 if (pidx < 0) 4969 return (-1); 4970 bp->b_bufsize = len; 4971 bp->b_npages = pidx; 4972 bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK; 4973 if (mapbuf || !unmapped_buf_allowed) { 4974 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4975 bp->b_data = bp->b_kvabase + bp->b_offset; 4976 } else 4977 bp->b_data = unmapped_buf; 4978 return (0); 4979 } 4980 4981 /* 4982 * Free the io map PTEs associated with this IO operation. 4983 * We also invalidate the TLB entries and restore the original b_addr. 4984 * 4985 * This function only works with pager buffers. 4986 */ 4987 void 4988 vunmapbuf(struct buf *bp) 4989 { 4990 int npages; 4991 4992 npages = bp->b_npages; 4993 if (buf_mapped(bp)) 4994 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4995 vm_page_unhold_pages(bp->b_pages, npages); 4996 4997 bp->b_data = unmapped_buf; 4998 } 4999 5000 void 5001 bdone(struct buf *bp) 5002 { 5003 struct mtx *mtxp; 5004 5005 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5006 mtx_lock(mtxp); 5007 bp->b_flags |= B_DONE; 5008 wakeup(bp); 5009 mtx_unlock(mtxp); 5010 } 5011 5012 void 5013 bwait(struct buf *bp, u_char pri, const char *wchan) 5014 { 5015 struct mtx *mtxp; 5016 5017 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5018 mtx_lock(mtxp); 5019 while ((bp->b_flags & B_DONE) == 0) 5020 msleep(bp, mtxp, pri, wchan, 0); 5021 mtx_unlock(mtxp); 5022 } 5023 5024 int 5025 bufsync(struct bufobj *bo, int waitfor) 5026 { 5027 5028 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 5029 } 5030 5031 void 5032 bufstrategy(struct bufobj *bo, struct buf *bp) 5033 { 5034 int i __unused; 5035 struct vnode *vp; 5036 5037 vp = bp->b_vp; 5038 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5039 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5040 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5041 i = VOP_STRATEGY(vp, bp); 5042 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5043 } 5044 5045 /* 5046 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5047 */ 5048 void 5049 bufobj_init(struct bufobj *bo, void *private) 5050 { 5051 static volatile int bufobj_cleanq; 5052 5053 bo->bo_domain = 5054 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5055 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5056 bo->bo_private = private; 5057 TAILQ_INIT(&bo->bo_clean.bv_hd); 5058 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5059 } 5060 5061 void 5062 bufobj_wrefl(struct bufobj *bo) 5063 { 5064 5065 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5066 ASSERT_BO_WLOCKED(bo); 5067 bo->bo_numoutput++; 5068 } 5069 5070 void 5071 bufobj_wref(struct bufobj *bo) 5072 { 5073 5074 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5075 BO_LOCK(bo); 5076 bo->bo_numoutput++; 5077 BO_UNLOCK(bo); 5078 } 5079 5080 void 5081 bufobj_wdrop(struct bufobj *bo) 5082 { 5083 5084 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5085 BO_LOCK(bo); 5086 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5087 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5088 bo->bo_flag &= ~BO_WWAIT; 5089 wakeup(&bo->bo_numoutput); 5090 } 5091 BO_UNLOCK(bo); 5092 } 5093 5094 int 5095 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5096 { 5097 int error; 5098 5099 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5100 ASSERT_BO_WLOCKED(bo); 5101 error = 0; 5102 while (bo->bo_numoutput) { 5103 bo->bo_flag |= BO_WWAIT; 5104 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5105 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5106 if (error) 5107 break; 5108 } 5109 return (error); 5110 } 5111 5112 /* 5113 * Set bio_data or bio_ma for struct bio from the struct buf. 5114 */ 5115 void 5116 bdata2bio(struct buf *bp, struct bio *bip) 5117 { 5118 5119 if (!buf_mapped(bp)) { 5120 KASSERT(unmapped_buf_allowed, ("unmapped")); 5121 bip->bio_ma = bp->b_pages; 5122 bip->bio_ma_n = bp->b_npages; 5123 bip->bio_data = unmapped_buf; 5124 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5125 bip->bio_flags |= BIO_UNMAPPED; 5126 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5127 PAGE_SIZE == bp->b_npages, 5128 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5129 (long long)bip->bio_length, bip->bio_ma_n)); 5130 } else { 5131 bip->bio_data = bp->b_data; 5132 bip->bio_ma = NULL; 5133 } 5134 } 5135 5136 /* 5137 * The MIPS pmap code currently doesn't handle aliased pages. 5138 * The VIPT caches may not handle page aliasing themselves, leading 5139 * to data corruption. 5140 * 5141 * As such, this code makes a system extremely unhappy if said 5142 * system doesn't support unaliasing the above situation in hardware. 5143 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 5144 * this feature at build time, so it has to be handled in software. 5145 * 5146 * Once the MIPS pmap/cache code grows to support this function on 5147 * earlier chips, it should be flipped back off. 5148 */ 5149 #ifdef __mips__ 5150 static int buf_pager_relbuf = 1; 5151 #else 5152 static int buf_pager_relbuf = 0; 5153 #endif 5154 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5155 &buf_pager_relbuf, 0, 5156 "Make buffer pager release buffers after reading"); 5157 5158 /* 5159 * The buffer pager. It uses buffer reads to validate pages. 5160 * 5161 * In contrast to the generic local pager from vm/vnode_pager.c, this 5162 * pager correctly and easily handles volumes where the underlying 5163 * device block size is greater than the machine page size. The 5164 * buffer cache transparently extends the requested page run to be 5165 * aligned at the block boundary, and does the necessary bogus page 5166 * replacements in the addends to avoid obliterating already valid 5167 * pages. 5168 * 5169 * The only non-trivial issue is that the exclusive busy state for 5170 * pages, which is assumed by the vm_pager_getpages() interface, is 5171 * incompatible with the VMIO buffer cache's desire to share-busy the 5172 * pages. This function performs a trivial downgrade of the pages' 5173 * state before reading buffers, and a less trivial upgrade from the 5174 * shared-busy to excl-busy state after the read. 5175 */ 5176 int 5177 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5178 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5179 vbg_get_blksize_t get_blksize) 5180 { 5181 vm_page_t m; 5182 vm_object_t object; 5183 struct buf *bp; 5184 struct mount *mp; 5185 daddr_t lbn, lbnp; 5186 vm_ooffset_t la, lb, poff, poffe; 5187 long bsize; 5188 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5189 bool redo, lpart; 5190 5191 object = vp->v_object; 5192 mp = vp->v_mount; 5193 error = 0; 5194 la = IDX_TO_OFF(ma[count - 1]->pindex); 5195 if (la >= object->un_pager.vnp.vnp_size) 5196 return (VM_PAGER_BAD); 5197 5198 /* 5199 * Change the meaning of la from where the last requested page starts 5200 * to where it ends, because that's the end of the requested region 5201 * and the start of the potential read-ahead region. 5202 */ 5203 la += PAGE_SIZE; 5204 lpart = la > object->un_pager.vnp.vnp_size; 5205 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 5206 5207 /* 5208 * Calculate read-ahead, behind and total pages. 5209 */ 5210 pgsin = count; 5211 lb = IDX_TO_OFF(ma[0]->pindex); 5212 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5213 pgsin += pgsin_b; 5214 if (rbehind != NULL) 5215 *rbehind = pgsin_b; 5216 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5217 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5218 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5219 PAGE_SIZE) - la); 5220 pgsin += pgsin_a; 5221 if (rahead != NULL) 5222 *rahead = pgsin_a; 5223 VM_CNT_INC(v_vnodein); 5224 VM_CNT_ADD(v_vnodepgsin, pgsin); 5225 5226 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5227 != 0) ? GB_UNMAPPED : 0; 5228 again: 5229 for (i = 0; i < count; i++) { 5230 if (ma[i] != bogus_page) 5231 vm_page_busy_downgrade(ma[i]); 5232 } 5233 5234 lbnp = -1; 5235 for (i = 0; i < count; i++) { 5236 m = ma[i]; 5237 if (m == bogus_page) 5238 continue; 5239 5240 /* 5241 * Pages are shared busy and the object lock is not 5242 * owned, which together allow for the pages' 5243 * invalidation. The racy test for validity avoids 5244 * useless creation of the buffer for the most typical 5245 * case when invalidation is not used in redo or for 5246 * parallel read. The shared->excl upgrade loop at 5247 * the end of the function catches the race in a 5248 * reliable way (protected by the object lock). 5249 */ 5250 if (vm_page_all_valid(m)) 5251 continue; 5252 5253 poff = IDX_TO_OFF(m->pindex); 5254 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5255 for (; poff < poffe; poff += bsize) { 5256 lbn = get_lblkno(vp, poff); 5257 if (lbn == lbnp) 5258 goto next_page; 5259 lbnp = lbn; 5260 5261 bsize = get_blksize(vp, lbn); 5262 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 5263 br_flags, &bp); 5264 if (error != 0) 5265 goto end_pages; 5266 if (bp->b_rcred == curthread->td_ucred) { 5267 crfree(bp->b_rcred); 5268 bp->b_rcred = NOCRED; 5269 } 5270 if (LIST_EMPTY(&bp->b_dep)) { 5271 /* 5272 * Invalidation clears m->valid, but 5273 * may leave B_CACHE flag if the 5274 * buffer existed at the invalidation 5275 * time. In this case, recycle the 5276 * buffer to do real read on next 5277 * bread() after redo. 5278 * 5279 * Otherwise B_RELBUF is not strictly 5280 * necessary, enable to reduce buf 5281 * cache pressure. 5282 */ 5283 if (buf_pager_relbuf || 5284 !vm_page_all_valid(m)) 5285 bp->b_flags |= B_RELBUF; 5286 5287 bp->b_flags &= ~B_NOCACHE; 5288 brelse(bp); 5289 } else { 5290 bqrelse(bp); 5291 } 5292 } 5293 KASSERT(1 /* racy, enable for debugging */ || 5294 vm_page_all_valid(m) || i == count - 1, 5295 ("buf %d %p invalid", i, m)); 5296 if (i == count - 1 && lpart) { 5297 if (!vm_page_none_valid(m) && 5298 !vm_page_all_valid(m)) 5299 vm_page_zero_invalid(m, TRUE); 5300 } 5301 next_page:; 5302 } 5303 end_pages: 5304 5305 redo = false; 5306 for (i = 0; i < count; i++) { 5307 if (ma[i] == bogus_page) 5308 continue; 5309 if (vm_page_busy_tryupgrade(ma[i]) == 0) { 5310 vm_page_sunbusy(ma[i]); 5311 ma[i] = vm_page_grab_unlocked(object, ma[i]->pindex, 5312 VM_ALLOC_NORMAL); 5313 } 5314 5315 /* 5316 * Since the pages were only sbusy while neither the 5317 * buffer nor the object lock was held by us, or 5318 * reallocated while vm_page_grab() slept for busy 5319 * relinguish, they could have been invalidated. 5320 * Recheck the valid bits and re-read as needed. 5321 * 5322 * Note that the last page is made fully valid in the 5323 * read loop, and partial validity for the page at 5324 * index count - 1 could mean that the page was 5325 * invalidated or removed, so we must restart for 5326 * safety as well. 5327 */ 5328 if (!vm_page_all_valid(ma[i])) 5329 redo = true; 5330 } 5331 if (redo && error == 0) 5332 goto again; 5333 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5334 } 5335 5336 #include "opt_ddb.h" 5337 #ifdef DDB 5338 #include <ddb/ddb.h> 5339 5340 /* DDB command to show buffer data */ 5341 DB_SHOW_COMMAND(buffer, db_show_buffer) 5342 { 5343 /* get args */ 5344 struct buf *bp = (struct buf *)addr; 5345 #ifdef FULL_BUF_TRACKING 5346 uint32_t i, j; 5347 #endif 5348 5349 if (!have_addr) { 5350 db_printf("usage: show buffer <addr>\n"); 5351 return; 5352 } 5353 5354 db_printf("buf at %p\n", bp); 5355 db_printf("b_flags = 0x%b, b_xflags=0x%b\n", 5356 (u_int)bp->b_flags, PRINT_BUF_FLAGS, 5357 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS); 5358 db_printf("b_vflags=0x%b b_ioflags0x%b\n", 5359 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS, 5360 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS); 5361 db_printf( 5362 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5363 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, " 5364 "b_vp = %p, b_dep = %p\n", 5365 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5366 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5367 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first); 5368 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5369 bp->b_kvabase, bp->b_kvasize); 5370 if (bp->b_npages) { 5371 int i; 5372 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5373 for (i = 0; i < bp->b_npages; i++) { 5374 vm_page_t m; 5375 m = bp->b_pages[i]; 5376 if (m != NULL) 5377 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5378 (u_long)m->pindex, 5379 (u_long)VM_PAGE_TO_PHYS(m)); 5380 else 5381 db_printf("( ??? )"); 5382 if ((i + 1) < bp->b_npages) 5383 db_printf(","); 5384 } 5385 db_printf("\n"); 5386 } 5387 BUF_LOCKPRINTINFO(bp); 5388 #if defined(FULL_BUF_TRACKING) 5389 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5390 5391 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5392 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5393 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5394 continue; 5395 db_printf(" %2u: %s\n", j, 5396 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5397 } 5398 #elif defined(BUF_TRACKING) 5399 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5400 #endif 5401 db_printf(" "); 5402 } 5403 5404 DB_SHOW_COMMAND(bufqueues, bufqueues) 5405 { 5406 struct bufdomain *bd; 5407 struct buf *bp; 5408 long total; 5409 int i, j, cnt; 5410 5411 db_printf("bqempty: %d\n", bqempty.bq_len); 5412 5413 for (i = 0; i < buf_domains; i++) { 5414 bd = &bdomain[i]; 5415 db_printf("Buf domain %d\n", i); 5416 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5417 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5418 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5419 db_printf("\n"); 5420 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5421 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5422 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5423 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5424 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5425 db_printf("\n"); 5426 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5427 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5428 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5429 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5430 db_printf("\n"); 5431 total = 0; 5432 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5433 total += bp->b_bufsize; 5434 db_printf("\tcleanq count\t%d (%ld)\n", 5435 bd->bd_cleanq->bq_len, total); 5436 total = 0; 5437 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5438 total += bp->b_bufsize; 5439 db_printf("\tdirtyq count\t%d (%ld)\n", 5440 bd->bd_dirtyq.bq_len, total); 5441 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5442 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5443 db_printf("\tCPU "); 5444 for (j = 0; j <= mp_maxid; j++) 5445 db_printf("%d, ", bd->bd_subq[j].bq_len); 5446 db_printf("\n"); 5447 cnt = 0; 5448 total = 0; 5449 for (j = 0; j < nbuf; j++) { 5450 bp = nbufp(j); 5451 if (bp->b_domain == i && BUF_ISLOCKED(bp)) { 5452 cnt++; 5453 total += bp->b_bufsize; 5454 } 5455 } 5456 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5457 cnt = 0; 5458 total = 0; 5459 for (j = 0; j < nbuf; j++) { 5460 bp = nbufp(j); 5461 if (bp->b_domain == i) { 5462 cnt++; 5463 total += bp->b_bufsize; 5464 } 5465 } 5466 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5467 } 5468 } 5469 5470 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 5471 { 5472 struct buf *bp; 5473 int i; 5474 5475 for (i = 0; i < nbuf; i++) { 5476 bp = nbufp(i); 5477 if (BUF_ISLOCKED(bp)) { 5478 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5479 db_printf("\n"); 5480 if (db_pager_quit) 5481 break; 5482 } 5483 } 5484 } 5485 5486 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5487 { 5488 struct vnode *vp; 5489 struct buf *bp; 5490 5491 if (!have_addr) { 5492 db_printf("usage: show vnodebufs <addr>\n"); 5493 return; 5494 } 5495 vp = (struct vnode *)addr; 5496 db_printf("Clean buffers:\n"); 5497 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5498 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5499 db_printf("\n"); 5500 } 5501 db_printf("Dirty buffers:\n"); 5502 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5503 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5504 db_printf("\n"); 5505 } 5506 } 5507 5508 DB_COMMAND(countfreebufs, db_coundfreebufs) 5509 { 5510 struct buf *bp; 5511 int i, used = 0, nfree = 0; 5512 5513 if (have_addr) { 5514 db_printf("usage: countfreebufs\n"); 5515 return; 5516 } 5517 5518 for (i = 0; i < nbuf; i++) { 5519 bp = nbufp(i); 5520 if (bp->b_qindex == QUEUE_EMPTY) 5521 nfree++; 5522 else 5523 used++; 5524 } 5525 5526 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5527 nfree + used); 5528 db_printf("numfreebuffers is %d\n", numfreebuffers); 5529 } 5530 #endif /* DDB */ 5531