1/* 2 * Copyright (c) 1994,1997 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Absolutely no warranty of function or purpose is made by the author 12 * John S. Dyson. 13 */ 14 15/* 16 * this file contains a new buffer I/O scheme implementing a coherent 17 * VM object and buffer cache scheme. Pains have been taken to make 18 * sure that the performance degradation associated with schemes such 19 * as this is not realized. 20 * 21 * Author: John S. Dyson 22 * Significant help during the development and debugging phases 23 * had been provided by David Greenman, also of the FreeBSD core team. 24 * 25 * see man buf(9) for more info. 26 */ 27 28#include <sys/cdefs.h>
| 1/* 2 * Copyright (c) 1994,1997 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Absolutely no warranty of function or purpose is made by the author 12 * John S. Dyson. 13 */ 14 15/* 16 * this file contains a new buffer I/O scheme implementing a coherent 17 * VM object and buffer cache scheme. Pains have been taken to make 18 * sure that the performance degradation associated with schemes such 19 * as this is not realized. 20 * 21 * Author: John S. Dyson 22 * Significant help during the development and debugging phases 23 * had been provided by David Greenman, also of the FreeBSD core team. 24 * 25 * see man buf(9) for more info. 26 */ 27 28#include <sys/cdefs.h>
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29__FBSDID("$FreeBSD: head/sys/kern/vfs_bio.c 130585 2004-06-16 09:47:26Z phk $");
| 29__FBSDID("$FreeBSD: head/sys/kern/vfs_bio.c 130640 2004-06-17 17:16:53Z phk $");
|
30 31#include <sys/param.h> 32#include <sys/systm.h> 33#include <sys/bio.h> 34#include <sys/conf.h> 35#include <sys/buf.h> 36#include <sys/devicestat.h> 37#include <sys/eventhandler.h> 38#include <sys/lock.h> 39#include <sys/malloc.h> 40#include <sys/mount.h> 41#include <sys/mutex.h> 42#include <sys/kernel.h> 43#include <sys/kthread.h> 44#include <sys/proc.h> 45#include <sys/resourcevar.h> 46#include <sys/sysctl.h> 47#include <sys/vmmeter.h> 48#include <sys/vnode.h> 49#include <vm/vm.h> 50#include <vm/vm_param.h> 51#include <vm/vm_kern.h> 52#include <vm/vm_pageout.h> 53#include <vm/vm_page.h> 54#include <vm/vm_object.h> 55#include <vm/vm_extern.h> 56#include <vm/vm_map.h> 57#include "opt_directio.h" 58#include "opt_swap.h" 59 60static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 61 62struct bio_ops bioops; /* I/O operation notification */ 63 64static int ibwrite(struct buf *); 65 66struct buf_ops buf_ops_bio = { 67 "buf_ops_bio", 68 ibwrite 69}; 70 71/* 72 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 73 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 74 */ 75struct buf *buf; /* buffer header pool */ 76 77static struct proc *bufdaemonproc; 78 79static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 80 vm_offset_t to); 81static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 82 vm_offset_t to); 83static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 84 int pageno, vm_page_t m); 85static void vfs_clean_pages(struct buf * bp); 86static void vfs_setdirty(struct buf *bp); 87static void vfs_vmio_release(struct buf *bp); 88static void vfs_backgroundwritedone(struct buf *bp); 89static int vfs_bio_clcheck(struct vnode *vp, int size, 90 daddr_t lblkno, daddr_t blkno); 91static int flushbufqueues(int flushdeps); 92static void buf_daemon(void); 93void bremfreel(struct buf * bp); 94 95int vmiodirenable = TRUE; 96SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 97 "Use the VM system for directory writes"); 98int runningbufspace; 99SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 100 "Amount of presently outstanding async buffer io"); 101static int bufspace; 102SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 103 "KVA memory used for bufs"); 104static int maxbufspace; 105SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 106 "Maximum allowed value of bufspace (including buf_daemon)"); 107static int bufmallocspace; 108SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 109 "Amount of malloced memory for buffers"); 110static int maxbufmallocspace; 111SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 112 "Maximum amount of malloced memory for buffers"); 113static int lobufspace; 114SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 115 "Minimum amount of buffers we want to have"); 116static int hibufspace; 117SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 118 "Maximum allowed value of bufspace (excluding buf_daemon)"); 119static int bufreusecnt; 120SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 121 "Number of times we have reused a buffer"); 122static int buffreekvacnt; 123SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 124 "Number of times we have freed the KVA space from some buffer"); 125static int bufdefragcnt; 126SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 127 "Number of times we have had to repeat buffer allocation to defragment"); 128static int lorunningspace; 129SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 130 "Minimum preferred space used for in-progress I/O"); 131static int hirunningspace; 132SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 133 "Maximum amount of space to use for in-progress I/O"); 134static int dirtybufferflushes; 135SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 136 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 137static int altbufferflushes; 138SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 139 0, "Number of fsync flushes to limit dirty buffers"); 140static int recursiveflushes; 141SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 142 0, "Number of flushes skipped due to being recursive"); 143static int numdirtybuffers; 144SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 145 "Number of buffers that are dirty (has unwritten changes) at the moment"); 146static int lodirtybuffers; 147SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 148 "How many buffers we want to have free before bufdaemon can sleep"); 149static int hidirtybuffers; 150SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 151 "When the number of dirty buffers is considered severe"); 152static int dirtybufthresh; 153SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 154 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 155static int numfreebuffers; 156SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 157 "Number of free buffers"); 158static int lofreebuffers; 159SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 160 "XXX Unused"); 161static int hifreebuffers; 162SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 163 "XXX Complicatedly unused"); 164static int getnewbufcalls; 165SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 166 "Number of calls to getnewbuf"); 167static int getnewbufrestarts; 168SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 169 "Number of times getnewbuf has had to restart a buffer aquisition"); 170static int dobkgrdwrite = 1; 171SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0, 172 "Do background writes (honoring the BV_BKGRDWRITE flag)?"); 173 174/* 175 * Wakeup point for bufdaemon, as well as indicator of whether it is already 176 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 177 * is idling. 178 */ 179static int bd_request; 180 181/* 182 * This lock synchronizes access to bd_request. 183 */ 184static struct mtx bdlock; 185 186/* 187 * bogus page -- for I/O to/from partially complete buffers 188 * this is a temporary solution to the problem, but it is not 189 * really that bad. it would be better to split the buffer 190 * for input in the case of buffers partially already in memory, 191 * but the code is intricate enough already. 192 */ 193vm_page_t bogus_page; 194 195/* 196 * Synchronization (sleep/wakeup) variable for active buffer space requests. 197 * Set when wait starts, cleared prior to wakeup(). 198 * Used in runningbufwakeup() and waitrunningbufspace(). 199 */ 200static int runningbufreq; 201 202/* 203 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 204 * waitrunningbufspace(). 205 */ 206static struct mtx rbreqlock; 207 208/* 209 * Synchronization (sleep/wakeup) variable for buffer requests. 210 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 211 * by and/or. 212 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 213 * getnewbuf(), and getblk(). 214 */ 215static int needsbuffer; 216 217/* 218 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 219 */ 220static struct mtx nblock; 221 222/* 223 * Lock that protects against bwait()/bdone()/B_DONE races. 224 */ 225 226static struct mtx bdonelock; 227 228/* 229 * Definitions for the buffer free lists. 230 */ 231#define BUFFER_QUEUES 5 /* number of free buffer queues */ 232 233#define QUEUE_NONE 0 /* on no queue */ 234#define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 235#define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 236#define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 237#define QUEUE_EMPTY 4 /* empty buffer headers */ 238 239/* Queues for free buffers with various properties */ 240static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 241 242/* Lock for the bufqueues */ 243static struct mtx bqlock; 244 245/* 246 * Single global constant for BUF_WMESG, to avoid getting multiple references. 247 * buf_wmesg is referred from macros. 248 */ 249const char *buf_wmesg = BUF_WMESG; 250 251#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 252#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 253#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 254#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 255 256#ifdef DIRECTIO 257extern void ffs_rawread_setup(void); 258#endif /* DIRECTIO */ 259/* 260 * numdirtywakeup: 261 * 262 * If someone is blocked due to there being too many dirty buffers, 263 * and numdirtybuffers is now reasonable, wake them up. 264 */ 265 266static __inline void 267numdirtywakeup(int level) 268{ 269 if (numdirtybuffers <= level) { 270 mtx_lock(&nblock); 271 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 272 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 273 wakeup(&needsbuffer); 274 } 275 mtx_unlock(&nblock); 276 } 277} 278 279/* 280 * bufspacewakeup: 281 * 282 * Called when buffer space is potentially available for recovery. 283 * getnewbuf() will block on this flag when it is unable to free 284 * sufficient buffer space. Buffer space becomes recoverable when 285 * bp's get placed back in the queues. 286 */ 287 288static __inline void 289bufspacewakeup(void) 290{ 291 /* 292 * If someone is waiting for BUF space, wake them up. Even 293 * though we haven't freed the kva space yet, the waiting 294 * process will be able to now. 295 */ 296 mtx_lock(&nblock); 297 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 298 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 299 wakeup(&needsbuffer); 300 } 301 mtx_unlock(&nblock); 302} 303 304/* 305 * runningbufwakeup() - in-progress I/O accounting. 306 * 307 */ 308static __inline void 309runningbufwakeup(struct buf *bp) 310{ 311 if (bp->b_runningbufspace) { 312 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 313 bp->b_runningbufspace = 0; 314 mtx_lock(&rbreqlock); 315 if (runningbufreq && runningbufspace <= lorunningspace) { 316 runningbufreq = 0; 317 wakeup(&runningbufreq); 318 } 319 mtx_unlock(&rbreqlock); 320 } 321} 322 323/* 324 * bufcountwakeup: 325 * 326 * Called when a buffer has been added to one of the free queues to 327 * account for the buffer and to wakeup anyone waiting for free buffers. 328 * This typically occurs when large amounts of metadata are being handled 329 * by the buffer cache ( else buffer space runs out first, usually ). 330 */ 331 332static __inline void 333bufcountwakeup(void) 334{ 335 atomic_add_int(&numfreebuffers, 1); 336 mtx_lock(&nblock); 337 if (needsbuffer) { 338 needsbuffer &= ~VFS_BIO_NEED_ANY; 339 if (numfreebuffers >= hifreebuffers) 340 needsbuffer &= ~VFS_BIO_NEED_FREE; 341 wakeup(&needsbuffer); 342 } 343 mtx_unlock(&nblock); 344} 345 346/* 347 * waitrunningbufspace() 348 * 349 * runningbufspace is a measure of the amount of I/O currently 350 * running. This routine is used in async-write situations to 351 * prevent creating huge backups of pending writes to a device. 352 * Only asynchronous writes are governed by this function. 353 * 354 * Reads will adjust runningbufspace, but will not block based on it. 355 * The read load has a side effect of reducing the allowed write load. 356 * 357 * This does NOT turn an async write into a sync write. It waits 358 * for earlier writes to complete and generally returns before the 359 * caller's write has reached the device. 360 */ 361static __inline void 362waitrunningbufspace(void) 363{ 364 mtx_lock(&rbreqlock); 365 while (runningbufspace > hirunningspace) { 366 ++runningbufreq; 367 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 368 } 369 mtx_unlock(&rbreqlock); 370} 371 372 373/* 374 * vfs_buf_test_cache: 375 * 376 * Called when a buffer is extended. This function clears the B_CACHE 377 * bit if the newly extended portion of the buffer does not contain 378 * valid data. 379 */ 380static __inline__ 381void 382vfs_buf_test_cache(struct buf *bp, 383 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 384 vm_page_t m) 385{ 386 GIANT_REQUIRED; 387 388 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 389 if (bp->b_flags & B_CACHE) { 390 int base = (foff + off) & PAGE_MASK; 391 if (vm_page_is_valid(m, base, size) == 0) 392 bp->b_flags &= ~B_CACHE; 393 } 394} 395 396/* Wake up the buffer deamon if necessary */ 397static __inline__ 398void 399bd_wakeup(int dirtybuflevel) 400{ 401 mtx_lock(&bdlock); 402 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 403 bd_request = 1; 404 wakeup(&bd_request); 405 } 406 mtx_unlock(&bdlock); 407} 408 409/* 410 * bd_speedup - speedup the buffer cache flushing code 411 */ 412 413static __inline__ 414void 415bd_speedup(void) 416{ 417 bd_wakeup(1); 418} 419 420/* 421 * Calculating buffer cache scaling values and reserve space for buffer 422 * headers. This is called during low level kernel initialization and 423 * may be called more then once. We CANNOT write to the memory area 424 * being reserved at this time. 425 */ 426caddr_t 427kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 428{ 429 /* 430 * physmem_est is in pages. Convert it to kilobytes (assumes 431 * PAGE_SIZE is >= 1K) 432 */ 433 physmem_est = physmem_est * (PAGE_SIZE / 1024); 434 435 /* 436 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 437 * For the first 64MB of ram nominally allocate sufficient buffers to 438 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 439 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 440 * the buffer cache we limit the eventual kva reservation to 441 * maxbcache bytes. 442 * 443 * factor represents the 1/4 x ram conversion. 444 */ 445 if (nbuf == 0) { 446 int factor = 4 * BKVASIZE / 1024; 447 448 nbuf = 50; 449 if (physmem_est > 4096) 450 nbuf += min((physmem_est - 4096) / factor, 451 65536 / factor); 452 if (physmem_est > 65536) 453 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 454 455 if (maxbcache && nbuf > maxbcache / BKVASIZE) 456 nbuf = maxbcache / BKVASIZE; 457 } 458 459#if 0 460 /* 461 * Do not allow the buffer_map to be more then 1/2 the size of the 462 * kernel_map. 463 */ 464 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 465 (BKVASIZE * 2)) { 466 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 467 (BKVASIZE * 2); 468 printf("Warning: nbufs capped at %d\n", nbuf); 469 } 470#endif 471 472 /* 473 * swbufs are used as temporary holders for I/O, such as paging I/O. 474 * We have no less then 16 and no more then 256. 475 */ 476 nswbuf = max(min(nbuf/4, 256), 16); 477#ifdef NSWBUF_MIN 478 if (nswbuf < NSWBUF_MIN) 479 nswbuf = NSWBUF_MIN; 480#endif 481#ifdef DIRECTIO 482 ffs_rawread_setup(); 483#endif 484 485 /* 486 * Reserve space for the buffer cache buffers 487 */ 488 swbuf = (void *)v; 489 v = (caddr_t)(swbuf + nswbuf); 490 buf = (void *)v; 491 v = (caddr_t)(buf + nbuf); 492 493 return(v); 494} 495 496/* Initialize the buffer subsystem. Called before use of any buffers. */ 497void 498bufinit(void) 499{ 500 struct buf *bp; 501 int i; 502 503 GIANT_REQUIRED; 504 505 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 506 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 507 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 508 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 509 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF); 510 511 /* next, make a null set of free lists */ 512 for (i = 0; i < BUFFER_QUEUES; i++) 513 TAILQ_INIT(&bufqueues[i]); 514 515 /* finally, initialize each buffer header and stick on empty q */ 516 for (i = 0; i < nbuf; i++) { 517 bp = &buf[i]; 518 bzero(bp, sizeof *bp); 519 bp->b_flags = B_INVAL; /* we're just an empty header */
| 30 31#include <sys/param.h> 32#include <sys/systm.h> 33#include <sys/bio.h> 34#include <sys/conf.h> 35#include <sys/buf.h> 36#include <sys/devicestat.h> 37#include <sys/eventhandler.h> 38#include <sys/lock.h> 39#include <sys/malloc.h> 40#include <sys/mount.h> 41#include <sys/mutex.h> 42#include <sys/kernel.h> 43#include <sys/kthread.h> 44#include <sys/proc.h> 45#include <sys/resourcevar.h> 46#include <sys/sysctl.h> 47#include <sys/vmmeter.h> 48#include <sys/vnode.h> 49#include <vm/vm.h> 50#include <vm/vm_param.h> 51#include <vm/vm_kern.h> 52#include <vm/vm_pageout.h> 53#include <vm/vm_page.h> 54#include <vm/vm_object.h> 55#include <vm/vm_extern.h> 56#include <vm/vm_map.h> 57#include "opt_directio.h" 58#include "opt_swap.h" 59 60static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 61 62struct bio_ops bioops; /* I/O operation notification */ 63 64static int ibwrite(struct buf *); 65 66struct buf_ops buf_ops_bio = { 67 "buf_ops_bio", 68 ibwrite 69}; 70 71/* 72 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 73 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 74 */ 75struct buf *buf; /* buffer header pool */ 76 77static struct proc *bufdaemonproc; 78 79static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 80 vm_offset_t to); 81static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 82 vm_offset_t to); 83static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 84 int pageno, vm_page_t m); 85static void vfs_clean_pages(struct buf * bp); 86static void vfs_setdirty(struct buf *bp); 87static void vfs_vmio_release(struct buf *bp); 88static void vfs_backgroundwritedone(struct buf *bp); 89static int vfs_bio_clcheck(struct vnode *vp, int size, 90 daddr_t lblkno, daddr_t blkno); 91static int flushbufqueues(int flushdeps); 92static void buf_daemon(void); 93void bremfreel(struct buf * bp); 94 95int vmiodirenable = TRUE; 96SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 97 "Use the VM system for directory writes"); 98int runningbufspace; 99SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 100 "Amount of presently outstanding async buffer io"); 101static int bufspace; 102SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 103 "KVA memory used for bufs"); 104static int maxbufspace; 105SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 106 "Maximum allowed value of bufspace (including buf_daemon)"); 107static int bufmallocspace; 108SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 109 "Amount of malloced memory for buffers"); 110static int maxbufmallocspace; 111SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 112 "Maximum amount of malloced memory for buffers"); 113static int lobufspace; 114SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 115 "Minimum amount of buffers we want to have"); 116static int hibufspace; 117SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 118 "Maximum allowed value of bufspace (excluding buf_daemon)"); 119static int bufreusecnt; 120SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 121 "Number of times we have reused a buffer"); 122static int buffreekvacnt; 123SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 124 "Number of times we have freed the KVA space from some buffer"); 125static int bufdefragcnt; 126SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 127 "Number of times we have had to repeat buffer allocation to defragment"); 128static int lorunningspace; 129SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 130 "Minimum preferred space used for in-progress I/O"); 131static int hirunningspace; 132SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 133 "Maximum amount of space to use for in-progress I/O"); 134static int dirtybufferflushes; 135SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 136 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 137static int altbufferflushes; 138SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 139 0, "Number of fsync flushes to limit dirty buffers"); 140static int recursiveflushes; 141SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 142 0, "Number of flushes skipped due to being recursive"); 143static int numdirtybuffers; 144SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 145 "Number of buffers that are dirty (has unwritten changes) at the moment"); 146static int lodirtybuffers; 147SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 148 "How many buffers we want to have free before bufdaemon can sleep"); 149static int hidirtybuffers; 150SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 151 "When the number of dirty buffers is considered severe"); 152static int dirtybufthresh; 153SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 154 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 155static int numfreebuffers; 156SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 157 "Number of free buffers"); 158static int lofreebuffers; 159SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 160 "XXX Unused"); 161static int hifreebuffers; 162SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 163 "XXX Complicatedly unused"); 164static int getnewbufcalls; 165SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 166 "Number of calls to getnewbuf"); 167static int getnewbufrestarts; 168SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 169 "Number of times getnewbuf has had to restart a buffer aquisition"); 170static int dobkgrdwrite = 1; 171SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0, 172 "Do background writes (honoring the BV_BKGRDWRITE flag)?"); 173 174/* 175 * Wakeup point for bufdaemon, as well as indicator of whether it is already 176 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 177 * is idling. 178 */ 179static int bd_request; 180 181/* 182 * This lock synchronizes access to bd_request. 183 */ 184static struct mtx bdlock; 185 186/* 187 * bogus page -- for I/O to/from partially complete buffers 188 * this is a temporary solution to the problem, but it is not 189 * really that bad. it would be better to split the buffer 190 * for input in the case of buffers partially already in memory, 191 * but the code is intricate enough already. 192 */ 193vm_page_t bogus_page; 194 195/* 196 * Synchronization (sleep/wakeup) variable for active buffer space requests. 197 * Set when wait starts, cleared prior to wakeup(). 198 * Used in runningbufwakeup() and waitrunningbufspace(). 199 */ 200static int runningbufreq; 201 202/* 203 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 204 * waitrunningbufspace(). 205 */ 206static struct mtx rbreqlock; 207 208/* 209 * Synchronization (sleep/wakeup) variable for buffer requests. 210 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 211 * by and/or. 212 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 213 * getnewbuf(), and getblk(). 214 */ 215static int needsbuffer; 216 217/* 218 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 219 */ 220static struct mtx nblock; 221 222/* 223 * Lock that protects against bwait()/bdone()/B_DONE races. 224 */ 225 226static struct mtx bdonelock; 227 228/* 229 * Definitions for the buffer free lists. 230 */ 231#define BUFFER_QUEUES 5 /* number of free buffer queues */ 232 233#define QUEUE_NONE 0 /* on no queue */ 234#define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 235#define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 236#define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 237#define QUEUE_EMPTY 4 /* empty buffer headers */ 238 239/* Queues for free buffers with various properties */ 240static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 241 242/* Lock for the bufqueues */ 243static struct mtx bqlock; 244 245/* 246 * Single global constant for BUF_WMESG, to avoid getting multiple references. 247 * buf_wmesg is referred from macros. 248 */ 249const char *buf_wmesg = BUF_WMESG; 250 251#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 252#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 253#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 254#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 255 256#ifdef DIRECTIO 257extern void ffs_rawread_setup(void); 258#endif /* DIRECTIO */ 259/* 260 * numdirtywakeup: 261 * 262 * If someone is blocked due to there being too many dirty buffers, 263 * and numdirtybuffers is now reasonable, wake them up. 264 */ 265 266static __inline void 267numdirtywakeup(int level) 268{ 269 if (numdirtybuffers <= level) { 270 mtx_lock(&nblock); 271 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 272 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 273 wakeup(&needsbuffer); 274 } 275 mtx_unlock(&nblock); 276 } 277} 278 279/* 280 * bufspacewakeup: 281 * 282 * Called when buffer space is potentially available for recovery. 283 * getnewbuf() will block on this flag when it is unable to free 284 * sufficient buffer space. Buffer space becomes recoverable when 285 * bp's get placed back in the queues. 286 */ 287 288static __inline void 289bufspacewakeup(void) 290{ 291 /* 292 * If someone is waiting for BUF space, wake them up. Even 293 * though we haven't freed the kva space yet, the waiting 294 * process will be able to now. 295 */ 296 mtx_lock(&nblock); 297 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 298 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 299 wakeup(&needsbuffer); 300 } 301 mtx_unlock(&nblock); 302} 303 304/* 305 * runningbufwakeup() - in-progress I/O accounting. 306 * 307 */ 308static __inline void 309runningbufwakeup(struct buf *bp) 310{ 311 if (bp->b_runningbufspace) { 312 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 313 bp->b_runningbufspace = 0; 314 mtx_lock(&rbreqlock); 315 if (runningbufreq && runningbufspace <= lorunningspace) { 316 runningbufreq = 0; 317 wakeup(&runningbufreq); 318 } 319 mtx_unlock(&rbreqlock); 320 } 321} 322 323/* 324 * bufcountwakeup: 325 * 326 * Called when a buffer has been added to one of the free queues to 327 * account for the buffer and to wakeup anyone waiting for free buffers. 328 * This typically occurs when large amounts of metadata are being handled 329 * by the buffer cache ( else buffer space runs out first, usually ). 330 */ 331 332static __inline void 333bufcountwakeup(void) 334{ 335 atomic_add_int(&numfreebuffers, 1); 336 mtx_lock(&nblock); 337 if (needsbuffer) { 338 needsbuffer &= ~VFS_BIO_NEED_ANY; 339 if (numfreebuffers >= hifreebuffers) 340 needsbuffer &= ~VFS_BIO_NEED_FREE; 341 wakeup(&needsbuffer); 342 } 343 mtx_unlock(&nblock); 344} 345 346/* 347 * waitrunningbufspace() 348 * 349 * runningbufspace is a measure of the amount of I/O currently 350 * running. This routine is used in async-write situations to 351 * prevent creating huge backups of pending writes to a device. 352 * Only asynchronous writes are governed by this function. 353 * 354 * Reads will adjust runningbufspace, but will not block based on it. 355 * The read load has a side effect of reducing the allowed write load. 356 * 357 * This does NOT turn an async write into a sync write. It waits 358 * for earlier writes to complete and generally returns before the 359 * caller's write has reached the device. 360 */ 361static __inline void 362waitrunningbufspace(void) 363{ 364 mtx_lock(&rbreqlock); 365 while (runningbufspace > hirunningspace) { 366 ++runningbufreq; 367 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 368 } 369 mtx_unlock(&rbreqlock); 370} 371 372 373/* 374 * vfs_buf_test_cache: 375 * 376 * Called when a buffer is extended. This function clears the B_CACHE 377 * bit if the newly extended portion of the buffer does not contain 378 * valid data. 379 */ 380static __inline__ 381void 382vfs_buf_test_cache(struct buf *bp, 383 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 384 vm_page_t m) 385{ 386 GIANT_REQUIRED; 387 388 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 389 if (bp->b_flags & B_CACHE) { 390 int base = (foff + off) & PAGE_MASK; 391 if (vm_page_is_valid(m, base, size) == 0) 392 bp->b_flags &= ~B_CACHE; 393 } 394} 395 396/* Wake up the buffer deamon if necessary */ 397static __inline__ 398void 399bd_wakeup(int dirtybuflevel) 400{ 401 mtx_lock(&bdlock); 402 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 403 bd_request = 1; 404 wakeup(&bd_request); 405 } 406 mtx_unlock(&bdlock); 407} 408 409/* 410 * bd_speedup - speedup the buffer cache flushing code 411 */ 412 413static __inline__ 414void 415bd_speedup(void) 416{ 417 bd_wakeup(1); 418} 419 420/* 421 * Calculating buffer cache scaling values and reserve space for buffer 422 * headers. This is called during low level kernel initialization and 423 * may be called more then once. We CANNOT write to the memory area 424 * being reserved at this time. 425 */ 426caddr_t 427kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 428{ 429 /* 430 * physmem_est is in pages. Convert it to kilobytes (assumes 431 * PAGE_SIZE is >= 1K) 432 */ 433 physmem_est = physmem_est * (PAGE_SIZE / 1024); 434 435 /* 436 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 437 * For the first 64MB of ram nominally allocate sufficient buffers to 438 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 439 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 440 * the buffer cache we limit the eventual kva reservation to 441 * maxbcache bytes. 442 * 443 * factor represents the 1/4 x ram conversion. 444 */ 445 if (nbuf == 0) { 446 int factor = 4 * BKVASIZE / 1024; 447 448 nbuf = 50; 449 if (physmem_est > 4096) 450 nbuf += min((physmem_est - 4096) / factor, 451 65536 / factor); 452 if (physmem_est > 65536) 453 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 454 455 if (maxbcache && nbuf > maxbcache / BKVASIZE) 456 nbuf = maxbcache / BKVASIZE; 457 } 458 459#if 0 460 /* 461 * Do not allow the buffer_map to be more then 1/2 the size of the 462 * kernel_map. 463 */ 464 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 465 (BKVASIZE * 2)) { 466 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 467 (BKVASIZE * 2); 468 printf("Warning: nbufs capped at %d\n", nbuf); 469 } 470#endif 471 472 /* 473 * swbufs are used as temporary holders for I/O, such as paging I/O. 474 * We have no less then 16 and no more then 256. 475 */ 476 nswbuf = max(min(nbuf/4, 256), 16); 477#ifdef NSWBUF_MIN 478 if (nswbuf < NSWBUF_MIN) 479 nswbuf = NSWBUF_MIN; 480#endif 481#ifdef DIRECTIO 482 ffs_rawread_setup(); 483#endif 484 485 /* 486 * Reserve space for the buffer cache buffers 487 */ 488 swbuf = (void *)v; 489 v = (caddr_t)(swbuf + nswbuf); 490 buf = (void *)v; 491 v = (caddr_t)(buf + nbuf); 492 493 return(v); 494} 495 496/* Initialize the buffer subsystem. Called before use of any buffers. */ 497void 498bufinit(void) 499{ 500 struct buf *bp; 501 int i; 502 503 GIANT_REQUIRED; 504 505 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 506 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 507 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 508 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 509 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF); 510 511 /* next, make a null set of free lists */ 512 for (i = 0; i < BUFFER_QUEUES; i++) 513 TAILQ_INIT(&bufqueues[i]); 514 515 /* finally, initialize each buffer header and stick on empty q */ 516 for (i = 0; i < nbuf; i++) { 517 bp = &buf[i]; 518 bzero(bp, sizeof *bp); 519 bp->b_flags = B_INVAL; /* we're just an empty header */
|
520 bp->b_dev = NODEV;
| 520 bp->b_dev = NULL;
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521 bp->b_rcred = NOCRED; 522 bp->b_wcred = NOCRED; 523 bp->b_qindex = QUEUE_EMPTY; 524 bp->b_vflags = 0; 525 bp->b_xflags = 0; 526 LIST_INIT(&bp->b_dep); 527 BUF_LOCKINIT(bp); 528 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 529 } 530 531 /* 532 * maxbufspace is the absolute maximum amount of buffer space we are 533 * allowed to reserve in KVM and in real terms. The absolute maximum 534 * is nominally used by buf_daemon. hibufspace is the nominal maximum 535 * used by most other processes. The differential is required to 536 * ensure that buf_daemon is able to run when other processes might 537 * be blocked waiting for buffer space. 538 * 539 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 540 * this may result in KVM fragmentation which is not handled optimally 541 * by the system. 542 */ 543 maxbufspace = nbuf * BKVASIZE; 544 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 545 lobufspace = hibufspace - MAXBSIZE; 546 547 lorunningspace = 512 * 1024; 548 hirunningspace = 1024 * 1024; 549 550/* 551 * Limit the amount of malloc memory since it is wired permanently into 552 * the kernel space. Even though this is accounted for in the buffer 553 * allocation, we don't want the malloced region to grow uncontrolled. 554 * The malloc scheme improves memory utilization significantly on average 555 * (small) directories. 556 */ 557 maxbufmallocspace = hibufspace / 20; 558 559/* 560 * Reduce the chance of a deadlock occuring by limiting the number 561 * of delayed-write dirty buffers we allow to stack up. 562 */ 563 hidirtybuffers = nbuf / 4 + 20; 564 dirtybufthresh = hidirtybuffers * 9 / 10; 565 numdirtybuffers = 0; 566/* 567 * To support extreme low-memory systems, make sure hidirtybuffers cannot 568 * eat up all available buffer space. This occurs when our minimum cannot 569 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 570 * BKVASIZE'd (8K) buffers. 571 */ 572 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 573 hidirtybuffers >>= 1; 574 } 575 lodirtybuffers = hidirtybuffers / 2; 576 577/* 578 * Try to keep the number of free buffers in the specified range, 579 * and give special processes (e.g. like buf_daemon) access to an 580 * emergency reserve. 581 */ 582 lofreebuffers = nbuf / 18 + 5; 583 hifreebuffers = 2 * lofreebuffers; 584 numfreebuffers = nbuf; 585 586/* 587 * Maximum number of async ops initiated per buf_daemon loop. This is 588 * somewhat of a hack at the moment, we really need to limit ourselves 589 * based on the number of bytes of I/O in-transit that were initiated 590 * from buf_daemon. 591 */ 592 593 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 594 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 595} 596 597/* 598 * bfreekva() - free the kva allocation for a buffer. 599 * 600 * Must be called at splbio() or higher as this is the only locking for 601 * buffer_map. 602 * 603 * Since this call frees up buffer space, we call bufspacewakeup(). 604 */ 605static void 606bfreekva(struct buf * bp) 607{ 608 GIANT_REQUIRED; 609 610 if (bp->b_kvasize) { 611 atomic_add_int(&buffreekvacnt, 1); 612 atomic_subtract_int(&bufspace, bp->b_kvasize); 613 vm_map_delete(buffer_map, 614 (vm_offset_t) bp->b_kvabase, 615 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 616 ); 617 bp->b_kvasize = 0; 618 bufspacewakeup(); 619 } 620} 621 622/* 623 * bremfree: 624 * 625 * Remove the buffer from the appropriate free list. 626 */ 627void 628bremfree(struct buf * bp) 629{ 630 mtx_lock(&bqlock); 631 bremfreel(bp); 632 mtx_unlock(&bqlock); 633} 634 635void 636bremfreel(struct buf * bp) 637{ 638 int s = splbio(); 639 int old_qindex = bp->b_qindex; 640 641 GIANT_REQUIRED; 642 643 if (bp->b_qindex != QUEUE_NONE) { 644 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 645 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 646 bp->b_qindex = QUEUE_NONE; 647 } else { 648 if (BUF_REFCNT(bp) <= 1) 649 panic("bremfree: removing a buffer not on a queue"); 650 } 651 652 /* 653 * Fixup numfreebuffers count. If the buffer is invalid or not 654 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 655 * the buffer was free and we must decrement numfreebuffers. 656 */ 657 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 658 switch(old_qindex) { 659 case QUEUE_DIRTY: 660 case QUEUE_CLEAN: 661 case QUEUE_EMPTY: 662 case QUEUE_EMPTYKVA: 663 atomic_subtract_int(&numfreebuffers, 1); 664 break; 665 default: 666 break; 667 } 668 } 669 splx(s); 670} 671 672 673/* 674 * Get a buffer with the specified data. Look in the cache first. We 675 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 676 * is set, the buffer is valid and we do not have to do anything ( see 677 * getblk() ). This is really just a special case of breadn(). 678 */ 679int 680bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 681 struct buf ** bpp) 682{ 683 684 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 685} 686 687/* 688 * Operates like bread, but also starts asynchronous I/O on 689 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 690 * to initiating I/O . If B_CACHE is set, the buffer is valid 691 * and we do not have to do anything. 692 */ 693int 694breadn(struct vnode * vp, daddr_t blkno, int size, 695 daddr_t * rablkno, int *rabsize, 696 int cnt, struct ucred * cred, struct buf ** bpp) 697{ 698 struct buf *bp, *rabp; 699 int i; 700 int rv = 0, readwait = 0; 701 702 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 703 704 /* if not found in cache, do some I/O */ 705 if ((bp->b_flags & B_CACHE) == 0) { 706 if (curthread != PCPU_GET(idlethread)) 707 curthread->td_proc->p_stats->p_ru.ru_inblock++; 708 bp->b_iocmd = BIO_READ; 709 bp->b_flags &= ~B_INVAL; 710 bp->b_ioflags &= ~BIO_ERROR; 711 if (bp->b_rcred == NOCRED && cred != NOCRED) 712 bp->b_rcred = crhold(cred); 713 vfs_busy_pages(bp, 0); 714 bp->b_iooffset = dbtob(bp->b_blkno); 715 if (vp->v_type == VCHR) 716 VOP_SPECSTRATEGY(vp, bp); 717 else 718 VOP_STRATEGY(vp, bp); 719 ++readwait; 720 } 721 722 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 723 if (inmem(vp, *rablkno)) 724 continue; 725 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 726 727 if ((rabp->b_flags & B_CACHE) == 0) { 728 if (curthread != PCPU_GET(idlethread)) 729 curthread->td_proc->p_stats->p_ru.ru_inblock++; 730 rabp->b_flags |= B_ASYNC; 731 rabp->b_flags &= ~B_INVAL; 732 rabp->b_ioflags &= ~BIO_ERROR; 733 rabp->b_iocmd = BIO_READ; 734 if (rabp->b_rcred == NOCRED && cred != NOCRED) 735 rabp->b_rcred = crhold(cred); 736 vfs_busy_pages(rabp, 0); 737 BUF_KERNPROC(rabp); 738 rabp->b_iooffset = dbtob(rabp->b_blkno); 739 if (vp->v_type == VCHR) 740 VOP_SPECSTRATEGY(vp, rabp); 741 else 742 VOP_STRATEGY(vp, rabp); 743 } else { 744 brelse(rabp); 745 } 746 } 747 748 if (readwait) { 749 rv = bufwait(bp); 750 } 751 return (rv); 752} 753 754/* 755 * Write, release buffer on completion. (Done by iodone 756 * if async). Do not bother writing anything if the buffer 757 * is invalid. 758 * 759 * Note that we set B_CACHE here, indicating that buffer is 760 * fully valid and thus cacheable. This is true even of NFS 761 * now so we set it generally. This could be set either here 762 * or in biodone() since the I/O is synchronous. We put it 763 * here. 764 */ 765int 766bwrite(struct buf * bp) 767{ 768 769 KASSERT(bp->b_op != NULL && bp->b_op->bop_write != NULL, 770 ("Martian buffer %p in bwrite: nobody to write it.", bp)); 771 return (bp->b_op->bop_write(bp)); 772} 773 774static int 775ibwrite(struct buf * bp) 776{ 777 int oldflags, s; 778 struct buf *newbp; 779 780 if (bp->b_flags & B_INVAL) { 781 brelse(bp); 782 return (0); 783 } 784 785 oldflags = bp->b_flags; 786 787 if (BUF_REFCNT(bp) == 0) 788 panic("ibwrite: buffer is not busy???"); 789 s = splbio(); 790 /* 791 * If a background write is already in progress, delay 792 * writing this block if it is asynchronous. Otherwise 793 * wait for the background write to complete. 794 */ 795 VI_LOCK(bp->b_vp); 796 if (bp->b_vflags & BV_BKGRDINPROG) { 797 if (bp->b_flags & B_ASYNC) { 798 VI_UNLOCK(bp->b_vp); 799 splx(s); 800 bdwrite(bp); 801 return (0); 802 } 803 bp->b_vflags |= BV_BKGRDWAIT; 804 msleep(&bp->b_xflags, VI_MTX(bp->b_vp), PRIBIO, "bwrbg", 0); 805 if (bp->b_vflags & BV_BKGRDINPROG) 806 panic("ibwrite: still writing"); 807 } 808 VI_UNLOCK(bp->b_vp); 809 810 /* Mark the buffer clean */ 811 bundirty(bp); 812 813 /* 814 * If this buffer is marked for background writing and we 815 * do not have to wait for it, make a copy and write the 816 * copy so as to leave this buffer ready for further use. 817 * 818 * This optimization eats a lot of memory. If we have a page 819 * or buffer shortfall we can't do it. 820 */ 821 if (dobkgrdwrite && (bp->b_xflags & BX_BKGRDWRITE) && 822 (bp->b_flags & B_ASYNC) && 823 !vm_page_count_severe() && 824 !buf_dirty_count_severe()) { 825 if (bp->b_iodone != NULL) { 826 printf("bp->b_iodone = %p\n", bp->b_iodone); 827 panic("ibwrite: need chained iodone"); 828 } 829 830 /* get a new block */ 831 newbp = geteblk(bp->b_bufsize); 832 833 /* 834 * set it to be identical to the old block. We have to 835 * set b_lblkno and BKGRDMARKER before calling bgetvp() 836 * to avoid confusing the splay tree and gbincore(). 837 */ 838 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 839 newbp->b_lblkno = bp->b_lblkno; 840 newbp->b_xflags |= BX_BKGRDMARKER; 841 VI_LOCK(bp->b_vp); 842 bp->b_vflags |= BV_BKGRDINPROG; 843 bgetvp(bp->b_vp, newbp); 844 VI_UNLOCK(bp->b_vp); 845 newbp->b_blkno = bp->b_blkno; 846 newbp->b_offset = bp->b_offset; 847 newbp->b_iodone = vfs_backgroundwritedone; 848 newbp->b_flags |= B_ASYNC; 849 newbp->b_flags &= ~B_INVAL; 850 851 /* move over the dependencies */ 852 if (LIST_FIRST(&bp->b_dep) != NULL) 853 buf_movedeps(bp, newbp); 854 855 /* 856 * Initiate write on the copy, release the original to 857 * the B_LOCKED queue so that it cannot go away until 858 * the background write completes. If not locked it could go 859 * away and then be reconstituted while it was being written. 860 * If the reconstituted buffer were written, we could end up 861 * with two background copies being written at the same time. 862 */ 863 bqrelse(bp); 864 bp = newbp; 865 } 866 867 bp->b_flags &= ~B_DONE; 868 bp->b_ioflags &= ~BIO_ERROR; 869 bp->b_flags |= B_WRITEINPROG | B_CACHE; 870 bp->b_iocmd = BIO_WRITE; 871 872 VI_LOCK(bp->b_vp); 873 bp->b_vp->v_numoutput++; 874 VI_UNLOCK(bp->b_vp); 875 vfs_busy_pages(bp, 1); 876 877 /* 878 * Normal bwrites pipeline writes 879 */ 880 bp->b_runningbufspace = bp->b_bufsize; 881 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 882 883 if (curthread != PCPU_GET(idlethread)) 884 curthread->td_proc->p_stats->p_ru.ru_oublock++; 885 splx(s); 886 if (oldflags & B_ASYNC) 887 BUF_KERNPROC(bp); 888 bp->b_iooffset = dbtob(bp->b_blkno); 889 if (bp->b_vp->v_type == VCHR) { 890 if (!buf_prewrite(bp->b_vp, bp)) 891 VOP_SPECSTRATEGY(bp->b_vp, bp); 892 } else { 893 VOP_STRATEGY(bp->b_vp, bp); 894 } 895 896 if ((oldflags & B_ASYNC) == 0) { 897 int rtval = bufwait(bp); 898 brelse(bp); 899 return (rtval); 900 } else { 901 /* 902 * don't allow the async write to saturate the I/O 903 * system. We will not deadlock here because 904 * we are blocking waiting for I/O that is already in-progress 905 * to complete. We do not block here if it is the update 906 * or syncer daemon trying to clean up as that can lead 907 * to deadlock. 908 */ 909 if (curthread->td_proc != bufdaemonproc && 910 curthread->td_proc != updateproc) 911 waitrunningbufspace(); 912 } 913 914 return (0); 915} 916 917/* 918 * Complete a background write started from bwrite. 919 */ 920static void 921vfs_backgroundwritedone(bp) 922 struct buf *bp; 923{ 924 struct buf *origbp; 925 926 /* 927 * Find the original buffer that we are writing. 928 */ 929 VI_LOCK(bp->b_vp); 930 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 931 panic("backgroundwritedone: lost buffer"); 932 933 /* 934 * Clear the BV_BKGRDINPROG flag in the original buffer 935 * and awaken it if it is waiting for the write to complete. 936 * If BV_BKGRDINPROG is not set in the original buffer it must 937 * have been released and re-instantiated - which is not legal. 938 */ 939 KASSERT((origbp->b_vflags & BV_BKGRDINPROG), 940 ("backgroundwritedone: lost buffer2")); 941 origbp->b_vflags &= ~BV_BKGRDINPROG; 942 if (origbp->b_vflags & BV_BKGRDWAIT) { 943 origbp->b_vflags &= ~BV_BKGRDWAIT; 944 wakeup(&origbp->b_xflags); 945 } 946 VI_UNLOCK(bp->b_vp); 947 /* 948 * Process dependencies then return any unfinished ones. 949 */ 950 if (LIST_FIRST(&bp->b_dep) != NULL) 951 buf_complete(bp); 952 if (LIST_FIRST(&bp->b_dep) != NULL) 953 buf_movedeps(bp, origbp); 954 955 /* 956 * This buffer is marked B_NOCACHE, so when it is released 957 * by biodone, it will be tossed. We mark it with BIO_READ 958 * to avoid biodone doing a second vwakeup. 959 */ 960 bp->b_flags |= B_NOCACHE; 961 bp->b_iocmd = BIO_READ; 962 bp->b_flags &= ~(B_CACHE | B_DONE); 963 bp->b_iodone = 0; 964 bufdone(bp); 965} 966 967/* 968 * Delayed write. (Buffer is marked dirty). Do not bother writing 969 * anything if the buffer is marked invalid. 970 * 971 * Note that since the buffer must be completely valid, we can safely 972 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 973 * biodone() in order to prevent getblk from writing the buffer 974 * out synchronously. 975 */ 976void 977bdwrite(struct buf * bp) 978{ 979 struct thread *td = curthread; 980 struct vnode *vp; 981 struct buf *nbp; 982 983 GIANT_REQUIRED; 984 985 if (BUF_REFCNT(bp) == 0) 986 panic("bdwrite: buffer is not busy"); 987 988 if (bp->b_flags & B_INVAL) { 989 brelse(bp); 990 return; 991 } 992 993 /* 994 * If we have too many dirty buffers, don't create any more. 995 * If we are wildly over our limit, then force a complete 996 * cleanup. Otherwise, just keep the situation from getting 997 * out of control. Note that we have to avoid a recursive 998 * disaster and not try to clean up after our own cleanup! 999 */ 1000 vp = bp->b_vp; 1001 VI_LOCK(vp); 1002 if (td->td_pflags & TDP_COWINPROGRESS) { 1003 recursiveflushes++; 1004 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh + 10) { 1005 VI_UNLOCK(vp); 1006 (void) VOP_FSYNC(vp, td->td_ucred, MNT_NOWAIT, td); 1007 VI_LOCK(vp); 1008 altbufferflushes++; 1009 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh) { 1010 /* 1011 * Try to find a buffer to flush. 1012 */ 1013 TAILQ_FOREACH(nbp, &vp->v_dirtyblkhd, b_vnbufs) { 1014 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1015 buf_countdeps(nbp, 0) || 1016 BUF_LOCK(nbp, LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1017 continue; 1018 if (bp == nbp) 1019 panic("bdwrite: found ourselves"); 1020 VI_UNLOCK(vp); 1021 if (nbp->b_flags & B_CLUSTEROK) { 1022 vfs_bio_awrite(nbp); 1023 } else { 1024 bremfree(nbp); 1025 bawrite(nbp); 1026 } 1027 VI_LOCK(vp); 1028 dirtybufferflushes++; 1029 break; 1030 } 1031 } 1032 VI_UNLOCK(vp); 1033 1034 bdirty(bp); 1035 /* 1036 * Set B_CACHE, indicating that the buffer is fully valid. This is 1037 * true even of NFS now. 1038 */ 1039 bp->b_flags |= B_CACHE; 1040 1041 /* 1042 * This bmap keeps the system from needing to do the bmap later, 1043 * perhaps when the system is attempting to do a sync. Since it 1044 * is likely that the indirect block -- or whatever other datastructure 1045 * that the filesystem needs is still in memory now, it is a good 1046 * thing to do this. Note also, that if the pageout daemon is 1047 * requesting a sync -- there might not be enough memory to do 1048 * the bmap then... So, this is important to do. 1049 */ 1050 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1051 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1052 } 1053 1054 /* 1055 * Set the *dirty* buffer range based upon the VM system dirty pages. 1056 */ 1057 vfs_setdirty(bp); 1058 1059 /* 1060 * We need to do this here to satisfy the vnode_pager and the 1061 * pageout daemon, so that it thinks that the pages have been 1062 * "cleaned". Note that since the pages are in a delayed write 1063 * buffer -- the VFS layer "will" see that the pages get written 1064 * out on the next sync, or perhaps the cluster will be completed. 1065 */ 1066 vfs_clean_pages(bp); 1067 bqrelse(bp); 1068 1069 /* 1070 * Wakeup the buffer flushing daemon if we have a lot of dirty 1071 * buffers (midpoint between our recovery point and our stall 1072 * point). 1073 */ 1074 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1075 1076 /* 1077 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1078 * due to the softdep code. 1079 */ 1080} 1081 1082/* 1083 * bdirty: 1084 * 1085 * Turn buffer into delayed write request. We must clear BIO_READ and 1086 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1087 * itself to properly update it in the dirty/clean lists. We mark it 1088 * B_DONE to ensure that any asynchronization of the buffer properly 1089 * clears B_DONE ( else a panic will occur later ). 1090 * 1091 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1092 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1093 * should only be called if the buffer is known-good. 1094 * 1095 * Since the buffer is not on a queue, we do not update the numfreebuffers 1096 * count. 1097 * 1098 * Must be called at splbio(). 1099 * The buffer must be on QUEUE_NONE. 1100 */ 1101void 1102bdirty(bp) 1103 struct buf *bp; 1104{ 1105 KASSERT(bp->b_qindex == QUEUE_NONE, 1106 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1107 bp->b_flags &= ~(B_RELBUF); 1108 bp->b_iocmd = BIO_WRITE; 1109 1110 if ((bp->b_flags & B_DELWRI) == 0) { 1111 bp->b_flags |= B_DONE | B_DELWRI; 1112 reassignbuf(bp, bp->b_vp); 1113 atomic_add_int(&numdirtybuffers, 1); 1114 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1115 } 1116} 1117 1118/* 1119 * bundirty: 1120 * 1121 * Clear B_DELWRI for buffer. 1122 * 1123 * Since the buffer is not on a queue, we do not update the numfreebuffers 1124 * count. 1125 * 1126 * Must be called at splbio(). 1127 * The buffer must be on QUEUE_NONE. 1128 */ 1129 1130void 1131bundirty(bp) 1132 struct buf *bp; 1133{ 1134 KASSERT(bp->b_qindex == QUEUE_NONE, 1135 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1136 1137 if (bp->b_flags & B_DELWRI) { 1138 bp->b_flags &= ~B_DELWRI; 1139 reassignbuf(bp, bp->b_vp); 1140 atomic_subtract_int(&numdirtybuffers, 1); 1141 numdirtywakeup(lodirtybuffers); 1142 } 1143 /* 1144 * Since it is now being written, we can clear its deferred write flag. 1145 */ 1146 bp->b_flags &= ~B_DEFERRED; 1147} 1148 1149/* 1150 * bawrite: 1151 * 1152 * Asynchronous write. Start output on a buffer, but do not wait for 1153 * it to complete. The buffer is released when the output completes. 1154 * 1155 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1156 * B_INVAL buffers. Not us. 1157 */ 1158void 1159bawrite(struct buf * bp) 1160{ 1161 bp->b_flags |= B_ASYNC; 1162 (void) bwrite(bp); 1163} 1164 1165/* 1166 * bwillwrite: 1167 * 1168 * Called prior to the locking of any vnodes when we are expecting to 1169 * write. We do not want to starve the buffer cache with too many 1170 * dirty buffers so we block here. By blocking prior to the locking 1171 * of any vnodes we attempt to avoid the situation where a locked vnode 1172 * prevents the various system daemons from flushing related buffers. 1173 */ 1174 1175void 1176bwillwrite(void) 1177{ 1178 if (numdirtybuffers >= hidirtybuffers) { 1179 int s; 1180 1181 mtx_lock(&Giant); 1182 s = splbio(); 1183 mtx_lock(&nblock); 1184 while (numdirtybuffers >= hidirtybuffers) { 1185 bd_wakeup(1); 1186 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1187 msleep(&needsbuffer, &nblock, 1188 (PRIBIO + 4), "flswai", 0); 1189 } 1190 splx(s); 1191 mtx_unlock(&nblock); 1192 mtx_unlock(&Giant); 1193 } 1194} 1195 1196/* 1197 * Return true if we have too many dirty buffers. 1198 */ 1199int 1200buf_dirty_count_severe(void) 1201{ 1202 return(numdirtybuffers >= hidirtybuffers); 1203} 1204 1205/* 1206 * brelse: 1207 * 1208 * Release a busy buffer and, if requested, free its resources. The 1209 * buffer will be stashed in the appropriate bufqueue[] allowing it 1210 * to be accessed later as a cache entity or reused for other purposes. 1211 */ 1212void 1213brelse(struct buf * bp) 1214{ 1215 int s; 1216 1217 GIANT_REQUIRED; 1218 1219 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1220 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1221 1222 s = splbio(); 1223 1224 if (bp->b_iocmd == BIO_WRITE && 1225 (bp->b_ioflags & BIO_ERROR) && 1226 !(bp->b_flags & B_INVAL)) { 1227 /* 1228 * Failed write, redirty. Must clear BIO_ERROR to prevent 1229 * pages from being scrapped. If B_INVAL is set then 1230 * this case is not run and the next case is run to 1231 * destroy the buffer. B_INVAL can occur if the buffer 1232 * is outside the range supported by the underlying device. 1233 */ 1234 bp->b_ioflags &= ~BIO_ERROR; 1235 bdirty(bp); 1236 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1237 (bp->b_ioflags & BIO_ERROR) || 1238 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) { 1239 /* 1240 * Either a failed I/O or we were asked to free or not 1241 * cache the buffer. 1242 */ 1243 bp->b_flags |= B_INVAL; 1244 if (LIST_FIRST(&bp->b_dep) != NULL) 1245 buf_deallocate(bp); 1246 if (bp->b_flags & B_DELWRI) { 1247 atomic_subtract_int(&numdirtybuffers, 1); 1248 numdirtywakeup(lodirtybuffers); 1249 } 1250 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1251 if ((bp->b_flags & B_VMIO) == 0) { 1252 if (bp->b_bufsize) 1253 allocbuf(bp, 0); 1254 if (bp->b_vp) 1255 brelvp(bp); 1256 } 1257 } 1258 1259 /* 1260 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1261 * is called with B_DELWRI set, the underlying pages may wind up 1262 * getting freed causing a previous write (bdwrite()) to get 'lost' 1263 * because pages associated with a B_DELWRI bp are marked clean. 1264 * 1265 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1266 * if B_DELWRI is set. 1267 * 1268 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1269 * on pages to return pages to the VM page queues. 1270 */ 1271 if (bp->b_flags & B_DELWRI) 1272 bp->b_flags &= ~B_RELBUF; 1273 else if (vm_page_count_severe()) { 1274 /* 1275 * XXX This lock may not be necessary since BKGRDINPROG 1276 * cannot be set while we hold the buf lock, it can only be 1277 * cleared if it is already pending. 1278 */ 1279 if (bp->b_vp) { 1280 VI_LOCK(bp->b_vp); 1281 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1282 bp->b_flags |= B_RELBUF; 1283 VI_UNLOCK(bp->b_vp); 1284 } else 1285 bp->b_flags |= B_RELBUF; 1286 } 1287 1288 /* 1289 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1290 * constituted, not even NFS buffers now. Two flags effect this. If 1291 * B_INVAL, the struct buf is invalidated but the VM object is kept 1292 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1293 * 1294 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1295 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1296 * buffer is also B_INVAL because it hits the re-dirtying code above. 1297 * 1298 * Normally we can do this whether a buffer is B_DELWRI or not. If 1299 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1300 * the commit state and we cannot afford to lose the buffer. If the 1301 * buffer has a background write in progress, we need to keep it 1302 * around to prevent it from being reconstituted and starting a second 1303 * background write. 1304 */ 1305 if ((bp->b_flags & B_VMIO) 1306 && !(bp->b_vp->v_mount != NULL && 1307 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1308 !vn_isdisk(bp->b_vp, NULL) && 1309 (bp->b_flags & B_DELWRI)) 1310 ) { 1311 1312 int i, j, resid; 1313 vm_page_t m; 1314 off_t foff; 1315 vm_pindex_t poff; 1316 vm_object_t obj; 1317 1318 obj = bp->b_object; 1319 1320 /* 1321 * Get the base offset and length of the buffer. Note that 1322 * in the VMIO case if the buffer block size is not 1323 * page-aligned then b_data pointer may not be page-aligned. 1324 * But our b_pages[] array *IS* page aligned. 1325 * 1326 * block sizes less then DEV_BSIZE (usually 512) are not 1327 * supported due to the page granularity bits (m->valid, 1328 * m->dirty, etc...). 1329 * 1330 * See man buf(9) for more information 1331 */ 1332 resid = bp->b_bufsize; 1333 foff = bp->b_offset; 1334 VM_OBJECT_LOCK(obj); 1335 for (i = 0; i < bp->b_npages; i++) { 1336 int had_bogus = 0; 1337 1338 m = bp->b_pages[i]; 1339 1340 /* 1341 * If we hit a bogus page, fixup *all* the bogus pages 1342 * now. 1343 */ 1344 if (m == bogus_page) { 1345 poff = OFF_TO_IDX(bp->b_offset); 1346 had_bogus = 1; 1347 1348 for (j = i; j < bp->b_npages; j++) { 1349 vm_page_t mtmp; 1350 mtmp = bp->b_pages[j]; 1351 if (mtmp == bogus_page) { 1352 mtmp = vm_page_lookup(obj, poff + j); 1353 if (!mtmp) { 1354 panic("brelse: page missing\n"); 1355 } 1356 bp->b_pages[j] = mtmp; 1357 } 1358 } 1359 1360 if ((bp->b_flags & B_INVAL) == 0) { 1361 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1362 } 1363 m = bp->b_pages[i]; 1364 } 1365 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1366 int poffset = foff & PAGE_MASK; 1367 int presid = resid > (PAGE_SIZE - poffset) ? 1368 (PAGE_SIZE - poffset) : resid; 1369 1370 KASSERT(presid >= 0, ("brelse: extra page")); 1371 vm_page_lock_queues(); 1372 vm_page_set_invalid(m, poffset, presid); 1373 vm_page_unlock_queues(); 1374 if (had_bogus) 1375 printf("avoided corruption bug in bogus_page/brelse code\n"); 1376 } 1377 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1378 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1379 } 1380 VM_OBJECT_UNLOCK(obj); 1381 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1382 vfs_vmio_release(bp); 1383 1384 } else if (bp->b_flags & B_VMIO) { 1385 1386 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1387 vfs_vmio_release(bp); 1388 } 1389 1390 } 1391 1392 if (bp->b_qindex != QUEUE_NONE) 1393 panic("brelse: free buffer onto another queue???"); 1394 if (BUF_REFCNT(bp) > 1) { 1395 /* do not release to free list */ 1396 BUF_UNLOCK(bp); 1397 splx(s); 1398 return; 1399 } 1400 1401 /* enqueue */ 1402 mtx_lock(&bqlock); 1403 1404 /* buffers with no memory */ 1405 if (bp->b_bufsize == 0) { 1406 bp->b_flags |= B_INVAL; 1407 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1408 if (bp->b_vflags & BV_BKGRDINPROG) 1409 panic("losing buffer 1"); 1410 if (bp->b_kvasize) { 1411 bp->b_qindex = QUEUE_EMPTYKVA; 1412 } else { 1413 bp->b_qindex = QUEUE_EMPTY; 1414 } 1415 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
| 521 bp->b_rcred = NOCRED; 522 bp->b_wcred = NOCRED; 523 bp->b_qindex = QUEUE_EMPTY; 524 bp->b_vflags = 0; 525 bp->b_xflags = 0; 526 LIST_INIT(&bp->b_dep); 527 BUF_LOCKINIT(bp); 528 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 529 } 530 531 /* 532 * maxbufspace is the absolute maximum amount of buffer space we are 533 * allowed to reserve in KVM and in real terms. The absolute maximum 534 * is nominally used by buf_daemon. hibufspace is the nominal maximum 535 * used by most other processes. The differential is required to 536 * ensure that buf_daemon is able to run when other processes might 537 * be blocked waiting for buffer space. 538 * 539 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 540 * this may result in KVM fragmentation which is not handled optimally 541 * by the system. 542 */ 543 maxbufspace = nbuf * BKVASIZE; 544 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 545 lobufspace = hibufspace - MAXBSIZE; 546 547 lorunningspace = 512 * 1024; 548 hirunningspace = 1024 * 1024; 549 550/* 551 * Limit the amount of malloc memory since it is wired permanently into 552 * the kernel space. Even though this is accounted for in the buffer 553 * allocation, we don't want the malloced region to grow uncontrolled. 554 * The malloc scheme improves memory utilization significantly on average 555 * (small) directories. 556 */ 557 maxbufmallocspace = hibufspace / 20; 558 559/* 560 * Reduce the chance of a deadlock occuring by limiting the number 561 * of delayed-write dirty buffers we allow to stack up. 562 */ 563 hidirtybuffers = nbuf / 4 + 20; 564 dirtybufthresh = hidirtybuffers * 9 / 10; 565 numdirtybuffers = 0; 566/* 567 * To support extreme low-memory systems, make sure hidirtybuffers cannot 568 * eat up all available buffer space. This occurs when our minimum cannot 569 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 570 * BKVASIZE'd (8K) buffers. 571 */ 572 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 573 hidirtybuffers >>= 1; 574 } 575 lodirtybuffers = hidirtybuffers / 2; 576 577/* 578 * Try to keep the number of free buffers in the specified range, 579 * and give special processes (e.g. like buf_daemon) access to an 580 * emergency reserve. 581 */ 582 lofreebuffers = nbuf / 18 + 5; 583 hifreebuffers = 2 * lofreebuffers; 584 numfreebuffers = nbuf; 585 586/* 587 * Maximum number of async ops initiated per buf_daemon loop. This is 588 * somewhat of a hack at the moment, we really need to limit ourselves 589 * based on the number of bytes of I/O in-transit that were initiated 590 * from buf_daemon. 591 */ 592 593 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 594 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 595} 596 597/* 598 * bfreekva() - free the kva allocation for a buffer. 599 * 600 * Must be called at splbio() or higher as this is the only locking for 601 * buffer_map. 602 * 603 * Since this call frees up buffer space, we call bufspacewakeup(). 604 */ 605static void 606bfreekva(struct buf * bp) 607{ 608 GIANT_REQUIRED; 609 610 if (bp->b_kvasize) { 611 atomic_add_int(&buffreekvacnt, 1); 612 atomic_subtract_int(&bufspace, bp->b_kvasize); 613 vm_map_delete(buffer_map, 614 (vm_offset_t) bp->b_kvabase, 615 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 616 ); 617 bp->b_kvasize = 0; 618 bufspacewakeup(); 619 } 620} 621 622/* 623 * bremfree: 624 * 625 * Remove the buffer from the appropriate free list. 626 */ 627void 628bremfree(struct buf * bp) 629{ 630 mtx_lock(&bqlock); 631 bremfreel(bp); 632 mtx_unlock(&bqlock); 633} 634 635void 636bremfreel(struct buf * bp) 637{ 638 int s = splbio(); 639 int old_qindex = bp->b_qindex; 640 641 GIANT_REQUIRED; 642 643 if (bp->b_qindex != QUEUE_NONE) { 644 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 645 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 646 bp->b_qindex = QUEUE_NONE; 647 } else { 648 if (BUF_REFCNT(bp) <= 1) 649 panic("bremfree: removing a buffer not on a queue"); 650 } 651 652 /* 653 * Fixup numfreebuffers count. If the buffer is invalid or not 654 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 655 * the buffer was free and we must decrement numfreebuffers. 656 */ 657 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 658 switch(old_qindex) { 659 case QUEUE_DIRTY: 660 case QUEUE_CLEAN: 661 case QUEUE_EMPTY: 662 case QUEUE_EMPTYKVA: 663 atomic_subtract_int(&numfreebuffers, 1); 664 break; 665 default: 666 break; 667 } 668 } 669 splx(s); 670} 671 672 673/* 674 * Get a buffer with the specified data. Look in the cache first. We 675 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 676 * is set, the buffer is valid and we do not have to do anything ( see 677 * getblk() ). This is really just a special case of breadn(). 678 */ 679int 680bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 681 struct buf ** bpp) 682{ 683 684 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 685} 686 687/* 688 * Operates like bread, but also starts asynchronous I/O on 689 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 690 * to initiating I/O . If B_CACHE is set, the buffer is valid 691 * and we do not have to do anything. 692 */ 693int 694breadn(struct vnode * vp, daddr_t blkno, int size, 695 daddr_t * rablkno, int *rabsize, 696 int cnt, struct ucred * cred, struct buf ** bpp) 697{ 698 struct buf *bp, *rabp; 699 int i; 700 int rv = 0, readwait = 0; 701 702 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 703 704 /* if not found in cache, do some I/O */ 705 if ((bp->b_flags & B_CACHE) == 0) { 706 if (curthread != PCPU_GET(idlethread)) 707 curthread->td_proc->p_stats->p_ru.ru_inblock++; 708 bp->b_iocmd = BIO_READ; 709 bp->b_flags &= ~B_INVAL; 710 bp->b_ioflags &= ~BIO_ERROR; 711 if (bp->b_rcred == NOCRED && cred != NOCRED) 712 bp->b_rcred = crhold(cred); 713 vfs_busy_pages(bp, 0); 714 bp->b_iooffset = dbtob(bp->b_blkno); 715 if (vp->v_type == VCHR) 716 VOP_SPECSTRATEGY(vp, bp); 717 else 718 VOP_STRATEGY(vp, bp); 719 ++readwait; 720 } 721 722 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 723 if (inmem(vp, *rablkno)) 724 continue; 725 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 726 727 if ((rabp->b_flags & B_CACHE) == 0) { 728 if (curthread != PCPU_GET(idlethread)) 729 curthread->td_proc->p_stats->p_ru.ru_inblock++; 730 rabp->b_flags |= B_ASYNC; 731 rabp->b_flags &= ~B_INVAL; 732 rabp->b_ioflags &= ~BIO_ERROR; 733 rabp->b_iocmd = BIO_READ; 734 if (rabp->b_rcred == NOCRED && cred != NOCRED) 735 rabp->b_rcred = crhold(cred); 736 vfs_busy_pages(rabp, 0); 737 BUF_KERNPROC(rabp); 738 rabp->b_iooffset = dbtob(rabp->b_blkno); 739 if (vp->v_type == VCHR) 740 VOP_SPECSTRATEGY(vp, rabp); 741 else 742 VOP_STRATEGY(vp, rabp); 743 } else { 744 brelse(rabp); 745 } 746 } 747 748 if (readwait) { 749 rv = bufwait(bp); 750 } 751 return (rv); 752} 753 754/* 755 * Write, release buffer on completion. (Done by iodone 756 * if async). Do not bother writing anything if the buffer 757 * is invalid. 758 * 759 * Note that we set B_CACHE here, indicating that buffer is 760 * fully valid and thus cacheable. This is true even of NFS 761 * now so we set it generally. This could be set either here 762 * or in biodone() since the I/O is synchronous. We put it 763 * here. 764 */ 765int 766bwrite(struct buf * bp) 767{ 768 769 KASSERT(bp->b_op != NULL && bp->b_op->bop_write != NULL, 770 ("Martian buffer %p in bwrite: nobody to write it.", bp)); 771 return (bp->b_op->bop_write(bp)); 772} 773 774static int 775ibwrite(struct buf * bp) 776{ 777 int oldflags, s; 778 struct buf *newbp; 779 780 if (bp->b_flags & B_INVAL) { 781 brelse(bp); 782 return (0); 783 } 784 785 oldflags = bp->b_flags; 786 787 if (BUF_REFCNT(bp) == 0) 788 panic("ibwrite: buffer is not busy???"); 789 s = splbio(); 790 /* 791 * If a background write is already in progress, delay 792 * writing this block if it is asynchronous. Otherwise 793 * wait for the background write to complete. 794 */ 795 VI_LOCK(bp->b_vp); 796 if (bp->b_vflags & BV_BKGRDINPROG) { 797 if (bp->b_flags & B_ASYNC) { 798 VI_UNLOCK(bp->b_vp); 799 splx(s); 800 bdwrite(bp); 801 return (0); 802 } 803 bp->b_vflags |= BV_BKGRDWAIT; 804 msleep(&bp->b_xflags, VI_MTX(bp->b_vp), PRIBIO, "bwrbg", 0); 805 if (bp->b_vflags & BV_BKGRDINPROG) 806 panic("ibwrite: still writing"); 807 } 808 VI_UNLOCK(bp->b_vp); 809 810 /* Mark the buffer clean */ 811 bundirty(bp); 812 813 /* 814 * If this buffer is marked for background writing and we 815 * do not have to wait for it, make a copy and write the 816 * copy so as to leave this buffer ready for further use. 817 * 818 * This optimization eats a lot of memory. If we have a page 819 * or buffer shortfall we can't do it. 820 */ 821 if (dobkgrdwrite && (bp->b_xflags & BX_BKGRDWRITE) && 822 (bp->b_flags & B_ASYNC) && 823 !vm_page_count_severe() && 824 !buf_dirty_count_severe()) { 825 if (bp->b_iodone != NULL) { 826 printf("bp->b_iodone = %p\n", bp->b_iodone); 827 panic("ibwrite: need chained iodone"); 828 } 829 830 /* get a new block */ 831 newbp = geteblk(bp->b_bufsize); 832 833 /* 834 * set it to be identical to the old block. We have to 835 * set b_lblkno and BKGRDMARKER before calling bgetvp() 836 * to avoid confusing the splay tree and gbincore(). 837 */ 838 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 839 newbp->b_lblkno = bp->b_lblkno; 840 newbp->b_xflags |= BX_BKGRDMARKER; 841 VI_LOCK(bp->b_vp); 842 bp->b_vflags |= BV_BKGRDINPROG; 843 bgetvp(bp->b_vp, newbp); 844 VI_UNLOCK(bp->b_vp); 845 newbp->b_blkno = bp->b_blkno; 846 newbp->b_offset = bp->b_offset; 847 newbp->b_iodone = vfs_backgroundwritedone; 848 newbp->b_flags |= B_ASYNC; 849 newbp->b_flags &= ~B_INVAL; 850 851 /* move over the dependencies */ 852 if (LIST_FIRST(&bp->b_dep) != NULL) 853 buf_movedeps(bp, newbp); 854 855 /* 856 * Initiate write on the copy, release the original to 857 * the B_LOCKED queue so that it cannot go away until 858 * the background write completes. If not locked it could go 859 * away and then be reconstituted while it was being written. 860 * If the reconstituted buffer were written, we could end up 861 * with two background copies being written at the same time. 862 */ 863 bqrelse(bp); 864 bp = newbp; 865 } 866 867 bp->b_flags &= ~B_DONE; 868 bp->b_ioflags &= ~BIO_ERROR; 869 bp->b_flags |= B_WRITEINPROG | B_CACHE; 870 bp->b_iocmd = BIO_WRITE; 871 872 VI_LOCK(bp->b_vp); 873 bp->b_vp->v_numoutput++; 874 VI_UNLOCK(bp->b_vp); 875 vfs_busy_pages(bp, 1); 876 877 /* 878 * Normal bwrites pipeline writes 879 */ 880 bp->b_runningbufspace = bp->b_bufsize; 881 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 882 883 if (curthread != PCPU_GET(idlethread)) 884 curthread->td_proc->p_stats->p_ru.ru_oublock++; 885 splx(s); 886 if (oldflags & B_ASYNC) 887 BUF_KERNPROC(bp); 888 bp->b_iooffset = dbtob(bp->b_blkno); 889 if (bp->b_vp->v_type == VCHR) { 890 if (!buf_prewrite(bp->b_vp, bp)) 891 VOP_SPECSTRATEGY(bp->b_vp, bp); 892 } else { 893 VOP_STRATEGY(bp->b_vp, bp); 894 } 895 896 if ((oldflags & B_ASYNC) == 0) { 897 int rtval = bufwait(bp); 898 brelse(bp); 899 return (rtval); 900 } else { 901 /* 902 * don't allow the async write to saturate the I/O 903 * system. We will not deadlock here because 904 * we are blocking waiting for I/O that is already in-progress 905 * to complete. We do not block here if it is the update 906 * or syncer daemon trying to clean up as that can lead 907 * to deadlock. 908 */ 909 if (curthread->td_proc != bufdaemonproc && 910 curthread->td_proc != updateproc) 911 waitrunningbufspace(); 912 } 913 914 return (0); 915} 916 917/* 918 * Complete a background write started from bwrite. 919 */ 920static void 921vfs_backgroundwritedone(bp) 922 struct buf *bp; 923{ 924 struct buf *origbp; 925 926 /* 927 * Find the original buffer that we are writing. 928 */ 929 VI_LOCK(bp->b_vp); 930 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 931 panic("backgroundwritedone: lost buffer"); 932 933 /* 934 * Clear the BV_BKGRDINPROG flag in the original buffer 935 * and awaken it if it is waiting for the write to complete. 936 * If BV_BKGRDINPROG is not set in the original buffer it must 937 * have been released and re-instantiated - which is not legal. 938 */ 939 KASSERT((origbp->b_vflags & BV_BKGRDINPROG), 940 ("backgroundwritedone: lost buffer2")); 941 origbp->b_vflags &= ~BV_BKGRDINPROG; 942 if (origbp->b_vflags & BV_BKGRDWAIT) { 943 origbp->b_vflags &= ~BV_BKGRDWAIT; 944 wakeup(&origbp->b_xflags); 945 } 946 VI_UNLOCK(bp->b_vp); 947 /* 948 * Process dependencies then return any unfinished ones. 949 */ 950 if (LIST_FIRST(&bp->b_dep) != NULL) 951 buf_complete(bp); 952 if (LIST_FIRST(&bp->b_dep) != NULL) 953 buf_movedeps(bp, origbp); 954 955 /* 956 * This buffer is marked B_NOCACHE, so when it is released 957 * by biodone, it will be tossed. We mark it with BIO_READ 958 * to avoid biodone doing a second vwakeup. 959 */ 960 bp->b_flags |= B_NOCACHE; 961 bp->b_iocmd = BIO_READ; 962 bp->b_flags &= ~(B_CACHE | B_DONE); 963 bp->b_iodone = 0; 964 bufdone(bp); 965} 966 967/* 968 * Delayed write. (Buffer is marked dirty). Do not bother writing 969 * anything if the buffer is marked invalid. 970 * 971 * Note that since the buffer must be completely valid, we can safely 972 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 973 * biodone() in order to prevent getblk from writing the buffer 974 * out synchronously. 975 */ 976void 977bdwrite(struct buf * bp) 978{ 979 struct thread *td = curthread; 980 struct vnode *vp; 981 struct buf *nbp; 982 983 GIANT_REQUIRED; 984 985 if (BUF_REFCNT(bp) == 0) 986 panic("bdwrite: buffer is not busy"); 987 988 if (bp->b_flags & B_INVAL) { 989 brelse(bp); 990 return; 991 } 992 993 /* 994 * If we have too many dirty buffers, don't create any more. 995 * If we are wildly over our limit, then force a complete 996 * cleanup. Otherwise, just keep the situation from getting 997 * out of control. Note that we have to avoid a recursive 998 * disaster and not try to clean up after our own cleanup! 999 */ 1000 vp = bp->b_vp; 1001 VI_LOCK(vp); 1002 if (td->td_pflags & TDP_COWINPROGRESS) { 1003 recursiveflushes++; 1004 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh + 10) { 1005 VI_UNLOCK(vp); 1006 (void) VOP_FSYNC(vp, td->td_ucred, MNT_NOWAIT, td); 1007 VI_LOCK(vp); 1008 altbufferflushes++; 1009 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh) { 1010 /* 1011 * Try to find a buffer to flush. 1012 */ 1013 TAILQ_FOREACH(nbp, &vp->v_dirtyblkhd, b_vnbufs) { 1014 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1015 buf_countdeps(nbp, 0) || 1016 BUF_LOCK(nbp, LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1017 continue; 1018 if (bp == nbp) 1019 panic("bdwrite: found ourselves"); 1020 VI_UNLOCK(vp); 1021 if (nbp->b_flags & B_CLUSTEROK) { 1022 vfs_bio_awrite(nbp); 1023 } else { 1024 bremfree(nbp); 1025 bawrite(nbp); 1026 } 1027 VI_LOCK(vp); 1028 dirtybufferflushes++; 1029 break; 1030 } 1031 } 1032 VI_UNLOCK(vp); 1033 1034 bdirty(bp); 1035 /* 1036 * Set B_CACHE, indicating that the buffer is fully valid. This is 1037 * true even of NFS now. 1038 */ 1039 bp->b_flags |= B_CACHE; 1040 1041 /* 1042 * This bmap keeps the system from needing to do the bmap later, 1043 * perhaps when the system is attempting to do a sync. Since it 1044 * is likely that the indirect block -- or whatever other datastructure 1045 * that the filesystem needs is still in memory now, it is a good 1046 * thing to do this. Note also, that if the pageout daemon is 1047 * requesting a sync -- there might not be enough memory to do 1048 * the bmap then... So, this is important to do. 1049 */ 1050 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1051 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1052 } 1053 1054 /* 1055 * Set the *dirty* buffer range based upon the VM system dirty pages. 1056 */ 1057 vfs_setdirty(bp); 1058 1059 /* 1060 * We need to do this here to satisfy the vnode_pager and the 1061 * pageout daemon, so that it thinks that the pages have been 1062 * "cleaned". Note that since the pages are in a delayed write 1063 * buffer -- the VFS layer "will" see that the pages get written 1064 * out on the next sync, or perhaps the cluster will be completed. 1065 */ 1066 vfs_clean_pages(bp); 1067 bqrelse(bp); 1068 1069 /* 1070 * Wakeup the buffer flushing daemon if we have a lot of dirty 1071 * buffers (midpoint between our recovery point and our stall 1072 * point). 1073 */ 1074 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1075 1076 /* 1077 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1078 * due to the softdep code. 1079 */ 1080} 1081 1082/* 1083 * bdirty: 1084 * 1085 * Turn buffer into delayed write request. We must clear BIO_READ and 1086 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1087 * itself to properly update it in the dirty/clean lists. We mark it 1088 * B_DONE to ensure that any asynchronization of the buffer properly 1089 * clears B_DONE ( else a panic will occur later ). 1090 * 1091 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1092 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1093 * should only be called if the buffer is known-good. 1094 * 1095 * Since the buffer is not on a queue, we do not update the numfreebuffers 1096 * count. 1097 * 1098 * Must be called at splbio(). 1099 * The buffer must be on QUEUE_NONE. 1100 */ 1101void 1102bdirty(bp) 1103 struct buf *bp; 1104{ 1105 KASSERT(bp->b_qindex == QUEUE_NONE, 1106 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1107 bp->b_flags &= ~(B_RELBUF); 1108 bp->b_iocmd = BIO_WRITE; 1109 1110 if ((bp->b_flags & B_DELWRI) == 0) { 1111 bp->b_flags |= B_DONE | B_DELWRI; 1112 reassignbuf(bp, bp->b_vp); 1113 atomic_add_int(&numdirtybuffers, 1); 1114 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1115 } 1116} 1117 1118/* 1119 * bundirty: 1120 * 1121 * Clear B_DELWRI for buffer. 1122 * 1123 * Since the buffer is not on a queue, we do not update the numfreebuffers 1124 * count. 1125 * 1126 * Must be called at splbio(). 1127 * The buffer must be on QUEUE_NONE. 1128 */ 1129 1130void 1131bundirty(bp) 1132 struct buf *bp; 1133{ 1134 KASSERT(bp->b_qindex == QUEUE_NONE, 1135 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1136 1137 if (bp->b_flags & B_DELWRI) { 1138 bp->b_flags &= ~B_DELWRI; 1139 reassignbuf(bp, bp->b_vp); 1140 atomic_subtract_int(&numdirtybuffers, 1); 1141 numdirtywakeup(lodirtybuffers); 1142 } 1143 /* 1144 * Since it is now being written, we can clear its deferred write flag. 1145 */ 1146 bp->b_flags &= ~B_DEFERRED; 1147} 1148 1149/* 1150 * bawrite: 1151 * 1152 * Asynchronous write. Start output on a buffer, but do not wait for 1153 * it to complete. The buffer is released when the output completes. 1154 * 1155 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1156 * B_INVAL buffers. Not us. 1157 */ 1158void 1159bawrite(struct buf * bp) 1160{ 1161 bp->b_flags |= B_ASYNC; 1162 (void) bwrite(bp); 1163} 1164 1165/* 1166 * bwillwrite: 1167 * 1168 * Called prior to the locking of any vnodes when we are expecting to 1169 * write. We do not want to starve the buffer cache with too many 1170 * dirty buffers so we block here. By blocking prior to the locking 1171 * of any vnodes we attempt to avoid the situation where a locked vnode 1172 * prevents the various system daemons from flushing related buffers. 1173 */ 1174 1175void 1176bwillwrite(void) 1177{ 1178 if (numdirtybuffers >= hidirtybuffers) { 1179 int s; 1180 1181 mtx_lock(&Giant); 1182 s = splbio(); 1183 mtx_lock(&nblock); 1184 while (numdirtybuffers >= hidirtybuffers) { 1185 bd_wakeup(1); 1186 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1187 msleep(&needsbuffer, &nblock, 1188 (PRIBIO + 4), "flswai", 0); 1189 } 1190 splx(s); 1191 mtx_unlock(&nblock); 1192 mtx_unlock(&Giant); 1193 } 1194} 1195 1196/* 1197 * Return true if we have too many dirty buffers. 1198 */ 1199int 1200buf_dirty_count_severe(void) 1201{ 1202 return(numdirtybuffers >= hidirtybuffers); 1203} 1204 1205/* 1206 * brelse: 1207 * 1208 * Release a busy buffer and, if requested, free its resources. The 1209 * buffer will be stashed in the appropriate bufqueue[] allowing it 1210 * to be accessed later as a cache entity or reused for other purposes. 1211 */ 1212void 1213brelse(struct buf * bp) 1214{ 1215 int s; 1216 1217 GIANT_REQUIRED; 1218 1219 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1220 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1221 1222 s = splbio(); 1223 1224 if (bp->b_iocmd == BIO_WRITE && 1225 (bp->b_ioflags & BIO_ERROR) && 1226 !(bp->b_flags & B_INVAL)) { 1227 /* 1228 * Failed write, redirty. Must clear BIO_ERROR to prevent 1229 * pages from being scrapped. If B_INVAL is set then 1230 * this case is not run and the next case is run to 1231 * destroy the buffer. B_INVAL can occur if the buffer 1232 * is outside the range supported by the underlying device. 1233 */ 1234 bp->b_ioflags &= ~BIO_ERROR; 1235 bdirty(bp); 1236 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1237 (bp->b_ioflags & BIO_ERROR) || 1238 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) { 1239 /* 1240 * Either a failed I/O or we were asked to free or not 1241 * cache the buffer. 1242 */ 1243 bp->b_flags |= B_INVAL; 1244 if (LIST_FIRST(&bp->b_dep) != NULL) 1245 buf_deallocate(bp); 1246 if (bp->b_flags & B_DELWRI) { 1247 atomic_subtract_int(&numdirtybuffers, 1); 1248 numdirtywakeup(lodirtybuffers); 1249 } 1250 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1251 if ((bp->b_flags & B_VMIO) == 0) { 1252 if (bp->b_bufsize) 1253 allocbuf(bp, 0); 1254 if (bp->b_vp) 1255 brelvp(bp); 1256 } 1257 } 1258 1259 /* 1260 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1261 * is called with B_DELWRI set, the underlying pages may wind up 1262 * getting freed causing a previous write (bdwrite()) to get 'lost' 1263 * because pages associated with a B_DELWRI bp are marked clean. 1264 * 1265 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1266 * if B_DELWRI is set. 1267 * 1268 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1269 * on pages to return pages to the VM page queues. 1270 */ 1271 if (bp->b_flags & B_DELWRI) 1272 bp->b_flags &= ~B_RELBUF; 1273 else if (vm_page_count_severe()) { 1274 /* 1275 * XXX This lock may not be necessary since BKGRDINPROG 1276 * cannot be set while we hold the buf lock, it can only be 1277 * cleared if it is already pending. 1278 */ 1279 if (bp->b_vp) { 1280 VI_LOCK(bp->b_vp); 1281 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1282 bp->b_flags |= B_RELBUF; 1283 VI_UNLOCK(bp->b_vp); 1284 } else 1285 bp->b_flags |= B_RELBUF; 1286 } 1287 1288 /* 1289 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1290 * constituted, not even NFS buffers now. Two flags effect this. If 1291 * B_INVAL, the struct buf is invalidated but the VM object is kept 1292 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1293 * 1294 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1295 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1296 * buffer is also B_INVAL because it hits the re-dirtying code above. 1297 * 1298 * Normally we can do this whether a buffer is B_DELWRI or not. If 1299 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1300 * the commit state and we cannot afford to lose the buffer. If the 1301 * buffer has a background write in progress, we need to keep it 1302 * around to prevent it from being reconstituted and starting a second 1303 * background write. 1304 */ 1305 if ((bp->b_flags & B_VMIO) 1306 && !(bp->b_vp->v_mount != NULL && 1307 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1308 !vn_isdisk(bp->b_vp, NULL) && 1309 (bp->b_flags & B_DELWRI)) 1310 ) { 1311 1312 int i, j, resid; 1313 vm_page_t m; 1314 off_t foff; 1315 vm_pindex_t poff; 1316 vm_object_t obj; 1317 1318 obj = bp->b_object; 1319 1320 /* 1321 * Get the base offset and length of the buffer. Note that 1322 * in the VMIO case if the buffer block size is not 1323 * page-aligned then b_data pointer may not be page-aligned. 1324 * But our b_pages[] array *IS* page aligned. 1325 * 1326 * block sizes less then DEV_BSIZE (usually 512) are not 1327 * supported due to the page granularity bits (m->valid, 1328 * m->dirty, etc...). 1329 * 1330 * See man buf(9) for more information 1331 */ 1332 resid = bp->b_bufsize; 1333 foff = bp->b_offset; 1334 VM_OBJECT_LOCK(obj); 1335 for (i = 0; i < bp->b_npages; i++) { 1336 int had_bogus = 0; 1337 1338 m = bp->b_pages[i]; 1339 1340 /* 1341 * If we hit a bogus page, fixup *all* the bogus pages 1342 * now. 1343 */ 1344 if (m == bogus_page) { 1345 poff = OFF_TO_IDX(bp->b_offset); 1346 had_bogus = 1; 1347 1348 for (j = i; j < bp->b_npages; j++) { 1349 vm_page_t mtmp; 1350 mtmp = bp->b_pages[j]; 1351 if (mtmp == bogus_page) { 1352 mtmp = vm_page_lookup(obj, poff + j); 1353 if (!mtmp) { 1354 panic("brelse: page missing\n"); 1355 } 1356 bp->b_pages[j] = mtmp; 1357 } 1358 } 1359 1360 if ((bp->b_flags & B_INVAL) == 0) { 1361 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1362 } 1363 m = bp->b_pages[i]; 1364 } 1365 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1366 int poffset = foff & PAGE_MASK; 1367 int presid = resid > (PAGE_SIZE - poffset) ? 1368 (PAGE_SIZE - poffset) : resid; 1369 1370 KASSERT(presid >= 0, ("brelse: extra page")); 1371 vm_page_lock_queues(); 1372 vm_page_set_invalid(m, poffset, presid); 1373 vm_page_unlock_queues(); 1374 if (had_bogus) 1375 printf("avoided corruption bug in bogus_page/brelse code\n"); 1376 } 1377 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1378 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1379 } 1380 VM_OBJECT_UNLOCK(obj); 1381 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1382 vfs_vmio_release(bp); 1383 1384 } else if (bp->b_flags & B_VMIO) { 1385 1386 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1387 vfs_vmio_release(bp); 1388 } 1389 1390 } 1391 1392 if (bp->b_qindex != QUEUE_NONE) 1393 panic("brelse: free buffer onto another queue???"); 1394 if (BUF_REFCNT(bp) > 1) { 1395 /* do not release to free list */ 1396 BUF_UNLOCK(bp); 1397 splx(s); 1398 return; 1399 } 1400 1401 /* enqueue */ 1402 mtx_lock(&bqlock); 1403 1404 /* buffers with no memory */ 1405 if (bp->b_bufsize == 0) { 1406 bp->b_flags |= B_INVAL; 1407 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1408 if (bp->b_vflags & BV_BKGRDINPROG) 1409 panic("losing buffer 1"); 1410 if (bp->b_kvasize) { 1411 bp->b_qindex = QUEUE_EMPTYKVA; 1412 } else { 1413 bp->b_qindex = QUEUE_EMPTY; 1414 } 1415 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
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1416 bp->b_dev = NODEV;
| 1416 bp->b_dev = NULL;
|
1417 /* buffers with junk contents */ 1418 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1419 (bp->b_ioflags & BIO_ERROR)) { 1420 bp->b_flags |= B_INVAL; 1421 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1422 if (bp->b_vflags & BV_BKGRDINPROG) 1423 panic("losing buffer 2"); 1424 bp->b_qindex = QUEUE_CLEAN; 1425 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
| 1417 /* buffers with junk contents */ 1418 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1419 (bp->b_ioflags & BIO_ERROR)) { 1420 bp->b_flags |= B_INVAL; 1421 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1422 if (bp->b_vflags & BV_BKGRDINPROG) 1423 panic("losing buffer 2"); 1424 bp->b_qindex = QUEUE_CLEAN; 1425 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
|
1426 bp->b_dev = NODEV;
| 1426 bp->b_dev = NULL;
|
1427 /* remaining buffers */ 1428 } else { 1429 if (bp->b_flags & B_DELWRI) 1430 bp->b_qindex = QUEUE_DIRTY; 1431 else 1432 bp->b_qindex = QUEUE_CLEAN; 1433 if (bp->b_flags & B_AGE) 1434 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1435 else 1436 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1437 } 1438 mtx_unlock(&bqlock); 1439 1440 /* 1441 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1442 * placed the buffer on the correct queue. We must also disassociate 1443 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1444 * find it. 1445 */ 1446 if (bp->b_flags & B_INVAL) { 1447 if (bp->b_flags & B_DELWRI) 1448 bundirty(bp); 1449 if (bp->b_vp) 1450 brelvp(bp); 1451 } 1452 1453 /* 1454 * Fixup numfreebuffers count. The bp is on an appropriate queue 1455 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1456 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1457 * if B_INVAL is set ). 1458 */ 1459 1460 if (!(bp->b_flags & B_DELWRI)) 1461 bufcountwakeup(); 1462 1463 /* 1464 * Something we can maybe free or reuse 1465 */ 1466 if (bp->b_bufsize || bp->b_kvasize) 1467 bufspacewakeup(); 1468 1469 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1470 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1471 panic("brelse: not dirty"); 1472 /* unlock */ 1473 BUF_UNLOCK(bp); 1474 splx(s); 1475} 1476 1477/* 1478 * Release a buffer back to the appropriate queue but do not try to free 1479 * it. The buffer is expected to be used again soon. 1480 * 1481 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1482 * biodone() to requeue an async I/O on completion. It is also used when 1483 * known good buffers need to be requeued but we think we may need the data 1484 * again soon. 1485 * 1486 * XXX we should be able to leave the B_RELBUF hint set on completion. 1487 */ 1488void 1489bqrelse(struct buf * bp) 1490{ 1491 int s; 1492 1493 s = splbio(); 1494 1495 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1496 1497 if (bp->b_qindex != QUEUE_NONE) 1498 panic("bqrelse: free buffer onto another queue???"); 1499 if (BUF_REFCNT(bp) > 1) { 1500 /* do not release to free list */ 1501 BUF_UNLOCK(bp); 1502 splx(s); 1503 return; 1504 } 1505 mtx_lock(&bqlock); 1506 /* buffers with stale but valid contents */ 1507 if (bp->b_flags & B_DELWRI) { 1508 bp->b_qindex = QUEUE_DIRTY; 1509 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1510 } else { 1511 /* 1512 * XXX This lock may not be necessary since BKGRDINPROG 1513 * cannot be set while we hold the buf lock, it can only be 1514 * cleared if it is already pending. 1515 */ 1516 VI_LOCK(bp->b_vp); 1517 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1518 VI_UNLOCK(bp->b_vp); 1519 bp->b_qindex = QUEUE_CLEAN; 1520 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1521 b_freelist); 1522 } else { 1523 /* 1524 * We are too low on memory, we have to try to free 1525 * the buffer (most importantly: the wired pages 1526 * making up its backing store) *now*. 1527 */ 1528 VI_UNLOCK(bp->b_vp); 1529 mtx_unlock(&bqlock); 1530 splx(s); 1531 brelse(bp); 1532 return; 1533 } 1534 } 1535 mtx_unlock(&bqlock); 1536 1537 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1538 bufcountwakeup(); 1539 1540 /* 1541 * Something we can maybe free or reuse. 1542 */ 1543 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1544 bufspacewakeup(); 1545 1546 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1547 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1548 panic("bqrelse: not dirty"); 1549 /* unlock */ 1550 BUF_UNLOCK(bp); 1551 splx(s); 1552} 1553 1554/* Give pages used by the bp back to the VM system (where possible) */ 1555static void 1556vfs_vmio_release(bp) 1557 struct buf *bp; 1558{ 1559 int i; 1560 vm_page_t m; 1561 1562 GIANT_REQUIRED; 1563 VM_OBJECT_LOCK(bp->b_object); 1564 vm_page_lock_queues(); 1565 for (i = 0; i < bp->b_npages; i++) { 1566 m = bp->b_pages[i]; 1567 bp->b_pages[i] = NULL; 1568 /* 1569 * In order to keep page LRU ordering consistent, put 1570 * everything on the inactive queue. 1571 */ 1572 vm_page_unwire(m, 0); 1573 /* 1574 * We don't mess with busy pages, it is 1575 * the responsibility of the process that 1576 * busied the pages to deal with them. 1577 */ 1578 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1579 continue; 1580 1581 if (m->wire_count == 0) { 1582 /* 1583 * Might as well free the page if we can and it has 1584 * no valid data. We also free the page if the 1585 * buffer was used for direct I/O 1586 */ 1587 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1588 m->hold_count == 0) { 1589 vm_page_busy(m); 1590 pmap_remove_all(m); 1591 vm_page_free(m); 1592 } else if (bp->b_flags & B_DIRECT) { 1593 vm_page_try_to_free(m); 1594 } else if (vm_page_count_severe()) { 1595 vm_page_try_to_cache(m); 1596 } 1597 } 1598 } 1599 vm_page_unlock_queues(); 1600 VM_OBJECT_UNLOCK(bp->b_object); 1601 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1602 1603 if (bp->b_bufsize) { 1604 bufspacewakeup(); 1605 bp->b_bufsize = 0; 1606 } 1607 bp->b_npages = 0; 1608 bp->b_flags &= ~B_VMIO; 1609 if (bp->b_vp) 1610 brelvp(bp); 1611} 1612 1613/* 1614 * Check to see if a block at a particular lbn is available for a clustered 1615 * write. 1616 */ 1617static int 1618vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1619{ 1620 struct buf *bpa; 1621 int match; 1622 1623 match = 0; 1624 1625 /* If the buf isn't in core skip it */ 1626 if ((bpa = gbincore(vp, lblkno)) == NULL) 1627 return (0); 1628 1629 /* If the buf is busy we don't want to wait for it */ 1630 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1631 return (0); 1632 1633 /* Only cluster with valid clusterable delayed write buffers */ 1634 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1635 (B_DELWRI | B_CLUSTEROK)) 1636 goto done; 1637 1638 if (bpa->b_bufsize != size) 1639 goto done; 1640 1641 /* 1642 * Check to see if it is in the expected place on disk and that the 1643 * block has been mapped. 1644 */ 1645 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1646 match = 1; 1647done: 1648 BUF_UNLOCK(bpa); 1649 return (match); 1650} 1651 1652/* 1653 * vfs_bio_awrite: 1654 * 1655 * Implement clustered async writes for clearing out B_DELWRI buffers. 1656 * This is much better then the old way of writing only one buffer at 1657 * a time. Note that we may not be presented with the buffers in the 1658 * correct order, so we search for the cluster in both directions. 1659 */ 1660int 1661vfs_bio_awrite(struct buf * bp) 1662{ 1663 int i; 1664 int j; 1665 daddr_t lblkno = bp->b_lblkno; 1666 struct vnode *vp = bp->b_vp; 1667 int s; 1668 int ncl; 1669 int nwritten; 1670 int size; 1671 int maxcl; 1672 1673 s = splbio(); 1674 /* 1675 * right now we support clustered writing only to regular files. If 1676 * we find a clusterable block we could be in the middle of a cluster 1677 * rather then at the beginning. 1678 */ 1679 if ((vp->v_type == VREG) && 1680 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1681 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1682 1683 size = vp->v_mount->mnt_stat.f_iosize; 1684 maxcl = MAXPHYS / size; 1685 1686 VI_LOCK(vp); 1687 for (i = 1; i < maxcl; i++) 1688 if (vfs_bio_clcheck(vp, size, lblkno + i, 1689 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1690 break; 1691 1692 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1693 if (vfs_bio_clcheck(vp, size, lblkno - j, 1694 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1695 break; 1696 1697 VI_UNLOCK(vp); 1698 --j; 1699 ncl = i + j; 1700 /* 1701 * this is a possible cluster write 1702 */ 1703 if (ncl != 1) { 1704 BUF_UNLOCK(bp); 1705 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1706 splx(s); 1707 return nwritten; 1708 } 1709 } 1710 1711 bremfree(bp); 1712 bp->b_flags |= B_ASYNC; 1713 1714 splx(s); 1715 /* 1716 * default (old) behavior, writing out only one block 1717 * 1718 * XXX returns b_bufsize instead of b_bcount for nwritten? 1719 */ 1720 nwritten = bp->b_bufsize; 1721 (void) bwrite(bp); 1722 1723 return nwritten; 1724} 1725 1726/* 1727 * getnewbuf: 1728 * 1729 * Find and initialize a new buffer header, freeing up existing buffers 1730 * in the bufqueues as necessary. The new buffer is returned locked. 1731 * 1732 * Important: B_INVAL is not set. If the caller wishes to throw the 1733 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1734 * 1735 * We block if: 1736 * We have insufficient buffer headers 1737 * We have insufficient buffer space 1738 * buffer_map is too fragmented ( space reservation fails ) 1739 * If we have to flush dirty buffers ( but we try to avoid this ) 1740 * 1741 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1742 * Instead we ask the buf daemon to do it for us. We attempt to 1743 * avoid piecemeal wakeups of the pageout daemon. 1744 */ 1745 1746static struct buf * 1747getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1748{ 1749 struct buf *bp; 1750 struct buf *nbp; 1751 int defrag = 0; 1752 int nqindex; 1753 static int flushingbufs; 1754 1755 GIANT_REQUIRED; 1756 1757 /* 1758 * We can't afford to block since we might be holding a vnode lock, 1759 * which may prevent system daemons from running. We deal with 1760 * low-memory situations by proactively returning memory and running 1761 * async I/O rather then sync I/O. 1762 */ 1763 1764 atomic_add_int(&getnewbufcalls, 1); 1765 atomic_subtract_int(&getnewbufrestarts, 1); 1766restart: 1767 atomic_add_int(&getnewbufrestarts, 1); 1768 1769 /* 1770 * Setup for scan. If we do not have enough free buffers, 1771 * we setup a degenerate case that immediately fails. Note 1772 * that if we are specially marked process, we are allowed to 1773 * dip into our reserves. 1774 * 1775 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1776 * 1777 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1778 * However, there are a number of cases (defragging, reusing, ...) 1779 * where we cannot backup. 1780 */ 1781 mtx_lock(&bqlock); 1782 nqindex = QUEUE_EMPTYKVA; 1783 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1784 1785 if (nbp == NULL) { 1786 /* 1787 * If no EMPTYKVA buffers and we are either 1788 * defragging or reusing, locate a CLEAN buffer 1789 * to free or reuse. If bufspace useage is low 1790 * skip this step so we can allocate a new buffer. 1791 */ 1792 if (defrag || bufspace >= lobufspace) { 1793 nqindex = QUEUE_CLEAN; 1794 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1795 } 1796 1797 /* 1798 * If we could not find or were not allowed to reuse a 1799 * CLEAN buffer, check to see if it is ok to use an EMPTY 1800 * buffer. We can only use an EMPTY buffer if allocating 1801 * its KVA would not otherwise run us out of buffer space. 1802 */ 1803 if (nbp == NULL && defrag == 0 && 1804 bufspace + maxsize < hibufspace) { 1805 nqindex = QUEUE_EMPTY; 1806 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1807 } 1808 } 1809 1810 /* 1811 * Run scan, possibly freeing data and/or kva mappings on the fly 1812 * depending. 1813 */ 1814 1815 while ((bp = nbp) != NULL) { 1816 int qindex = nqindex; 1817 1818 /* 1819 * Calculate next bp ( we can only use it if we do not block 1820 * or do other fancy things ). 1821 */ 1822 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1823 switch(qindex) { 1824 case QUEUE_EMPTY: 1825 nqindex = QUEUE_EMPTYKVA; 1826 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1827 break; 1828 /* FALLTHROUGH */ 1829 case QUEUE_EMPTYKVA: 1830 nqindex = QUEUE_CLEAN; 1831 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1832 break; 1833 /* FALLTHROUGH */ 1834 case QUEUE_CLEAN: 1835 /* 1836 * nbp is NULL. 1837 */ 1838 break; 1839 } 1840 } 1841 if (bp->b_vp) { 1842 VI_LOCK(bp->b_vp); 1843 if (bp->b_vflags & BV_BKGRDINPROG) { 1844 VI_UNLOCK(bp->b_vp); 1845 continue; 1846 } 1847 VI_UNLOCK(bp->b_vp); 1848 } 1849 1850 /* 1851 * Sanity Checks 1852 */ 1853 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1854 1855 /* 1856 * Note: we no longer distinguish between VMIO and non-VMIO 1857 * buffers. 1858 */ 1859 1860 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1861 1862 /* 1863 * If we are defragging then we need a buffer with 1864 * b_kvasize != 0. XXX this situation should no longer 1865 * occur, if defrag is non-zero the buffer's b_kvasize 1866 * should also be non-zero at this point. XXX 1867 */ 1868 if (defrag && bp->b_kvasize == 0) { 1869 printf("Warning: defrag empty buffer %p\n", bp); 1870 continue; 1871 } 1872 1873 /* 1874 * Start freeing the bp. This is somewhat involved. nbp 1875 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1876 */ 1877 1878 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1879 panic("getnewbuf: locked buf"); 1880 bremfreel(bp); 1881 mtx_unlock(&bqlock); 1882 1883 if (qindex == QUEUE_CLEAN) { 1884 if (bp->b_flags & B_VMIO) { 1885 bp->b_flags &= ~B_ASYNC; 1886 vfs_vmio_release(bp); 1887 } 1888 if (bp->b_vp) 1889 brelvp(bp); 1890 } 1891 1892 /* 1893 * NOTE: nbp is now entirely invalid. We can only restart 1894 * the scan from this point on. 1895 * 1896 * Get the rest of the buffer freed up. b_kva* is still 1897 * valid after this operation. 1898 */ 1899 1900 if (bp->b_rcred != NOCRED) { 1901 crfree(bp->b_rcred); 1902 bp->b_rcred = NOCRED; 1903 } 1904 if (bp->b_wcred != NOCRED) { 1905 crfree(bp->b_wcred); 1906 bp->b_wcred = NOCRED; 1907 } 1908 if (LIST_FIRST(&bp->b_dep) != NULL) 1909 buf_deallocate(bp); 1910 if (bp->b_vflags & BV_BKGRDINPROG) 1911 panic("losing buffer 3"); 1912 1913 if (bp->b_bufsize) 1914 allocbuf(bp, 0); 1915 1916 bp->b_flags = 0; 1917 bp->b_ioflags = 0; 1918 bp->b_xflags = 0; 1919 bp->b_vflags = 0;
| 1427 /* remaining buffers */ 1428 } else { 1429 if (bp->b_flags & B_DELWRI) 1430 bp->b_qindex = QUEUE_DIRTY; 1431 else 1432 bp->b_qindex = QUEUE_CLEAN; 1433 if (bp->b_flags & B_AGE) 1434 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1435 else 1436 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1437 } 1438 mtx_unlock(&bqlock); 1439 1440 /* 1441 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1442 * placed the buffer on the correct queue. We must also disassociate 1443 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1444 * find it. 1445 */ 1446 if (bp->b_flags & B_INVAL) { 1447 if (bp->b_flags & B_DELWRI) 1448 bundirty(bp); 1449 if (bp->b_vp) 1450 brelvp(bp); 1451 } 1452 1453 /* 1454 * Fixup numfreebuffers count. The bp is on an appropriate queue 1455 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1456 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1457 * if B_INVAL is set ). 1458 */ 1459 1460 if (!(bp->b_flags & B_DELWRI)) 1461 bufcountwakeup(); 1462 1463 /* 1464 * Something we can maybe free or reuse 1465 */ 1466 if (bp->b_bufsize || bp->b_kvasize) 1467 bufspacewakeup(); 1468 1469 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1470 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1471 panic("brelse: not dirty"); 1472 /* unlock */ 1473 BUF_UNLOCK(bp); 1474 splx(s); 1475} 1476 1477/* 1478 * Release a buffer back to the appropriate queue but do not try to free 1479 * it. The buffer is expected to be used again soon. 1480 * 1481 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1482 * biodone() to requeue an async I/O on completion. It is also used when 1483 * known good buffers need to be requeued but we think we may need the data 1484 * again soon. 1485 * 1486 * XXX we should be able to leave the B_RELBUF hint set on completion. 1487 */ 1488void 1489bqrelse(struct buf * bp) 1490{ 1491 int s; 1492 1493 s = splbio(); 1494 1495 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1496 1497 if (bp->b_qindex != QUEUE_NONE) 1498 panic("bqrelse: free buffer onto another queue???"); 1499 if (BUF_REFCNT(bp) > 1) { 1500 /* do not release to free list */ 1501 BUF_UNLOCK(bp); 1502 splx(s); 1503 return; 1504 } 1505 mtx_lock(&bqlock); 1506 /* buffers with stale but valid contents */ 1507 if (bp->b_flags & B_DELWRI) { 1508 bp->b_qindex = QUEUE_DIRTY; 1509 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1510 } else { 1511 /* 1512 * XXX This lock may not be necessary since BKGRDINPROG 1513 * cannot be set while we hold the buf lock, it can only be 1514 * cleared if it is already pending. 1515 */ 1516 VI_LOCK(bp->b_vp); 1517 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1518 VI_UNLOCK(bp->b_vp); 1519 bp->b_qindex = QUEUE_CLEAN; 1520 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1521 b_freelist); 1522 } else { 1523 /* 1524 * We are too low on memory, we have to try to free 1525 * the buffer (most importantly: the wired pages 1526 * making up its backing store) *now*. 1527 */ 1528 VI_UNLOCK(bp->b_vp); 1529 mtx_unlock(&bqlock); 1530 splx(s); 1531 brelse(bp); 1532 return; 1533 } 1534 } 1535 mtx_unlock(&bqlock); 1536 1537 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1538 bufcountwakeup(); 1539 1540 /* 1541 * Something we can maybe free or reuse. 1542 */ 1543 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1544 bufspacewakeup(); 1545 1546 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1547 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1548 panic("bqrelse: not dirty"); 1549 /* unlock */ 1550 BUF_UNLOCK(bp); 1551 splx(s); 1552} 1553 1554/* Give pages used by the bp back to the VM system (where possible) */ 1555static void 1556vfs_vmio_release(bp) 1557 struct buf *bp; 1558{ 1559 int i; 1560 vm_page_t m; 1561 1562 GIANT_REQUIRED; 1563 VM_OBJECT_LOCK(bp->b_object); 1564 vm_page_lock_queues(); 1565 for (i = 0; i < bp->b_npages; i++) { 1566 m = bp->b_pages[i]; 1567 bp->b_pages[i] = NULL; 1568 /* 1569 * In order to keep page LRU ordering consistent, put 1570 * everything on the inactive queue. 1571 */ 1572 vm_page_unwire(m, 0); 1573 /* 1574 * We don't mess with busy pages, it is 1575 * the responsibility of the process that 1576 * busied the pages to deal with them. 1577 */ 1578 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1579 continue; 1580 1581 if (m->wire_count == 0) { 1582 /* 1583 * Might as well free the page if we can and it has 1584 * no valid data. We also free the page if the 1585 * buffer was used for direct I/O 1586 */ 1587 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1588 m->hold_count == 0) { 1589 vm_page_busy(m); 1590 pmap_remove_all(m); 1591 vm_page_free(m); 1592 } else if (bp->b_flags & B_DIRECT) { 1593 vm_page_try_to_free(m); 1594 } else if (vm_page_count_severe()) { 1595 vm_page_try_to_cache(m); 1596 } 1597 } 1598 } 1599 vm_page_unlock_queues(); 1600 VM_OBJECT_UNLOCK(bp->b_object); 1601 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1602 1603 if (bp->b_bufsize) { 1604 bufspacewakeup(); 1605 bp->b_bufsize = 0; 1606 } 1607 bp->b_npages = 0; 1608 bp->b_flags &= ~B_VMIO; 1609 if (bp->b_vp) 1610 brelvp(bp); 1611} 1612 1613/* 1614 * Check to see if a block at a particular lbn is available for a clustered 1615 * write. 1616 */ 1617static int 1618vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1619{ 1620 struct buf *bpa; 1621 int match; 1622 1623 match = 0; 1624 1625 /* If the buf isn't in core skip it */ 1626 if ((bpa = gbincore(vp, lblkno)) == NULL) 1627 return (0); 1628 1629 /* If the buf is busy we don't want to wait for it */ 1630 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1631 return (0); 1632 1633 /* Only cluster with valid clusterable delayed write buffers */ 1634 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1635 (B_DELWRI | B_CLUSTEROK)) 1636 goto done; 1637 1638 if (bpa->b_bufsize != size) 1639 goto done; 1640 1641 /* 1642 * Check to see if it is in the expected place on disk and that the 1643 * block has been mapped. 1644 */ 1645 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1646 match = 1; 1647done: 1648 BUF_UNLOCK(bpa); 1649 return (match); 1650} 1651 1652/* 1653 * vfs_bio_awrite: 1654 * 1655 * Implement clustered async writes for clearing out B_DELWRI buffers. 1656 * This is much better then the old way of writing only one buffer at 1657 * a time. Note that we may not be presented with the buffers in the 1658 * correct order, so we search for the cluster in both directions. 1659 */ 1660int 1661vfs_bio_awrite(struct buf * bp) 1662{ 1663 int i; 1664 int j; 1665 daddr_t lblkno = bp->b_lblkno; 1666 struct vnode *vp = bp->b_vp; 1667 int s; 1668 int ncl; 1669 int nwritten; 1670 int size; 1671 int maxcl; 1672 1673 s = splbio(); 1674 /* 1675 * right now we support clustered writing only to regular files. If 1676 * we find a clusterable block we could be in the middle of a cluster 1677 * rather then at the beginning. 1678 */ 1679 if ((vp->v_type == VREG) && 1680 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1681 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1682 1683 size = vp->v_mount->mnt_stat.f_iosize; 1684 maxcl = MAXPHYS / size; 1685 1686 VI_LOCK(vp); 1687 for (i = 1; i < maxcl; i++) 1688 if (vfs_bio_clcheck(vp, size, lblkno + i, 1689 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1690 break; 1691 1692 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1693 if (vfs_bio_clcheck(vp, size, lblkno - j, 1694 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1695 break; 1696 1697 VI_UNLOCK(vp); 1698 --j; 1699 ncl = i + j; 1700 /* 1701 * this is a possible cluster write 1702 */ 1703 if (ncl != 1) { 1704 BUF_UNLOCK(bp); 1705 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1706 splx(s); 1707 return nwritten; 1708 } 1709 } 1710 1711 bremfree(bp); 1712 bp->b_flags |= B_ASYNC; 1713 1714 splx(s); 1715 /* 1716 * default (old) behavior, writing out only one block 1717 * 1718 * XXX returns b_bufsize instead of b_bcount for nwritten? 1719 */ 1720 nwritten = bp->b_bufsize; 1721 (void) bwrite(bp); 1722 1723 return nwritten; 1724} 1725 1726/* 1727 * getnewbuf: 1728 * 1729 * Find and initialize a new buffer header, freeing up existing buffers 1730 * in the bufqueues as necessary. The new buffer is returned locked. 1731 * 1732 * Important: B_INVAL is not set. If the caller wishes to throw the 1733 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1734 * 1735 * We block if: 1736 * We have insufficient buffer headers 1737 * We have insufficient buffer space 1738 * buffer_map is too fragmented ( space reservation fails ) 1739 * If we have to flush dirty buffers ( but we try to avoid this ) 1740 * 1741 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1742 * Instead we ask the buf daemon to do it for us. We attempt to 1743 * avoid piecemeal wakeups of the pageout daemon. 1744 */ 1745 1746static struct buf * 1747getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1748{ 1749 struct buf *bp; 1750 struct buf *nbp; 1751 int defrag = 0; 1752 int nqindex; 1753 static int flushingbufs; 1754 1755 GIANT_REQUIRED; 1756 1757 /* 1758 * We can't afford to block since we might be holding a vnode lock, 1759 * which may prevent system daemons from running. We deal with 1760 * low-memory situations by proactively returning memory and running 1761 * async I/O rather then sync I/O. 1762 */ 1763 1764 atomic_add_int(&getnewbufcalls, 1); 1765 atomic_subtract_int(&getnewbufrestarts, 1); 1766restart: 1767 atomic_add_int(&getnewbufrestarts, 1); 1768 1769 /* 1770 * Setup for scan. If we do not have enough free buffers, 1771 * we setup a degenerate case that immediately fails. Note 1772 * that if we are specially marked process, we are allowed to 1773 * dip into our reserves. 1774 * 1775 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1776 * 1777 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1778 * However, there are a number of cases (defragging, reusing, ...) 1779 * where we cannot backup. 1780 */ 1781 mtx_lock(&bqlock); 1782 nqindex = QUEUE_EMPTYKVA; 1783 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1784 1785 if (nbp == NULL) { 1786 /* 1787 * If no EMPTYKVA buffers and we are either 1788 * defragging or reusing, locate a CLEAN buffer 1789 * to free or reuse. If bufspace useage is low 1790 * skip this step so we can allocate a new buffer. 1791 */ 1792 if (defrag || bufspace >= lobufspace) { 1793 nqindex = QUEUE_CLEAN; 1794 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1795 } 1796 1797 /* 1798 * If we could not find or were not allowed to reuse a 1799 * CLEAN buffer, check to see if it is ok to use an EMPTY 1800 * buffer. We can only use an EMPTY buffer if allocating 1801 * its KVA would not otherwise run us out of buffer space. 1802 */ 1803 if (nbp == NULL && defrag == 0 && 1804 bufspace + maxsize < hibufspace) { 1805 nqindex = QUEUE_EMPTY; 1806 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1807 } 1808 } 1809 1810 /* 1811 * Run scan, possibly freeing data and/or kva mappings on the fly 1812 * depending. 1813 */ 1814 1815 while ((bp = nbp) != NULL) { 1816 int qindex = nqindex; 1817 1818 /* 1819 * Calculate next bp ( we can only use it if we do not block 1820 * or do other fancy things ). 1821 */ 1822 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1823 switch(qindex) { 1824 case QUEUE_EMPTY: 1825 nqindex = QUEUE_EMPTYKVA; 1826 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1827 break; 1828 /* FALLTHROUGH */ 1829 case QUEUE_EMPTYKVA: 1830 nqindex = QUEUE_CLEAN; 1831 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1832 break; 1833 /* FALLTHROUGH */ 1834 case QUEUE_CLEAN: 1835 /* 1836 * nbp is NULL. 1837 */ 1838 break; 1839 } 1840 } 1841 if (bp->b_vp) { 1842 VI_LOCK(bp->b_vp); 1843 if (bp->b_vflags & BV_BKGRDINPROG) { 1844 VI_UNLOCK(bp->b_vp); 1845 continue; 1846 } 1847 VI_UNLOCK(bp->b_vp); 1848 } 1849 1850 /* 1851 * Sanity Checks 1852 */ 1853 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1854 1855 /* 1856 * Note: we no longer distinguish between VMIO and non-VMIO 1857 * buffers. 1858 */ 1859 1860 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1861 1862 /* 1863 * If we are defragging then we need a buffer with 1864 * b_kvasize != 0. XXX this situation should no longer 1865 * occur, if defrag is non-zero the buffer's b_kvasize 1866 * should also be non-zero at this point. XXX 1867 */ 1868 if (defrag && bp->b_kvasize == 0) { 1869 printf("Warning: defrag empty buffer %p\n", bp); 1870 continue; 1871 } 1872 1873 /* 1874 * Start freeing the bp. This is somewhat involved. nbp 1875 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1876 */ 1877 1878 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1879 panic("getnewbuf: locked buf"); 1880 bremfreel(bp); 1881 mtx_unlock(&bqlock); 1882 1883 if (qindex == QUEUE_CLEAN) { 1884 if (bp->b_flags & B_VMIO) { 1885 bp->b_flags &= ~B_ASYNC; 1886 vfs_vmio_release(bp); 1887 } 1888 if (bp->b_vp) 1889 brelvp(bp); 1890 } 1891 1892 /* 1893 * NOTE: nbp is now entirely invalid. We can only restart 1894 * the scan from this point on. 1895 * 1896 * Get the rest of the buffer freed up. b_kva* is still 1897 * valid after this operation. 1898 */ 1899 1900 if (bp->b_rcred != NOCRED) { 1901 crfree(bp->b_rcred); 1902 bp->b_rcred = NOCRED; 1903 } 1904 if (bp->b_wcred != NOCRED) { 1905 crfree(bp->b_wcred); 1906 bp->b_wcred = NOCRED; 1907 } 1908 if (LIST_FIRST(&bp->b_dep) != NULL) 1909 buf_deallocate(bp); 1910 if (bp->b_vflags & BV_BKGRDINPROG) 1911 panic("losing buffer 3"); 1912 1913 if (bp->b_bufsize) 1914 allocbuf(bp, 0); 1915 1916 bp->b_flags = 0; 1917 bp->b_ioflags = 0; 1918 bp->b_xflags = 0; 1919 bp->b_vflags = 0;
|
1920 bp->b_dev = NODEV;
| 1920 bp->b_dev = NULL;
|
1921 bp->b_vp = NULL; 1922 bp->b_blkno = bp->b_lblkno = 0; 1923 bp->b_offset = NOOFFSET; 1924 bp->b_iodone = 0; 1925 bp->b_error = 0; 1926 bp->b_resid = 0; 1927 bp->b_bcount = 0; 1928 bp->b_npages = 0; 1929 bp->b_dirtyoff = bp->b_dirtyend = 0; 1930 bp->b_magic = B_MAGIC_BIO; 1931 bp->b_op = &buf_ops_bio; 1932 bp->b_object = NULL; 1933 1934 LIST_INIT(&bp->b_dep); 1935 1936 /* 1937 * If we are defragging then free the buffer. 1938 */ 1939 if (defrag) { 1940 bp->b_flags |= B_INVAL; 1941 bfreekva(bp); 1942 brelse(bp); 1943 defrag = 0; 1944 goto restart; 1945 } 1946 1947 /* 1948 * If we are overcomitted then recover the buffer and its 1949 * KVM space. This occurs in rare situations when multiple 1950 * processes are blocked in getnewbuf() or allocbuf(). 1951 */ 1952 if (bufspace >= hibufspace) 1953 flushingbufs = 1; 1954 if (flushingbufs && bp->b_kvasize != 0) { 1955 bp->b_flags |= B_INVAL; 1956 bfreekva(bp); 1957 brelse(bp); 1958 goto restart; 1959 } 1960 if (bufspace < lobufspace) 1961 flushingbufs = 0; 1962 break; 1963 } 1964 1965 /* 1966 * If we exhausted our list, sleep as appropriate. We may have to 1967 * wakeup various daemons and write out some dirty buffers. 1968 * 1969 * Generally we are sleeping due to insufficient buffer space. 1970 */ 1971 1972 if (bp == NULL) { 1973 int flags; 1974 char *waitmsg; 1975 1976 mtx_unlock(&bqlock); 1977 if (defrag) { 1978 flags = VFS_BIO_NEED_BUFSPACE; 1979 waitmsg = "nbufkv"; 1980 } else if (bufspace >= hibufspace) { 1981 waitmsg = "nbufbs"; 1982 flags = VFS_BIO_NEED_BUFSPACE; 1983 } else { 1984 waitmsg = "newbuf"; 1985 flags = VFS_BIO_NEED_ANY; 1986 } 1987 1988 bd_speedup(); /* heeeelp */ 1989 1990 mtx_lock(&nblock); 1991 needsbuffer |= flags; 1992 while (needsbuffer & flags) { 1993 if (msleep(&needsbuffer, &nblock, 1994 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1995 mtx_unlock(&nblock); 1996 return (NULL); 1997 } 1998 } 1999 mtx_unlock(&nblock); 2000 } else { 2001 /* 2002 * We finally have a valid bp. We aren't quite out of the 2003 * woods, we still have to reserve kva space. In order 2004 * to keep fragmentation sane we only allocate kva in 2005 * BKVASIZE chunks. 2006 */ 2007 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2008 2009 if (maxsize != bp->b_kvasize) { 2010 vm_offset_t addr = 0; 2011 2012 bfreekva(bp); 2013 2014 if (vm_map_findspace(buffer_map, 2015 vm_map_min(buffer_map), maxsize, &addr)) { 2016 /* 2017 * Uh oh. Buffer map is to fragmented. We 2018 * must defragment the map. 2019 */ 2020 atomic_add_int(&bufdefragcnt, 1); 2021 defrag = 1; 2022 bp->b_flags |= B_INVAL; 2023 brelse(bp); 2024 goto restart; 2025 } 2026 if (addr) { 2027 vm_map_insert(buffer_map, NULL, 0, 2028 addr, addr + maxsize, 2029 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2030 2031 bp->b_kvabase = (caddr_t) addr; 2032 bp->b_kvasize = maxsize; 2033 atomic_add_int(&bufspace, bp->b_kvasize); 2034 atomic_add_int(&bufreusecnt, 1); 2035 } 2036 } 2037 bp->b_saveaddr = bp->b_kvabase; 2038 bp->b_data = bp->b_saveaddr; 2039 } 2040 return(bp); 2041} 2042 2043/* 2044 * buf_daemon: 2045 * 2046 * buffer flushing daemon. Buffers are normally flushed by the 2047 * update daemon but if it cannot keep up this process starts to 2048 * take the load in an attempt to prevent getnewbuf() from blocking. 2049 */ 2050 2051static struct kproc_desc buf_kp = { 2052 "bufdaemon", 2053 buf_daemon, 2054 &bufdaemonproc 2055}; 2056SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2057 2058static void 2059buf_daemon() 2060{ 2061 int s; 2062 2063 mtx_lock(&Giant); 2064 2065 /* 2066 * This process needs to be suspended prior to shutdown sync. 2067 */ 2068 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2069 SHUTDOWN_PRI_LAST); 2070 2071 /* 2072 * This process is allowed to take the buffer cache to the limit 2073 */ 2074 s = splbio(); 2075 mtx_lock(&bdlock); 2076 2077 for (;;) { 2078 bd_request = 0; 2079 mtx_unlock(&bdlock); 2080 2081 kthread_suspend_check(bufdaemonproc); 2082 2083 /* 2084 * Do the flush. Limit the amount of in-transit I/O we 2085 * allow to build up, otherwise we would completely saturate 2086 * the I/O system. Wakeup any waiting processes before we 2087 * normally would so they can run in parallel with our drain. 2088 */ 2089 while (numdirtybuffers > lodirtybuffers) { 2090 if (flushbufqueues(0) == 0) { 2091 /* 2092 * Could not find any buffers without rollback 2093 * dependencies, so just write the first one 2094 * in the hopes of eventually making progress. 2095 */ 2096 flushbufqueues(1); 2097 break; 2098 } 2099 waitrunningbufspace(); 2100 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2101 } 2102 2103 /* 2104 * Only clear bd_request if we have reached our low water 2105 * mark. The buf_daemon normally waits 1 second and 2106 * then incrementally flushes any dirty buffers that have 2107 * built up, within reason. 2108 * 2109 * If we were unable to hit our low water mark and couldn't 2110 * find any flushable buffers, we sleep half a second. 2111 * Otherwise we loop immediately. 2112 */ 2113 mtx_lock(&bdlock); 2114 if (numdirtybuffers <= lodirtybuffers) { 2115 /* 2116 * We reached our low water mark, reset the 2117 * request and sleep until we are needed again. 2118 * The sleep is just so the suspend code works. 2119 */ 2120 bd_request = 0; 2121 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2122 } else { 2123 /* 2124 * We couldn't find any flushable dirty buffers but 2125 * still have too many dirty buffers, we 2126 * have to sleep and try again. (rare) 2127 */ 2128 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2129 } 2130 } 2131} 2132 2133/* 2134 * flushbufqueues: 2135 * 2136 * Try to flush a buffer in the dirty queue. We must be careful to 2137 * free up B_INVAL buffers instead of write them, which NFS is 2138 * particularly sensitive to. 2139 */ 2140int flushwithdeps = 0; 2141SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2142 0, "Number of buffers flushed with dependecies that require rollbacks"); 2143static int 2144flushbufqueues(int flushdeps) 2145{ 2146 struct thread *td = curthread; 2147 struct vnode *vp; 2148 struct mount *mp; 2149 struct buf *bp; 2150 int hasdeps; 2151 2152 mtx_lock(&bqlock); 2153 TAILQ_FOREACH(bp, &bufqueues[QUEUE_DIRTY], b_freelist) { 2154 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2155 continue; 2156 KASSERT((bp->b_flags & B_DELWRI), 2157 ("unexpected clean buffer %p", bp)); 2158 VI_LOCK(bp->b_vp); 2159 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 2160 VI_UNLOCK(bp->b_vp); 2161 BUF_UNLOCK(bp); 2162 continue; 2163 } 2164 VI_UNLOCK(bp->b_vp); 2165 if (bp->b_flags & B_INVAL) { 2166 bremfreel(bp); 2167 mtx_unlock(&bqlock); 2168 brelse(bp); 2169 return (1); 2170 } 2171 2172 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) { 2173 if (flushdeps == 0) { 2174 BUF_UNLOCK(bp); 2175 continue; 2176 } 2177 hasdeps = 1; 2178 } else 2179 hasdeps = 0; 2180 /* 2181 * We must hold the lock on a vnode before writing 2182 * one of its buffers. Otherwise we may confuse, or 2183 * in the case of a snapshot vnode, deadlock the 2184 * system. 2185 * 2186 * The lock order here is the reverse of the normal 2187 * of vnode followed by buf lock. This is ok because 2188 * the NOWAIT will prevent deadlock. 2189 */ 2190 vp = bp->b_vp; 2191 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2192 BUF_UNLOCK(bp); 2193 continue; 2194 } 2195 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2196 mtx_unlock(&bqlock); 2197 vfs_bio_awrite(bp); 2198 vn_finished_write(mp); 2199 VOP_UNLOCK(vp, 0, td); 2200 flushwithdeps += hasdeps; 2201 return (1); 2202 } 2203 vn_finished_write(mp); 2204 BUF_UNLOCK(bp); 2205 } 2206 mtx_unlock(&bqlock); 2207 return (0); 2208} 2209 2210/* 2211 * Check to see if a block is currently memory resident. 2212 */ 2213struct buf * 2214incore(struct vnode * vp, daddr_t blkno) 2215{ 2216 struct buf *bp; 2217 2218 int s = splbio(); 2219 VI_LOCK(vp); 2220 bp = gbincore(vp, blkno); 2221 VI_UNLOCK(vp); 2222 splx(s); 2223 return (bp); 2224} 2225 2226/* 2227 * Returns true if no I/O is needed to access the 2228 * associated VM object. This is like incore except 2229 * it also hunts around in the VM system for the data. 2230 */ 2231 2232int 2233inmem(struct vnode * vp, daddr_t blkno) 2234{ 2235 vm_object_t obj; 2236 vm_offset_t toff, tinc, size; 2237 vm_page_t m; 2238 vm_ooffset_t off; 2239 2240 GIANT_REQUIRED; 2241 ASSERT_VOP_LOCKED(vp, "inmem"); 2242 2243 if (incore(vp, blkno)) 2244 return 1; 2245 if (vp->v_mount == NULL) 2246 return 0; 2247 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_vflag & VV_OBJBUF) == 0) 2248 return 0; 2249 2250 size = PAGE_SIZE; 2251 if (size > vp->v_mount->mnt_stat.f_iosize) 2252 size = vp->v_mount->mnt_stat.f_iosize; 2253 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2254 2255 VM_OBJECT_LOCK(obj); 2256 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2257 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2258 if (!m) 2259 goto notinmem; 2260 tinc = size; 2261 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2262 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2263 if (vm_page_is_valid(m, 2264 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2265 goto notinmem; 2266 } 2267 VM_OBJECT_UNLOCK(obj); 2268 return 1; 2269 2270notinmem: 2271 VM_OBJECT_UNLOCK(obj); 2272 return (0); 2273} 2274 2275/* 2276 * vfs_setdirty: 2277 * 2278 * Sets the dirty range for a buffer based on the status of the dirty 2279 * bits in the pages comprising the buffer. 2280 * 2281 * The range is limited to the size of the buffer. 2282 * 2283 * This routine is primarily used by NFS, but is generalized for the 2284 * B_VMIO case. 2285 */ 2286static void 2287vfs_setdirty(struct buf *bp) 2288{ 2289 int i; 2290 vm_object_t object; 2291 2292 GIANT_REQUIRED; 2293 /* 2294 * Degenerate case - empty buffer 2295 */ 2296 2297 if (bp->b_bufsize == 0) 2298 return; 2299 2300 /* 2301 * We qualify the scan for modified pages on whether the 2302 * object has been flushed yet. The OBJ_WRITEABLE flag 2303 * is not cleared simply by protecting pages off. 2304 */ 2305 2306 if ((bp->b_flags & B_VMIO) == 0) 2307 return; 2308 2309 object = bp->b_pages[0]->object; 2310 VM_OBJECT_LOCK(object); 2311 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2312 printf("Warning: object %p writeable but not mightbedirty\n", object); 2313 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2314 printf("Warning: object %p mightbedirty but not writeable\n", object); 2315 2316 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2317 vm_offset_t boffset; 2318 vm_offset_t eoffset; 2319 2320 vm_page_lock_queues(); 2321 /* 2322 * test the pages to see if they have been modified directly 2323 * by users through the VM system. 2324 */ 2325 for (i = 0; i < bp->b_npages; i++) 2326 vm_page_test_dirty(bp->b_pages[i]); 2327 2328 /* 2329 * Calculate the encompassing dirty range, boffset and eoffset, 2330 * (eoffset - boffset) bytes. 2331 */ 2332 2333 for (i = 0; i < bp->b_npages; i++) { 2334 if (bp->b_pages[i]->dirty) 2335 break; 2336 } 2337 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2338 2339 for (i = bp->b_npages - 1; i >= 0; --i) { 2340 if (bp->b_pages[i]->dirty) { 2341 break; 2342 } 2343 } 2344 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2345 2346 vm_page_unlock_queues(); 2347 /* 2348 * Fit it to the buffer. 2349 */ 2350 2351 if (eoffset > bp->b_bcount) 2352 eoffset = bp->b_bcount; 2353 2354 /* 2355 * If we have a good dirty range, merge with the existing 2356 * dirty range. 2357 */ 2358 2359 if (boffset < eoffset) { 2360 if (bp->b_dirtyoff > boffset) 2361 bp->b_dirtyoff = boffset; 2362 if (bp->b_dirtyend < eoffset) 2363 bp->b_dirtyend = eoffset; 2364 } 2365 } 2366 VM_OBJECT_UNLOCK(object); 2367} 2368 2369/* 2370 * getblk: 2371 * 2372 * Get a block given a specified block and offset into a file/device. 2373 * The buffers B_DONE bit will be cleared on return, making it almost 2374 * ready for an I/O initiation. B_INVAL may or may not be set on 2375 * return. The caller should clear B_INVAL prior to initiating a 2376 * READ. 2377 * 2378 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2379 * an existing buffer. 2380 * 2381 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2382 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2383 * and then cleared based on the backing VM. If the previous buffer is 2384 * non-0-sized but invalid, B_CACHE will be cleared. 2385 * 2386 * If getblk() must create a new buffer, the new buffer is returned with 2387 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2388 * case it is returned with B_INVAL clear and B_CACHE set based on the 2389 * backing VM. 2390 * 2391 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2392 * B_CACHE bit is clear. 2393 * 2394 * What this means, basically, is that the caller should use B_CACHE to 2395 * determine whether the buffer is fully valid or not and should clear 2396 * B_INVAL prior to issuing a read. If the caller intends to validate 2397 * the buffer by loading its data area with something, the caller needs 2398 * to clear B_INVAL. If the caller does this without issuing an I/O, 2399 * the caller should set B_CACHE ( as an optimization ), else the caller 2400 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2401 * a write attempt or if it was a successfull read. If the caller 2402 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2403 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2404 */ 2405struct buf * 2406getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2407 int flags) 2408{ 2409 struct buf *bp; 2410 int s; 2411 int error; 2412 ASSERT_VOP_LOCKED(vp, "getblk"); 2413 2414 if (size > MAXBSIZE) 2415 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2416 2417 s = splbio(); 2418loop: 2419 /* 2420 * Block if we are low on buffers. Certain processes are allowed 2421 * to completely exhaust the buffer cache. 2422 * 2423 * If this check ever becomes a bottleneck it may be better to 2424 * move it into the else, when gbincore() fails. At the moment 2425 * it isn't a problem. 2426 * 2427 * XXX remove if 0 sections (clean this up after its proven) 2428 */ 2429 if (numfreebuffers == 0) { 2430 if (curthread == PCPU_GET(idlethread)) 2431 return NULL; 2432 mtx_lock(&nblock); 2433 needsbuffer |= VFS_BIO_NEED_ANY; 2434 mtx_unlock(&nblock); 2435 } 2436 2437 VI_LOCK(vp); 2438 if ((bp = gbincore(vp, blkno))) { 2439 int lockflags; 2440 /* 2441 * Buffer is in-core. If the buffer is not busy, it must 2442 * be on a queue. 2443 */ 2444 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2445 2446 if (flags & GB_LOCK_NOWAIT) 2447 lockflags |= LK_NOWAIT; 2448 2449 error = BUF_TIMELOCK(bp, lockflags, 2450 VI_MTX(vp), "getblk", slpflag, slptimeo); 2451 2452 /* 2453 * If we slept and got the lock we have to restart in case 2454 * the buffer changed identities. 2455 */ 2456 if (error == ENOLCK) 2457 goto loop; 2458 /* We timed out or were interrupted. */ 2459 else if (error) 2460 return (NULL); 2461 2462 /* 2463 * The buffer is locked. B_CACHE is cleared if the buffer is 2464 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2465 * and for a VMIO buffer B_CACHE is adjusted according to the 2466 * backing VM cache. 2467 */ 2468 if (bp->b_flags & B_INVAL) 2469 bp->b_flags &= ~B_CACHE; 2470 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2471 bp->b_flags |= B_CACHE; 2472 bremfree(bp); 2473 2474 /* 2475 * check for size inconsistancies for non-VMIO case. 2476 */ 2477 2478 if (bp->b_bcount != size) { 2479 if ((bp->b_flags & B_VMIO) == 0 || 2480 (size > bp->b_kvasize)) { 2481 if (bp->b_flags & B_DELWRI) { 2482 bp->b_flags |= B_NOCACHE; 2483 bwrite(bp); 2484 } else { 2485 if ((bp->b_flags & B_VMIO) && 2486 (LIST_FIRST(&bp->b_dep) == NULL)) { 2487 bp->b_flags |= B_RELBUF; 2488 brelse(bp); 2489 } else { 2490 bp->b_flags |= B_NOCACHE; 2491 bwrite(bp); 2492 } 2493 } 2494 goto loop; 2495 } 2496 } 2497 2498 /* 2499 * If the size is inconsistant in the VMIO case, we can resize 2500 * the buffer. This might lead to B_CACHE getting set or 2501 * cleared. If the size has not changed, B_CACHE remains 2502 * unchanged from its previous state. 2503 */ 2504 2505 if (bp->b_bcount != size) 2506 allocbuf(bp, size); 2507 2508 KASSERT(bp->b_offset != NOOFFSET, 2509 ("getblk: no buffer offset")); 2510 2511 /* 2512 * A buffer with B_DELWRI set and B_CACHE clear must 2513 * be committed before we can return the buffer in 2514 * order to prevent the caller from issuing a read 2515 * ( due to B_CACHE not being set ) and overwriting 2516 * it. 2517 * 2518 * Most callers, including NFS and FFS, need this to 2519 * operate properly either because they assume they 2520 * can issue a read if B_CACHE is not set, or because 2521 * ( for example ) an uncached B_DELWRI might loop due 2522 * to softupdates re-dirtying the buffer. In the latter 2523 * case, B_CACHE is set after the first write completes, 2524 * preventing further loops. 2525 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2526 * above while extending the buffer, we cannot allow the 2527 * buffer to remain with B_CACHE set after the write 2528 * completes or it will represent a corrupt state. To 2529 * deal with this we set B_NOCACHE to scrap the buffer 2530 * after the write. 2531 * 2532 * We might be able to do something fancy, like setting 2533 * B_CACHE in bwrite() except if B_DELWRI is already set, 2534 * so the below call doesn't set B_CACHE, but that gets real 2535 * confusing. This is much easier. 2536 */ 2537 2538 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2539 bp->b_flags |= B_NOCACHE; 2540 bwrite(bp); 2541 goto loop; 2542 } 2543 2544 splx(s); 2545 bp->b_flags &= ~B_DONE; 2546 } else { 2547 int bsize, maxsize, vmio; 2548 off_t offset; 2549 2550 /* 2551 * Buffer is not in-core, create new buffer. The buffer 2552 * returned by getnewbuf() is locked. Note that the returned 2553 * buffer is also considered valid (not marked B_INVAL). 2554 */ 2555 VI_UNLOCK(vp); 2556 /* 2557 * If the user does not want us to create the buffer, bail out 2558 * here. 2559 */ 2560 if (flags & GB_NOCREAT) { 2561 splx(s); 2562 return NULL; 2563 } 2564 if (vn_isdisk(vp, NULL)) 2565 bsize = DEV_BSIZE; 2566 else if (vp->v_mountedhere) 2567 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2568 else if (vp->v_mount) 2569 bsize = vp->v_mount->mnt_stat.f_iosize; 2570 else 2571 bsize = size; 2572 2573 offset = blkno * bsize; 2574 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && 2575 (vp->v_vflag & VV_OBJBUF); 2576 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2577 maxsize = imax(maxsize, bsize); 2578 2579 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2580 if (slpflag || slptimeo) { 2581 splx(s); 2582 return NULL; 2583 } 2584 goto loop; 2585 } 2586 2587 /* 2588 * This code is used to make sure that a buffer is not 2589 * created while the getnewbuf routine is blocked. 2590 * This can be a problem whether the vnode is locked or not. 2591 * If the buffer is created out from under us, we have to 2592 * throw away the one we just created. There is now window 2593 * race because we are safely running at splbio() from the 2594 * point of the duplicate buffer creation through to here, 2595 * and we've locked the buffer. 2596 * 2597 * Note: this must occur before we associate the buffer 2598 * with the vp especially considering limitations in 2599 * the splay tree implementation when dealing with duplicate 2600 * lblkno's. 2601 */ 2602 VI_LOCK(vp); 2603 if (gbincore(vp, blkno)) { 2604 VI_UNLOCK(vp); 2605 bp->b_flags |= B_INVAL; 2606 brelse(bp); 2607 goto loop; 2608 } 2609 2610 /* 2611 * Insert the buffer into the hash, so that it can 2612 * be found by incore. 2613 */ 2614 bp->b_blkno = bp->b_lblkno = blkno; 2615 bp->b_offset = offset; 2616 2617 bgetvp(vp, bp); 2618 VI_UNLOCK(vp); 2619 2620 /* 2621 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2622 * buffer size starts out as 0, B_CACHE will be set by 2623 * allocbuf() for the VMIO case prior to it testing the 2624 * backing store for validity. 2625 */ 2626 2627 if (vmio) { 2628 bp->b_flags |= B_VMIO; 2629#if defined(VFS_BIO_DEBUG) 2630 if (vn_canvmio(vp) != TRUE) 2631 printf("getblk: VMIO on vnode type %d\n", 2632 vp->v_type); 2633#endif 2634 VOP_GETVOBJECT(vp, &bp->b_object); 2635 } else { 2636 bp->b_flags &= ~B_VMIO; 2637 bp->b_object = NULL; 2638 } 2639 2640 allocbuf(bp, size); 2641 2642 splx(s); 2643 bp->b_flags &= ~B_DONE; 2644 } 2645 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2646 return (bp); 2647} 2648 2649/* 2650 * Get an empty, disassociated buffer of given size. The buffer is initially 2651 * set to B_INVAL. 2652 */ 2653struct buf * 2654geteblk(int size) 2655{ 2656 struct buf *bp; 2657 int s; 2658 int maxsize; 2659 2660 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2661 2662 s = splbio(); 2663 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2664 continue; 2665 splx(s); 2666 allocbuf(bp, size); 2667 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2668 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2669 return (bp); 2670} 2671 2672 2673/* 2674 * This code constitutes the buffer memory from either anonymous system 2675 * memory (in the case of non-VMIO operations) or from an associated 2676 * VM object (in the case of VMIO operations). This code is able to 2677 * resize a buffer up or down. 2678 * 2679 * Note that this code is tricky, and has many complications to resolve 2680 * deadlock or inconsistant data situations. Tread lightly!!! 2681 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2682 * the caller. Calling this code willy nilly can result in the loss of data. 2683 * 2684 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2685 * B_CACHE for the non-VMIO case. 2686 */ 2687 2688int 2689allocbuf(struct buf *bp, int size) 2690{ 2691 int newbsize, mbsize; 2692 int i; 2693 2694 GIANT_REQUIRED; 2695 2696 if (BUF_REFCNT(bp) == 0) 2697 panic("allocbuf: buffer not busy"); 2698 2699 if (bp->b_kvasize < size) 2700 panic("allocbuf: buffer too small"); 2701 2702 if ((bp->b_flags & B_VMIO) == 0) { 2703 caddr_t origbuf; 2704 int origbufsize; 2705 /* 2706 * Just get anonymous memory from the kernel. Don't 2707 * mess with B_CACHE. 2708 */ 2709 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2710 if (bp->b_flags & B_MALLOC) 2711 newbsize = mbsize; 2712 else 2713 newbsize = round_page(size); 2714 2715 if (newbsize < bp->b_bufsize) { 2716 /* 2717 * malloced buffers are not shrunk 2718 */ 2719 if (bp->b_flags & B_MALLOC) { 2720 if (newbsize) { 2721 bp->b_bcount = size; 2722 } else { 2723 free(bp->b_data, M_BIOBUF); 2724 if (bp->b_bufsize) { 2725 atomic_subtract_int( 2726 &bufmallocspace, 2727 bp->b_bufsize); 2728 bufspacewakeup(); 2729 bp->b_bufsize = 0; 2730 } 2731 bp->b_saveaddr = bp->b_kvabase; 2732 bp->b_data = bp->b_saveaddr; 2733 bp->b_bcount = 0; 2734 bp->b_flags &= ~B_MALLOC; 2735 } 2736 return 1; 2737 } 2738 vm_hold_free_pages( 2739 bp, 2740 (vm_offset_t) bp->b_data + newbsize, 2741 (vm_offset_t) bp->b_data + bp->b_bufsize); 2742 } else if (newbsize > bp->b_bufsize) { 2743 /* 2744 * We only use malloced memory on the first allocation. 2745 * and revert to page-allocated memory when the buffer 2746 * grows. 2747 */ 2748 /* 2749 * There is a potential smp race here that could lead 2750 * to bufmallocspace slightly passing the max. It 2751 * is probably extremely rare and not worth worrying 2752 * over. 2753 */ 2754 if ( (bufmallocspace < maxbufmallocspace) && 2755 (bp->b_bufsize == 0) && 2756 (mbsize <= PAGE_SIZE/2)) { 2757 2758 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2759 bp->b_bufsize = mbsize; 2760 bp->b_bcount = size; 2761 bp->b_flags |= B_MALLOC; 2762 atomic_add_int(&bufmallocspace, mbsize); 2763 return 1; 2764 } 2765 origbuf = NULL; 2766 origbufsize = 0; 2767 /* 2768 * If the buffer is growing on its other-than-first allocation, 2769 * then we revert to the page-allocation scheme. 2770 */ 2771 if (bp->b_flags & B_MALLOC) { 2772 origbuf = bp->b_data; 2773 origbufsize = bp->b_bufsize; 2774 bp->b_data = bp->b_kvabase; 2775 if (bp->b_bufsize) { 2776 atomic_subtract_int(&bufmallocspace, 2777 bp->b_bufsize); 2778 bufspacewakeup(); 2779 bp->b_bufsize = 0; 2780 } 2781 bp->b_flags &= ~B_MALLOC; 2782 newbsize = round_page(newbsize); 2783 } 2784 vm_hold_load_pages( 2785 bp, 2786 (vm_offset_t) bp->b_data + bp->b_bufsize, 2787 (vm_offset_t) bp->b_data + newbsize); 2788 if (origbuf) { 2789 bcopy(origbuf, bp->b_data, origbufsize); 2790 free(origbuf, M_BIOBUF); 2791 } 2792 } 2793 } else { 2794 int desiredpages; 2795 2796 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2797 desiredpages = (size == 0) ? 0 : 2798 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2799 2800 if (bp->b_flags & B_MALLOC) 2801 panic("allocbuf: VMIO buffer can't be malloced"); 2802 /* 2803 * Set B_CACHE initially if buffer is 0 length or will become 2804 * 0-length. 2805 */ 2806 if (size == 0 || bp->b_bufsize == 0) 2807 bp->b_flags |= B_CACHE; 2808 2809 if (newbsize < bp->b_bufsize) { 2810 /* 2811 * DEV_BSIZE aligned new buffer size is less then the 2812 * DEV_BSIZE aligned existing buffer size. Figure out 2813 * if we have to remove any pages. 2814 */ 2815 if (desiredpages < bp->b_npages) { 2816 vm_page_t m; 2817 2818 vm_page_lock_queues(); 2819 for (i = desiredpages; i < bp->b_npages; i++) { 2820 /* 2821 * the page is not freed here -- it 2822 * is the responsibility of 2823 * vnode_pager_setsize 2824 */ 2825 m = bp->b_pages[i]; 2826 KASSERT(m != bogus_page, 2827 ("allocbuf: bogus page found")); 2828 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2829 vm_page_lock_queues(); 2830 2831 bp->b_pages[i] = NULL; 2832 vm_page_unwire(m, 0); 2833 } 2834 vm_page_unlock_queues(); 2835 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2836 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2837 bp->b_npages = desiredpages; 2838 } 2839 } else if (size > bp->b_bcount) { 2840 /* 2841 * We are growing the buffer, possibly in a 2842 * byte-granular fashion. 2843 */ 2844 struct vnode *vp; 2845 vm_object_t obj; 2846 vm_offset_t toff; 2847 vm_offset_t tinc; 2848 2849 /* 2850 * Step 1, bring in the VM pages from the object, 2851 * allocating them if necessary. We must clear 2852 * B_CACHE if these pages are not valid for the 2853 * range covered by the buffer. 2854 */ 2855 2856 vp = bp->b_vp; 2857 obj = bp->b_object; 2858 2859 VM_OBJECT_LOCK(obj); 2860 while (bp->b_npages < desiredpages) { 2861 vm_page_t m; 2862 vm_pindex_t pi; 2863 2864 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2865 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2866 /* 2867 * note: must allocate system pages 2868 * since blocking here could intefere 2869 * with paging I/O, no matter which 2870 * process we are. 2871 */ 2872 m = vm_page_alloc(obj, pi, 2873 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 2874 if (m == NULL) { 2875 atomic_add_int(&vm_pageout_deficit, 2876 desiredpages - bp->b_npages); 2877 VM_OBJECT_UNLOCK(obj); 2878 VM_WAIT; 2879 VM_OBJECT_LOCK(obj); 2880 } else { 2881 vm_page_lock_queues(); 2882 vm_page_wakeup(m); 2883 vm_page_unlock_queues(); 2884 bp->b_flags &= ~B_CACHE; 2885 bp->b_pages[bp->b_npages] = m; 2886 ++bp->b_npages; 2887 } 2888 continue; 2889 } 2890 2891 /* 2892 * We found a page. If we have to sleep on it, 2893 * retry because it might have gotten freed out 2894 * from under us. 2895 * 2896 * We can only test PG_BUSY here. Blocking on 2897 * m->busy might lead to a deadlock: 2898 * 2899 * vm_fault->getpages->cluster_read->allocbuf 2900 * 2901 */ 2902 vm_page_lock_queues(); 2903 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2904 continue; 2905 2906 /* 2907 * We have a good page. Should we wakeup the 2908 * page daemon? 2909 */ 2910 if ((curproc != pageproc) && 2911 ((m->queue - m->pc) == PQ_CACHE) && 2912 ((cnt.v_free_count + cnt.v_cache_count) < 2913 (cnt.v_free_min + cnt.v_cache_min))) { 2914 pagedaemon_wakeup(); 2915 } 2916 vm_page_wire(m); 2917 vm_page_unlock_queues(); 2918 bp->b_pages[bp->b_npages] = m; 2919 ++bp->b_npages; 2920 } 2921 2922 /* 2923 * Step 2. We've loaded the pages into the buffer, 2924 * we have to figure out if we can still have B_CACHE 2925 * set. Note that B_CACHE is set according to the 2926 * byte-granular range ( bcount and size ), new the 2927 * aligned range ( newbsize ). 2928 * 2929 * The VM test is against m->valid, which is DEV_BSIZE 2930 * aligned. Needless to say, the validity of the data 2931 * needs to also be DEV_BSIZE aligned. Note that this 2932 * fails with NFS if the server or some other client 2933 * extends the file's EOF. If our buffer is resized, 2934 * B_CACHE may remain set! XXX 2935 */ 2936 2937 toff = bp->b_bcount; 2938 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2939 2940 while ((bp->b_flags & B_CACHE) && toff < size) { 2941 vm_pindex_t pi; 2942 2943 if (tinc > (size - toff)) 2944 tinc = size - toff; 2945 2946 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2947 PAGE_SHIFT; 2948 2949 vfs_buf_test_cache( 2950 bp, 2951 bp->b_offset, 2952 toff, 2953 tinc, 2954 bp->b_pages[pi] 2955 ); 2956 toff += tinc; 2957 tinc = PAGE_SIZE; 2958 } 2959 VM_OBJECT_UNLOCK(obj); 2960 2961 /* 2962 * Step 3, fixup the KVM pmap. Remember that 2963 * bp->b_data is relative to bp->b_offset, but 2964 * bp->b_offset may be offset into the first page. 2965 */ 2966 2967 bp->b_data = (caddr_t) 2968 trunc_page((vm_offset_t)bp->b_data); 2969 pmap_qenter( 2970 (vm_offset_t)bp->b_data, 2971 bp->b_pages, 2972 bp->b_npages 2973 ); 2974 2975 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2976 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2977 } 2978 } 2979 if (newbsize < bp->b_bufsize) 2980 bufspacewakeup(); 2981 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2982 bp->b_bcount = size; /* requested buffer size */ 2983 return 1; 2984} 2985 2986void 2987biodone(struct bio *bp) 2988{ 2989 mtx_lock(&bdonelock); 2990 bp->bio_flags |= BIO_DONE; 2991 if (bp->bio_done == NULL) 2992 wakeup(bp); 2993 mtx_unlock(&bdonelock); 2994 if (bp->bio_done != NULL) 2995 bp->bio_done(bp); 2996} 2997 2998/* 2999 * Wait for a BIO to finish. 3000 * 3001 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3002 * case is not yet clear. 3003 */ 3004int 3005biowait(struct bio *bp, const char *wchan) 3006{ 3007 3008 mtx_lock(&bdonelock); 3009 while ((bp->bio_flags & BIO_DONE) == 0) 3010 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3011 mtx_unlock(&bdonelock); 3012 if (bp->bio_error != 0) 3013 return (bp->bio_error); 3014 if (!(bp->bio_flags & BIO_ERROR)) 3015 return (0); 3016 return (EIO); 3017} 3018 3019void 3020biofinish(struct bio *bp, struct devstat *stat, int error) 3021{ 3022 3023 if (error) { 3024 bp->bio_error = error; 3025 bp->bio_flags |= BIO_ERROR; 3026 } 3027 if (stat != NULL) 3028 devstat_end_transaction_bio(stat, bp); 3029 biodone(bp); 3030} 3031 3032/* 3033 * bufwait: 3034 * 3035 * Wait for buffer I/O completion, returning error status. The buffer 3036 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3037 * error and cleared. 3038 */ 3039int 3040bufwait(register struct buf * bp) 3041{ 3042 int s; 3043 3044 s = splbio(); 3045 if (bp->b_iocmd == BIO_READ) 3046 bwait(bp, PRIBIO, "biord"); 3047 else 3048 bwait(bp, PRIBIO, "biowr"); 3049 splx(s); 3050 if (bp->b_flags & B_EINTR) { 3051 bp->b_flags &= ~B_EINTR; 3052 return (EINTR); 3053 } 3054 if (bp->b_ioflags & BIO_ERROR) { 3055 return (bp->b_error ? bp->b_error : EIO); 3056 } else { 3057 return (0); 3058 } 3059} 3060 3061 /* 3062 * Call back function from struct bio back up to struct buf. 3063 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY(). 3064 */ 3065static void 3066bufdonebio(struct bio *bp) 3067{ 3068 3069 /* Device drivers may or may not hold giant, hold it here. */ 3070 mtx_lock(&Giant); 3071 bufdone(bp->bio_caller2); 3072 mtx_unlock(&Giant); 3073} 3074 3075void 3076dev_strategy(struct buf *bp) 3077{ 3078 struct cdevsw *csw; 3079 3080 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3081 panic("b_iocmd botch"); 3082 bp->b_io.bio_done = bufdonebio; 3083 bp->b_io.bio_caller2 = bp; 3084 csw = devsw(bp->b_io.bio_dev); 3085 KASSERT(bp->b_io.bio_dev->si_refcount > 0, 3086 ("dev_strategy on un-referenced struct cdev *(%s)", 3087 devtoname(bp->b_io.bio_dev))); 3088 cdevsw_ref(csw); 3089 (*devsw(bp->b_io.bio_dev)->d_strategy)(&bp->b_io); 3090 cdevsw_rel(csw); 3091} 3092 3093/* 3094 * bufdone: 3095 * 3096 * Finish I/O on a buffer, optionally calling a completion function. 3097 * This is usually called from an interrupt so process blocking is 3098 * not allowed. 3099 * 3100 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3101 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3102 * assuming B_INVAL is clear. 3103 * 3104 * For the VMIO case, we set B_CACHE if the op was a read and no 3105 * read error occured, or if the op was a write. B_CACHE is never 3106 * set if the buffer is invalid or otherwise uncacheable. 3107 * 3108 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3109 * initiator to leave B_INVAL set to brelse the buffer out of existance 3110 * in the biodone routine. 3111 */ 3112void 3113bufdone(struct buf *bp) 3114{ 3115 int s; 3116 void (*biodone)(struct buf *); 3117 3118 3119 s = splbio(); 3120 3121 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 3122 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3123 3124 bp->b_flags |= B_DONE; 3125 runningbufwakeup(bp); 3126 3127 if (bp->b_iocmd == BIO_DELETE) { 3128 brelse(bp); 3129 splx(s); 3130 return; 3131 } 3132 3133 if (bp->b_iocmd == BIO_WRITE) { 3134 vwakeup(bp); 3135 } 3136 3137 /* call optional completion function if requested */ 3138 if (bp->b_iodone != NULL) { 3139 biodone = bp->b_iodone; 3140 bp->b_iodone = NULL; 3141 (*biodone) (bp); 3142 splx(s); 3143 return; 3144 } 3145 if (LIST_FIRST(&bp->b_dep) != NULL) 3146 buf_complete(bp); 3147 3148 if (bp->b_flags & B_VMIO) { 3149 int i; 3150 vm_ooffset_t foff; 3151 vm_page_t m; 3152 vm_object_t obj; 3153 int iosize; 3154 struct vnode *vp = bp->b_vp; 3155 3156 obj = bp->b_object; 3157 3158#if defined(VFS_BIO_DEBUG) 3159 mp_fixme("usecount and vflag accessed without locks."); 3160 if (vp->v_usecount == 0) { 3161 panic("biodone: zero vnode ref count"); 3162 } 3163 3164 if ((vp->v_vflag & VV_OBJBUF) == 0) { 3165 panic("biodone: vnode is not setup for merged cache"); 3166 } 3167#endif 3168 3169 foff = bp->b_offset; 3170 KASSERT(bp->b_offset != NOOFFSET, 3171 ("biodone: no buffer offset")); 3172 3173 VM_OBJECT_LOCK(obj); 3174#if defined(VFS_BIO_DEBUG) 3175 if (obj->paging_in_progress < bp->b_npages) { 3176 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3177 obj->paging_in_progress, bp->b_npages); 3178 } 3179#endif 3180 3181 /* 3182 * Set B_CACHE if the op was a normal read and no error 3183 * occured. B_CACHE is set for writes in the b*write() 3184 * routines. 3185 */ 3186 iosize = bp->b_bcount - bp->b_resid; 3187 if (bp->b_iocmd == BIO_READ && 3188 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3189 !(bp->b_ioflags & BIO_ERROR)) { 3190 bp->b_flags |= B_CACHE; 3191 } 3192 vm_page_lock_queues(); 3193 for (i = 0; i < bp->b_npages; i++) { 3194 int bogusflag = 0; 3195 int resid; 3196 3197 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3198 if (resid > iosize) 3199 resid = iosize; 3200 3201 /* 3202 * cleanup bogus pages, restoring the originals 3203 */ 3204 m = bp->b_pages[i]; 3205 if (m == bogus_page) { 3206 bogusflag = 1; 3207 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3208 if (m == NULL) 3209 panic("biodone: page disappeared!"); 3210 bp->b_pages[i] = m; 3211 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3212 } 3213#if defined(VFS_BIO_DEBUG) 3214 if (OFF_TO_IDX(foff) != m->pindex) { 3215 printf( 3216"biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3217 (intmax_t)foff, (uintmax_t)m->pindex); 3218 } 3219#endif 3220 3221 /* 3222 * In the write case, the valid and clean bits are 3223 * already changed correctly ( see bdwrite() ), so we 3224 * only need to do this here in the read case. 3225 */ 3226 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3227 vfs_page_set_valid(bp, foff, i, m); 3228 } 3229 3230 /* 3231 * when debugging new filesystems or buffer I/O methods, this 3232 * is the most common error that pops up. if you see this, you 3233 * have not set the page busy flag correctly!!! 3234 */ 3235 if (m->busy == 0) { 3236 printf("biodone: page busy < 0, " 3237 "pindex: %d, foff: 0x(%x,%x), " 3238 "resid: %d, index: %d\n", 3239 (int) m->pindex, (int)(foff >> 32), 3240 (int) foff & 0xffffffff, resid, i); 3241 if (!vn_isdisk(vp, NULL)) 3242 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3243 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3244 (intmax_t) bp->b_lblkno, 3245 bp->b_flags, bp->b_npages); 3246 else 3247 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3248 (intmax_t) bp->b_lblkno, 3249 bp->b_flags, bp->b_npages); 3250 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3251 (u_long)m->valid, (u_long)m->dirty, 3252 m->wire_count); 3253 panic("biodone: page busy < 0\n"); 3254 } 3255 vm_page_io_finish(m); 3256 vm_object_pip_subtract(obj, 1); 3257 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3258 iosize -= resid; 3259 } 3260 vm_page_unlock_queues(); 3261 vm_object_pip_wakeupn(obj, 0); 3262 VM_OBJECT_UNLOCK(obj); 3263 } 3264 3265 /* 3266 * For asynchronous completions, release the buffer now. The brelse 3267 * will do a wakeup there if necessary - so no need to do a wakeup 3268 * here in the async case. The sync case always needs to do a wakeup. 3269 */ 3270 3271 if (bp->b_flags & B_ASYNC) { 3272 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3273 brelse(bp); 3274 else 3275 bqrelse(bp); 3276 } else { 3277 bdone(bp); 3278 } 3279 splx(s); 3280} 3281 3282/* 3283 * This routine is called in lieu of iodone in the case of 3284 * incomplete I/O. This keeps the busy status for pages 3285 * consistant. 3286 */ 3287void 3288vfs_unbusy_pages(struct buf * bp) 3289{ 3290 int i; 3291 3292 runningbufwakeup(bp); 3293 if (bp->b_flags & B_VMIO) { 3294 vm_object_t obj; 3295 3296 obj = bp->b_object; 3297 VM_OBJECT_LOCK(obj); 3298 vm_page_lock_queues(); 3299 for (i = 0; i < bp->b_npages; i++) { 3300 vm_page_t m = bp->b_pages[i]; 3301 3302 if (m == bogus_page) { 3303 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3304 if (!m) { 3305 panic("vfs_unbusy_pages: page missing\n"); 3306 } 3307 bp->b_pages[i] = m; 3308 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3309 } 3310 vm_object_pip_subtract(obj, 1); 3311 vm_page_io_finish(m); 3312 } 3313 vm_page_unlock_queues(); 3314 vm_object_pip_wakeupn(obj, 0); 3315 VM_OBJECT_UNLOCK(obj); 3316 } 3317} 3318 3319/* 3320 * vfs_page_set_valid: 3321 * 3322 * Set the valid bits in a page based on the supplied offset. The 3323 * range is restricted to the buffer's size. 3324 * 3325 * This routine is typically called after a read completes. 3326 */ 3327static void 3328vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3329{ 3330 vm_ooffset_t soff, eoff; 3331 3332 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3333 /* 3334 * Start and end offsets in buffer. eoff - soff may not cross a 3335 * page boundry or cross the end of the buffer. The end of the 3336 * buffer, in this case, is our file EOF, not the allocation size 3337 * of the buffer. 3338 */ 3339 soff = off; 3340 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3341 if (eoff > bp->b_offset + bp->b_bcount) 3342 eoff = bp->b_offset + bp->b_bcount; 3343 3344 /* 3345 * Set valid range. This is typically the entire buffer and thus the 3346 * entire page. 3347 */ 3348 if (eoff > soff) { 3349 vm_page_set_validclean( 3350 m, 3351 (vm_offset_t) (soff & PAGE_MASK), 3352 (vm_offset_t) (eoff - soff) 3353 ); 3354 } 3355} 3356 3357/* 3358 * This routine is called before a device strategy routine. 3359 * It is used to tell the VM system that paging I/O is in 3360 * progress, and treat the pages associated with the buffer 3361 * almost as being PG_BUSY. Also the object paging_in_progress 3362 * flag is handled to make sure that the object doesn't become 3363 * inconsistant. 3364 * 3365 * Since I/O has not been initiated yet, certain buffer flags 3366 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3367 * and should be ignored. 3368 */ 3369void 3370vfs_busy_pages(struct buf * bp, int clear_modify) 3371{ 3372 int i, bogus; 3373 3374 if (bp->b_flags & B_VMIO) { 3375 vm_object_t obj; 3376 vm_ooffset_t foff; 3377 3378 obj = bp->b_object; 3379 foff = bp->b_offset; 3380 KASSERT(bp->b_offset != NOOFFSET, 3381 ("vfs_busy_pages: no buffer offset")); 3382 vfs_setdirty(bp); 3383 VM_OBJECT_LOCK(obj); 3384retry: 3385 vm_page_lock_queues(); 3386 for (i = 0; i < bp->b_npages; i++) { 3387 vm_page_t m = bp->b_pages[i]; 3388 3389 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3390 goto retry; 3391 } 3392 bogus = 0; 3393 for (i = 0; i < bp->b_npages; i++) { 3394 vm_page_t m = bp->b_pages[i]; 3395 3396 if ((bp->b_flags & B_CLUSTER) == 0) { 3397 vm_object_pip_add(obj, 1); 3398 vm_page_io_start(m); 3399 } 3400 /* 3401 * When readying a buffer for a read ( i.e 3402 * clear_modify == 0 ), it is important to do 3403 * bogus_page replacement for valid pages in 3404 * partially instantiated buffers. Partially 3405 * instantiated buffers can, in turn, occur when 3406 * reconstituting a buffer from its VM backing store 3407 * base. We only have to do this if B_CACHE is 3408 * clear ( which causes the I/O to occur in the 3409 * first place ). The replacement prevents the read 3410 * I/O from overwriting potentially dirty VM-backed 3411 * pages. XXX bogus page replacement is, uh, bogus. 3412 * It may not work properly with small-block devices. 3413 * We need to find a better way. 3414 */ 3415 pmap_remove_all(m); 3416 if (clear_modify) 3417 vfs_page_set_valid(bp, foff, i, m); 3418 else if (m->valid == VM_PAGE_BITS_ALL && 3419 (bp->b_flags & B_CACHE) == 0) { 3420 bp->b_pages[i] = bogus_page; 3421 bogus++; 3422 } 3423 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3424 } 3425 vm_page_unlock_queues(); 3426 VM_OBJECT_UNLOCK(obj); 3427 if (bogus) 3428 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3429 } 3430} 3431 3432/* 3433 * Tell the VM system that the pages associated with this buffer 3434 * are clean. This is used for delayed writes where the data is 3435 * going to go to disk eventually without additional VM intevention. 3436 * 3437 * Note that while we only really need to clean through to b_bcount, we 3438 * just go ahead and clean through to b_bufsize. 3439 */ 3440static void 3441vfs_clean_pages(struct buf * bp) 3442{ 3443 int i; 3444 3445 if (bp->b_flags & B_VMIO) { 3446 vm_ooffset_t foff; 3447 3448 foff = bp->b_offset; 3449 KASSERT(bp->b_offset != NOOFFSET, 3450 ("vfs_clean_pages: no buffer offset")); 3451 VM_OBJECT_LOCK(bp->b_object); 3452 vm_page_lock_queues(); 3453 for (i = 0; i < bp->b_npages; i++) { 3454 vm_page_t m = bp->b_pages[i]; 3455 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3456 vm_ooffset_t eoff = noff; 3457 3458 if (eoff > bp->b_offset + bp->b_bufsize) 3459 eoff = bp->b_offset + bp->b_bufsize; 3460 vfs_page_set_valid(bp, foff, i, m); 3461 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3462 foff = noff; 3463 } 3464 vm_page_unlock_queues(); 3465 VM_OBJECT_UNLOCK(bp->b_object); 3466 } 3467} 3468 3469/* 3470 * vfs_bio_set_validclean: 3471 * 3472 * Set the range within the buffer to valid and clean. The range is 3473 * relative to the beginning of the buffer, b_offset. Note that b_offset 3474 * itself may be offset from the beginning of the first page. 3475 * 3476 */ 3477 3478void 3479vfs_bio_set_validclean(struct buf *bp, int base, int size) 3480{ 3481 if (bp->b_flags & B_VMIO) { 3482 int i; 3483 int n; 3484 3485 /* 3486 * Fixup base to be relative to beginning of first page. 3487 * Set initial n to be the maximum number of bytes in the 3488 * first page that can be validated. 3489 */ 3490 3491 base += (bp->b_offset & PAGE_MASK); 3492 n = PAGE_SIZE - (base & PAGE_MASK); 3493 3494 VM_OBJECT_LOCK(bp->b_object); 3495 vm_page_lock_queues(); 3496 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3497 vm_page_t m = bp->b_pages[i]; 3498 3499 if (n > size) 3500 n = size; 3501 3502 vm_page_set_validclean(m, base & PAGE_MASK, n); 3503 base += n; 3504 size -= n; 3505 n = PAGE_SIZE; 3506 } 3507 vm_page_unlock_queues(); 3508 VM_OBJECT_UNLOCK(bp->b_object); 3509 } 3510} 3511 3512/* 3513 * vfs_bio_clrbuf: 3514 * 3515 * clear a buffer. This routine essentially fakes an I/O, so we need 3516 * to clear BIO_ERROR and B_INVAL. 3517 * 3518 * Note that while we only theoretically need to clear through b_bcount, 3519 * we go ahead and clear through b_bufsize. 3520 */ 3521 3522void 3523vfs_bio_clrbuf(struct buf *bp) 3524{ 3525 int i, j, mask = 0; 3526 caddr_t sa, ea; 3527 3528 GIANT_REQUIRED; 3529 3530 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3531 bp->b_flags &= ~B_INVAL; 3532 bp->b_ioflags &= ~BIO_ERROR; 3533 VM_OBJECT_LOCK(bp->b_object); 3534 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3535 (bp->b_offset & PAGE_MASK) == 0) { 3536 if (bp->b_pages[0] == bogus_page) 3537 goto unlock; 3538 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3539 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3540 if ((bp->b_pages[0]->valid & mask) == mask) 3541 goto unlock; 3542 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3543 ((bp->b_pages[0]->valid & mask) == 0)) { 3544 bzero(bp->b_data, bp->b_bufsize); 3545 bp->b_pages[0]->valid |= mask; 3546 goto unlock; 3547 } 3548 } 3549 ea = sa = bp->b_data; 3550 for(i=0;i<bp->b_npages;i++,sa=ea) { 3551 if (bp->b_pages[i] == bogus_page) 3552 continue; 3553 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3554 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3555 ea = (caddr_t)(vm_offset_t)ulmin( 3556 (u_long)(vm_offset_t)ea, 3557 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3558 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3559 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3560 if ((bp->b_pages[i]->valid & mask) == mask) 3561 continue; 3562 if ((bp->b_pages[i]->valid & mask) == 0) { 3563 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3564 bzero(sa, ea - sa); 3565 } 3566 } else { 3567 for (; sa < ea; sa += DEV_BSIZE, j++) { 3568 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3569 (bp->b_pages[i]->valid & (1<<j)) == 0) 3570 bzero(sa, DEV_BSIZE); 3571 } 3572 } 3573 bp->b_pages[i]->valid |= mask; 3574 } 3575unlock: 3576 VM_OBJECT_UNLOCK(bp->b_object); 3577 bp->b_resid = 0; 3578 } else { 3579 clrbuf(bp); 3580 } 3581} 3582 3583/* 3584 * vm_hold_load_pages and vm_hold_free_pages get pages into 3585 * a buffers address space. The pages are anonymous and are 3586 * not associated with a file object. 3587 */ 3588static void 3589vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3590{ 3591 vm_offset_t pg; 3592 vm_page_t p; 3593 int index; 3594 3595 to = round_page(to); 3596 from = round_page(from); 3597 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3598 3599 VM_OBJECT_LOCK(kernel_object); 3600 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3601tryagain: 3602 /* 3603 * note: must allocate system pages since blocking here 3604 * could intefere with paging I/O, no matter which 3605 * process we are. 3606 */ 3607 p = vm_page_alloc(kernel_object, 3608 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3609 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3610 if (!p) { 3611 atomic_add_int(&vm_pageout_deficit, 3612 (to - pg) >> PAGE_SHIFT); 3613 VM_OBJECT_UNLOCK(kernel_object); 3614 VM_WAIT; 3615 VM_OBJECT_LOCK(kernel_object); 3616 goto tryagain; 3617 } 3618 p->valid = VM_PAGE_BITS_ALL; 3619 pmap_qenter(pg, &p, 1); 3620 bp->b_pages[index] = p; 3621 vm_page_lock_queues(); 3622 vm_page_wakeup(p); 3623 vm_page_unlock_queues(); 3624 } 3625 VM_OBJECT_UNLOCK(kernel_object); 3626 bp->b_npages = index; 3627} 3628 3629/* Return pages associated with this buf to the vm system */ 3630static void 3631vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3632{ 3633 vm_offset_t pg; 3634 vm_page_t p; 3635 int index, newnpages; 3636 3637 GIANT_REQUIRED; 3638 3639 from = round_page(from); 3640 to = round_page(to); 3641 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3642 3643 VM_OBJECT_LOCK(kernel_object); 3644 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3645 p = bp->b_pages[index]; 3646 if (p && (index < bp->b_npages)) { 3647 if (p->busy) { 3648 printf( 3649 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3650 (intmax_t)bp->b_blkno, 3651 (intmax_t)bp->b_lblkno); 3652 } 3653 bp->b_pages[index] = NULL; 3654 pmap_qremove(pg, 1); 3655 vm_page_lock_queues(); 3656 vm_page_busy(p); 3657 vm_page_unwire(p, 0); 3658 vm_page_free(p); 3659 vm_page_unlock_queues(); 3660 } 3661 } 3662 VM_OBJECT_UNLOCK(kernel_object); 3663 bp->b_npages = newnpages; 3664} 3665 3666/* 3667 * Map an IO request into kernel virtual address space. 3668 * 3669 * All requests are (re)mapped into kernel VA space. 3670 * Notice that we use b_bufsize for the size of the buffer 3671 * to be mapped. b_bcount might be modified by the driver. 3672 * 3673 * Note that even if the caller determines that the address space should 3674 * be valid, a race or a smaller-file mapped into a larger space may 3675 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3676 * check the return value. 3677 */ 3678int 3679vmapbuf(struct buf *bp) 3680{ 3681 caddr_t addr, kva; 3682 vm_prot_t prot; 3683 int pidx, i; 3684 struct vm_page *m; 3685 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3686 3687 GIANT_REQUIRED; 3688 3689 if (bp->b_bufsize < 0) 3690 return (-1); 3691 prot = (bp->b_iocmd == BIO_READ) ? VM_PROT_READ | VM_PROT_WRITE : 3692 VM_PROT_READ; 3693 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3694 addr < bp->b_data + bp->b_bufsize; 3695 addr += PAGE_SIZE, pidx++) { 3696 /* 3697 * Do the vm_fault if needed; do the copy-on-write thing 3698 * when reading stuff off device into memory. 3699 * 3700 * NOTE! Must use pmap_extract() because addr may be in 3701 * the userland address space, and kextract is only guarenteed 3702 * to work for the kernland address space (see: sparc64 port). 3703 */ 3704retry: 3705 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3706 prot) < 0) { 3707 vm_page_lock_queues(); 3708 for (i = 0; i < pidx; ++i) { 3709 vm_page_unhold(bp->b_pages[i]); 3710 bp->b_pages[i] = NULL; 3711 } 3712 vm_page_unlock_queues(); 3713 return(-1); 3714 } 3715 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3716 if (m == NULL) 3717 goto retry; 3718 bp->b_pages[pidx] = m; 3719 } 3720 if (pidx > btoc(MAXPHYS)) 3721 panic("vmapbuf: mapped more than MAXPHYS"); 3722 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3723 3724 kva = bp->b_saveaddr; 3725 bp->b_npages = pidx; 3726 bp->b_saveaddr = bp->b_data; 3727 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3728 return(0); 3729} 3730 3731/* 3732 * Free the io map PTEs associated with this IO operation. 3733 * We also invalidate the TLB entries and restore the original b_addr. 3734 */ 3735void 3736vunmapbuf(struct buf *bp) 3737{ 3738 int pidx; 3739 int npages; 3740 3741 npages = bp->b_npages; 3742 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), 3743 npages); 3744 vm_page_lock_queues(); 3745 for (pidx = 0; pidx < npages; pidx++) 3746 vm_page_unhold(bp->b_pages[pidx]); 3747 vm_page_unlock_queues(); 3748 3749 bp->b_data = bp->b_saveaddr; 3750} 3751 3752void 3753bdone(struct buf *bp) 3754{ 3755 mtx_lock(&bdonelock); 3756 bp->b_flags |= B_DONE; 3757 wakeup(bp); 3758 mtx_unlock(&bdonelock); 3759} 3760 3761void 3762bwait(struct buf *bp, u_char pri, const char *wchan) 3763{ 3764 mtx_lock(&bdonelock); 3765 while ((bp->b_flags & B_DONE) == 0) 3766 msleep(bp, &bdonelock, pri, wchan, 0); 3767 mtx_unlock(&bdonelock); 3768} 3769 3770#include "opt_ddb.h" 3771#ifdef DDB 3772#include <ddb/ddb.h> 3773 3774/* DDB command to show buffer data */ 3775DB_SHOW_COMMAND(buffer, db_show_buffer) 3776{ 3777 /* get args */ 3778 struct buf *bp = (struct buf *)addr; 3779 3780 if (!have_addr) { 3781 db_printf("usage: show buffer <addr>\n"); 3782 return; 3783 } 3784 3785 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3786 db_printf( 3787 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3788 "b_dev = (%d,%d), b_data = %p, b_blkno = %jd\n", 3789 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3790 major(bp->b_dev), minor(bp->b_dev), bp->b_data, 3791 (intmax_t)bp->b_blkno); 3792 if (bp->b_npages) { 3793 int i; 3794 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3795 for (i = 0; i < bp->b_npages; i++) { 3796 vm_page_t m; 3797 m = bp->b_pages[i]; 3798 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3799 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3800 if ((i + 1) < bp->b_npages) 3801 db_printf(","); 3802 } 3803 db_printf("\n"); 3804 } 3805} 3806#endif /* DDB */
| 1921 bp->b_vp = NULL; 1922 bp->b_blkno = bp->b_lblkno = 0; 1923 bp->b_offset = NOOFFSET; 1924 bp->b_iodone = 0; 1925 bp->b_error = 0; 1926 bp->b_resid = 0; 1927 bp->b_bcount = 0; 1928 bp->b_npages = 0; 1929 bp->b_dirtyoff = bp->b_dirtyend = 0; 1930 bp->b_magic = B_MAGIC_BIO; 1931 bp->b_op = &buf_ops_bio; 1932 bp->b_object = NULL; 1933 1934 LIST_INIT(&bp->b_dep); 1935 1936 /* 1937 * If we are defragging then free the buffer. 1938 */ 1939 if (defrag) { 1940 bp->b_flags |= B_INVAL; 1941 bfreekva(bp); 1942 brelse(bp); 1943 defrag = 0; 1944 goto restart; 1945 } 1946 1947 /* 1948 * If we are overcomitted then recover the buffer and its 1949 * KVM space. This occurs in rare situations when multiple 1950 * processes are blocked in getnewbuf() or allocbuf(). 1951 */ 1952 if (bufspace >= hibufspace) 1953 flushingbufs = 1; 1954 if (flushingbufs && bp->b_kvasize != 0) { 1955 bp->b_flags |= B_INVAL; 1956 bfreekva(bp); 1957 brelse(bp); 1958 goto restart; 1959 } 1960 if (bufspace < lobufspace) 1961 flushingbufs = 0; 1962 break; 1963 } 1964 1965 /* 1966 * If we exhausted our list, sleep as appropriate. We may have to 1967 * wakeup various daemons and write out some dirty buffers. 1968 * 1969 * Generally we are sleeping due to insufficient buffer space. 1970 */ 1971 1972 if (bp == NULL) { 1973 int flags; 1974 char *waitmsg; 1975 1976 mtx_unlock(&bqlock); 1977 if (defrag) { 1978 flags = VFS_BIO_NEED_BUFSPACE; 1979 waitmsg = "nbufkv"; 1980 } else if (bufspace >= hibufspace) { 1981 waitmsg = "nbufbs"; 1982 flags = VFS_BIO_NEED_BUFSPACE; 1983 } else { 1984 waitmsg = "newbuf"; 1985 flags = VFS_BIO_NEED_ANY; 1986 } 1987 1988 bd_speedup(); /* heeeelp */ 1989 1990 mtx_lock(&nblock); 1991 needsbuffer |= flags; 1992 while (needsbuffer & flags) { 1993 if (msleep(&needsbuffer, &nblock, 1994 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1995 mtx_unlock(&nblock); 1996 return (NULL); 1997 } 1998 } 1999 mtx_unlock(&nblock); 2000 } else { 2001 /* 2002 * We finally have a valid bp. We aren't quite out of the 2003 * woods, we still have to reserve kva space. In order 2004 * to keep fragmentation sane we only allocate kva in 2005 * BKVASIZE chunks. 2006 */ 2007 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2008 2009 if (maxsize != bp->b_kvasize) { 2010 vm_offset_t addr = 0; 2011 2012 bfreekva(bp); 2013 2014 if (vm_map_findspace(buffer_map, 2015 vm_map_min(buffer_map), maxsize, &addr)) { 2016 /* 2017 * Uh oh. Buffer map is to fragmented. We 2018 * must defragment the map. 2019 */ 2020 atomic_add_int(&bufdefragcnt, 1); 2021 defrag = 1; 2022 bp->b_flags |= B_INVAL; 2023 brelse(bp); 2024 goto restart; 2025 } 2026 if (addr) { 2027 vm_map_insert(buffer_map, NULL, 0, 2028 addr, addr + maxsize, 2029 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2030 2031 bp->b_kvabase = (caddr_t) addr; 2032 bp->b_kvasize = maxsize; 2033 atomic_add_int(&bufspace, bp->b_kvasize); 2034 atomic_add_int(&bufreusecnt, 1); 2035 } 2036 } 2037 bp->b_saveaddr = bp->b_kvabase; 2038 bp->b_data = bp->b_saveaddr; 2039 } 2040 return(bp); 2041} 2042 2043/* 2044 * buf_daemon: 2045 * 2046 * buffer flushing daemon. Buffers are normally flushed by the 2047 * update daemon but if it cannot keep up this process starts to 2048 * take the load in an attempt to prevent getnewbuf() from blocking. 2049 */ 2050 2051static struct kproc_desc buf_kp = { 2052 "bufdaemon", 2053 buf_daemon, 2054 &bufdaemonproc 2055}; 2056SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2057 2058static void 2059buf_daemon() 2060{ 2061 int s; 2062 2063 mtx_lock(&Giant); 2064 2065 /* 2066 * This process needs to be suspended prior to shutdown sync. 2067 */ 2068 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2069 SHUTDOWN_PRI_LAST); 2070 2071 /* 2072 * This process is allowed to take the buffer cache to the limit 2073 */ 2074 s = splbio(); 2075 mtx_lock(&bdlock); 2076 2077 for (;;) { 2078 bd_request = 0; 2079 mtx_unlock(&bdlock); 2080 2081 kthread_suspend_check(bufdaemonproc); 2082 2083 /* 2084 * Do the flush. Limit the amount of in-transit I/O we 2085 * allow to build up, otherwise we would completely saturate 2086 * the I/O system. Wakeup any waiting processes before we 2087 * normally would so they can run in parallel with our drain. 2088 */ 2089 while (numdirtybuffers > lodirtybuffers) { 2090 if (flushbufqueues(0) == 0) { 2091 /* 2092 * Could not find any buffers without rollback 2093 * dependencies, so just write the first one 2094 * in the hopes of eventually making progress. 2095 */ 2096 flushbufqueues(1); 2097 break; 2098 } 2099 waitrunningbufspace(); 2100 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2101 } 2102 2103 /* 2104 * Only clear bd_request if we have reached our low water 2105 * mark. The buf_daemon normally waits 1 second and 2106 * then incrementally flushes any dirty buffers that have 2107 * built up, within reason. 2108 * 2109 * If we were unable to hit our low water mark and couldn't 2110 * find any flushable buffers, we sleep half a second. 2111 * Otherwise we loop immediately. 2112 */ 2113 mtx_lock(&bdlock); 2114 if (numdirtybuffers <= lodirtybuffers) { 2115 /* 2116 * We reached our low water mark, reset the 2117 * request and sleep until we are needed again. 2118 * The sleep is just so the suspend code works. 2119 */ 2120 bd_request = 0; 2121 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2122 } else { 2123 /* 2124 * We couldn't find any flushable dirty buffers but 2125 * still have too many dirty buffers, we 2126 * have to sleep and try again. (rare) 2127 */ 2128 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2129 } 2130 } 2131} 2132 2133/* 2134 * flushbufqueues: 2135 * 2136 * Try to flush a buffer in the dirty queue. We must be careful to 2137 * free up B_INVAL buffers instead of write them, which NFS is 2138 * particularly sensitive to. 2139 */ 2140int flushwithdeps = 0; 2141SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2142 0, "Number of buffers flushed with dependecies that require rollbacks"); 2143static int 2144flushbufqueues(int flushdeps) 2145{ 2146 struct thread *td = curthread; 2147 struct vnode *vp; 2148 struct mount *mp; 2149 struct buf *bp; 2150 int hasdeps; 2151 2152 mtx_lock(&bqlock); 2153 TAILQ_FOREACH(bp, &bufqueues[QUEUE_DIRTY], b_freelist) { 2154 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2155 continue; 2156 KASSERT((bp->b_flags & B_DELWRI), 2157 ("unexpected clean buffer %p", bp)); 2158 VI_LOCK(bp->b_vp); 2159 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 2160 VI_UNLOCK(bp->b_vp); 2161 BUF_UNLOCK(bp); 2162 continue; 2163 } 2164 VI_UNLOCK(bp->b_vp); 2165 if (bp->b_flags & B_INVAL) { 2166 bremfreel(bp); 2167 mtx_unlock(&bqlock); 2168 brelse(bp); 2169 return (1); 2170 } 2171 2172 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) { 2173 if (flushdeps == 0) { 2174 BUF_UNLOCK(bp); 2175 continue; 2176 } 2177 hasdeps = 1; 2178 } else 2179 hasdeps = 0; 2180 /* 2181 * We must hold the lock on a vnode before writing 2182 * one of its buffers. Otherwise we may confuse, or 2183 * in the case of a snapshot vnode, deadlock the 2184 * system. 2185 * 2186 * The lock order here is the reverse of the normal 2187 * of vnode followed by buf lock. This is ok because 2188 * the NOWAIT will prevent deadlock. 2189 */ 2190 vp = bp->b_vp; 2191 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2192 BUF_UNLOCK(bp); 2193 continue; 2194 } 2195 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2196 mtx_unlock(&bqlock); 2197 vfs_bio_awrite(bp); 2198 vn_finished_write(mp); 2199 VOP_UNLOCK(vp, 0, td); 2200 flushwithdeps += hasdeps; 2201 return (1); 2202 } 2203 vn_finished_write(mp); 2204 BUF_UNLOCK(bp); 2205 } 2206 mtx_unlock(&bqlock); 2207 return (0); 2208} 2209 2210/* 2211 * Check to see if a block is currently memory resident. 2212 */ 2213struct buf * 2214incore(struct vnode * vp, daddr_t blkno) 2215{ 2216 struct buf *bp; 2217 2218 int s = splbio(); 2219 VI_LOCK(vp); 2220 bp = gbincore(vp, blkno); 2221 VI_UNLOCK(vp); 2222 splx(s); 2223 return (bp); 2224} 2225 2226/* 2227 * Returns true if no I/O is needed to access the 2228 * associated VM object. This is like incore except 2229 * it also hunts around in the VM system for the data. 2230 */ 2231 2232int 2233inmem(struct vnode * vp, daddr_t blkno) 2234{ 2235 vm_object_t obj; 2236 vm_offset_t toff, tinc, size; 2237 vm_page_t m; 2238 vm_ooffset_t off; 2239 2240 GIANT_REQUIRED; 2241 ASSERT_VOP_LOCKED(vp, "inmem"); 2242 2243 if (incore(vp, blkno)) 2244 return 1; 2245 if (vp->v_mount == NULL) 2246 return 0; 2247 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_vflag & VV_OBJBUF) == 0) 2248 return 0; 2249 2250 size = PAGE_SIZE; 2251 if (size > vp->v_mount->mnt_stat.f_iosize) 2252 size = vp->v_mount->mnt_stat.f_iosize; 2253 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2254 2255 VM_OBJECT_LOCK(obj); 2256 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2257 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2258 if (!m) 2259 goto notinmem; 2260 tinc = size; 2261 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2262 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2263 if (vm_page_is_valid(m, 2264 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2265 goto notinmem; 2266 } 2267 VM_OBJECT_UNLOCK(obj); 2268 return 1; 2269 2270notinmem: 2271 VM_OBJECT_UNLOCK(obj); 2272 return (0); 2273} 2274 2275/* 2276 * vfs_setdirty: 2277 * 2278 * Sets the dirty range for a buffer based on the status of the dirty 2279 * bits in the pages comprising the buffer. 2280 * 2281 * The range is limited to the size of the buffer. 2282 * 2283 * This routine is primarily used by NFS, but is generalized for the 2284 * B_VMIO case. 2285 */ 2286static void 2287vfs_setdirty(struct buf *bp) 2288{ 2289 int i; 2290 vm_object_t object; 2291 2292 GIANT_REQUIRED; 2293 /* 2294 * Degenerate case - empty buffer 2295 */ 2296 2297 if (bp->b_bufsize == 0) 2298 return; 2299 2300 /* 2301 * We qualify the scan for modified pages on whether the 2302 * object has been flushed yet. The OBJ_WRITEABLE flag 2303 * is not cleared simply by protecting pages off. 2304 */ 2305 2306 if ((bp->b_flags & B_VMIO) == 0) 2307 return; 2308 2309 object = bp->b_pages[0]->object; 2310 VM_OBJECT_LOCK(object); 2311 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2312 printf("Warning: object %p writeable but not mightbedirty\n", object); 2313 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2314 printf("Warning: object %p mightbedirty but not writeable\n", object); 2315 2316 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2317 vm_offset_t boffset; 2318 vm_offset_t eoffset; 2319 2320 vm_page_lock_queues(); 2321 /* 2322 * test the pages to see if they have been modified directly 2323 * by users through the VM system. 2324 */ 2325 for (i = 0; i < bp->b_npages; i++) 2326 vm_page_test_dirty(bp->b_pages[i]); 2327 2328 /* 2329 * Calculate the encompassing dirty range, boffset and eoffset, 2330 * (eoffset - boffset) bytes. 2331 */ 2332 2333 for (i = 0; i < bp->b_npages; i++) { 2334 if (bp->b_pages[i]->dirty) 2335 break; 2336 } 2337 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2338 2339 for (i = bp->b_npages - 1; i >= 0; --i) { 2340 if (bp->b_pages[i]->dirty) { 2341 break; 2342 } 2343 } 2344 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2345 2346 vm_page_unlock_queues(); 2347 /* 2348 * Fit it to the buffer. 2349 */ 2350 2351 if (eoffset > bp->b_bcount) 2352 eoffset = bp->b_bcount; 2353 2354 /* 2355 * If we have a good dirty range, merge with the existing 2356 * dirty range. 2357 */ 2358 2359 if (boffset < eoffset) { 2360 if (bp->b_dirtyoff > boffset) 2361 bp->b_dirtyoff = boffset; 2362 if (bp->b_dirtyend < eoffset) 2363 bp->b_dirtyend = eoffset; 2364 } 2365 } 2366 VM_OBJECT_UNLOCK(object); 2367} 2368 2369/* 2370 * getblk: 2371 * 2372 * Get a block given a specified block and offset into a file/device. 2373 * The buffers B_DONE bit will be cleared on return, making it almost 2374 * ready for an I/O initiation. B_INVAL may or may not be set on 2375 * return. The caller should clear B_INVAL prior to initiating a 2376 * READ. 2377 * 2378 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2379 * an existing buffer. 2380 * 2381 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2382 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2383 * and then cleared based on the backing VM. If the previous buffer is 2384 * non-0-sized but invalid, B_CACHE will be cleared. 2385 * 2386 * If getblk() must create a new buffer, the new buffer is returned with 2387 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2388 * case it is returned with B_INVAL clear and B_CACHE set based on the 2389 * backing VM. 2390 * 2391 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2392 * B_CACHE bit is clear. 2393 * 2394 * What this means, basically, is that the caller should use B_CACHE to 2395 * determine whether the buffer is fully valid or not and should clear 2396 * B_INVAL prior to issuing a read. If the caller intends to validate 2397 * the buffer by loading its data area with something, the caller needs 2398 * to clear B_INVAL. If the caller does this without issuing an I/O, 2399 * the caller should set B_CACHE ( as an optimization ), else the caller 2400 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2401 * a write attempt or if it was a successfull read. If the caller 2402 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2403 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2404 */ 2405struct buf * 2406getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2407 int flags) 2408{ 2409 struct buf *bp; 2410 int s; 2411 int error; 2412 ASSERT_VOP_LOCKED(vp, "getblk"); 2413 2414 if (size > MAXBSIZE) 2415 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2416 2417 s = splbio(); 2418loop: 2419 /* 2420 * Block if we are low on buffers. Certain processes are allowed 2421 * to completely exhaust the buffer cache. 2422 * 2423 * If this check ever becomes a bottleneck it may be better to 2424 * move it into the else, when gbincore() fails. At the moment 2425 * it isn't a problem. 2426 * 2427 * XXX remove if 0 sections (clean this up after its proven) 2428 */ 2429 if (numfreebuffers == 0) { 2430 if (curthread == PCPU_GET(idlethread)) 2431 return NULL; 2432 mtx_lock(&nblock); 2433 needsbuffer |= VFS_BIO_NEED_ANY; 2434 mtx_unlock(&nblock); 2435 } 2436 2437 VI_LOCK(vp); 2438 if ((bp = gbincore(vp, blkno))) { 2439 int lockflags; 2440 /* 2441 * Buffer is in-core. If the buffer is not busy, it must 2442 * be on a queue. 2443 */ 2444 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2445 2446 if (flags & GB_LOCK_NOWAIT) 2447 lockflags |= LK_NOWAIT; 2448 2449 error = BUF_TIMELOCK(bp, lockflags, 2450 VI_MTX(vp), "getblk", slpflag, slptimeo); 2451 2452 /* 2453 * If we slept and got the lock we have to restart in case 2454 * the buffer changed identities. 2455 */ 2456 if (error == ENOLCK) 2457 goto loop; 2458 /* We timed out or were interrupted. */ 2459 else if (error) 2460 return (NULL); 2461 2462 /* 2463 * The buffer is locked. B_CACHE is cleared if the buffer is 2464 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2465 * and for a VMIO buffer B_CACHE is adjusted according to the 2466 * backing VM cache. 2467 */ 2468 if (bp->b_flags & B_INVAL) 2469 bp->b_flags &= ~B_CACHE; 2470 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2471 bp->b_flags |= B_CACHE; 2472 bremfree(bp); 2473 2474 /* 2475 * check for size inconsistancies for non-VMIO case. 2476 */ 2477 2478 if (bp->b_bcount != size) { 2479 if ((bp->b_flags & B_VMIO) == 0 || 2480 (size > bp->b_kvasize)) { 2481 if (bp->b_flags & B_DELWRI) { 2482 bp->b_flags |= B_NOCACHE; 2483 bwrite(bp); 2484 } else { 2485 if ((bp->b_flags & B_VMIO) && 2486 (LIST_FIRST(&bp->b_dep) == NULL)) { 2487 bp->b_flags |= B_RELBUF; 2488 brelse(bp); 2489 } else { 2490 bp->b_flags |= B_NOCACHE; 2491 bwrite(bp); 2492 } 2493 } 2494 goto loop; 2495 } 2496 } 2497 2498 /* 2499 * If the size is inconsistant in the VMIO case, we can resize 2500 * the buffer. This might lead to B_CACHE getting set or 2501 * cleared. If the size has not changed, B_CACHE remains 2502 * unchanged from its previous state. 2503 */ 2504 2505 if (bp->b_bcount != size) 2506 allocbuf(bp, size); 2507 2508 KASSERT(bp->b_offset != NOOFFSET, 2509 ("getblk: no buffer offset")); 2510 2511 /* 2512 * A buffer with B_DELWRI set and B_CACHE clear must 2513 * be committed before we can return the buffer in 2514 * order to prevent the caller from issuing a read 2515 * ( due to B_CACHE not being set ) and overwriting 2516 * it. 2517 * 2518 * Most callers, including NFS and FFS, need this to 2519 * operate properly either because they assume they 2520 * can issue a read if B_CACHE is not set, or because 2521 * ( for example ) an uncached B_DELWRI might loop due 2522 * to softupdates re-dirtying the buffer. In the latter 2523 * case, B_CACHE is set after the first write completes, 2524 * preventing further loops. 2525 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2526 * above while extending the buffer, we cannot allow the 2527 * buffer to remain with B_CACHE set after the write 2528 * completes or it will represent a corrupt state. To 2529 * deal with this we set B_NOCACHE to scrap the buffer 2530 * after the write. 2531 * 2532 * We might be able to do something fancy, like setting 2533 * B_CACHE in bwrite() except if B_DELWRI is already set, 2534 * so the below call doesn't set B_CACHE, but that gets real 2535 * confusing. This is much easier. 2536 */ 2537 2538 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2539 bp->b_flags |= B_NOCACHE; 2540 bwrite(bp); 2541 goto loop; 2542 } 2543 2544 splx(s); 2545 bp->b_flags &= ~B_DONE; 2546 } else { 2547 int bsize, maxsize, vmio; 2548 off_t offset; 2549 2550 /* 2551 * Buffer is not in-core, create new buffer. The buffer 2552 * returned by getnewbuf() is locked. Note that the returned 2553 * buffer is also considered valid (not marked B_INVAL). 2554 */ 2555 VI_UNLOCK(vp); 2556 /* 2557 * If the user does not want us to create the buffer, bail out 2558 * here. 2559 */ 2560 if (flags & GB_NOCREAT) { 2561 splx(s); 2562 return NULL; 2563 } 2564 if (vn_isdisk(vp, NULL)) 2565 bsize = DEV_BSIZE; 2566 else if (vp->v_mountedhere) 2567 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2568 else if (vp->v_mount) 2569 bsize = vp->v_mount->mnt_stat.f_iosize; 2570 else 2571 bsize = size; 2572 2573 offset = blkno * bsize; 2574 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && 2575 (vp->v_vflag & VV_OBJBUF); 2576 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2577 maxsize = imax(maxsize, bsize); 2578 2579 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2580 if (slpflag || slptimeo) { 2581 splx(s); 2582 return NULL; 2583 } 2584 goto loop; 2585 } 2586 2587 /* 2588 * This code is used to make sure that a buffer is not 2589 * created while the getnewbuf routine is blocked. 2590 * This can be a problem whether the vnode is locked or not. 2591 * If the buffer is created out from under us, we have to 2592 * throw away the one we just created. There is now window 2593 * race because we are safely running at splbio() from the 2594 * point of the duplicate buffer creation through to here, 2595 * and we've locked the buffer. 2596 * 2597 * Note: this must occur before we associate the buffer 2598 * with the vp especially considering limitations in 2599 * the splay tree implementation when dealing with duplicate 2600 * lblkno's. 2601 */ 2602 VI_LOCK(vp); 2603 if (gbincore(vp, blkno)) { 2604 VI_UNLOCK(vp); 2605 bp->b_flags |= B_INVAL; 2606 brelse(bp); 2607 goto loop; 2608 } 2609 2610 /* 2611 * Insert the buffer into the hash, so that it can 2612 * be found by incore. 2613 */ 2614 bp->b_blkno = bp->b_lblkno = blkno; 2615 bp->b_offset = offset; 2616 2617 bgetvp(vp, bp); 2618 VI_UNLOCK(vp); 2619 2620 /* 2621 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2622 * buffer size starts out as 0, B_CACHE will be set by 2623 * allocbuf() for the VMIO case prior to it testing the 2624 * backing store for validity. 2625 */ 2626 2627 if (vmio) { 2628 bp->b_flags |= B_VMIO; 2629#if defined(VFS_BIO_DEBUG) 2630 if (vn_canvmio(vp) != TRUE) 2631 printf("getblk: VMIO on vnode type %d\n", 2632 vp->v_type); 2633#endif 2634 VOP_GETVOBJECT(vp, &bp->b_object); 2635 } else { 2636 bp->b_flags &= ~B_VMIO; 2637 bp->b_object = NULL; 2638 } 2639 2640 allocbuf(bp, size); 2641 2642 splx(s); 2643 bp->b_flags &= ~B_DONE; 2644 } 2645 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2646 return (bp); 2647} 2648 2649/* 2650 * Get an empty, disassociated buffer of given size. The buffer is initially 2651 * set to B_INVAL. 2652 */ 2653struct buf * 2654geteblk(int size) 2655{ 2656 struct buf *bp; 2657 int s; 2658 int maxsize; 2659 2660 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2661 2662 s = splbio(); 2663 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2664 continue; 2665 splx(s); 2666 allocbuf(bp, size); 2667 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2668 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2669 return (bp); 2670} 2671 2672 2673/* 2674 * This code constitutes the buffer memory from either anonymous system 2675 * memory (in the case of non-VMIO operations) or from an associated 2676 * VM object (in the case of VMIO operations). This code is able to 2677 * resize a buffer up or down. 2678 * 2679 * Note that this code is tricky, and has many complications to resolve 2680 * deadlock or inconsistant data situations. Tread lightly!!! 2681 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2682 * the caller. Calling this code willy nilly can result in the loss of data. 2683 * 2684 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2685 * B_CACHE for the non-VMIO case. 2686 */ 2687 2688int 2689allocbuf(struct buf *bp, int size) 2690{ 2691 int newbsize, mbsize; 2692 int i; 2693 2694 GIANT_REQUIRED; 2695 2696 if (BUF_REFCNT(bp) == 0) 2697 panic("allocbuf: buffer not busy"); 2698 2699 if (bp->b_kvasize < size) 2700 panic("allocbuf: buffer too small"); 2701 2702 if ((bp->b_flags & B_VMIO) == 0) { 2703 caddr_t origbuf; 2704 int origbufsize; 2705 /* 2706 * Just get anonymous memory from the kernel. Don't 2707 * mess with B_CACHE. 2708 */ 2709 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2710 if (bp->b_flags & B_MALLOC) 2711 newbsize = mbsize; 2712 else 2713 newbsize = round_page(size); 2714 2715 if (newbsize < bp->b_bufsize) { 2716 /* 2717 * malloced buffers are not shrunk 2718 */ 2719 if (bp->b_flags & B_MALLOC) { 2720 if (newbsize) { 2721 bp->b_bcount = size; 2722 } else { 2723 free(bp->b_data, M_BIOBUF); 2724 if (bp->b_bufsize) { 2725 atomic_subtract_int( 2726 &bufmallocspace, 2727 bp->b_bufsize); 2728 bufspacewakeup(); 2729 bp->b_bufsize = 0; 2730 } 2731 bp->b_saveaddr = bp->b_kvabase; 2732 bp->b_data = bp->b_saveaddr; 2733 bp->b_bcount = 0; 2734 bp->b_flags &= ~B_MALLOC; 2735 } 2736 return 1; 2737 } 2738 vm_hold_free_pages( 2739 bp, 2740 (vm_offset_t) bp->b_data + newbsize, 2741 (vm_offset_t) bp->b_data + bp->b_bufsize); 2742 } else if (newbsize > bp->b_bufsize) { 2743 /* 2744 * We only use malloced memory on the first allocation. 2745 * and revert to page-allocated memory when the buffer 2746 * grows. 2747 */ 2748 /* 2749 * There is a potential smp race here that could lead 2750 * to bufmallocspace slightly passing the max. It 2751 * is probably extremely rare and not worth worrying 2752 * over. 2753 */ 2754 if ( (bufmallocspace < maxbufmallocspace) && 2755 (bp->b_bufsize == 0) && 2756 (mbsize <= PAGE_SIZE/2)) { 2757 2758 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2759 bp->b_bufsize = mbsize; 2760 bp->b_bcount = size; 2761 bp->b_flags |= B_MALLOC; 2762 atomic_add_int(&bufmallocspace, mbsize); 2763 return 1; 2764 } 2765 origbuf = NULL; 2766 origbufsize = 0; 2767 /* 2768 * If the buffer is growing on its other-than-first allocation, 2769 * then we revert to the page-allocation scheme. 2770 */ 2771 if (bp->b_flags & B_MALLOC) { 2772 origbuf = bp->b_data; 2773 origbufsize = bp->b_bufsize; 2774 bp->b_data = bp->b_kvabase; 2775 if (bp->b_bufsize) { 2776 atomic_subtract_int(&bufmallocspace, 2777 bp->b_bufsize); 2778 bufspacewakeup(); 2779 bp->b_bufsize = 0; 2780 } 2781 bp->b_flags &= ~B_MALLOC; 2782 newbsize = round_page(newbsize); 2783 } 2784 vm_hold_load_pages( 2785 bp, 2786 (vm_offset_t) bp->b_data + bp->b_bufsize, 2787 (vm_offset_t) bp->b_data + newbsize); 2788 if (origbuf) { 2789 bcopy(origbuf, bp->b_data, origbufsize); 2790 free(origbuf, M_BIOBUF); 2791 } 2792 } 2793 } else { 2794 int desiredpages; 2795 2796 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2797 desiredpages = (size == 0) ? 0 : 2798 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2799 2800 if (bp->b_flags & B_MALLOC) 2801 panic("allocbuf: VMIO buffer can't be malloced"); 2802 /* 2803 * Set B_CACHE initially if buffer is 0 length or will become 2804 * 0-length. 2805 */ 2806 if (size == 0 || bp->b_bufsize == 0) 2807 bp->b_flags |= B_CACHE; 2808 2809 if (newbsize < bp->b_bufsize) { 2810 /* 2811 * DEV_BSIZE aligned new buffer size is less then the 2812 * DEV_BSIZE aligned existing buffer size. Figure out 2813 * if we have to remove any pages. 2814 */ 2815 if (desiredpages < bp->b_npages) { 2816 vm_page_t m; 2817 2818 vm_page_lock_queues(); 2819 for (i = desiredpages; i < bp->b_npages; i++) { 2820 /* 2821 * the page is not freed here -- it 2822 * is the responsibility of 2823 * vnode_pager_setsize 2824 */ 2825 m = bp->b_pages[i]; 2826 KASSERT(m != bogus_page, 2827 ("allocbuf: bogus page found")); 2828 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2829 vm_page_lock_queues(); 2830 2831 bp->b_pages[i] = NULL; 2832 vm_page_unwire(m, 0); 2833 } 2834 vm_page_unlock_queues(); 2835 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2836 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2837 bp->b_npages = desiredpages; 2838 } 2839 } else if (size > bp->b_bcount) { 2840 /* 2841 * We are growing the buffer, possibly in a 2842 * byte-granular fashion. 2843 */ 2844 struct vnode *vp; 2845 vm_object_t obj; 2846 vm_offset_t toff; 2847 vm_offset_t tinc; 2848 2849 /* 2850 * Step 1, bring in the VM pages from the object, 2851 * allocating them if necessary. We must clear 2852 * B_CACHE if these pages are not valid for the 2853 * range covered by the buffer. 2854 */ 2855 2856 vp = bp->b_vp; 2857 obj = bp->b_object; 2858 2859 VM_OBJECT_LOCK(obj); 2860 while (bp->b_npages < desiredpages) { 2861 vm_page_t m; 2862 vm_pindex_t pi; 2863 2864 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2865 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2866 /* 2867 * note: must allocate system pages 2868 * since blocking here could intefere 2869 * with paging I/O, no matter which 2870 * process we are. 2871 */ 2872 m = vm_page_alloc(obj, pi, 2873 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 2874 if (m == NULL) { 2875 atomic_add_int(&vm_pageout_deficit, 2876 desiredpages - bp->b_npages); 2877 VM_OBJECT_UNLOCK(obj); 2878 VM_WAIT; 2879 VM_OBJECT_LOCK(obj); 2880 } else { 2881 vm_page_lock_queues(); 2882 vm_page_wakeup(m); 2883 vm_page_unlock_queues(); 2884 bp->b_flags &= ~B_CACHE; 2885 bp->b_pages[bp->b_npages] = m; 2886 ++bp->b_npages; 2887 } 2888 continue; 2889 } 2890 2891 /* 2892 * We found a page. If we have to sleep on it, 2893 * retry because it might have gotten freed out 2894 * from under us. 2895 * 2896 * We can only test PG_BUSY here. Blocking on 2897 * m->busy might lead to a deadlock: 2898 * 2899 * vm_fault->getpages->cluster_read->allocbuf 2900 * 2901 */ 2902 vm_page_lock_queues(); 2903 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2904 continue; 2905 2906 /* 2907 * We have a good page. Should we wakeup the 2908 * page daemon? 2909 */ 2910 if ((curproc != pageproc) && 2911 ((m->queue - m->pc) == PQ_CACHE) && 2912 ((cnt.v_free_count + cnt.v_cache_count) < 2913 (cnt.v_free_min + cnt.v_cache_min))) { 2914 pagedaemon_wakeup(); 2915 } 2916 vm_page_wire(m); 2917 vm_page_unlock_queues(); 2918 bp->b_pages[bp->b_npages] = m; 2919 ++bp->b_npages; 2920 } 2921 2922 /* 2923 * Step 2. We've loaded the pages into the buffer, 2924 * we have to figure out if we can still have B_CACHE 2925 * set. Note that B_CACHE is set according to the 2926 * byte-granular range ( bcount and size ), new the 2927 * aligned range ( newbsize ). 2928 * 2929 * The VM test is against m->valid, which is DEV_BSIZE 2930 * aligned. Needless to say, the validity of the data 2931 * needs to also be DEV_BSIZE aligned. Note that this 2932 * fails with NFS if the server or some other client 2933 * extends the file's EOF. If our buffer is resized, 2934 * B_CACHE may remain set! XXX 2935 */ 2936 2937 toff = bp->b_bcount; 2938 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2939 2940 while ((bp->b_flags & B_CACHE) && toff < size) { 2941 vm_pindex_t pi; 2942 2943 if (tinc > (size - toff)) 2944 tinc = size - toff; 2945 2946 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2947 PAGE_SHIFT; 2948 2949 vfs_buf_test_cache( 2950 bp, 2951 bp->b_offset, 2952 toff, 2953 tinc, 2954 bp->b_pages[pi] 2955 ); 2956 toff += tinc; 2957 tinc = PAGE_SIZE; 2958 } 2959 VM_OBJECT_UNLOCK(obj); 2960 2961 /* 2962 * Step 3, fixup the KVM pmap. Remember that 2963 * bp->b_data is relative to bp->b_offset, but 2964 * bp->b_offset may be offset into the first page. 2965 */ 2966 2967 bp->b_data = (caddr_t) 2968 trunc_page((vm_offset_t)bp->b_data); 2969 pmap_qenter( 2970 (vm_offset_t)bp->b_data, 2971 bp->b_pages, 2972 bp->b_npages 2973 ); 2974 2975 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2976 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2977 } 2978 } 2979 if (newbsize < bp->b_bufsize) 2980 bufspacewakeup(); 2981 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2982 bp->b_bcount = size; /* requested buffer size */ 2983 return 1; 2984} 2985 2986void 2987biodone(struct bio *bp) 2988{ 2989 mtx_lock(&bdonelock); 2990 bp->bio_flags |= BIO_DONE; 2991 if (bp->bio_done == NULL) 2992 wakeup(bp); 2993 mtx_unlock(&bdonelock); 2994 if (bp->bio_done != NULL) 2995 bp->bio_done(bp); 2996} 2997 2998/* 2999 * Wait for a BIO to finish. 3000 * 3001 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3002 * case is not yet clear. 3003 */ 3004int 3005biowait(struct bio *bp, const char *wchan) 3006{ 3007 3008 mtx_lock(&bdonelock); 3009 while ((bp->bio_flags & BIO_DONE) == 0) 3010 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3011 mtx_unlock(&bdonelock); 3012 if (bp->bio_error != 0) 3013 return (bp->bio_error); 3014 if (!(bp->bio_flags & BIO_ERROR)) 3015 return (0); 3016 return (EIO); 3017} 3018 3019void 3020biofinish(struct bio *bp, struct devstat *stat, int error) 3021{ 3022 3023 if (error) { 3024 bp->bio_error = error; 3025 bp->bio_flags |= BIO_ERROR; 3026 } 3027 if (stat != NULL) 3028 devstat_end_transaction_bio(stat, bp); 3029 biodone(bp); 3030} 3031 3032/* 3033 * bufwait: 3034 * 3035 * Wait for buffer I/O completion, returning error status. The buffer 3036 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3037 * error and cleared. 3038 */ 3039int 3040bufwait(register struct buf * bp) 3041{ 3042 int s; 3043 3044 s = splbio(); 3045 if (bp->b_iocmd == BIO_READ) 3046 bwait(bp, PRIBIO, "biord"); 3047 else 3048 bwait(bp, PRIBIO, "biowr"); 3049 splx(s); 3050 if (bp->b_flags & B_EINTR) { 3051 bp->b_flags &= ~B_EINTR; 3052 return (EINTR); 3053 } 3054 if (bp->b_ioflags & BIO_ERROR) { 3055 return (bp->b_error ? bp->b_error : EIO); 3056 } else { 3057 return (0); 3058 } 3059} 3060 3061 /* 3062 * Call back function from struct bio back up to struct buf. 3063 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY(). 3064 */ 3065static void 3066bufdonebio(struct bio *bp) 3067{ 3068 3069 /* Device drivers may or may not hold giant, hold it here. */ 3070 mtx_lock(&Giant); 3071 bufdone(bp->bio_caller2); 3072 mtx_unlock(&Giant); 3073} 3074 3075void 3076dev_strategy(struct buf *bp) 3077{ 3078 struct cdevsw *csw; 3079 3080 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3081 panic("b_iocmd botch"); 3082 bp->b_io.bio_done = bufdonebio; 3083 bp->b_io.bio_caller2 = bp; 3084 csw = devsw(bp->b_io.bio_dev); 3085 KASSERT(bp->b_io.bio_dev->si_refcount > 0, 3086 ("dev_strategy on un-referenced struct cdev *(%s)", 3087 devtoname(bp->b_io.bio_dev))); 3088 cdevsw_ref(csw); 3089 (*devsw(bp->b_io.bio_dev)->d_strategy)(&bp->b_io); 3090 cdevsw_rel(csw); 3091} 3092 3093/* 3094 * bufdone: 3095 * 3096 * Finish I/O on a buffer, optionally calling a completion function. 3097 * This is usually called from an interrupt so process blocking is 3098 * not allowed. 3099 * 3100 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3101 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3102 * assuming B_INVAL is clear. 3103 * 3104 * For the VMIO case, we set B_CACHE if the op was a read and no 3105 * read error occured, or if the op was a write. B_CACHE is never 3106 * set if the buffer is invalid or otherwise uncacheable. 3107 * 3108 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3109 * initiator to leave B_INVAL set to brelse the buffer out of existance 3110 * in the biodone routine. 3111 */ 3112void 3113bufdone(struct buf *bp) 3114{ 3115 int s; 3116 void (*biodone)(struct buf *); 3117 3118 3119 s = splbio(); 3120 3121 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 3122 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3123 3124 bp->b_flags |= B_DONE; 3125 runningbufwakeup(bp); 3126 3127 if (bp->b_iocmd == BIO_DELETE) { 3128 brelse(bp); 3129 splx(s); 3130 return; 3131 } 3132 3133 if (bp->b_iocmd == BIO_WRITE) { 3134 vwakeup(bp); 3135 } 3136 3137 /* call optional completion function if requested */ 3138 if (bp->b_iodone != NULL) { 3139 biodone = bp->b_iodone; 3140 bp->b_iodone = NULL; 3141 (*biodone) (bp); 3142 splx(s); 3143 return; 3144 } 3145 if (LIST_FIRST(&bp->b_dep) != NULL) 3146 buf_complete(bp); 3147 3148 if (bp->b_flags & B_VMIO) { 3149 int i; 3150 vm_ooffset_t foff; 3151 vm_page_t m; 3152 vm_object_t obj; 3153 int iosize; 3154 struct vnode *vp = bp->b_vp; 3155 3156 obj = bp->b_object; 3157 3158#if defined(VFS_BIO_DEBUG) 3159 mp_fixme("usecount and vflag accessed without locks."); 3160 if (vp->v_usecount == 0) { 3161 panic("biodone: zero vnode ref count"); 3162 } 3163 3164 if ((vp->v_vflag & VV_OBJBUF) == 0) { 3165 panic("biodone: vnode is not setup for merged cache"); 3166 } 3167#endif 3168 3169 foff = bp->b_offset; 3170 KASSERT(bp->b_offset != NOOFFSET, 3171 ("biodone: no buffer offset")); 3172 3173 VM_OBJECT_LOCK(obj); 3174#if defined(VFS_BIO_DEBUG) 3175 if (obj->paging_in_progress < bp->b_npages) { 3176 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3177 obj->paging_in_progress, bp->b_npages); 3178 } 3179#endif 3180 3181 /* 3182 * Set B_CACHE if the op was a normal read and no error 3183 * occured. B_CACHE is set for writes in the b*write() 3184 * routines. 3185 */ 3186 iosize = bp->b_bcount - bp->b_resid; 3187 if (bp->b_iocmd == BIO_READ && 3188 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3189 !(bp->b_ioflags & BIO_ERROR)) { 3190 bp->b_flags |= B_CACHE; 3191 } 3192 vm_page_lock_queues(); 3193 for (i = 0; i < bp->b_npages; i++) { 3194 int bogusflag = 0; 3195 int resid; 3196 3197 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3198 if (resid > iosize) 3199 resid = iosize; 3200 3201 /* 3202 * cleanup bogus pages, restoring the originals 3203 */ 3204 m = bp->b_pages[i]; 3205 if (m == bogus_page) { 3206 bogusflag = 1; 3207 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3208 if (m == NULL) 3209 panic("biodone: page disappeared!"); 3210 bp->b_pages[i] = m; 3211 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3212 } 3213#if defined(VFS_BIO_DEBUG) 3214 if (OFF_TO_IDX(foff) != m->pindex) { 3215 printf( 3216"biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3217 (intmax_t)foff, (uintmax_t)m->pindex); 3218 } 3219#endif 3220 3221 /* 3222 * In the write case, the valid and clean bits are 3223 * already changed correctly ( see bdwrite() ), so we 3224 * only need to do this here in the read case. 3225 */ 3226 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3227 vfs_page_set_valid(bp, foff, i, m); 3228 } 3229 3230 /* 3231 * when debugging new filesystems or buffer I/O methods, this 3232 * is the most common error that pops up. if you see this, you 3233 * have not set the page busy flag correctly!!! 3234 */ 3235 if (m->busy == 0) { 3236 printf("biodone: page busy < 0, " 3237 "pindex: %d, foff: 0x(%x,%x), " 3238 "resid: %d, index: %d\n", 3239 (int) m->pindex, (int)(foff >> 32), 3240 (int) foff & 0xffffffff, resid, i); 3241 if (!vn_isdisk(vp, NULL)) 3242 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3243 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3244 (intmax_t) bp->b_lblkno, 3245 bp->b_flags, bp->b_npages); 3246 else 3247 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3248 (intmax_t) bp->b_lblkno, 3249 bp->b_flags, bp->b_npages); 3250 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3251 (u_long)m->valid, (u_long)m->dirty, 3252 m->wire_count); 3253 panic("biodone: page busy < 0\n"); 3254 } 3255 vm_page_io_finish(m); 3256 vm_object_pip_subtract(obj, 1); 3257 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3258 iosize -= resid; 3259 } 3260 vm_page_unlock_queues(); 3261 vm_object_pip_wakeupn(obj, 0); 3262 VM_OBJECT_UNLOCK(obj); 3263 } 3264 3265 /* 3266 * For asynchronous completions, release the buffer now. The brelse 3267 * will do a wakeup there if necessary - so no need to do a wakeup 3268 * here in the async case. The sync case always needs to do a wakeup. 3269 */ 3270 3271 if (bp->b_flags & B_ASYNC) { 3272 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3273 brelse(bp); 3274 else 3275 bqrelse(bp); 3276 } else { 3277 bdone(bp); 3278 } 3279 splx(s); 3280} 3281 3282/* 3283 * This routine is called in lieu of iodone in the case of 3284 * incomplete I/O. This keeps the busy status for pages 3285 * consistant. 3286 */ 3287void 3288vfs_unbusy_pages(struct buf * bp) 3289{ 3290 int i; 3291 3292 runningbufwakeup(bp); 3293 if (bp->b_flags & B_VMIO) { 3294 vm_object_t obj; 3295 3296 obj = bp->b_object; 3297 VM_OBJECT_LOCK(obj); 3298 vm_page_lock_queues(); 3299 for (i = 0; i < bp->b_npages; i++) { 3300 vm_page_t m = bp->b_pages[i]; 3301 3302 if (m == bogus_page) { 3303 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3304 if (!m) { 3305 panic("vfs_unbusy_pages: page missing\n"); 3306 } 3307 bp->b_pages[i] = m; 3308 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3309 } 3310 vm_object_pip_subtract(obj, 1); 3311 vm_page_io_finish(m); 3312 } 3313 vm_page_unlock_queues(); 3314 vm_object_pip_wakeupn(obj, 0); 3315 VM_OBJECT_UNLOCK(obj); 3316 } 3317} 3318 3319/* 3320 * vfs_page_set_valid: 3321 * 3322 * Set the valid bits in a page based on the supplied offset. The 3323 * range is restricted to the buffer's size. 3324 * 3325 * This routine is typically called after a read completes. 3326 */ 3327static void 3328vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3329{ 3330 vm_ooffset_t soff, eoff; 3331 3332 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3333 /* 3334 * Start and end offsets in buffer. eoff - soff may not cross a 3335 * page boundry or cross the end of the buffer. The end of the 3336 * buffer, in this case, is our file EOF, not the allocation size 3337 * of the buffer. 3338 */ 3339 soff = off; 3340 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3341 if (eoff > bp->b_offset + bp->b_bcount) 3342 eoff = bp->b_offset + bp->b_bcount; 3343 3344 /* 3345 * Set valid range. This is typically the entire buffer and thus the 3346 * entire page. 3347 */ 3348 if (eoff > soff) { 3349 vm_page_set_validclean( 3350 m, 3351 (vm_offset_t) (soff & PAGE_MASK), 3352 (vm_offset_t) (eoff - soff) 3353 ); 3354 } 3355} 3356 3357/* 3358 * This routine is called before a device strategy routine. 3359 * It is used to tell the VM system that paging I/O is in 3360 * progress, and treat the pages associated with the buffer 3361 * almost as being PG_BUSY. Also the object paging_in_progress 3362 * flag is handled to make sure that the object doesn't become 3363 * inconsistant. 3364 * 3365 * Since I/O has not been initiated yet, certain buffer flags 3366 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3367 * and should be ignored. 3368 */ 3369void 3370vfs_busy_pages(struct buf * bp, int clear_modify) 3371{ 3372 int i, bogus; 3373 3374 if (bp->b_flags & B_VMIO) { 3375 vm_object_t obj; 3376 vm_ooffset_t foff; 3377 3378 obj = bp->b_object; 3379 foff = bp->b_offset; 3380 KASSERT(bp->b_offset != NOOFFSET, 3381 ("vfs_busy_pages: no buffer offset")); 3382 vfs_setdirty(bp); 3383 VM_OBJECT_LOCK(obj); 3384retry: 3385 vm_page_lock_queues(); 3386 for (i = 0; i < bp->b_npages; i++) { 3387 vm_page_t m = bp->b_pages[i]; 3388 3389 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3390 goto retry; 3391 } 3392 bogus = 0; 3393 for (i = 0; i < bp->b_npages; i++) { 3394 vm_page_t m = bp->b_pages[i]; 3395 3396 if ((bp->b_flags & B_CLUSTER) == 0) { 3397 vm_object_pip_add(obj, 1); 3398 vm_page_io_start(m); 3399 } 3400 /* 3401 * When readying a buffer for a read ( i.e 3402 * clear_modify == 0 ), it is important to do 3403 * bogus_page replacement for valid pages in 3404 * partially instantiated buffers. Partially 3405 * instantiated buffers can, in turn, occur when 3406 * reconstituting a buffer from its VM backing store 3407 * base. We only have to do this if B_CACHE is 3408 * clear ( which causes the I/O to occur in the 3409 * first place ). The replacement prevents the read 3410 * I/O from overwriting potentially dirty VM-backed 3411 * pages. XXX bogus page replacement is, uh, bogus. 3412 * It may not work properly with small-block devices. 3413 * We need to find a better way. 3414 */ 3415 pmap_remove_all(m); 3416 if (clear_modify) 3417 vfs_page_set_valid(bp, foff, i, m); 3418 else if (m->valid == VM_PAGE_BITS_ALL && 3419 (bp->b_flags & B_CACHE) == 0) { 3420 bp->b_pages[i] = bogus_page; 3421 bogus++; 3422 } 3423 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3424 } 3425 vm_page_unlock_queues(); 3426 VM_OBJECT_UNLOCK(obj); 3427 if (bogus) 3428 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3429 } 3430} 3431 3432/* 3433 * Tell the VM system that the pages associated with this buffer 3434 * are clean. This is used for delayed writes where the data is 3435 * going to go to disk eventually without additional VM intevention. 3436 * 3437 * Note that while we only really need to clean through to b_bcount, we 3438 * just go ahead and clean through to b_bufsize. 3439 */ 3440static void 3441vfs_clean_pages(struct buf * bp) 3442{ 3443 int i; 3444 3445 if (bp->b_flags & B_VMIO) { 3446 vm_ooffset_t foff; 3447 3448 foff = bp->b_offset; 3449 KASSERT(bp->b_offset != NOOFFSET, 3450 ("vfs_clean_pages: no buffer offset")); 3451 VM_OBJECT_LOCK(bp->b_object); 3452 vm_page_lock_queues(); 3453 for (i = 0; i < bp->b_npages; i++) { 3454 vm_page_t m = bp->b_pages[i]; 3455 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3456 vm_ooffset_t eoff = noff; 3457 3458 if (eoff > bp->b_offset + bp->b_bufsize) 3459 eoff = bp->b_offset + bp->b_bufsize; 3460 vfs_page_set_valid(bp, foff, i, m); 3461 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3462 foff = noff; 3463 } 3464 vm_page_unlock_queues(); 3465 VM_OBJECT_UNLOCK(bp->b_object); 3466 } 3467} 3468 3469/* 3470 * vfs_bio_set_validclean: 3471 * 3472 * Set the range within the buffer to valid and clean. The range is 3473 * relative to the beginning of the buffer, b_offset. Note that b_offset 3474 * itself may be offset from the beginning of the first page. 3475 * 3476 */ 3477 3478void 3479vfs_bio_set_validclean(struct buf *bp, int base, int size) 3480{ 3481 if (bp->b_flags & B_VMIO) { 3482 int i; 3483 int n; 3484 3485 /* 3486 * Fixup base to be relative to beginning of first page. 3487 * Set initial n to be the maximum number of bytes in the 3488 * first page that can be validated. 3489 */ 3490 3491 base += (bp->b_offset & PAGE_MASK); 3492 n = PAGE_SIZE - (base & PAGE_MASK); 3493 3494 VM_OBJECT_LOCK(bp->b_object); 3495 vm_page_lock_queues(); 3496 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3497 vm_page_t m = bp->b_pages[i]; 3498 3499 if (n > size) 3500 n = size; 3501 3502 vm_page_set_validclean(m, base & PAGE_MASK, n); 3503 base += n; 3504 size -= n; 3505 n = PAGE_SIZE; 3506 } 3507 vm_page_unlock_queues(); 3508 VM_OBJECT_UNLOCK(bp->b_object); 3509 } 3510} 3511 3512/* 3513 * vfs_bio_clrbuf: 3514 * 3515 * clear a buffer. This routine essentially fakes an I/O, so we need 3516 * to clear BIO_ERROR and B_INVAL. 3517 * 3518 * Note that while we only theoretically need to clear through b_bcount, 3519 * we go ahead and clear through b_bufsize. 3520 */ 3521 3522void 3523vfs_bio_clrbuf(struct buf *bp) 3524{ 3525 int i, j, mask = 0; 3526 caddr_t sa, ea; 3527 3528 GIANT_REQUIRED; 3529 3530 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3531 bp->b_flags &= ~B_INVAL; 3532 bp->b_ioflags &= ~BIO_ERROR; 3533 VM_OBJECT_LOCK(bp->b_object); 3534 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3535 (bp->b_offset & PAGE_MASK) == 0) { 3536 if (bp->b_pages[0] == bogus_page) 3537 goto unlock; 3538 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3539 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3540 if ((bp->b_pages[0]->valid & mask) == mask) 3541 goto unlock; 3542 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3543 ((bp->b_pages[0]->valid & mask) == 0)) { 3544 bzero(bp->b_data, bp->b_bufsize); 3545 bp->b_pages[0]->valid |= mask; 3546 goto unlock; 3547 } 3548 } 3549 ea = sa = bp->b_data; 3550 for(i=0;i<bp->b_npages;i++,sa=ea) { 3551 if (bp->b_pages[i] == bogus_page) 3552 continue; 3553 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3554 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3555 ea = (caddr_t)(vm_offset_t)ulmin( 3556 (u_long)(vm_offset_t)ea, 3557 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3558 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3559 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3560 if ((bp->b_pages[i]->valid & mask) == mask) 3561 continue; 3562 if ((bp->b_pages[i]->valid & mask) == 0) { 3563 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3564 bzero(sa, ea - sa); 3565 } 3566 } else { 3567 for (; sa < ea; sa += DEV_BSIZE, j++) { 3568 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3569 (bp->b_pages[i]->valid & (1<<j)) == 0) 3570 bzero(sa, DEV_BSIZE); 3571 } 3572 } 3573 bp->b_pages[i]->valid |= mask; 3574 } 3575unlock: 3576 VM_OBJECT_UNLOCK(bp->b_object); 3577 bp->b_resid = 0; 3578 } else { 3579 clrbuf(bp); 3580 } 3581} 3582 3583/* 3584 * vm_hold_load_pages and vm_hold_free_pages get pages into 3585 * a buffers address space. The pages are anonymous and are 3586 * not associated with a file object. 3587 */ 3588static void 3589vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3590{ 3591 vm_offset_t pg; 3592 vm_page_t p; 3593 int index; 3594 3595 to = round_page(to); 3596 from = round_page(from); 3597 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3598 3599 VM_OBJECT_LOCK(kernel_object); 3600 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3601tryagain: 3602 /* 3603 * note: must allocate system pages since blocking here 3604 * could intefere with paging I/O, no matter which 3605 * process we are. 3606 */ 3607 p = vm_page_alloc(kernel_object, 3608 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3609 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3610 if (!p) { 3611 atomic_add_int(&vm_pageout_deficit, 3612 (to - pg) >> PAGE_SHIFT); 3613 VM_OBJECT_UNLOCK(kernel_object); 3614 VM_WAIT; 3615 VM_OBJECT_LOCK(kernel_object); 3616 goto tryagain; 3617 } 3618 p->valid = VM_PAGE_BITS_ALL; 3619 pmap_qenter(pg, &p, 1); 3620 bp->b_pages[index] = p; 3621 vm_page_lock_queues(); 3622 vm_page_wakeup(p); 3623 vm_page_unlock_queues(); 3624 } 3625 VM_OBJECT_UNLOCK(kernel_object); 3626 bp->b_npages = index; 3627} 3628 3629/* Return pages associated with this buf to the vm system */ 3630static void 3631vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3632{ 3633 vm_offset_t pg; 3634 vm_page_t p; 3635 int index, newnpages; 3636 3637 GIANT_REQUIRED; 3638 3639 from = round_page(from); 3640 to = round_page(to); 3641 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3642 3643 VM_OBJECT_LOCK(kernel_object); 3644 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3645 p = bp->b_pages[index]; 3646 if (p && (index < bp->b_npages)) { 3647 if (p->busy) { 3648 printf( 3649 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3650 (intmax_t)bp->b_blkno, 3651 (intmax_t)bp->b_lblkno); 3652 } 3653 bp->b_pages[index] = NULL; 3654 pmap_qremove(pg, 1); 3655 vm_page_lock_queues(); 3656 vm_page_busy(p); 3657 vm_page_unwire(p, 0); 3658 vm_page_free(p); 3659 vm_page_unlock_queues(); 3660 } 3661 } 3662 VM_OBJECT_UNLOCK(kernel_object); 3663 bp->b_npages = newnpages; 3664} 3665 3666/* 3667 * Map an IO request into kernel virtual address space. 3668 * 3669 * All requests are (re)mapped into kernel VA space. 3670 * Notice that we use b_bufsize for the size of the buffer 3671 * to be mapped. b_bcount might be modified by the driver. 3672 * 3673 * Note that even if the caller determines that the address space should 3674 * be valid, a race or a smaller-file mapped into a larger space may 3675 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3676 * check the return value. 3677 */ 3678int 3679vmapbuf(struct buf *bp) 3680{ 3681 caddr_t addr, kva; 3682 vm_prot_t prot; 3683 int pidx, i; 3684 struct vm_page *m; 3685 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3686 3687 GIANT_REQUIRED; 3688 3689 if (bp->b_bufsize < 0) 3690 return (-1); 3691 prot = (bp->b_iocmd == BIO_READ) ? VM_PROT_READ | VM_PROT_WRITE : 3692 VM_PROT_READ; 3693 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3694 addr < bp->b_data + bp->b_bufsize; 3695 addr += PAGE_SIZE, pidx++) { 3696 /* 3697 * Do the vm_fault if needed; do the copy-on-write thing 3698 * when reading stuff off device into memory. 3699 * 3700 * NOTE! Must use pmap_extract() because addr may be in 3701 * the userland address space, and kextract is only guarenteed 3702 * to work for the kernland address space (see: sparc64 port). 3703 */ 3704retry: 3705 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3706 prot) < 0) { 3707 vm_page_lock_queues(); 3708 for (i = 0; i < pidx; ++i) { 3709 vm_page_unhold(bp->b_pages[i]); 3710 bp->b_pages[i] = NULL; 3711 } 3712 vm_page_unlock_queues(); 3713 return(-1); 3714 } 3715 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3716 if (m == NULL) 3717 goto retry; 3718 bp->b_pages[pidx] = m; 3719 } 3720 if (pidx > btoc(MAXPHYS)) 3721 panic("vmapbuf: mapped more than MAXPHYS"); 3722 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3723 3724 kva = bp->b_saveaddr; 3725 bp->b_npages = pidx; 3726 bp->b_saveaddr = bp->b_data; 3727 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3728 return(0); 3729} 3730 3731/* 3732 * Free the io map PTEs associated with this IO operation. 3733 * We also invalidate the TLB entries and restore the original b_addr. 3734 */ 3735void 3736vunmapbuf(struct buf *bp) 3737{ 3738 int pidx; 3739 int npages; 3740 3741 npages = bp->b_npages; 3742 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), 3743 npages); 3744 vm_page_lock_queues(); 3745 for (pidx = 0; pidx < npages; pidx++) 3746 vm_page_unhold(bp->b_pages[pidx]); 3747 vm_page_unlock_queues(); 3748 3749 bp->b_data = bp->b_saveaddr; 3750} 3751 3752void 3753bdone(struct buf *bp) 3754{ 3755 mtx_lock(&bdonelock); 3756 bp->b_flags |= B_DONE; 3757 wakeup(bp); 3758 mtx_unlock(&bdonelock); 3759} 3760 3761void 3762bwait(struct buf *bp, u_char pri, const char *wchan) 3763{ 3764 mtx_lock(&bdonelock); 3765 while ((bp->b_flags & B_DONE) == 0) 3766 msleep(bp, &bdonelock, pri, wchan, 0); 3767 mtx_unlock(&bdonelock); 3768} 3769 3770#include "opt_ddb.h" 3771#ifdef DDB 3772#include <ddb/ddb.h> 3773 3774/* DDB command to show buffer data */ 3775DB_SHOW_COMMAND(buffer, db_show_buffer) 3776{ 3777 /* get args */ 3778 struct buf *bp = (struct buf *)addr; 3779 3780 if (!have_addr) { 3781 db_printf("usage: show buffer <addr>\n"); 3782 return; 3783 } 3784 3785 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3786 db_printf( 3787 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3788 "b_dev = (%d,%d), b_data = %p, b_blkno = %jd\n", 3789 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3790 major(bp->b_dev), minor(bp->b_dev), bp->b_data, 3791 (intmax_t)bp->b_blkno); 3792 if (bp->b_npages) { 3793 int i; 3794 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3795 for (i = 0; i < bp->b_npages; i++) { 3796 vm_page_t m; 3797 m = bp->b_pages[i]; 3798 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3799 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3800 if ((i + 1) < bp->b_npages) 3801 db_printf(","); 3802 } 3803 db_printf("\n"); 3804 } 3805} 3806#endif /* DDB */
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