FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_bio.c
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>
29 __FBSDID("$FreeBSD$");
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
60 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
61
62 struct bio_ops bioops; /* I/O operation notification */
63
64 static int ibwrite(struct buf *);
65
66 struct 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 */
75 struct buf *buf; /* buffer header pool */
76
77 static struct proc *bufdaemonproc;
78
79 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from,
80 vm_offset_t to);
81 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from,
82 vm_offset_t to);
83 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
84 int pageno, vm_page_t m);
85 static void vfs_clean_pages(struct buf * bp);
86 static void vfs_setdirty(struct buf *bp);
87 static void vfs_vmio_release(struct buf *bp);
88 static void vfs_backgroundwritedone(struct buf *bp);
89 static int vfs_bio_clcheck(struct vnode *vp, int size,
90 daddr_t lblkno, daddr_t blkno);
91 static int flushbufqueues(int flushdeps);
92 static void buf_daemon(void);
93 void bremfreel(struct buf * bp);
94
95 int vmiodirenable = TRUE;
96 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
97 "Use the VM system for directory writes");
98 int runningbufspace;
99 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
100 "Amount of presently outstanding async buffer io");
101 static int bufspace;
102 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
103 "KVA memory used for bufs");
104 static int maxbufspace;
105 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
106 "Maximum allowed value of bufspace (including buf_daemon)");
107 static int bufmallocspace;
108 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
109 "Amount of malloced memory for buffers");
110 static int maxbufmallocspace;
111 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
112 "Maximum amount of malloced memory for buffers");
113 static int lobufspace;
114 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
115 "Minimum amount of buffers we want to have");
116 int hibufspace;
117 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
118 "Maximum allowed value of bufspace (excluding buf_daemon)");
119 static int bufreusecnt;
120 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
121 "Number of times we have reused a buffer");
122 static int buffreekvacnt;
123 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
124 "Number of times we have freed the KVA space from some buffer");
125 static int bufdefragcnt;
126 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
127 "Number of times we have had to repeat buffer allocation to defragment");
128 static int lorunningspace;
129 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
130 "Minimum preferred space used for in-progress I/O");
131 static int hirunningspace;
132 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
133 "Maximum amount of space to use for in-progress I/O");
134 static int dirtybufferflushes;
135 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
136 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
137 static int altbufferflushes;
138 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
139 0, "Number of fsync flushes to limit dirty buffers");
140 static int recursiveflushes;
141 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
142 0, "Number of flushes skipped due to being recursive");
143 static int numdirtybuffers;
144 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
145 "Number of buffers that are dirty (has unwritten changes) at the moment");
146 static int lodirtybuffers;
147 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
148 "How many buffers we want to have free before bufdaemon can sleep");
149 static int hidirtybuffers;
150 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
151 "When the number of dirty buffers is considered severe");
152 static int dirtybufthresh;
153 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
154 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
155 static int numfreebuffers;
156 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
157 "Number of free buffers");
158 static int lofreebuffers;
159 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
160 "XXX Unused");
161 static int hifreebuffers;
162 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
163 "XXX Complicatedly unused");
164 static int getnewbufcalls;
165 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
166 "Number of calls to getnewbuf");
167 static int getnewbufrestarts;
168 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
169 "Number of times getnewbuf has had to restart a buffer aquisition");
170 static int dobkgrdwrite = 1;
171 SYSCTL_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 */
179 static int bd_request;
180
181 /*
182 * This lock synchronizes access to bd_request.
183 */
184 static 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 */
193 vm_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 */
200 static int runningbufreq;
201
202 /*
203 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
204 * waitrunningbufspace().
205 */
206 static 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 */
215 static int needsbuffer;
216
217 /*
218 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
219 */
220 static struct mtx nblock;
221
222 /*
223 * Lock that protects against bwait()/bdone()/B_DONE races.
224 */
225
226 static 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 */
240 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
241
242 /* Lock for the bufqueues */
243 static 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 */
249 const 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
257 extern 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
266 static __inline void
267 numdirtywakeup(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
288 static __inline void
289 bufspacewakeup(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 */
308 static __inline void
309 runningbufwakeup(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
332 static __inline void
333 bufcountwakeup(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 */
361 static __inline void
362 waitrunningbufspace(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 */
380 static __inline
381 void
382 vfs_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 */
397 static __inline
398 void
399 bd_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
413 static __inline
414 void
415 bd_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 */
426 caddr_t
427 kern_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. */
497 void
498 bufinit(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 = NULL;
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 */
605 static void
606 bfreekva(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 */
627 void
628 bremfree(struct buf * bp)
629 {
630 mtx_lock(&bqlock);
631 bremfreel(bp);
632 mtx_unlock(&bqlock);
633 }
634
635 void
636 bremfreel(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 */
679 int
680 bread(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 */
693 int
694 breadn(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 */
765 int
766 bwrite(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
774 static int
775 ibwrite(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 */
920 static void
921 vfs_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 */
976 void
977 bdwrite(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 */
1101 void
1102 bdirty(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);
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
1130 void
1131 bundirty(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);
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 */
1158 void
1159 bawrite(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
1175 void
1176 bwillwrite(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 */
1199 int
1200 buf_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 */
1212 void
1213 brelse(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);
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);
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 */
1488 void
1489 bqrelse(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) */
1555 static void
1556 vfs_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 pmap_remove_all(m);
1590 vm_page_free(m);
1591 } else if (bp->b_flags & B_DIRECT) {
1592 vm_page_try_to_free(m);
1593 } else if (vm_page_count_severe()) {
1594 vm_page_try_to_cache(m);
1595 }
1596 }
1597 }
1598 vm_page_unlock_queues();
1599 VM_OBJECT_UNLOCK(bp->b_object);
1600 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
1601
1602 if (bp->b_bufsize) {
1603 bufspacewakeup();
1604 bp->b_bufsize = 0;
1605 }
1606 bp->b_npages = 0;
1607 bp->b_flags &= ~B_VMIO;
1608 if (bp->b_vp)
1609 brelvp(bp);
1610 }
1611
1612 /*
1613 * Check to see if a block at a particular lbn is available for a clustered
1614 * write.
1615 */
1616 static int
1617 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1618 {
1619 struct buf *bpa;
1620 int match;
1621
1622 match = 0;
1623
1624 /* If the buf isn't in core skip it */
1625 if ((bpa = gbincore(vp, lblkno)) == NULL)
1626 return (0);
1627
1628 /* If the buf is busy we don't want to wait for it */
1629 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1630 return (0);
1631
1632 /* Only cluster with valid clusterable delayed write buffers */
1633 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1634 (B_DELWRI | B_CLUSTEROK))
1635 goto done;
1636
1637 if (bpa->b_bufsize != size)
1638 goto done;
1639
1640 /*
1641 * Check to see if it is in the expected place on disk and that the
1642 * block has been mapped.
1643 */
1644 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1645 match = 1;
1646 done:
1647 BUF_UNLOCK(bpa);
1648 return (match);
1649 }
1650
1651 /*
1652 * vfs_bio_awrite:
1653 *
1654 * Implement clustered async writes for clearing out B_DELWRI buffers.
1655 * This is much better then the old way of writing only one buffer at
1656 * a time. Note that we may not be presented with the buffers in the
1657 * correct order, so we search for the cluster in both directions.
1658 */
1659 int
1660 vfs_bio_awrite(struct buf * bp)
1661 {
1662 int i;
1663 int j;
1664 daddr_t lblkno = bp->b_lblkno;
1665 struct vnode *vp = bp->b_vp;
1666 int s;
1667 int ncl;
1668 int nwritten;
1669 int size;
1670 int maxcl;
1671
1672 s = splbio();
1673 /*
1674 * right now we support clustered writing only to regular files. If
1675 * we find a clusterable block we could be in the middle of a cluster
1676 * rather then at the beginning.
1677 */
1678 if ((vp->v_type == VREG) &&
1679 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1680 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1681
1682 size = vp->v_mount->mnt_stat.f_iosize;
1683 maxcl = MAXPHYS / size;
1684
1685 VI_LOCK(vp);
1686 for (i = 1; i < maxcl; i++)
1687 if (vfs_bio_clcheck(vp, size, lblkno + i,
1688 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1689 break;
1690
1691 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1692 if (vfs_bio_clcheck(vp, size, lblkno - j,
1693 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1694 break;
1695
1696 VI_UNLOCK(vp);
1697 --j;
1698 ncl = i + j;
1699 /*
1700 * this is a possible cluster write
1701 */
1702 if (ncl != 1) {
1703 BUF_UNLOCK(bp);
1704 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1705 splx(s);
1706 return nwritten;
1707 }
1708 }
1709
1710 bremfree(bp);
1711 bp->b_flags |= B_ASYNC;
1712
1713 splx(s);
1714 /*
1715 * default (old) behavior, writing out only one block
1716 *
1717 * XXX returns b_bufsize instead of b_bcount for nwritten?
1718 */
1719 nwritten = bp->b_bufsize;
1720 (void) bwrite(bp);
1721
1722 return nwritten;
1723 }
1724
1725 /*
1726 * getnewbuf:
1727 *
1728 * Find and initialize a new buffer header, freeing up existing buffers
1729 * in the bufqueues as necessary. The new buffer is returned locked.
1730 *
1731 * Important: B_INVAL is not set. If the caller wishes to throw the
1732 * buffer away, the caller must set B_INVAL prior to calling brelse().
1733 *
1734 * We block if:
1735 * We have insufficient buffer headers
1736 * We have insufficient buffer space
1737 * buffer_map is too fragmented ( space reservation fails )
1738 * If we have to flush dirty buffers ( but we try to avoid this )
1739 *
1740 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1741 * Instead we ask the buf daemon to do it for us. We attempt to
1742 * avoid piecemeal wakeups of the pageout daemon.
1743 */
1744
1745 static struct buf *
1746 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1747 {
1748 struct buf *bp;
1749 struct buf *nbp;
1750 int defrag = 0;
1751 int nqindex;
1752 static int flushingbufs;
1753
1754 GIANT_REQUIRED;
1755
1756 /*
1757 * We can't afford to block since we might be holding a vnode lock,
1758 * which may prevent system daemons from running. We deal with
1759 * low-memory situations by proactively returning memory and running
1760 * async I/O rather then sync I/O.
1761 */
1762
1763 atomic_add_int(&getnewbufcalls, 1);
1764 atomic_subtract_int(&getnewbufrestarts, 1);
1765 restart:
1766 atomic_add_int(&getnewbufrestarts, 1);
1767
1768 /*
1769 * Setup for scan. If we do not have enough free buffers,
1770 * we setup a degenerate case that immediately fails. Note
1771 * that if we are specially marked process, we are allowed to
1772 * dip into our reserves.
1773 *
1774 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1775 *
1776 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1777 * However, there are a number of cases (defragging, reusing, ...)
1778 * where we cannot backup.
1779 */
1780 mtx_lock(&bqlock);
1781 nqindex = QUEUE_EMPTYKVA;
1782 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1783
1784 if (nbp == NULL) {
1785 /*
1786 * If no EMPTYKVA buffers and we are either
1787 * defragging or reusing, locate a CLEAN buffer
1788 * to free or reuse. If bufspace useage is low
1789 * skip this step so we can allocate a new buffer.
1790 */
1791 if (defrag || bufspace >= lobufspace) {
1792 nqindex = QUEUE_CLEAN;
1793 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1794 }
1795
1796 /*
1797 * If we could not find or were not allowed to reuse a
1798 * CLEAN buffer, check to see if it is ok to use an EMPTY
1799 * buffer. We can only use an EMPTY buffer if allocating
1800 * its KVA would not otherwise run us out of buffer space.
1801 */
1802 if (nbp == NULL && defrag == 0 &&
1803 bufspace + maxsize < hibufspace) {
1804 nqindex = QUEUE_EMPTY;
1805 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1806 }
1807 }
1808
1809 /*
1810 * Run scan, possibly freeing data and/or kva mappings on the fly
1811 * depending.
1812 */
1813
1814 while ((bp = nbp) != NULL) {
1815 int qindex = nqindex;
1816
1817 /*
1818 * Calculate next bp ( we can only use it if we do not block
1819 * or do other fancy things ).
1820 */
1821 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1822 switch(qindex) {
1823 case QUEUE_EMPTY:
1824 nqindex = QUEUE_EMPTYKVA;
1825 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1826 break;
1827 /* FALLTHROUGH */
1828 case QUEUE_EMPTYKVA:
1829 nqindex = QUEUE_CLEAN;
1830 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1831 break;
1832 /* FALLTHROUGH */
1833 case QUEUE_CLEAN:
1834 /*
1835 * nbp is NULL.
1836 */
1837 break;
1838 }
1839 }
1840 if (bp->b_vp) {
1841 VI_LOCK(bp->b_vp);
1842 if (bp->b_vflags & BV_BKGRDINPROG) {
1843 VI_UNLOCK(bp->b_vp);
1844 continue;
1845 }
1846 VI_UNLOCK(bp->b_vp);
1847 }
1848
1849 /*
1850 * Sanity Checks
1851 */
1852 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1853
1854 /*
1855 * Note: we no longer distinguish between VMIO and non-VMIO
1856 * buffers.
1857 */
1858
1859 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1860
1861 /*
1862 * If we are defragging then we need a buffer with
1863 * b_kvasize != 0. XXX this situation should no longer
1864 * occur, if defrag is non-zero the buffer's b_kvasize
1865 * should also be non-zero at this point. XXX
1866 */
1867 if (defrag && bp->b_kvasize == 0) {
1868 printf("Warning: defrag empty buffer %p\n", bp);
1869 continue;
1870 }
1871
1872 /*
1873 * Start freeing the bp. This is somewhat involved. nbp
1874 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1875 */
1876
1877 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1878 panic("getnewbuf: locked buf");
1879 bremfreel(bp);
1880 mtx_unlock(&bqlock);
1881
1882 if (qindex == QUEUE_CLEAN) {
1883 if (bp->b_flags & B_VMIO) {
1884 bp->b_flags &= ~B_ASYNC;
1885 vfs_vmio_release(bp);
1886 }
1887 if (bp->b_vp)
1888 brelvp(bp);
1889 }
1890
1891 /*
1892 * NOTE: nbp is now entirely invalid. We can only restart
1893 * the scan from this point on.
1894 *
1895 * Get the rest of the buffer freed up. b_kva* is still
1896 * valid after this operation.
1897 */
1898
1899 if (bp->b_rcred != NOCRED) {
1900 crfree(bp->b_rcred);
1901 bp->b_rcred = NOCRED;
1902 }
1903 if (bp->b_wcred != NOCRED) {
1904 crfree(bp->b_wcred);
1905 bp->b_wcred = NOCRED;
1906 }
1907 if (LIST_FIRST(&bp->b_dep) != NULL)
1908 buf_deallocate(bp);
1909 if (bp->b_vflags & BV_BKGRDINPROG)
1910 panic("losing buffer 3");
1911
1912 if (bp->b_bufsize)
1913 allocbuf(bp, 0);
1914
1915 bp->b_flags = 0;
1916 bp->b_ioflags = 0;
1917 bp->b_xflags = 0;
1918 bp->b_vflags = 0;
1919 bp->b_dev = NULL;
1920 bp->b_vp = NULL;
1921 bp->b_blkno = bp->b_lblkno = 0;
1922 bp->b_offset = NOOFFSET;
1923 bp->b_iodone = 0;
1924 bp->b_error = 0;
1925 bp->b_resid = 0;
1926 bp->b_bcount = 0;
1927 bp->b_npages = 0;
1928 bp->b_dirtyoff = bp->b_dirtyend = 0;
1929 bp->b_magic = B_MAGIC_BIO;
1930 bp->b_op = &buf_ops_bio;
1931 bp->b_object = NULL;
1932
1933 LIST_INIT(&bp->b_dep);
1934
1935 /*
1936 * If we are defragging then free the buffer.
1937 */
1938 if (defrag) {
1939 bp->b_flags |= B_INVAL;
1940 bfreekva(bp);
1941 brelse(bp);
1942 defrag = 0;
1943 goto restart;
1944 }
1945
1946 /*
1947 * If we are overcomitted then recover the buffer and its
1948 * KVM space. This occurs in rare situations when multiple
1949 * processes are blocked in getnewbuf() or allocbuf().
1950 */
1951 if (bufspace >= hibufspace)
1952 flushingbufs = 1;
1953 if (flushingbufs && bp->b_kvasize != 0) {
1954 bp->b_flags |= B_INVAL;
1955 bfreekva(bp);
1956 brelse(bp);
1957 goto restart;
1958 }
1959 if (bufspace < lobufspace)
1960 flushingbufs = 0;
1961 break;
1962 }
1963
1964 /*
1965 * If we exhausted our list, sleep as appropriate. We may have to
1966 * wakeup various daemons and write out some dirty buffers.
1967 *
1968 * Generally we are sleeping due to insufficient buffer space.
1969 */
1970
1971 if (bp == NULL) {
1972 int flags;
1973 char *waitmsg;
1974
1975 mtx_unlock(&bqlock);
1976 if (defrag) {
1977 flags = VFS_BIO_NEED_BUFSPACE;
1978 waitmsg = "nbufkv";
1979 } else if (bufspace >= hibufspace) {
1980 waitmsg = "nbufbs";
1981 flags = VFS_BIO_NEED_BUFSPACE;
1982 } else {
1983 waitmsg = "newbuf";
1984 flags = VFS_BIO_NEED_ANY;
1985 }
1986
1987 bd_speedup(); /* heeeelp */
1988
1989 mtx_lock(&nblock);
1990 needsbuffer |= flags;
1991 while (needsbuffer & flags) {
1992 if (msleep(&needsbuffer, &nblock,
1993 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
1994 mtx_unlock(&nblock);
1995 return (NULL);
1996 }
1997 }
1998 mtx_unlock(&nblock);
1999 } else {
2000 /*
2001 * We finally have a valid bp. We aren't quite out of the
2002 * woods, we still have to reserve kva space. In order
2003 * to keep fragmentation sane we only allocate kva in
2004 * BKVASIZE chunks.
2005 */
2006 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2007
2008 if (maxsize != bp->b_kvasize) {
2009 vm_offset_t addr = 0;
2010
2011 bfreekva(bp);
2012
2013 if (vm_map_findspace(buffer_map,
2014 vm_map_min(buffer_map), maxsize, &addr)) {
2015 /*
2016 * Uh oh. Buffer map is to fragmented. We
2017 * must defragment the map.
2018 */
2019 atomic_add_int(&bufdefragcnt, 1);
2020 defrag = 1;
2021 bp->b_flags |= B_INVAL;
2022 brelse(bp);
2023 goto restart;
2024 }
2025 if (addr) {
2026 vm_map_insert(buffer_map, NULL, 0,
2027 addr, addr + maxsize,
2028 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
2029
2030 bp->b_kvabase = (caddr_t) addr;
2031 bp->b_kvasize = maxsize;
2032 atomic_add_int(&bufspace, bp->b_kvasize);
2033 atomic_add_int(&bufreusecnt, 1);
2034 }
2035 }
2036 bp->b_saveaddr = bp->b_kvabase;
2037 bp->b_data = bp->b_saveaddr;
2038 }
2039 return(bp);
2040 }
2041
2042 /*
2043 * buf_daemon:
2044 *
2045 * buffer flushing daemon. Buffers are normally flushed by the
2046 * update daemon but if it cannot keep up this process starts to
2047 * take the load in an attempt to prevent getnewbuf() from blocking.
2048 */
2049
2050 static struct kproc_desc buf_kp = {
2051 "bufdaemon",
2052 buf_daemon,
2053 &bufdaemonproc
2054 };
2055 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
2056
2057 static void
2058 buf_daemon()
2059 {
2060 int s;
2061
2062 mtx_lock(&Giant);
2063
2064 /*
2065 * This process needs to be suspended prior to shutdown sync.
2066 */
2067 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2068 SHUTDOWN_PRI_LAST);
2069
2070 /*
2071 * This process is allowed to take the buffer cache to the limit
2072 */
2073 s = splbio();
2074 mtx_lock(&bdlock);
2075
2076 for (;;) {
2077 bd_request = 0;
2078 mtx_unlock(&bdlock);
2079
2080 kthread_suspend_check(bufdaemonproc);
2081
2082 /*
2083 * Do the flush. Limit the amount of in-transit I/O we
2084 * allow to build up, otherwise we would completely saturate
2085 * the I/O system. Wakeup any waiting processes before we
2086 * normally would so they can run in parallel with our drain.
2087 */
2088 while (numdirtybuffers > lodirtybuffers) {
2089 if (flushbufqueues(0) == 0) {
2090 /*
2091 * Could not find any buffers without rollback
2092 * dependencies, so just write the first one
2093 * in the hopes of eventually making progress.
2094 */
2095 flushbufqueues(1);
2096 break;
2097 }
2098 waitrunningbufspace();
2099 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2100 }
2101
2102 /*
2103 * Only clear bd_request if we have reached our low water
2104 * mark. The buf_daemon normally waits 1 second and
2105 * then incrementally flushes any dirty buffers that have
2106 * built up, within reason.
2107 *
2108 * If we were unable to hit our low water mark and couldn't
2109 * find any flushable buffers, we sleep half a second.
2110 * Otherwise we loop immediately.
2111 */
2112 mtx_lock(&bdlock);
2113 if (numdirtybuffers <= lodirtybuffers) {
2114 /*
2115 * We reached our low water mark, reset the
2116 * request and sleep until we are needed again.
2117 * The sleep is just so the suspend code works.
2118 */
2119 bd_request = 0;
2120 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2121 } else {
2122 /*
2123 * We couldn't find any flushable dirty buffers but
2124 * still have too many dirty buffers, we
2125 * have to sleep and try again. (rare)
2126 */
2127 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2128 }
2129 }
2130 }
2131
2132 /*
2133 * flushbufqueues:
2134 *
2135 * Try to flush a buffer in the dirty queue. We must be careful to
2136 * free up B_INVAL buffers instead of write them, which NFS is
2137 * particularly sensitive to.
2138 */
2139 int flushwithdeps = 0;
2140 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2141 0, "Number of buffers flushed with dependecies that require rollbacks");
2142 static int
2143 flushbufqueues(int flushdeps)
2144 {
2145 struct thread *td = curthread;
2146 struct vnode *vp;
2147 struct mount *mp;
2148 struct buf *bp;
2149 int hasdeps;
2150
2151 mtx_lock(&bqlock);
2152 TAILQ_FOREACH(bp, &bufqueues[QUEUE_DIRTY], b_freelist) {
2153 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2154 continue;
2155 KASSERT((bp->b_flags & B_DELWRI),
2156 ("unexpected clean buffer %p", bp));
2157 VI_LOCK(bp->b_vp);
2158 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
2159 VI_UNLOCK(bp->b_vp);
2160 BUF_UNLOCK(bp);
2161 continue;
2162 }
2163 VI_UNLOCK(bp->b_vp);
2164 if (bp->b_flags & B_INVAL) {
2165 bremfreel(bp);
2166 mtx_unlock(&bqlock);
2167 brelse(bp);
2168 return (1);
2169 }
2170
2171 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) {
2172 if (flushdeps == 0) {
2173 BUF_UNLOCK(bp);
2174 continue;
2175 }
2176 hasdeps = 1;
2177 } else
2178 hasdeps = 0;
2179 /*
2180 * We must hold the lock on a vnode before writing
2181 * one of its buffers. Otherwise we may confuse, or
2182 * in the case of a snapshot vnode, deadlock the
2183 * system.
2184 *
2185 * The lock order here is the reverse of the normal
2186 * of vnode followed by buf lock. This is ok because
2187 * the NOWAIT will prevent deadlock.
2188 */
2189 vp = bp->b_vp;
2190 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2191 BUF_UNLOCK(bp);
2192 continue;
2193 }
2194 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) {
2195 mtx_unlock(&bqlock);
2196 vfs_bio_awrite(bp);
2197 vn_finished_write(mp);
2198 VOP_UNLOCK(vp, 0, td);
2199 flushwithdeps += hasdeps;
2200 return (1);
2201 }
2202 vn_finished_write(mp);
2203 BUF_UNLOCK(bp);
2204 }
2205 mtx_unlock(&bqlock);
2206 return (0);
2207 }
2208
2209 /*
2210 * Check to see if a block is currently memory resident.
2211 */
2212 struct buf *
2213 incore(struct vnode * vp, daddr_t blkno)
2214 {
2215 struct buf *bp;
2216
2217 int s = splbio();
2218 VI_LOCK(vp);
2219 bp = gbincore(vp, blkno);
2220 VI_UNLOCK(vp);
2221 splx(s);
2222 return (bp);
2223 }
2224
2225 /*
2226 * Returns true if no I/O is needed to access the
2227 * associated VM object. This is like incore except
2228 * it also hunts around in the VM system for the data.
2229 */
2230
2231 int
2232 inmem(struct vnode * vp, daddr_t blkno)
2233 {
2234 vm_object_t obj;
2235 vm_offset_t toff, tinc, size;
2236 vm_page_t m;
2237 vm_ooffset_t off;
2238
2239 GIANT_REQUIRED;
2240 ASSERT_VOP_LOCKED(vp, "inmem");
2241
2242 if (incore(vp, blkno))
2243 return 1;
2244 if (vp->v_mount == NULL)
2245 return 0;
2246 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_vflag & VV_OBJBUF) == 0)
2247 return 0;
2248
2249 size = PAGE_SIZE;
2250 if (size > vp->v_mount->mnt_stat.f_iosize)
2251 size = vp->v_mount->mnt_stat.f_iosize;
2252 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2253
2254 VM_OBJECT_LOCK(obj);
2255 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2256 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2257 if (!m)
2258 goto notinmem;
2259 tinc = size;
2260 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2261 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2262 if (vm_page_is_valid(m,
2263 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2264 goto notinmem;
2265 }
2266 VM_OBJECT_UNLOCK(obj);
2267 return 1;
2268
2269 notinmem:
2270 VM_OBJECT_UNLOCK(obj);
2271 return (0);
2272 }
2273
2274 /*
2275 * vfs_setdirty:
2276 *
2277 * Sets the dirty range for a buffer based on the status of the dirty
2278 * bits in the pages comprising the buffer.
2279 *
2280 * The range is limited to the size of the buffer.
2281 *
2282 * This routine is primarily used by NFS, but is generalized for the
2283 * B_VMIO case.
2284 */
2285 static void
2286 vfs_setdirty(struct buf *bp)
2287 {
2288 int i;
2289 vm_object_t object;
2290
2291 GIANT_REQUIRED;
2292 /*
2293 * Degenerate case - empty buffer
2294 */
2295
2296 if (bp->b_bufsize == 0)
2297 return;
2298
2299 /*
2300 * We qualify the scan for modified pages on whether the
2301 * object has been flushed yet. The OBJ_WRITEABLE flag
2302 * is not cleared simply by protecting pages off.
2303 */
2304
2305 if ((bp->b_flags & B_VMIO) == 0)
2306 return;
2307
2308 object = bp->b_pages[0]->object;
2309 VM_OBJECT_LOCK(object);
2310 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
2311 printf("Warning: object %p writeable but not mightbedirty\n", object);
2312 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
2313 printf("Warning: object %p mightbedirty but not writeable\n", object);
2314
2315 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2316 vm_offset_t boffset;
2317 vm_offset_t eoffset;
2318
2319 vm_page_lock_queues();
2320 /*
2321 * test the pages to see if they have been modified directly
2322 * by users through the VM system.
2323 */
2324 for (i = 0; i < bp->b_npages; i++)
2325 vm_page_test_dirty(bp->b_pages[i]);
2326
2327 /*
2328 * Calculate the encompassing dirty range, boffset and eoffset,
2329 * (eoffset - boffset) bytes.
2330 */
2331
2332 for (i = 0; i < bp->b_npages; i++) {
2333 if (bp->b_pages[i]->dirty)
2334 break;
2335 }
2336 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2337
2338 for (i = bp->b_npages - 1; i >= 0; --i) {
2339 if (bp->b_pages[i]->dirty) {
2340 break;
2341 }
2342 }
2343 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2344
2345 vm_page_unlock_queues();
2346 /*
2347 * Fit it to the buffer.
2348 */
2349
2350 if (eoffset > bp->b_bcount)
2351 eoffset = bp->b_bcount;
2352
2353 /*
2354 * If we have a good dirty range, merge with the existing
2355 * dirty range.
2356 */
2357
2358 if (boffset < eoffset) {
2359 if (bp->b_dirtyoff > boffset)
2360 bp->b_dirtyoff = boffset;
2361 if (bp->b_dirtyend < eoffset)
2362 bp->b_dirtyend = eoffset;
2363 }
2364 }
2365 VM_OBJECT_UNLOCK(object);
2366 }
2367
2368 /*
2369 * getblk:
2370 *
2371 * Get a block given a specified block and offset into a file/device.
2372 * The buffers B_DONE bit will be cleared on return, making it almost
2373 * ready for an I/O initiation. B_INVAL may or may not be set on
2374 * return. The caller should clear B_INVAL prior to initiating a
2375 * READ.
2376 *
2377 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2378 * an existing buffer.
2379 *
2380 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2381 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2382 * and then cleared based on the backing VM. If the previous buffer is
2383 * non-0-sized but invalid, B_CACHE will be cleared.
2384 *
2385 * If getblk() must create a new buffer, the new buffer is returned with
2386 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2387 * case it is returned with B_INVAL clear and B_CACHE set based on the
2388 * backing VM.
2389 *
2390 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2391 * B_CACHE bit is clear.
2392 *
2393 * What this means, basically, is that the caller should use B_CACHE to
2394 * determine whether the buffer is fully valid or not and should clear
2395 * B_INVAL prior to issuing a read. If the caller intends to validate
2396 * the buffer by loading its data area with something, the caller needs
2397 * to clear B_INVAL. If the caller does this without issuing an I/O,
2398 * the caller should set B_CACHE ( as an optimization ), else the caller
2399 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2400 * a write attempt or if it was a successfull read. If the caller
2401 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2402 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2403 */
2404 struct buf *
2405 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2406 int flags)
2407 {
2408 struct buf *bp;
2409 int s;
2410 int error;
2411 ASSERT_VOP_LOCKED(vp, "getblk");
2412
2413 if (size > MAXBSIZE)
2414 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2415
2416 s = splbio();
2417 loop:
2418 /*
2419 * Block if we are low on buffers. Certain processes are allowed
2420 * to completely exhaust the buffer cache.
2421 *
2422 * If this check ever becomes a bottleneck it may be better to
2423 * move it into the else, when gbincore() fails. At the moment
2424 * it isn't a problem.
2425 *
2426 * XXX remove if 0 sections (clean this up after its proven)
2427 */
2428 if (numfreebuffers == 0) {
2429 if (curthread == PCPU_GET(idlethread))
2430 return NULL;
2431 mtx_lock(&nblock);
2432 needsbuffer |= VFS_BIO_NEED_ANY;
2433 mtx_unlock(&nblock);
2434 }
2435
2436 VI_LOCK(vp);
2437 if ((bp = gbincore(vp, blkno))) {
2438 int lockflags;
2439 /*
2440 * Buffer is in-core. If the buffer is not busy, it must
2441 * be on a queue.
2442 */
2443 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2444
2445 if (flags & GB_LOCK_NOWAIT)
2446 lockflags |= LK_NOWAIT;
2447
2448 error = BUF_TIMELOCK(bp, lockflags,
2449 VI_MTX(vp), "getblk", slpflag, slptimeo);
2450
2451 /*
2452 * If we slept and got the lock we have to restart in case
2453 * the buffer changed identities.
2454 */
2455 if (error == ENOLCK)
2456 goto loop;
2457 /* We timed out or were interrupted. */
2458 else if (error)
2459 return (NULL);
2460
2461 /*
2462 * The buffer is locked. B_CACHE is cleared if the buffer is
2463 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2464 * and for a VMIO buffer B_CACHE is adjusted according to the
2465 * backing VM cache.
2466 */
2467 if (bp->b_flags & B_INVAL)
2468 bp->b_flags &= ~B_CACHE;
2469 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2470 bp->b_flags |= B_CACHE;
2471 bremfree(bp);
2472
2473 /*
2474 * check for size inconsistancies for non-VMIO case.
2475 */
2476
2477 if (bp->b_bcount != size) {
2478 if ((bp->b_flags & B_VMIO) == 0 ||
2479 (size > bp->b_kvasize)) {
2480 if (bp->b_flags & B_DELWRI) {
2481 bp->b_flags |= B_NOCACHE;
2482 bwrite(bp);
2483 } else {
2484 if ((bp->b_flags & B_VMIO) &&
2485 (LIST_FIRST(&bp->b_dep) == NULL)) {
2486 bp->b_flags |= B_RELBUF;
2487 brelse(bp);
2488 } else {
2489 bp->b_flags |= B_NOCACHE;
2490 bwrite(bp);
2491 }
2492 }
2493 goto loop;
2494 }
2495 }
2496
2497 /*
2498 * If the size is inconsistant in the VMIO case, we can resize
2499 * the buffer. This might lead to B_CACHE getting set or
2500 * cleared. If the size has not changed, B_CACHE remains
2501 * unchanged from its previous state.
2502 */
2503
2504 if (bp->b_bcount != size)
2505 allocbuf(bp, size);
2506
2507 KASSERT(bp->b_offset != NOOFFSET,
2508 ("getblk: no buffer offset"));
2509
2510 /*
2511 * A buffer with B_DELWRI set and B_CACHE clear must
2512 * be committed before we can return the buffer in
2513 * order to prevent the caller from issuing a read
2514 * ( due to B_CACHE not being set ) and overwriting
2515 * it.
2516 *
2517 * Most callers, including NFS and FFS, need this to
2518 * operate properly either because they assume they
2519 * can issue a read if B_CACHE is not set, or because
2520 * ( for example ) an uncached B_DELWRI might loop due
2521 * to softupdates re-dirtying the buffer. In the latter
2522 * case, B_CACHE is set after the first write completes,
2523 * preventing further loops.
2524 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2525 * above while extending the buffer, we cannot allow the
2526 * buffer to remain with B_CACHE set after the write
2527 * completes or it will represent a corrupt state. To
2528 * deal with this we set B_NOCACHE to scrap the buffer
2529 * after the write.
2530 *
2531 * We might be able to do something fancy, like setting
2532 * B_CACHE in bwrite() except if B_DELWRI is already set,
2533 * so the below call doesn't set B_CACHE, but that gets real
2534 * confusing. This is much easier.
2535 */
2536
2537 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2538 bp->b_flags |= B_NOCACHE;
2539 bwrite(bp);
2540 goto loop;
2541 }
2542
2543 splx(s);
2544 bp->b_flags &= ~B_DONE;
2545 } else {
2546 int bsize, maxsize, vmio;
2547 off_t offset;
2548
2549 /*
2550 * Buffer is not in-core, create new buffer. The buffer
2551 * returned by getnewbuf() is locked. Note that the returned
2552 * buffer is also considered valid (not marked B_INVAL).
2553 */
2554 VI_UNLOCK(vp);
2555 /*
2556 * If the user does not want us to create the buffer, bail out
2557 * here.
2558 */
2559 if (flags & GB_NOCREAT) {
2560 splx(s);
2561 return NULL;
2562 }
2563 if (vn_isdisk(vp, NULL))
2564 bsize = DEV_BSIZE;
2565 else if (vp->v_mountedhere)
2566 bsize = vp->v_mountedhere->mnt_stat.f_iosize;
2567 else if (vp->v_mount)
2568 bsize = vp->v_mount->mnt_stat.f_iosize;
2569 else
2570 bsize = size;
2571
2572 if (vp->v_bsize != bsize) {
2573 #if 0
2574 printf("WARNING: Wrong block size on vnode: %d should be %d\n", vp->v_bsize, bsize);
2575 #endif
2576 vp->v_bsize = bsize;
2577 }
2578
2579 offset = blkno * bsize;
2580 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) &&
2581 (vp->v_vflag & VV_OBJBUF);
2582 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2583 maxsize = imax(maxsize, bsize);
2584
2585 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) {
2586 if (slpflag || slptimeo) {
2587 splx(s);
2588 return NULL;
2589 }
2590 goto loop;
2591 }
2592
2593 /*
2594 * This code is used to make sure that a buffer is not
2595 * created while the getnewbuf routine is blocked.
2596 * This can be a problem whether the vnode is locked or not.
2597 * If the buffer is created out from under us, we have to
2598 * throw away the one we just created. There is now window
2599 * race because we are safely running at splbio() from the
2600 * point of the duplicate buffer creation through to here,
2601 * and we've locked the buffer.
2602 *
2603 * Note: this must occur before we associate the buffer
2604 * with the vp especially considering limitations in
2605 * the splay tree implementation when dealing with duplicate
2606 * lblkno's.
2607 */
2608 VI_LOCK(vp);
2609 if (gbincore(vp, blkno)) {
2610 VI_UNLOCK(vp);
2611 bp->b_flags |= B_INVAL;
2612 brelse(bp);
2613 goto loop;
2614 }
2615
2616 /*
2617 * Insert the buffer into the hash, so that it can
2618 * be found by incore.
2619 */
2620 bp->b_blkno = bp->b_lblkno = blkno;
2621 bp->b_offset = offset;
2622
2623 bgetvp(vp, bp);
2624 VI_UNLOCK(vp);
2625
2626 /*
2627 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2628 * buffer size starts out as 0, B_CACHE will be set by
2629 * allocbuf() for the VMIO case prior to it testing the
2630 * backing store for validity.
2631 */
2632
2633 if (vmio) {
2634 bp->b_flags |= B_VMIO;
2635 #if defined(VFS_BIO_DEBUG)
2636 if (vn_canvmio(vp) != TRUE)
2637 printf("getblk: VMIO on vnode type %d\n",
2638 vp->v_type);
2639 #endif
2640 VOP_GETVOBJECT(vp, &bp->b_object);
2641 } else {
2642 bp->b_flags &= ~B_VMIO;
2643 bp->b_object = NULL;
2644 }
2645
2646 allocbuf(bp, size);
2647
2648 splx(s);
2649 bp->b_flags &= ~B_DONE;
2650 }
2651 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
2652 return (bp);
2653 }
2654
2655 /*
2656 * Get an empty, disassociated buffer of given size. The buffer is initially
2657 * set to B_INVAL.
2658 */
2659 struct buf *
2660 geteblk(int size)
2661 {
2662 struct buf *bp;
2663 int s;
2664 int maxsize;
2665
2666 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2667
2668 s = splbio();
2669 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
2670 continue;
2671 splx(s);
2672 allocbuf(bp, size);
2673 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2674 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
2675 return (bp);
2676 }
2677
2678
2679 /*
2680 * This code constitutes the buffer memory from either anonymous system
2681 * memory (in the case of non-VMIO operations) or from an associated
2682 * VM object (in the case of VMIO operations). This code is able to
2683 * resize a buffer up or down.
2684 *
2685 * Note that this code is tricky, and has many complications to resolve
2686 * deadlock or inconsistant data situations. Tread lightly!!!
2687 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2688 * the caller. Calling this code willy nilly can result in the loss of data.
2689 *
2690 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2691 * B_CACHE for the non-VMIO case.
2692 */
2693
2694 int
2695 allocbuf(struct buf *bp, int size)
2696 {
2697 int newbsize, mbsize;
2698 int i;
2699
2700 GIANT_REQUIRED;
2701
2702 if (BUF_REFCNT(bp) == 0)
2703 panic("allocbuf: buffer not busy");
2704
2705 if (bp->b_kvasize < size)
2706 panic("allocbuf: buffer too small");
2707
2708 if ((bp->b_flags & B_VMIO) == 0) {
2709 caddr_t origbuf;
2710 int origbufsize;
2711 /*
2712 * Just get anonymous memory from the kernel. Don't
2713 * mess with B_CACHE.
2714 */
2715 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2716 if (bp->b_flags & B_MALLOC)
2717 newbsize = mbsize;
2718 else
2719 newbsize = round_page(size);
2720
2721 if (newbsize < bp->b_bufsize) {
2722 /*
2723 * malloced buffers are not shrunk
2724 */
2725 if (bp->b_flags & B_MALLOC) {
2726 if (newbsize) {
2727 bp->b_bcount = size;
2728 } else {
2729 free(bp->b_data, M_BIOBUF);
2730 if (bp->b_bufsize) {
2731 atomic_subtract_int(
2732 &bufmallocspace,
2733 bp->b_bufsize);
2734 bufspacewakeup();
2735 bp->b_bufsize = 0;
2736 }
2737 bp->b_saveaddr = bp->b_kvabase;
2738 bp->b_data = bp->b_saveaddr;
2739 bp->b_bcount = 0;
2740 bp->b_flags &= ~B_MALLOC;
2741 }
2742 return 1;
2743 }
2744 vm_hold_free_pages(
2745 bp,
2746 (vm_offset_t) bp->b_data + newbsize,
2747 (vm_offset_t) bp->b_data + bp->b_bufsize);
2748 } else if (newbsize > bp->b_bufsize) {
2749 /*
2750 * We only use malloced memory on the first allocation.
2751 * and revert to page-allocated memory when the buffer
2752 * grows.
2753 */
2754 /*
2755 * There is a potential smp race here that could lead
2756 * to bufmallocspace slightly passing the max. It
2757 * is probably extremely rare and not worth worrying
2758 * over.
2759 */
2760 if ( (bufmallocspace < maxbufmallocspace) &&
2761 (bp->b_bufsize == 0) &&
2762 (mbsize <= PAGE_SIZE/2)) {
2763
2764 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2765 bp->b_bufsize = mbsize;
2766 bp->b_bcount = size;
2767 bp->b_flags |= B_MALLOC;
2768 atomic_add_int(&bufmallocspace, mbsize);
2769 return 1;
2770 }
2771 origbuf = NULL;
2772 origbufsize = 0;
2773 /*
2774 * If the buffer is growing on its other-than-first allocation,
2775 * then we revert to the page-allocation scheme.
2776 */
2777 if (bp->b_flags & B_MALLOC) {
2778 origbuf = bp->b_data;
2779 origbufsize = bp->b_bufsize;
2780 bp->b_data = bp->b_kvabase;
2781 if (bp->b_bufsize) {
2782 atomic_subtract_int(&bufmallocspace,
2783 bp->b_bufsize);
2784 bufspacewakeup();
2785 bp->b_bufsize = 0;
2786 }
2787 bp->b_flags &= ~B_MALLOC;
2788 newbsize = round_page(newbsize);
2789 }
2790 vm_hold_load_pages(
2791 bp,
2792 (vm_offset_t) bp->b_data + bp->b_bufsize,
2793 (vm_offset_t) bp->b_data + newbsize);
2794 if (origbuf) {
2795 bcopy(origbuf, bp->b_data, origbufsize);
2796 free(origbuf, M_BIOBUF);
2797 }
2798 }
2799 } else {
2800 int desiredpages;
2801
2802 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2803 desiredpages = (size == 0) ? 0 :
2804 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2805
2806 if (bp->b_flags & B_MALLOC)
2807 panic("allocbuf: VMIO buffer can't be malloced");
2808 /*
2809 * Set B_CACHE initially if buffer is 0 length or will become
2810 * 0-length.
2811 */
2812 if (size == 0 || bp->b_bufsize == 0)
2813 bp->b_flags |= B_CACHE;
2814
2815 if (newbsize < bp->b_bufsize) {
2816 /*
2817 * DEV_BSIZE aligned new buffer size is less then the
2818 * DEV_BSIZE aligned existing buffer size. Figure out
2819 * if we have to remove any pages.
2820 */
2821 if (desiredpages < bp->b_npages) {
2822 vm_page_t m;
2823
2824 VM_OBJECT_LOCK(bp->b_object);
2825 vm_page_lock_queues();
2826 for (i = desiredpages; i < bp->b_npages; i++) {
2827 /*
2828 * the page is not freed here -- it
2829 * is the responsibility of
2830 * vnode_pager_setsize
2831 */
2832 m = bp->b_pages[i];
2833 KASSERT(m != bogus_page,
2834 ("allocbuf: bogus page found"));
2835 while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
2836 vm_page_lock_queues();
2837
2838 bp->b_pages[i] = NULL;
2839 vm_page_unwire(m, 0);
2840 }
2841 vm_page_unlock_queues();
2842 VM_OBJECT_UNLOCK(bp->b_object);
2843 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2844 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
2845 bp->b_npages = desiredpages;
2846 }
2847 } else if (size > bp->b_bcount) {
2848 /*
2849 * We are growing the buffer, possibly in a
2850 * byte-granular fashion.
2851 */
2852 struct vnode *vp;
2853 vm_object_t obj;
2854 vm_offset_t toff;
2855 vm_offset_t tinc;
2856
2857 /*
2858 * Step 1, bring in the VM pages from the object,
2859 * allocating them if necessary. We must clear
2860 * B_CACHE if these pages are not valid for the
2861 * range covered by the buffer.
2862 */
2863
2864 vp = bp->b_vp;
2865 obj = bp->b_object;
2866
2867 VM_OBJECT_LOCK(obj);
2868 while (bp->b_npages < desiredpages) {
2869 vm_page_t m;
2870 vm_pindex_t pi;
2871
2872 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
2873 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2874 /*
2875 * note: must allocate system pages
2876 * since blocking here could intefere
2877 * with paging I/O, no matter which
2878 * process we are.
2879 */
2880 m = vm_page_alloc(obj, pi,
2881 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
2882 VM_ALLOC_WIRED);
2883 if (m == NULL) {
2884 atomic_add_int(&vm_pageout_deficit,
2885 desiredpages - bp->b_npages);
2886 VM_OBJECT_UNLOCK(obj);
2887 VM_WAIT;
2888 VM_OBJECT_LOCK(obj);
2889 } else {
2890 bp->b_flags &= ~B_CACHE;
2891 bp->b_pages[bp->b_npages] = m;
2892 ++bp->b_npages;
2893 }
2894 continue;
2895 }
2896
2897 /*
2898 * We found a page. If we have to sleep on it,
2899 * retry because it might have gotten freed out
2900 * from under us.
2901 *
2902 * We can only test PG_BUSY here. Blocking on
2903 * m->busy might lead to a deadlock:
2904 *
2905 * vm_fault->getpages->cluster_read->allocbuf
2906 *
2907 */
2908 vm_page_lock_queues();
2909 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
2910 continue;
2911
2912 /*
2913 * We have a good page. Should we wakeup the
2914 * page daemon?
2915 */
2916 if ((curproc != pageproc) &&
2917 ((m->queue - m->pc) == PQ_CACHE) &&
2918 ((cnt.v_free_count + cnt.v_cache_count) <
2919 (cnt.v_free_min + cnt.v_cache_min))) {
2920 pagedaemon_wakeup();
2921 }
2922 vm_page_wire(m);
2923 vm_page_unlock_queues();
2924 bp->b_pages[bp->b_npages] = m;
2925 ++bp->b_npages;
2926 }
2927
2928 /*
2929 * Step 2. We've loaded the pages into the buffer,
2930 * we have to figure out if we can still have B_CACHE
2931 * set. Note that B_CACHE is set according to the
2932 * byte-granular range ( bcount and size ), new the
2933 * aligned range ( newbsize ).
2934 *
2935 * The VM test is against m->valid, which is DEV_BSIZE
2936 * aligned. Needless to say, the validity of the data
2937 * needs to also be DEV_BSIZE aligned. Note that this
2938 * fails with NFS if the server or some other client
2939 * extends the file's EOF. If our buffer is resized,
2940 * B_CACHE may remain set! XXX
2941 */
2942
2943 toff = bp->b_bcount;
2944 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2945
2946 while ((bp->b_flags & B_CACHE) && toff < size) {
2947 vm_pindex_t pi;
2948
2949 if (tinc > (size - toff))
2950 tinc = size - toff;
2951
2952 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2953 PAGE_SHIFT;
2954
2955 vfs_buf_test_cache(
2956 bp,
2957 bp->b_offset,
2958 toff,
2959 tinc,
2960 bp->b_pages[pi]
2961 );
2962 toff += tinc;
2963 tinc = PAGE_SIZE;
2964 }
2965 VM_OBJECT_UNLOCK(obj);
2966
2967 /*
2968 * Step 3, fixup the KVM pmap. Remember that
2969 * bp->b_data is relative to bp->b_offset, but
2970 * bp->b_offset may be offset into the first page.
2971 */
2972
2973 bp->b_data = (caddr_t)
2974 trunc_page((vm_offset_t)bp->b_data);
2975 pmap_qenter(
2976 (vm_offset_t)bp->b_data,
2977 bp->b_pages,
2978 bp->b_npages
2979 );
2980
2981 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2982 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2983 }
2984 }
2985 if (newbsize < bp->b_bufsize)
2986 bufspacewakeup();
2987 bp->b_bufsize = newbsize; /* actual buffer allocation */
2988 bp->b_bcount = size; /* requested buffer size */
2989 return 1;
2990 }
2991
2992 void
2993 biodone(struct bio *bp)
2994 {
2995 mtx_lock(&bdonelock);
2996 bp->bio_flags |= BIO_DONE;
2997 if (bp->bio_done == NULL)
2998 wakeup(bp);
2999 mtx_unlock(&bdonelock);
3000 if (bp->bio_done != NULL)
3001 bp->bio_done(bp);
3002 }
3003
3004 /*
3005 * Wait for a BIO to finish.
3006 *
3007 * XXX: resort to a timeout for now. The optimal locking (if any) for this
3008 * case is not yet clear.
3009 */
3010 int
3011 biowait(struct bio *bp, const char *wchan)
3012 {
3013
3014 mtx_lock(&bdonelock);
3015 while ((bp->bio_flags & BIO_DONE) == 0)
3016 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
3017 mtx_unlock(&bdonelock);
3018 if (bp->bio_error != 0)
3019 return (bp->bio_error);
3020 if (!(bp->bio_flags & BIO_ERROR))
3021 return (0);
3022 return (EIO);
3023 }
3024
3025 void
3026 biofinish(struct bio *bp, struct devstat *stat, int error)
3027 {
3028
3029 if (error) {
3030 bp->bio_error = error;
3031 bp->bio_flags |= BIO_ERROR;
3032 }
3033 if (stat != NULL)
3034 devstat_end_transaction_bio(stat, bp);
3035 biodone(bp);
3036 }
3037
3038 /*
3039 * bufwait:
3040 *
3041 * Wait for buffer I/O completion, returning error status. The buffer
3042 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3043 * error and cleared.
3044 */
3045 int
3046 bufwait(register struct buf * bp)
3047 {
3048 int s;
3049
3050 s = splbio();
3051 if (bp->b_iocmd == BIO_READ)
3052 bwait(bp, PRIBIO, "biord");
3053 else
3054 bwait(bp, PRIBIO, "biowr");
3055 splx(s);
3056 if (bp->b_flags & B_EINTR) {
3057 bp->b_flags &= ~B_EINTR;
3058 return (EINTR);
3059 }
3060 if (bp->b_ioflags & BIO_ERROR) {
3061 return (bp->b_error ? bp->b_error : EIO);
3062 } else {
3063 return (0);
3064 }
3065 }
3066
3067 /*
3068 * Call back function from struct bio back up to struct buf.
3069 */
3070 static void
3071 bufdonebio(struct bio *bp)
3072 {
3073
3074 /* Device drivers may or may not hold giant, hold it here. */
3075 mtx_lock(&Giant);
3076 bufdone(bp->bio_caller2);
3077 mtx_unlock(&Giant);
3078 }
3079
3080 void
3081 dev_strategy(struct buf *bp)
3082 {
3083 struct cdevsw *csw;
3084
3085 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
3086 panic("b_iocmd botch");
3087 bp->b_io.bio_done = bufdonebio;
3088 bp->b_io.bio_caller2 = bp;
3089 csw = devsw(bp->b_io.bio_dev);
3090 KASSERT(bp->b_io.bio_dev->si_refcount > 0,
3091 ("dev_strategy on un-referenced struct cdev *(%s)",
3092 devtoname(bp->b_io.bio_dev)));
3093 cdevsw_ref(csw);
3094 (*devsw(bp->b_io.bio_dev)->d_strategy)(&bp->b_io);
3095 cdevsw_rel(csw);
3096 }
3097
3098 /*
3099 * bufdone:
3100 *
3101 * Finish I/O on a buffer, optionally calling a completion function.
3102 * This is usually called from an interrupt so process blocking is
3103 * not allowed.
3104 *
3105 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3106 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3107 * assuming B_INVAL is clear.
3108 *
3109 * For the VMIO case, we set B_CACHE if the op was a read and no
3110 * read error occured, or if the op was a write. B_CACHE is never
3111 * set if the buffer is invalid or otherwise uncacheable.
3112 *
3113 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3114 * initiator to leave B_INVAL set to brelse the buffer out of existance
3115 * in the biodone routine.
3116 */
3117 void
3118 bufdone(struct buf *bp)
3119 {
3120 int s;
3121 void (*biodone)(struct buf *);
3122
3123
3124 s = splbio();
3125
3126 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp)));
3127 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3128
3129 bp->b_flags |= B_DONE;
3130 runningbufwakeup(bp);
3131
3132 if (bp->b_iocmd == BIO_DELETE) {
3133 brelse(bp);
3134 splx(s);
3135 return;
3136 }
3137
3138 if (bp->b_iocmd == BIO_WRITE) {
3139 vwakeup(bp);
3140 }
3141
3142 /* call optional completion function if requested */
3143 if (bp->b_iodone != NULL) {
3144 biodone = bp->b_iodone;
3145 bp->b_iodone = NULL;
3146 (*biodone) (bp);
3147 splx(s);
3148 return;
3149 }
3150 if (LIST_FIRST(&bp->b_dep) != NULL)
3151 buf_complete(bp);
3152
3153 if (bp->b_flags & B_VMIO) {
3154 int i;
3155 vm_ooffset_t foff;
3156 vm_page_t m;
3157 vm_object_t obj;
3158 int iosize;
3159 struct vnode *vp = bp->b_vp;
3160
3161 obj = bp->b_object;
3162
3163 #if defined(VFS_BIO_DEBUG)
3164 mp_fixme("usecount and vflag accessed without locks.");
3165 if (vp->v_usecount == 0) {
3166 panic("biodone: zero vnode ref count");
3167 }
3168
3169 if ((vp->v_vflag & VV_OBJBUF) == 0) {
3170 panic("biodone: vnode is not setup for merged cache");
3171 }
3172 #endif
3173
3174 foff = bp->b_offset;
3175 KASSERT(bp->b_offset != NOOFFSET,
3176 ("biodone: no buffer offset"));
3177
3178 VM_OBJECT_LOCK(obj);
3179 #if defined(VFS_BIO_DEBUG)
3180 if (obj->paging_in_progress < bp->b_npages) {
3181 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
3182 obj->paging_in_progress, bp->b_npages);
3183 }
3184 #endif
3185
3186 /*
3187 * Set B_CACHE if the op was a normal read and no error
3188 * occured. B_CACHE is set for writes in the b*write()
3189 * routines.
3190 */
3191 iosize = bp->b_bcount - bp->b_resid;
3192 if (bp->b_iocmd == BIO_READ &&
3193 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3194 !(bp->b_ioflags & BIO_ERROR)) {
3195 bp->b_flags |= B_CACHE;
3196 }
3197 vm_page_lock_queues();
3198 for (i = 0; i < bp->b_npages; i++) {
3199 int bogusflag = 0;
3200 int resid;
3201
3202 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3203 if (resid > iosize)
3204 resid = iosize;
3205
3206 /*
3207 * cleanup bogus pages, restoring the originals
3208 */
3209 m = bp->b_pages[i];
3210 if (m == bogus_page) {
3211 bogusflag = 1;
3212 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3213 if (m == NULL)
3214 panic("biodone: page disappeared!");
3215 bp->b_pages[i] = m;
3216 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3217 }
3218 #if defined(VFS_BIO_DEBUG)
3219 if (OFF_TO_IDX(foff) != m->pindex) {
3220 printf(
3221 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
3222 (intmax_t)foff, (uintmax_t)m->pindex);
3223 }
3224 #endif
3225
3226 /*
3227 * In the write case, the valid and clean bits are
3228 * already changed correctly ( see bdwrite() ), so we
3229 * only need to do this here in the read case.
3230 */
3231 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3232 vfs_page_set_valid(bp, foff, i, m);
3233 }
3234
3235 /*
3236 * when debugging new filesystems or buffer I/O methods, this
3237 * is the most common error that pops up. if you see this, you
3238 * have not set the page busy flag correctly!!!
3239 */
3240 if (m->busy == 0) {
3241 printf("biodone: page busy < 0, "
3242 "pindex: %d, foff: 0x(%x,%x), "
3243 "resid: %d, index: %d\n",
3244 (int) m->pindex, (int)(foff >> 32),
3245 (int) foff & 0xffffffff, resid, i);
3246 if (!vn_isdisk(vp, NULL))
3247 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
3248 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
3249 (intmax_t) bp->b_lblkno,
3250 bp->b_flags, bp->b_npages);
3251 else
3252 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
3253 (intmax_t) bp->b_lblkno,
3254 bp->b_flags, bp->b_npages);
3255 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
3256 (u_long)m->valid, (u_long)m->dirty,
3257 m->wire_count);
3258 panic("biodone: page busy < 0\n");
3259 }
3260 vm_page_io_finish(m);
3261 vm_object_pip_subtract(obj, 1);
3262 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3263 iosize -= resid;
3264 }
3265 vm_page_unlock_queues();
3266 vm_object_pip_wakeupn(obj, 0);
3267 VM_OBJECT_UNLOCK(obj);
3268 }
3269
3270 /*
3271 * For asynchronous completions, release the buffer now. The brelse
3272 * will do a wakeup there if necessary - so no need to do a wakeup
3273 * here in the async case. The sync case always needs to do a wakeup.
3274 */
3275
3276 if (bp->b_flags & B_ASYNC) {
3277 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3278 brelse(bp);
3279 else
3280 bqrelse(bp);
3281 } else {
3282 bdone(bp);
3283 }
3284 splx(s);
3285 }
3286
3287 /*
3288 * This routine is called in lieu of iodone in the case of
3289 * incomplete I/O. This keeps the busy status for pages
3290 * consistant.
3291 */
3292 void
3293 vfs_unbusy_pages(struct buf * bp)
3294 {
3295 int i;
3296
3297 runningbufwakeup(bp);
3298 if (bp->b_flags & B_VMIO) {
3299 vm_object_t obj;
3300
3301 obj = bp->b_object;
3302 VM_OBJECT_LOCK(obj);
3303 vm_page_lock_queues();
3304 for (i = 0; i < bp->b_npages; i++) {
3305 vm_page_t m = bp->b_pages[i];
3306
3307 if (m == bogus_page) {
3308 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3309 if (!m) {
3310 panic("vfs_unbusy_pages: page missing\n");
3311 }
3312 bp->b_pages[i] = m;
3313 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3314 }
3315 vm_object_pip_subtract(obj, 1);
3316 vm_page_io_finish(m);
3317 }
3318 vm_page_unlock_queues();
3319 vm_object_pip_wakeupn(obj, 0);
3320 VM_OBJECT_UNLOCK(obj);
3321 }
3322 }
3323
3324 /*
3325 * vfs_page_set_valid:
3326 *
3327 * Set the valid bits in a page based on the supplied offset. The
3328 * range is restricted to the buffer's size.
3329 *
3330 * This routine is typically called after a read completes.
3331 */
3332 static void
3333 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3334 {
3335 vm_ooffset_t soff, eoff;
3336
3337 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
3338 /*
3339 * Start and end offsets in buffer. eoff - soff may not cross a
3340 * page boundry or cross the end of the buffer. The end of the
3341 * buffer, in this case, is our file EOF, not the allocation size
3342 * of the buffer.
3343 */
3344 soff = off;
3345 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3346 if (eoff > bp->b_offset + bp->b_bcount)
3347 eoff = bp->b_offset + bp->b_bcount;
3348
3349 /*
3350 * Set valid range. This is typically the entire buffer and thus the
3351 * entire page.
3352 */
3353 if (eoff > soff) {
3354 vm_page_set_validclean(
3355 m,
3356 (vm_offset_t) (soff & PAGE_MASK),
3357 (vm_offset_t) (eoff - soff)
3358 );
3359 }
3360 }
3361
3362 /*
3363 * This routine is called before a device strategy routine.
3364 * It is used to tell the VM system that paging I/O is in
3365 * progress, and treat the pages associated with the buffer
3366 * almost as being PG_BUSY. Also the object paging_in_progress
3367 * flag is handled to make sure that the object doesn't become
3368 * inconsistant.
3369 *
3370 * Since I/O has not been initiated yet, certain buffer flags
3371 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3372 * and should be ignored.
3373 */
3374 void
3375 vfs_busy_pages(struct buf * bp, int clear_modify)
3376 {
3377 int i, bogus;
3378
3379 if (bp->b_flags & B_VMIO) {
3380 vm_object_t obj;
3381 vm_ooffset_t foff;
3382
3383 obj = bp->b_object;
3384 foff = bp->b_offset;
3385 KASSERT(bp->b_offset != NOOFFSET,
3386 ("vfs_busy_pages: no buffer offset"));
3387 vfs_setdirty(bp);
3388 VM_OBJECT_LOCK(obj);
3389 retry:
3390 vm_page_lock_queues();
3391 for (i = 0; i < bp->b_npages; i++) {
3392 vm_page_t m = bp->b_pages[i];
3393
3394 if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
3395 goto retry;
3396 }
3397 bogus = 0;
3398 for (i = 0; i < bp->b_npages; i++) {
3399 vm_page_t m = bp->b_pages[i];
3400
3401 if ((bp->b_flags & B_CLUSTER) == 0) {
3402 vm_object_pip_add(obj, 1);
3403 vm_page_io_start(m);
3404 }
3405 /*
3406 * When readying a buffer for a read ( i.e
3407 * clear_modify == 0 ), it is important to do
3408 * bogus_page replacement for valid pages in
3409 * partially instantiated buffers. Partially
3410 * instantiated buffers can, in turn, occur when
3411 * reconstituting a buffer from its VM backing store
3412 * base. We only have to do this if B_CACHE is
3413 * clear ( which causes the I/O to occur in the
3414 * first place ). The replacement prevents the read
3415 * I/O from overwriting potentially dirty VM-backed
3416 * pages. XXX bogus page replacement is, uh, bogus.
3417 * It may not work properly with small-block devices.
3418 * We need to find a better way.
3419 */
3420 pmap_remove_all(m);
3421 if (clear_modify)
3422 vfs_page_set_valid(bp, foff, i, m);
3423 else if (m->valid == VM_PAGE_BITS_ALL &&
3424 (bp->b_flags & B_CACHE) == 0) {
3425 bp->b_pages[i] = bogus_page;
3426 bogus++;
3427 }
3428 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3429 }
3430 vm_page_unlock_queues();
3431 VM_OBJECT_UNLOCK(obj);
3432 if (bogus)
3433 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3434 }
3435 }
3436
3437 /*
3438 * Tell the VM system that the pages associated with this buffer
3439 * are clean. This is used for delayed writes where the data is
3440 * going to go to disk eventually without additional VM intevention.
3441 *
3442 * Note that while we only really need to clean through to b_bcount, we
3443 * just go ahead and clean through to b_bufsize.
3444 */
3445 static void
3446 vfs_clean_pages(struct buf * bp)
3447 {
3448 int i;
3449
3450 if (bp->b_flags & B_VMIO) {
3451 vm_ooffset_t foff;
3452
3453 foff = bp->b_offset;
3454 KASSERT(bp->b_offset != NOOFFSET,
3455 ("vfs_clean_pages: no buffer offset"));
3456 VM_OBJECT_LOCK(bp->b_object);
3457 vm_page_lock_queues();
3458 for (i = 0; i < bp->b_npages; i++) {
3459 vm_page_t m = bp->b_pages[i];
3460 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3461 vm_ooffset_t eoff = noff;
3462
3463 if (eoff > bp->b_offset + bp->b_bufsize)
3464 eoff = bp->b_offset + bp->b_bufsize;
3465 vfs_page_set_valid(bp, foff, i, m);
3466 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3467 foff = noff;
3468 }
3469 vm_page_unlock_queues();
3470 VM_OBJECT_UNLOCK(bp->b_object);
3471 }
3472 }
3473
3474 /*
3475 * vfs_bio_set_validclean:
3476 *
3477 * Set the range within the buffer to valid and clean. The range is
3478 * relative to the beginning of the buffer, b_offset. Note that b_offset
3479 * itself may be offset from the beginning of the first page.
3480 *
3481 */
3482
3483 void
3484 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3485 {
3486 if (bp->b_flags & B_VMIO) {
3487 int i;
3488 int n;
3489
3490 /*
3491 * Fixup base to be relative to beginning of first page.
3492 * Set initial n to be the maximum number of bytes in the
3493 * first page that can be validated.
3494 */
3495
3496 base += (bp->b_offset & PAGE_MASK);
3497 n = PAGE_SIZE - (base & PAGE_MASK);
3498
3499 VM_OBJECT_LOCK(bp->b_object);
3500 vm_page_lock_queues();
3501 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3502 vm_page_t m = bp->b_pages[i];
3503
3504 if (n > size)
3505 n = size;
3506
3507 vm_page_set_validclean(m, base & PAGE_MASK, n);
3508 base += n;
3509 size -= n;
3510 n = PAGE_SIZE;
3511 }
3512 vm_page_unlock_queues();
3513 VM_OBJECT_UNLOCK(bp->b_object);
3514 }
3515 }
3516
3517 /*
3518 * vfs_bio_clrbuf:
3519 *
3520 * clear a buffer. This routine essentially fakes an I/O, so we need
3521 * to clear BIO_ERROR and B_INVAL.
3522 *
3523 * Note that while we only theoretically need to clear through b_bcount,
3524 * we go ahead and clear through b_bufsize.
3525 */
3526
3527 void
3528 vfs_bio_clrbuf(struct buf *bp)
3529 {
3530 int i, j, mask = 0;
3531 caddr_t sa, ea;
3532
3533 GIANT_REQUIRED;
3534
3535 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) {
3536 bp->b_flags &= ~B_INVAL;
3537 bp->b_ioflags &= ~BIO_ERROR;
3538 VM_OBJECT_LOCK(bp->b_object);
3539 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3540 (bp->b_offset & PAGE_MASK) == 0) {
3541 if (bp->b_pages[0] == bogus_page)
3542 goto unlock;
3543 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3544 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3545 if ((bp->b_pages[0]->valid & mask) == mask)
3546 goto unlock;
3547 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
3548 ((bp->b_pages[0]->valid & mask) == 0)) {
3549 bzero(bp->b_data, bp->b_bufsize);
3550 bp->b_pages[0]->valid |= mask;
3551 goto unlock;
3552 }
3553 }
3554 ea = sa = bp->b_data;
3555 for(i=0;i<bp->b_npages;i++,sa=ea) {
3556 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3557 ea = (caddr_t)(vm_offset_t)ulmin(
3558 (u_long)(vm_offset_t)ea,
3559 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3560 if (bp->b_pages[i] == bogus_page)
3561 continue;
3562 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3563 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3564 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3565 if ((bp->b_pages[i]->valid & mask) == mask)
3566 continue;
3567 if ((bp->b_pages[i]->valid & mask) == 0) {
3568 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) {
3569 bzero(sa, ea - sa);
3570 }
3571 } else {
3572 for (; sa < ea; sa += DEV_BSIZE, j++) {
3573 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
3574 (bp->b_pages[i]->valid & (1<<j)) == 0)
3575 bzero(sa, DEV_BSIZE);
3576 }
3577 }
3578 bp->b_pages[i]->valid |= mask;
3579 }
3580 unlock:
3581 VM_OBJECT_UNLOCK(bp->b_object);
3582 bp->b_resid = 0;
3583 } else {
3584 clrbuf(bp);
3585 }
3586 }
3587
3588 /*
3589 * vm_hold_load_pages and vm_hold_free_pages get pages into
3590 * a buffers address space. The pages are anonymous and are
3591 * not associated with a file object.
3592 */
3593 static void
3594 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to)
3595 {
3596 vm_offset_t pg;
3597 vm_page_t p;
3598 int index;
3599
3600 to = round_page(to);
3601 from = round_page(from);
3602 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3603
3604 VM_OBJECT_LOCK(kernel_object);
3605 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3606 tryagain:
3607 /*
3608 * note: must allocate system pages since blocking here
3609 * could intefere with paging I/O, no matter which
3610 * process we are.
3611 */
3612 p = vm_page_alloc(kernel_object,
3613 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3614 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
3615 if (!p) {
3616 atomic_add_int(&vm_pageout_deficit,
3617 (to - pg) >> PAGE_SHIFT);
3618 VM_OBJECT_UNLOCK(kernel_object);
3619 VM_WAIT;
3620 VM_OBJECT_LOCK(kernel_object);
3621 goto tryagain;
3622 }
3623 p->valid = VM_PAGE_BITS_ALL;
3624 pmap_qenter(pg, &p, 1);
3625 bp->b_pages[index] = p;
3626 }
3627 VM_OBJECT_UNLOCK(kernel_object);
3628 bp->b_npages = index;
3629 }
3630
3631 /* Return pages associated with this buf to the vm system */
3632 static void
3633 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to)
3634 {
3635 vm_offset_t pg;
3636 vm_page_t p;
3637 int index, newnpages;
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_unwire(p, 0);
3657 vm_page_free(p);
3658 vm_page_unlock_queues();
3659 }
3660 }
3661 VM_OBJECT_UNLOCK(kernel_object);
3662 bp->b_npages = newnpages;
3663 }
3664
3665 /*
3666 * Map an IO request into kernel virtual address space.
3667 *
3668 * All requests are (re)mapped into kernel VA space.
3669 * Notice that we use b_bufsize for the size of the buffer
3670 * to be mapped. b_bcount might be modified by the driver.
3671 *
3672 * Note that even if the caller determines that the address space should
3673 * be valid, a race or a smaller-file mapped into a larger space may
3674 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3675 * check the return value.
3676 */
3677 int
3678 vmapbuf(struct buf *bp)
3679 {
3680 caddr_t addr, kva;
3681 vm_prot_t prot;
3682 int pidx, i;
3683 struct vm_page *m;
3684 struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
3685
3686 if (bp->b_bufsize < 0)
3687 return (-1);
3688 prot = (bp->b_iocmd == BIO_READ) ? VM_PROT_READ | VM_PROT_WRITE :
3689 VM_PROT_READ;
3690 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
3691 addr < bp->b_data + bp->b_bufsize;
3692 addr += PAGE_SIZE, pidx++) {
3693 /*
3694 * Do the vm_fault if needed; do the copy-on-write thing
3695 * when reading stuff off device into memory.
3696 *
3697 * NOTE! Must use pmap_extract() because addr may be in
3698 * the userland address space, and kextract is only guarenteed
3699 * to work for the kernland address space (see: sparc64 port).
3700 */
3701 retry:
3702 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
3703 prot) < 0) {
3704 vm_page_lock_queues();
3705 for (i = 0; i < pidx; ++i) {
3706 vm_page_unhold(bp->b_pages[i]);
3707 bp->b_pages[i] = NULL;
3708 }
3709 vm_page_unlock_queues();
3710 return(-1);
3711 }
3712 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
3713 if (m == NULL)
3714 goto retry;
3715 bp->b_pages[pidx] = m;
3716 }
3717 if (pidx > btoc(MAXPHYS))
3718 panic("vmapbuf: mapped more than MAXPHYS");
3719 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3720
3721 kva = bp->b_saveaddr;
3722 bp->b_npages = pidx;
3723 bp->b_saveaddr = bp->b_data;
3724 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3725 return(0);
3726 }
3727
3728 /*
3729 * Free the io map PTEs associated with this IO operation.
3730 * We also invalidate the TLB entries and restore the original b_addr.
3731 */
3732 void
3733 vunmapbuf(struct buf *bp)
3734 {
3735 int pidx;
3736 int npages;
3737
3738 npages = bp->b_npages;
3739 pmap_qremove(trunc_page((vm_offset_t)bp->b_data),
3740 npages);
3741 vm_page_lock_queues();
3742 for (pidx = 0; pidx < npages; pidx++)
3743 vm_page_unhold(bp->b_pages[pidx]);
3744 vm_page_unlock_queues();
3745
3746 bp->b_data = bp->b_saveaddr;
3747 }
3748
3749 void
3750 bdone(struct buf *bp)
3751 {
3752 mtx_lock(&bdonelock);
3753 bp->b_flags |= B_DONE;
3754 wakeup(bp);
3755 mtx_unlock(&bdonelock);
3756 }
3757
3758 void
3759 bwait(struct buf *bp, u_char pri, const char *wchan)
3760 {
3761 mtx_lock(&bdonelock);
3762 while ((bp->b_flags & B_DONE) == 0)
3763 msleep(bp, &bdonelock, pri, wchan, 0);
3764 mtx_unlock(&bdonelock);
3765 }
3766
3767 #include "opt_ddb.h"
3768 #ifdef DDB
3769 #include <ddb/ddb.h>
3770
3771 /* DDB command to show buffer data */
3772 DB_SHOW_COMMAND(buffer, db_show_buffer)
3773 {
3774 /* get args */
3775 struct buf *bp = (struct buf *)addr;
3776
3777 if (!have_addr) {
3778 db_printf("usage: show buffer <addr>\n");
3779 return;
3780 }
3781
3782 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3783 db_printf(
3784 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
3785 "b_dev = (%d,%d), b_data = %p, b_blkno = %jd\n",
3786 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3787 major(bp->b_dev), minor(bp->b_dev), bp->b_data,
3788 (intmax_t)bp->b_blkno);
3789 if (bp->b_npages) {
3790 int i;
3791 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
3792 for (i = 0; i < bp->b_npages; i++) {
3793 vm_page_t m;
3794 m = bp->b_pages[i];
3795 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3796 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3797 if ((i + 1) < bp->b_npages)
3798 db_printf(",");
3799 }
3800 db_printf("\n");
3801 }
3802 }
3803 #endif /* DDB */
Cache object: 429736c34f29364ff264dfffc3d64765
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