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: releng/5.2/sys/kern/vfs_bio.c 122747 2003-11-15 09:28:09Z phk $");
30
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/bio.h>
34 #include <sys/conf.h>
35 #include <sys/buf.h>
36 #include <sys/devicestat.h>
37 #include <sys/eventhandler.h>
38 #include <sys/lock.h>
39 #include <sys/malloc.h>
40 #include <sys/mount.h>
41 #include <sys/mutex.h>
42 #include <sys/kernel.h>
43 #include <sys/kthread.h>
44 #include <sys/proc.h>
45 #include <sys/resourcevar.h>
46 #include <sys/sysctl.h>
47 #include <sys/vmmeter.h>
48 #include <sys/vnode.h>
49 #include <vm/vm.h>
50 #include <vm/vm_param.h>
51 #include <vm/vm_kern.h>
52 #include <vm/vm_pageout.h>
53 #include <vm/vm_page.h>
54 #include <vm/vm_object.h>
55 #include <vm/vm_extern.h>
56 #include <vm/vm_map.h>
57 #include "opt_directio.h"
58 #include "opt_swap.h"
59
60 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
61
62 struct bio_ops bioops; /* I/O operation notification */
63
64 struct buf_ops buf_ops_bio = {
65 "buf_ops_bio",
66 bwrite
67 };
68
69 /*
70 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
71 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
72 */
73 struct buf *buf; /* buffer header pool */
74
75 static struct proc *bufdaemonproc;
76
77 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from,
78 vm_offset_t to);
79 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from,
80 vm_offset_t to);
81 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
82 int pageno, vm_page_t m);
83 static void vfs_clean_pages(struct buf * bp);
84 static void vfs_setdirty(struct buf *bp);
85 static void vfs_vmio_release(struct buf *bp);
86 static void vfs_backgroundwritedone(struct buf *bp);
87 static int vfs_bio_clcheck(struct vnode *vp, int size,
88 daddr_t lblkno, daddr_t blkno);
89 static int flushbufqueues(int flushdeps);
90 static void buf_daemon(void);
91 void bremfreel(struct buf * bp);
92
93 int vmiodirenable = TRUE;
94 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
95 "Use the VM system for directory writes");
96 int runningbufspace;
97 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
98 "Amount of presently outstanding async buffer io");
99 static int bufspace;
100 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
101 "KVA memory used for bufs");
102 static int maxbufspace;
103 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
104 "Maximum allowed value of bufspace (including buf_daemon)");
105 static int bufmallocspace;
106 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
107 "Amount of malloced memory for buffers");
108 static int maxbufmallocspace;
109 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
110 "Maximum amount of malloced memory for buffers");
111 static int lobufspace;
112 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
113 "Minimum amount of buffers we want to have");
114 static int hibufspace;
115 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
116 "Maximum allowed value of bufspace (excluding buf_daemon)");
117 static int bufreusecnt;
118 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
119 "Number of times we have reused a buffer");
120 static int buffreekvacnt;
121 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
122 "Number of times we have freed the KVA space from some buffer");
123 static int bufdefragcnt;
124 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
125 "Number of times we have had to repeat buffer allocation to defragment");
126 static int lorunningspace;
127 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
128 "Minimum preferred space used for in-progress I/O");
129 static int hirunningspace;
130 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
131 "Maximum amount of space to use for in-progress I/O");
132 static int dirtybufferflushes;
133 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
134 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
135 static int altbufferflushes;
136 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
137 0, "Number of fsync flushes to limit dirty buffers");
138 static int recursiveflushes;
139 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
140 0, "Number of flushes skipped due to being recursive");
141 static int numdirtybuffers;
142 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
143 "Number of buffers that are dirty (has unwritten changes) at the moment");
144 static int lodirtybuffers;
145 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
146 "How many buffers we want to have free before bufdaemon can sleep");
147 static int hidirtybuffers;
148 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
149 "When the number of dirty buffers is considered severe");
150 static int dirtybufthresh;
151 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
152 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
153 static int numfreebuffers;
154 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
155 "Number of free buffers");
156 static int lofreebuffers;
157 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
158 "XXX Unused");
159 static int hifreebuffers;
160 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
161 "XXX Complicatedly unused");
162 static int getnewbufcalls;
163 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
164 "Number of calls to getnewbuf");
165 static int getnewbufrestarts;
166 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
167 "Number of times getnewbuf has had to restart a buffer aquisition");
168 static int dobkgrdwrite = 1;
169 SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0,
170 "Do background writes (honoring the BV_BKGRDWRITE flag)?");
171
172 /*
173 * Wakeup point for bufdaemon, as well as indicator of whether it is already
174 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
175 * is idling.
176 */
177 static int bd_request;
178
179 /*
180 * This lock synchronizes access to bd_request.
181 */
182 static struct mtx bdlock;
183
184 /*
185 * bogus page -- for I/O to/from partially complete buffers
186 * this is a temporary solution to the problem, but it is not
187 * really that bad. it would be better to split the buffer
188 * for input in the case of buffers partially already in memory,
189 * but the code is intricate enough already.
190 */
191 vm_page_t bogus_page;
192
193 /*
194 * Synchronization (sleep/wakeup) variable for active buffer space requests.
195 * Set when wait starts, cleared prior to wakeup().
196 * Used in runningbufwakeup() and waitrunningbufspace().
197 */
198 static int runningbufreq;
199
200 /*
201 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
202 * waitrunningbufspace().
203 */
204 static struct mtx rbreqlock;
205
206 /*
207 * Synchronization (sleep/wakeup) variable for buffer requests.
208 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
209 * by and/or.
210 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
211 * getnewbuf(), and getblk().
212 */
213 static int needsbuffer;
214
215 /*
216 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
217 */
218 static struct mtx nblock;
219
220 /*
221 * Lock that protects against bwait()/bdone()/B_DONE races.
222 */
223
224 static struct mtx bdonelock;
225
226 /*
227 * Definitions for the buffer free lists.
228 */
229 #define BUFFER_QUEUES 5 /* number of free buffer queues */
230
231 #define QUEUE_NONE 0 /* on no queue */
232 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
233 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
234 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
235 #define QUEUE_EMPTY 4 /* empty buffer headers */
236
237 /* Queues for free buffers with various properties */
238 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
239
240 /* Lock for the bufqueues */
241 static struct mtx bqlock;
242
243 /*
244 * Single global constant for BUF_WMESG, to avoid getting multiple references.
245 * buf_wmesg is referred from macros.
246 */
247 const char *buf_wmesg = BUF_WMESG;
248
249 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
250 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
251 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
252 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
253
254 #ifdef DIRECTIO
255 extern void ffs_rawread_setup(void);
256 #endif /* DIRECTIO */
257 /*
258 * numdirtywakeup:
259 *
260 * If someone is blocked due to there being too many dirty buffers,
261 * and numdirtybuffers is now reasonable, wake them up.
262 */
263
264 static __inline void
265 numdirtywakeup(int level)
266 {
267 if (numdirtybuffers <= level) {
268 mtx_lock(&nblock);
269 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
270 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
271 wakeup(&needsbuffer);
272 }
273 mtx_unlock(&nblock);
274 }
275 }
276
277 /*
278 * bufspacewakeup:
279 *
280 * Called when buffer space is potentially available for recovery.
281 * getnewbuf() will block on this flag when it is unable to free
282 * sufficient buffer space. Buffer space becomes recoverable when
283 * bp's get placed back in the queues.
284 */
285
286 static __inline void
287 bufspacewakeup(void)
288 {
289 /*
290 * If someone is waiting for BUF space, wake them up. Even
291 * though we haven't freed the kva space yet, the waiting
292 * process will be able to now.
293 */
294 mtx_lock(&nblock);
295 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
296 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
297 wakeup(&needsbuffer);
298 }
299 mtx_unlock(&nblock);
300 }
301
302 /*
303 * runningbufwakeup() - in-progress I/O accounting.
304 *
305 */
306 static __inline void
307 runningbufwakeup(struct buf *bp)
308 {
309 if (bp->b_runningbufspace) {
310 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace);
311 bp->b_runningbufspace = 0;
312 mtx_lock(&rbreqlock);
313 if (runningbufreq && runningbufspace <= lorunningspace) {
314 runningbufreq = 0;
315 wakeup(&runningbufreq);
316 }
317 mtx_unlock(&rbreqlock);
318 }
319 }
320
321 /*
322 * bufcountwakeup:
323 *
324 * Called when a buffer has been added to one of the free queues to
325 * account for the buffer and to wakeup anyone waiting for free buffers.
326 * This typically occurs when large amounts of metadata are being handled
327 * by the buffer cache ( else buffer space runs out first, usually ).
328 */
329
330 static __inline void
331 bufcountwakeup(void)
332 {
333 atomic_add_int(&numfreebuffers, 1);
334 mtx_lock(&nblock);
335 if (needsbuffer) {
336 needsbuffer &= ~VFS_BIO_NEED_ANY;
337 if (numfreebuffers >= hifreebuffers)
338 needsbuffer &= ~VFS_BIO_NEED_FREE;
339 wakeup(&needsbuffer);
340 }
341 mtx_unlock(&nblock);
342 }
343
344 /*
345 * waitrunningbufspace()
346 *
347 * runningbufspace is a measure of the amount of I/O currently
348 * running. This routine is used in async-write situations to
349 * prevent creating huge backups of pending writes to a device.
350 * Only asynchronous writes are governed by this function.
351 *
352 * Reads will adjust runningbufspace, but will not block based on it.
353 * The read load has a side effect of reducing the allowed write load.
354 *
355 * This does NOT turn an async write into a sync write. It waits
356 * for earlier writes to complete and generally returns before the
357 * caller's write has reached the device.
358 */
359 static __inline void
360 waitrunningbufspace(void)
361 {
362 mtx_lock(&rbreqlock);
363 while (runningbufspace > hirunningspace) {
364 ++runningbufreq;
365 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
366 }
367 mtx_unlock(&rbreqlock);
368 }
369
370
371 /*
372 * vfs_buf_test_cache:
373 *
374 * Called when a buffer is extended. This function clears the B_CACHE
375 * bit if the newly extended portion of the buffer does not contain
376 * valid data.
377 */
378 static __inline__
379 void
380 vfs_buf_test_cache(struct buf *bp,
381 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
382 vm_page_t m)
383 {
384 GIANT_REQUIRED;
385
386 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
387 if (bp->b_flags & B_CACHE) {
388 int base = (foff + off) & PAGE_MASK;
389 if (vm_page_is_valid(m, base, size) == 0)
390 bp->b_flags &= ~B_CACHE;
391 }
392 }
393
394 /* Wake up the buffer deamon if necessary */
395 static __inline__
396 void
397 bd_wakeup(int dirtybuflevel)
398 {
399 mtx_lock(&bdlock);
400 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
401 bd_request = 1;
402 wakeup(&bd_request);
403 }
404 mtx_unlock(&bdlock);
405 }
406
407 /*
408 * bd_speedup - speedup the buffer cache flushing code
409 */
410
411 static __inline__
412 void
413 bd_speedup(void)
414 {
415 bd_wakeup(1);
416 }
417
418 /*
419 * Calculating buffer cache scaling values and reserve space for buffer
420 * headers. This is called during low level kernel initialization and
421 * may be called more then once. We CANNOT write to the memory area
422 * being reserved at this time.
423 */
424 caddr_t
425 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
426 {
427 /*
428 * physmem_est is in pages. Convert it to kilobytes (assumes
429 * PAGE_SIZE is >= 1K)
430 */
431 physmem_est = physmem_est * (PAGE_SIZE / 1024);
432
433 /*
434 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
435 * For the first 64MB of ram nominally allocate sufficient buffers to
436 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
437 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing
438 * the buffer cache we limit the eventual kva reservation to
439 * maxbcache bytes.
440 *
441 * factor represents the 1/4 x ram conversion.
442 */
443 if (nbuf == 0) {
444 int factor = 4 * BKVASIZE / 1024;
445
446 nbuf = 50;
447 if (physmem_est > 4096)
448 nbuf += min((physmem_est - 4096) / factor,
449 65536 / factor);
450 if (physmem_est > 65536)
451 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
452
453 if (maxbcache && nbuf > maxbcache / BKVASIZE)
454 nbuf = maxbcache / BKVASIZE;
455 }
456
457 #if 0
458 /*
459 * Do not allow the buffer_map to be more then 1/2 the size of the
460 * kernel_map.
461 */
462 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) /
463 (BKVASIZE * 2)) {
464 nbuf = (kernel_map->max_offset - kernel_map->min_offset) /
465 (BKVASIZE * 2);
466 printf("Warning: nbufs capped at %d\n", nbuf);
467 }
468 #endif
469
470 /*
471 * swbufs are used as temporary holders for I/O, such as paging I/O.
472 * We have no less then 16 and no more then 256.
473 */
474 nswbuf = max(min(nbuf/4, 256), 16);
475 #ifdef NSWBUF_MIN
476 if (nswbuf < NSWBUF_MIN)
477 nswbuf = NSWBUF_MIN;
478 #endif
479 #ifdef DIRECTIO
480 ffs_rawread_setup();
481 #endif
482
483 /*
484 * Reserve space for the buffer cache buffers
485 */
486 swbuf = (void *)v;
487 v = (caddr_t)(swbuf + nswbuf);
488 buf = (void *)v;
489 v = (caddr_t)(buf + nbuf);
490
491 return(v);
492 }
493
494 /* Initialize the buffer subsystem. Called before use of any buffers. */
495 void
496 bufinit(void)
497 {
498 struct buf *bp;
499 int i;
500
501 GIANT_REQUIRED;
502
503 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
504 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
505 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
506 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
507 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF);
508
509 /* next, make a null set of free lists */
510 for (i = 0; i < BUFFER_QUEUES; i++)
511 TAILQ_INIT(&bufqueues[i]);
512
513 /* finally, initialize each buffer header and stick on empty q */
514 for (i = 0; i < nbuf; i++) {
515 bp = &buf[i];
516 bzero(bp, sizeof *bp);
517 bp->b_flags = B_INVAL; /* we're just an empty header */
518 bp->b_dev = NODEV;
519 bp->b_rcred = NOCRED;
520 bp->b_wcred = NOCRED;
521 bp->b_qindex = QUEUE_EMPTY;
522 bp->b_vflags = 0;
523 bp->b_xflags = 0;
524 LIST_INIT(&bp->b_dep);
525 BUF_LOCKINIT(bp);
526 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
527 }
528
529 /*
530 * maxbufspace is the absolute maximum amount of buffer space we are
531 * allowed to reserve in KVM and in real terms. The absolute maximum
532 * is nominally used by buf_daemon. hibufspace is the nominal maximum
533 * used by most other processes. The differential is required to
534 * ensure that buf_daemon is able to run when other processes might
535 * be blocked waiting for buffer space.
536 *
537 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
538 * this may result in KVM fragmentation which is not handled optimally
539 * by the system.
540 */
541 maxbufspace = nbuf * BKVASIZE;
542 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
543 lobufspace = hibufspace - MAXBSIZE;
544
545 lorunningspace = 512 * 1024;
546 hirunningspace = 1024 * 1024;
547
548 /*
549 * Limit the amount of malloc memory since it is wired permanently into
550 * the kernel space. Even though this is accounted for in the buffer
551 * allocation, we don't want the malloced region to grow uncontrolled.
552 * The malloc scheme improves memory utilization significantly on average
553 * (small) directories.
554 */
555 maxbufmallocspace = hibufspace / 20;
556
557 /*
558 * Reduce the chance of a deadlock occuring by limiting the number
559 * of delayed-write dirty buffers we allow to stack up.
560 */
561 hidirtybuffers = nbuf / 4 + 20;
562 dirtybufthresh = hidirtybuffers * 9 / 10;
563 numdirtybuffers = 0;
564 /*
565 * To support extreme low-memory systems, make sure hidirtybuffers cannot
566 * eat up all available buffer space. This occurs when our minimum cannot
567 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
568 * BKVASIZE'd (8K) buffers.
569 */
570 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
571 hidirtybuffers >>= 1;
572 }
573 lodirtybuffers = hidirtybuffers / 2;
574
575 /*
576 * Try to keep the number of free buffers in the specified range,
577 * and give special processes (e.g. like buf_daemon) access to an
578 * emergency reserve.
579 */
580 lofreebuffers = nbuf / 18 + 5;
581 hifreebuffers = 2 * lofreebuffers;
582 numfreebuffers = nbuf;
583
584 /*
585 * Maximum number of async ops initiated per buf_daemon loop. This is
586 * somewhat of a hack at the moment, we really need to limit ourselves
587 * based on the number of bytes of I/O in-transit that were initiated
588 * from buf_daemon.
589 */
590
591 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
592 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
593 }
594
595 /*
596 * bfreekva() - free the kva allocation for a buffer.
597 *
598 * Must be called at splbio() or higher as this is the only locking for
599 * buffer_map.
600 *
601 * Since this call frees up buffer space, we call bufspacewakeup().
602 */
603 static void
604 bfreekva(struct buf * bp)
605 {
606 GIANT_REQUIRED;
607
608 if (bp->b_kvasize) {
609 atomic_add_int(&buffreekvacnt, 1);
610 atomic_subtract_int(&bufspace, bp->b_kvasize);
611 vm_map_delete(buffer_map,
612 (vm_offset_t) bp->b_kvabase,
613 (vm_offset_t) bp->b_kvabase + bp->b_kvasize
614 );
615 bp->b_kvasize = 0;
616 bufspacewakeup();
617 }
618 }
619
620 /*
621 * bremfree:
622 *
623 * Remove the buffer from the appropriate free list.
624 */
625 void
626 bremfree(struct buf * bp)
627 {
628 mtx_lock(&bqlock);
629 bremfreel(bp);
630 mtx_unlock(&bqlock);
631 }
632
633 void
634 bremfreel(struct buf * bp)
635 {
636 int s = splbio();
637 int old_qindex = bp->b_qindex;
638
639 GIANT_REQUIRED;
640
641 if (bp->b_qindex != QUEUE_NONE) {
642 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp));
643 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
644 bp->b_qindex = QUEUE_NONE;
645 } else {
646 if (BUF_REFCNT(bp) <= 1)
647 panic("bremfree: removing a buffer not on a queue");
648 }
649
650 /*
651 * Fixup numfreebuffers count. If the buffer is invalid or not
652 * delayed-write, and it was on the EMPTY, LRU, or AGE queues,
653 * the buffer was free and we must decrement numfreebuffers.
654 */
655 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
656 switch(old_qindex) {
657 case QUEUE_DIRTY:
658 case QUEUE_CLEAN:
659 case QUEUE_EMPTY:
660 case QUEUE_EMPTYKVA:
661 atomic_subtract_int(&numfreebuffers, 1);
662 break;
663 default:
664 break;
665 }
666 }
667 splx(s);
668 }
669
670
671 /*
672 * Get a buffer with the specified data. Look in the cache first. We
673 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
674 * is set, the buffer is valid and we do not have to do anything ( see
675 * getblk() ). This is really just a special case of breadn().
676 */
677 int
678 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
679 struct buf ** bpp)
680 {
681
682 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
683 }
684
685 /*
686 * Operates like bread, but also starts asynchronous I/O on
687 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior
688 * to initiating I/O . If B_CACHE is set, the buffer is valid
689 * and we do not have to do anything.
690 */
691 int
692 breadn(struct vnode * vp, daddr_t blkno, int size,
693 daddr_t * rablkno, int *rabsize,
694 int cnt, struct ucred * cred, struct buf ** bpp)
695 {
696 struct buf *bp, *rabp;
697 int i;
698 int rv = 0, readwait = 0;
699
700 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
701
702 /* if not found in cache, do some I/O */
703 if ((bp->b_flags & B_CACHE) == 0) {
704 if (curthread != PCPU_GET(idlethread))
705 curthread->td_proc->p_stats->p_ru.ru_inblock++;
706 bp->b_iocmd = BIO_READ;
707 bp->b_flags &= ~B_INVAL;
708 bp->b_ioflags &= ~BIO_ERROR;
709 if (bp->b_rcred == NOCRED && cred != NOCRED)
710 bp->b_rcred = crhold(cred);
711 vfs_busy_pages(bp, 0);
712 bp->b_iooffset = dbtob(bp->b_blkno);
713 if (vp->v_type == VCHR)
714 VOP_SPECSTRATEGY(vp, bp);
715 else
716 VOP_STRATEGY(vp, bp);
717 ++readwait;
718 }
719
720 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
721 if (inmem(vp, *rablkno))
722 continue;
723 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
724
725 if ((rabp->b_flags & B_CACHE) == 0) {
726 if (curthread != PCPU_GET(idlethread))
727 curthread->td_proc->p_stats->p_ru.ru_inblock++;
728 rabp->b_flags |= B_ASYNC;
729 rabp->b_flags &= ~B_INVAL;
730 rabp->b_ioflags &= ~BIO_ERROR;
731 rabp->b_iocmd = BIO_READ;
732 if (rabp->b_rcred == NOCRED && cred != NOCRED)
733 rabp->b_rcred = crhold(cred);
734 vfs_busy_pages(rabp, 0);
735 BUF_KERNPROC(rabp);
736 rabp->b_iooffset = dbtob(rabp->b_blkno);
737 if (vp->v_type == VCHR)
738 VOP_SPECSTRATEGY(vp, rabp);
739 else
740 VOP_STRATEGY(vp, rabp);
741 } else {
742 brelse(rabp);
743 }
744 }
745
746 if (readwait) {
747 rv = bufwait(bp);
748 }
749 return (rv);
750 }
751
752 /*
753 * Write, release buffer on completion. (Done by iodone
754 * if async). Do not bother writing anything if the buffer
755 * is invalid.
756 *
757 * Note that we set B_CACHE here, indicating that buffer is
758 * fully valid and thus cacheable. This is true even of NFS
759 * now so we set it generally. This could be set either here
760 * or in biodone() since the I/O is synchronous. We put it
761 * here.
762 */
763
764 int
765 bwrite(struct buf * bp)
766 {
767 int oldflags, s;
768 struct buf *newbp;
769
770 if (bp->b_flags & B_INVAL) {
771 brelse(bp);
772 return (0);
773 }
774
775 oldflags = bp->b_flags;
776
777 if (BUF_REFCNT(bp) == 0)
778 panic("bwrite: buffer is not busy???");
779 s = splbio();
780 /*
781 * If a background write is already in progress, delay
782 * writing this block if it is asynchronous. Otherwise
783 * wait for the background write to complete.
784 */
785 VI_LOCK(bp->b_vp);
786 if (bp->b_vflags & BV_BKGRDINPROG) {
787 if (bp->b_flags & B_ASYNC) {
788 VI_UNLOCK(bp->b_vp);
789 splx(s);
790 bdwrite(bp);
791 return (0);
792 }
793 bp->b_vflags |= BV_BKGRDWAIT;
794 msleep(&bp->b_xflags, VI_MTX(bp->b_vp), PRIBIO, "bwrbg", 0);
795 if (bp->b_vflags & BV_BKGRDINPROG)
796 panic("bwrite: still writing");
797 }
798 VI_UNLOCK(bp->b_vp);
799
800 /* Mark the buffer clean */
801 bundirty(bp);
802
803 /*
804 * If this buffer is marked for background writing and we
805 * do not have to wait for it, make a copy and write the
806 * copy so as to leave this buffer ready for further use.
807 *
808 * This optimization eats a lot of memory. If we have a page
809 * or buffer shortfall we can't do it.
810 */
811 if (dobkgrdwrite && (bp->b_xflags & BX_BKGRDWRITE) &&
812 (bp->b_flags & B_ASYNC) &&
813 !vm_page_count_severe() &&
814 !buf_dirty_count_severe()) {
815 if (bp->b_iodone != NULL) {
816 printf("bp->b_iodone = %p\n", bp->b_iodone);
817 panic("bwrite: need chained iodone");
818 }
819
820 /* get a new block */
821 newbp = geteblk(bp->b_bufsize);
822
823 /*
824 * set it to be identical to the old block. We have to
825 * set b_lblkno and BKGRDMARKER before calling bgetvp()
826 * to avoid confusing the splay tree and gbincore().
827 */
828 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize);
829 newbp->b_lblkno = bp->b_lblkno;
830 newbp->b_xflags |= BX_BKGRDMARKER;
831 VI_LOCK(bp->b_vp);
832 bp->b_vflags |= BV_BKGRDINPROG;
833 bgetvp(bp->b_vp, newbp);
834 VI_UNLOCK(bp->b_vp);
835 newbp->b_blkno = bp->b_blkno;
836 newbp->b_offset = bp->b_offset;
837 newbp->b_iodone = vfs_backgroundwritedone;
838 newbp->b_flags |= B_ASYNC;
839 newbp->b_flags &= ~B_INVAL;
840
841 /* move over the dependencies */
842 if (LIST_FIRST(&bp->b_dep) != NULL)
843 buf_movedeps(bp, newbp);
844
845 /*
846 * Initiate write on the copy, release the original to
847 * the B_LOCKED queue so that it cannot go away until
848 * the background write completes. If not locked it could go
849 * away and then be reconstituted while it was being written.
850 * If the reconstituted buffer were written, we could end up
851 * with two background copies being written at the same time.
852 */
853 bqrelse(bp);
854 bp = newbp;
855 }
856
857 bp->b_flags &= ~B_DONE;
858 bp->b_ioflags &= ~BIO_ERROR;
859 bp->b_flags |= B_WRITEINPROG | B_CACHE;
860 bp->b_iocmd = BIO_WRITE;
861
862 VI_LOCK(bp->b_vp);
863 bp->b_vp->v_numoutput++;
864 VI_UNLOCK(bp->b_vp);
865 vfs_busy_pages(bp, 1);
866
867 /*
868 * Normal bwrites pipeline writes
869 */
870 bp->b_runningbufspace = bp->b_bufsize;
871 atomic_add_int(&runningbufspace, bp->b_runningbufspace);
872
873 if (curthread != PCPU_GET(idlethread))
874 curthread->td_proc->p_stats->p_ru.ru_oublock++;
875 splx(s);
876 if (oldflags & B_ASYNC)
877 BUF_KERNPROC(bp);
878 bp->b_iooffset = dbtob(bp->b_blkno);
879 if (bp->b_vp->v_type == VCHR)
880 VOP_SPECSTRATEGY(bp->b_vp, bp);
881 else
882 VOP_STRATEGY(bp->b_vp, bp);
883
884 if ((oldflags & B_ASYNC) == 0) {
885 int rtval = bufwait(bp);
886 brelse(bp);
887 return (rtval);
888 } else {
889 /*
890 * don't allow the async write to saturate the I/O
891 * system. We will not deadlock here because
892 * we are blocking waiting for I/O that is already in-progress
893 * to complete. We do not block here if it is the update
894 * or syncer daemon trying to clean up as that can lead
895 * to deadlock.
896 */
897 if (curthread->td_proc != bufdaemonproc &&
898 curthread->td_proc != updateproc)
899 waitrunningbufspace();
900 }
901
902 return (0);
903 }
904
905 /*
906 * Complete a background write started from bwrite.
907 */
908 static void
909 vfs_backgroundwritedone(bp)
910 struct buf *bp;
911 {
912 struct buf *origbp;
913
914 /*
915 * Find the original buffer that we are writing.
916 */
917 VI_LOCK(bp->b_vp);
918 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL)
919 panic("backgroundwritedone: lost buffer");
920
921 /*
922 * Clear the BV_BKGRDINPROG flag in the original buffer
923 * and awaken it if it is waiting for the write to complete.
924 * If BV_BKGRDINPROG is not set in the original buffer it must
925 * have been released and re-instantiated - which is not legal.
926 */
927 KASSERT((origbp->b_vflags & BV_BKGRDINPROG),
928 ("backgroundwritedone: lost buffer2"));
929 origbp->b_vflags &= ~BV_BKGRDINPROG;
930 if (origbp->b_vflags & BV_BKGRDWAIT) {
931 origbp->b_vflags &= ~BV_BKGRDWAIT;
932 wakeup(&origbp->b_xflags);
933 }
934 VI_UNLOCK(bp->b_vp);
935 /*
936 * Process dependencies then return any unfinished ones.
937 */
938 if (LIST_FIRST(&bp->b_dep) != NULL)
939 buf_complete(bp);
940 if (LIST_FIRST(&bp->b_dep) != NULL)
941 buf_movedeps(bp, origbp);
942
943 /*
944 * This buffer is marked B_NOCACHE, so when it is released
945 * by biodone, it will be tossed. We mark it with BIO_READ
946 * to avoid biodone doing a second vwakeup.
947 */
948 bp->b_flags |= B_NOCACHE;
949 bp->b_iocmd = BIO_READ;
950 bp->b_flags &= ~(B_CACHE | B_DONE);
951 bp->b_iodone = 0;
952 bufdone(bp);
953 }
954
955 /*
956 * Delayed write. (Buffer is marked dirty). Do not bother writing
957 * anything if the buffer is marked invalid.
958 *
959 * Note that since the buffer must be completely valid, we can safely
960 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
961 * biodone() in order to prevent getblk from writing the buffer
962 * out synchronously.
963 */
964 void
965 bdwrite(struct buf * bp)
966 {
967 struct thread *td = curthread;
968 struct vnode *vp;
969 struct buf *nbp;
970
971 GIANT_REQUIRED;
972
973 if (BUF_REFCNT(bp) == 0)
974 panic("bdwrite: buffer is not busy");
975
976 if (bp->b_flags & B_INVAL) {
977 brelse(bp);
978 return;
979 }
980
981 /*
982 * If we have too many dirty buffers, don't create any more.
983 * If we are wildly over our limit, then force a complete
984 * cleanup. Otherwise, just keep the situation from getting
985 * out of control. Note that we have to avoid a recursive
986 * disaster and not try to clean up after our own cleanup!
987 */
988 vp = bp->b_vp;
989 VI_LOCK(vp);
990 if (td->td_pflags & TDP_COWINPROGRESS) {
991 recursiveflushes++;
992 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh + 10) {
993 VI_UNLOCK(vp);
994 (void) VOP_FSYNC(vp, td->td_ucred, MNT_NOWAIT, td);
995 VI_LOCK(vp);
996 altbufferflushes++;
997 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh) {
998 /*
999 * Try to find a buffer to flush.
1000 */
1001 TAILQ_FOREACH(nbp, &vp->v_dirtyblkhd, b_vnbufs) {
1002 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
1003 buf_countdeps(nbp, 0) ||
1004 BUF_LOCK(nbp, LK_EXCLUSIVE | LK_NOWAIT, NULL))
1005 continue;
1006 if (bp == nbp)
1007 panic("bdwrite: found ourselves");
1008 VI_UNLOCK(vp);
1009 if (nbp->b_flags & B_CLUSTEROK) {
1010 vfs_bio_awrite(nbp);
1011 } else {
1012 bremfree(nbp);
1013 bawrite(nbp);
1014 }
1015 VI_LOCK(vp);
1016 dirtybufferflushes++;
1017 break;
1018 }
1019 }
1020 VI_UNLOCK(vp);
1021
1022 bdirty(bp);
1023 /*
1024 * Set B_CACHE, indicating that the buffer is fully valid. This is
1025 * true even of NFS now.
1026 */
1027 bp->b_flags |= B_CACHE;
1028
1029 /*
1030 * This bmap keeps the system from needing to do the bmap later,
1031 * perhaps when the system is attempting to do a sync. Since it
1032 * is likely that the indirect block -- or whatever other datastructure
1033 * that the filesystem needs is still in memory now, it is a good
1034 * thing to do this. Note also, that if the pageout daemon is
1035 * requesting a sync -- there might not be enough memory to do
1036 * the bmap then... So, this is important to do.
1037 */
1038 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1039 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1040 }
1041
1042 /*
1043 * Set the *dirty* buffer range based upon the VM system dirty pages.
1044 */
1045 vfs_setdirty(bp);
1046
1047 /*
1048 * We need to do this here to satisfy the vnode_pager and the
1049 * pageout daemon, so that it thinks that the pages have been
1050 * "cleaned". Note that since the pages are in a delayed write
1051 * buffer -- the VFS layer "will" see that the pages get written
1052 * out on the next sync, or perhaps the cluster will be completed.
1053 */
1054 vfs_clean_pages(bp);
1055 bqrelse(bp);
1056
1057 /*
1058 * Wakeup the buffer flushing daemon if we have a lot of dirty
1059 * buffers (midpoint between our recovery point and our stall
1060 * point).
1061 */
1062 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1063
1064 /*
1065 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1066 * due to the softdep code.
1067 */
1068 }
1069
1070 /*
1071 * bdirty:
1072 *
1073 * Turn buffer into delayed write request. We must clear BIO_READ and
1074 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1075 * itself to properly update it in the dirty/clean lists. We mark it
1076 * B_DONE to ensure that any asynchronization of the buffer properly
1077 * clears B_DONE ( else a panic will occur later ).
1078 *
1079 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1080 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1081 * should only be called if the buffer is known-good.
1082 *
1083 * Since the buffer is not on a queue, we do not update the numfreebuffers
1084 * count.
1085 *
1086 * Must be called at splbio().
1087 * The buffer must be on QUEUE_NONE.
1088 */
1089 void
1090 bdirty(bp)
1091 struct buf *bp;
1092 {
1093 KASSERT(bp->b_qindex == QUEUE_NONE,
1094 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1095 bp->b_flags &= ~(B_RELBUF);
1096 bp->b_iocmd = BIO_WRITE;
1097
1098 if ((bp->b_flags & B_DELWRI) == 0) {
1099 bp->b_flags |= B_DONE | B_DELWRI;
1100 reassignbuf(bp, bp->b_vp);
1101 atomic_add_int(&numdirtybuffers, 1);
1102 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1103 }
1104 }
1105
1106 /*
1107 * bundirty:
1108 *
1109 * Clear B_DELWRI for buffer.
1110 *
1111 * Since the buffer is not on a queue, we do not update the numfreebuffers
1112 * count.
1113 *
1114 * Must be called at splbio().
1115 * The buffer must be on QUEUE_NONE.
1116 */
1117
1118 void
1119 bundirty(bp)
1120 struct buf *bp;
1121 {
1122 KASSERT(bp->b_qindex == QUEUE_NONE,
1123 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1124
1125 if (bp->b_flags & B_DELWRI) {
1126 bp->b_flags &= ~B_DELWRI;
1127 reassignbuf(bp, bp->b_vp);
1128 atomic_subtract_int(&numdirtybuffers, 1);
1129 numdirtywakeup(lodirtybuffers);
1130 }
1131 /*
1132 * Since it is now being written, we can clear its deferred write flag.
1133 */
1134 bp->b_flags &= ~B_DEFERRED;
1135 }
1136
1137 /*
1138 * bawrite:
1139 *
1140 * Asynchronous write. Start output on a buffer, but do not wait for
1141 * it to complete. The buffer is released when the output completes.
1142 *
1143 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1144 * B_INVAL buffers. Not us.
1145 */
1146 void
1147 bawrite(struct buf * bp)
1148 {
1149 bp->b_flags |= B_ASYNC;
1150 (void) BUF_WRITE(bp);
1151 }
1152
1153 /*
1154 * bwillwrite:
1155 *
1156 * Called prior to the locking of any vnodes when we are expecting to
1157 * write. We do not want to starve the buffer cache with too many
1158 * dirty buffers so we block here. By blocking prior to the locking
1159 * of any vnodes we attempt to avoid the situation where a locked vnode
1160 * prevents the various system daemons from flushing related buffers.
1161 */
1162
1163 void
1164 bwillwrite(void)
1165 {
1166 if (numdirtybuffers >= hidirtybuffers) {
1167 int s;
1168
1169 mtx_lock(&Giant);
1170 s = splbio();
1171 mtx_lock(&nblock);
1172 while (numdirtybuffers >= hidirtybuffers) {
1173 bd_wakeup(1);
1174 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1175 msleep(&needsbuffer, &nblock,
1176 (PRIBIO + 4), "flswai", 0);
1177 }
1178 splx(s);
1179 mtx_unlock(&nblock);
1180 mtx_unlock(&Giant);
1181 }
1182 }
1183
1184 /*
1185 * Return true if we have too many dirty buffers.
1186 */
1187 int
1188 buf_dirty_count_severe(void)
1189 {
1190 return(numdirtybuffers >= hidirtybuffers);
1191 }
1192
1193 /*
1194 * brelse:
1195 *
1196 * Release a busy buffer and, if requested, free its resources. The
1197 * buffer will be stashed in the appropriate bufqueue[] allowing it
1198 * to be accessed later as a cache entity or reused for other purposes.
1199 */
1200 void
1201 brelse(struct buf * bp)
1202 {
1203 int s;
1204
1205 GIANT_REQUIRED;
1206
1207 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1208 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1209
1210 s = splbio();
1211
1212 if (bp->b_iocmd == BIO_WRITE &&
1213 (bp->b_ioflags & BIO_ERROR) &&
1214 !(bp->b_flags & B_INVAL)) {
1215 /*
1216 * Failed write, redirty. Must clear BIO_ERROR to prevent
1217 * pages from being scrapped. If B_INVAL is set then
1218 * this case is not run and the next case is run to
1219 * destroy the buffer. B_INVAL can occur if the buffer
1220 * is outside the range supported by the underlying device.
1221 */
1222 bp->b_ioflags &= ~BIO_ERROR;
1223 bdirty(bp);
1224 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1225 (bp->b_ioflags & BIO_ERROR) ||
1226 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) {
1227 /*
1228 * Either a failed I/O or we were asked to free or not
1229 * cache the buffer.
1230 */
1231 bp->b_flags |= B_INVAL;
1232 if (LIST_FIRST(&bp->b_dep) != NULL)
1233 buf_deallocate(bp);
1234 if (bp->b_flags & B_DELWRI) {
1235 atomic_subtract_int(&numdirtybuffers, 1);
1236 numdirtywakeup(lodirtybuffers);
1237 }
1238 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1239 if ((bp->b_flags & B_VMIO) == 0) {
1240 if (bp->b_bufsize)
1241 allocbuf(bp, 0);
1242 if (bp->b_vp)
1243 brelvp(bp);
1244 }
1245 }
1246
1247 /*
1248 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1249 * is called with B_DELWRI set, the underlying pages may wind up
1250 * getting freed causing a previous write (bdwrite()) to get 'lost'
1251 * because pages associated with a B_DELWRI bp are marked clean.
1252 *
1253 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1254 * if B_DELWRI is set.
1255 *
1256 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1257 * on pages to return pages to the VM page queues.
1258 */
1259 if (bp->b_flags & B_DELWRI)
1260 bp->b_flags &= ~B_RELBUF;
1261 else if (vm_page_count_severe()) {
1262 /*
1263 * XXX This lock may not be necessary since BKGRDINPROG
1264 * cannot be set while we hold the buf lock, it can only be
1265 * cleared if it is already pending.
1266 */
1267 if (bp->b_vp) {
1268 VI_LOCK(bp->b_vp);
1269 if (!(bp->b_vflags & BV_BKGRDINPROG))
1270 bp->b_flags |= B_RELBUF;
1271 VI_UNLOCK(bp->b_vp);
1272 } else
1273 bp->b_flags |= B_RELBUF;
1274 }
1275
1276 /*
1277 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1278 * constituted, not even NFS buffers now. Two flags effect this. If
1279 * B_INVAL, the struct buf is invalidated but the VM object is kept
1280 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1281 *
1282 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1283 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1284 * buffer is also B_INVAL because it hits the re-dirtying code above.
1285 *
1286 * Normally we can do this whether a buffer is B_DELWRI or not. If
1287 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1288 * the commit state and we cannot afford to lose the buffer. If the
1289 * buffer has a background write in progress, we need to keep it
1290 * around to prevent it from being reconstituted and starting a second
1291 * background write.
1292 */
1293 if ((bp->b_flags & B_VMIO)
1294 && !(bp->b_vp->v_mount != NULL &&
1295 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1296 !vn_isdisk(bp->b_vp, NULL) &&
1297 (bp->b_flags & B_DELWRI))
1298 ) {
1299
1300 int i, j, resid;
1301 vm_page_t m;
1302 off_t foff;
1303 vm_pindex_t poff;
1304 vm_object_t obj;
1305 struct vnode *vp;
1306
1307 vp = bp->b_vp;
1308 obj = bp->b_object;
1309
1310 /*
1311 * Get the base offset and length of the buffer. Note that
1312 * in the VMIO case if the buffer block size is not
1313 * page-aligned then b_data pointer may not be page-aligned.
1314 * But our b_pages[] array *IS* page aligned.
1315 *
1316 * block sizes less then DEV_BSIZE (usually 512) are not
1317 * supported due to the page granularity bits (m->valid,
1318 * m->dirty, etc...).
1319 *
1320 * See man buf(9) for more information
1321 */
1322 resid = bp->b_bufsize;
1323 foff = bp->b_offset;
1324 VM_OBJECT_LOCK(obj);
1325 for (i = 0; i < bp->b_npages; i++) {
1326 int had_bogus = 0;
1327
1328 m = bp->b_pages[i];
1329 vm_page_lock_queues();
1330 vm_page_flag_clear(m, PG_ZERO);
1331 vm_page_unlock_queues();
1332
1333 /*
1334 * If we hit a bogus page, fixup *all* the bogus pages
1335 * now.
1336 */
1337 if (m == bogus_page) {
1338 poff = OFF_TO_IDX(bp->b_offset);
1339 had_bogus = 1;
1340
1341 for (j = i; j < bp->b_npages; j++) {
1342 vm_page_t mtmp;
1343 mtmp = bp->b_pages[j];
1344 if (mtmp == bogus_page) {
1345 mtmp = vm_page_lookup(obj, poff + j);
1346 if (!mtmp) {
1347 panic("brelse: page missing\n");
1348 }
1349 bp->b_pages[j] = mtmp;
1350 }
1351 }
1352
1353 if ((bp->b_flags & B_INVAL) == 0) {
1354 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
1355 }
1356 m = bp->b_pages[i];
1357 }
1358 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) {
1359 int poffset = foff & PAGE_MASK;
1360 int presid = resid > (PAGE_SIZE - poffset) ?
1361 (PAGE_SIZE - poffset) : resid;
1362
1363 KASSERT(presid >= 0, ("brelse: extra page"));
1364 vm_page_lock_queues();
1365 vm_page_set_invalid(m, poffset, presid);
1366 vm_page_unlock_queues();
1367 if (had_bogus)
1368 printf("avoided corruption bug in bogus_page/brelse code\n");
1369 }
1370 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1371 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1372 }
1373 VM_OBJECT_UNLOCK(obj);
1374 if (bp->b_flags & (B_INVAL | B_RELBUF))
1375 vfs_vmio_release(bp);
1376
1377 } else if (bp->b_flags & B_VMIO) {
1378
1379 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1380 vfs_vmio_release(bp);
1381 }
1382
1383 }
1384
1385 if (bp->b_qindex != QUEUE_NONE)
1386 panic("brelse: free buffer onto another queue???");
1387 if (BUF_REFCNT(bp) > 1) {
1388 /* do not release to free list */
1389 BUF_UNLOCK(bp);
1390 splx(s);
1391 return;
1392 }
1393
1394 /* enqueue */
1395 mtx_lock(&bqlock);
1396
1397 /* buffers with no memory */
1398 if (bp->b_bufsize == 0) {
1399 bp->b_flags |= B_INVAL;
1400 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1401 if (bp->b_vflags & BV_BKGRDINPROG)
1402 panic("losing buffer 1");
1403 if (bp->b_kvasize) {
1404 bp->b_qindex = QUEUE_EMPTYKVA;
1405 } else {
1406 bp->b_qindex = QUEUE_EMPTY;
1407 }
1408 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1409 bp->b_dev = NODEV;
1410 /* buffers with junk contents */
1411 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1412 (bp->b_ioflags & BIO_ERROR)) {
1413 bp->b_flags |= B_INVAL;
1414 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1415 if (bp->b_vflags & BV_BKGRDINPROG)
1416 panic("losing buffer 2");
1417 bp->b_qindex = QUEUE_CLEAN;
1418 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1419 bp->b_dev = NODEV;
1420 /* remaining buffers */
1421 } else {
1422 if (bp->b_flags & B_DELWRI)
1423 bp->b_qindex = QUEUE_DIRTY;
1424 else
1425 bp->b_qindex = QUEUE_CLEAN;
1426 if (bp->b_flags & B_AGE)
1427 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1428 else
1429 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1430 }
1431 mtx_unlock(&bqlock);
1432
1433 /*
1434 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already
1435 * placed the buffer on the correct queue. We must also disassociate
1436 * the device and vnode for a B_INVAL buffer so gbincore() doesn't
1437 * find it.
1438 */
1439 if (bp->b_flags & B_INVAL) {
1440 if (bp->b_flags & B_DELWRI)
1441 bundirty(bp);
1442 if (bp->b_vp)
1443 brelvp(bp);
1444 }
1445
1446 /*
1447 * Fixup numfreebuffers count. The bp is on an appropriate queue
1448 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1449 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1450 * if B_INVAL is set ).
1451 */
1452
1453 if (!(bp->b_flags & B_DELWRI))
1454 bufcountwakeup();
1455
1456 /*
1457 * Something we can maybe free or reuse
1458 */
1459 if (bp->b_bufsize || bp->b_kvasize)
1460 bufspacewakeup();
1461
1462 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1463 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1464 panic("brelse: not dirty");
1465 /* unlock */
1466 BUF_UNLOCK(bp);
1467 splx(s);
1468 }
1469
1470 /*
1471 * Release a buffer back to the appropriate queue but do not try to free
1472 * it. The buffer is expected to be used again soon.
1473 *
1474 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1475 * biodone() to requeue an async I/O on completion. It is also used when
1476 * known good buffers need to be requeued but we think we may need the data
1477 * again soon.
1478 *
1479 * XXX we should be able to leave the B_RELBUF hint set on completion.
1480 */
1481 void
1482 bqrelse(struct buf * bp)
1483 {
1484 int s;
1485
1486 s = splbio();
1487
1488 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1489
1490 if (bp->b_qindex != QUEUE_NONE)
1491 panic("bqrelse: free buffer onto another queue???");
1492 if (BUF_REFCNT(bp) > 1) {
1493 /* do not release to free list */
1494 BUF_UNLOCK(bp);
1495 splx(s);
1496 return;
1497 }
1498 mtx_lock(&bqlock);
1499 /* buffers with stale but valid contents */
1500 if (bp->b_flags & B_DELWRI) {
1501 bp->b_qindex = QUEUE_DIRTY;
1502 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1503 } else {
1504 /*
1505 * XXX This lock may not be necessary since BKGRDINPROG
1506 * cannot be set while we hold the buf lock, it can only be
1507 * cleared if it is already pending.
1508 */
1509 VI_LOCK(bp->b_vp);
1510 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) {
1511 VI_UNLOCK(bp->b_vp);
1512 bp->b_qindex = QUEUE_CLEAN;
1513 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1514 b_freelist);
1515 } else {
1516 /*
1517 * We are too low on memory, we have to try to free
1518 * the buffer (most importantly: the wired pages
1519 * making up its backing store) *now*.
1520 */
1521 VI_UNLOCK(bp->b_vp);
1522 mtx_unlock(&bqlock);
1523 splx(s);
1524 brelse(bp);
1525 return;
1526 }
1527 }
1528 mtx_unlock(&bqlock);
1529
1530 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
1531 bufcountwakeup();
1532
1533 /*
1534 * Something we can maybe free or reuse.
1535 */
1536 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1537 bufspacewakeup();
1538
1539 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1540 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1541 panic("bqrelse: not dirty");
1542 /* unlock */
1543 BUF_UNLOCK(bp);
1544 splx(s);
1545 }
1546
1547 /* Give pages used by the bp back to the VM system (where possible) */
1548 static void
1549 vfs_vmio_release(bp)
1550 struct buf *bp;
1551 {
1552 int i;
1553 vm_page_t m;
1554
1555 GIANT_REQUIRED;
1556 VM_OBJECT_LOCK(bp->b_object);
1557 vm_page_lock_queues();
1558 for (i = 0; i < bp->b_npages; i++) {
1559 m = bp->b_pages[i];
1560 bp->b_pages[i] = NULL;
1561 /*
1562 * In order to keep page LRU ordering consistent, put
1563 * everything on the inactive queue.
1564 */
1565 vm_page_unwire(m, 0);
1566 /*
1567 * We don't mess with busy pages, it is
1568 * the responsibility of the process that
1569 * busied the pages to deal with them.
1570 */
1571 if ((m->flags & PG_BUSY) || (m->busy != 0))
1572 continue;
1573
1574 if (m->wire_count == 0) {
1575 vm_page_flag_clear(m, PG_ZERO);
1576 /*
1577 * Might as well free the page if we can and it has
1578 * no valid data. We also free the page if the
1579 * buffer was used for direct I/O
1580 */
1581 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1582 m->hold_count == 0) {
1583 vm_page_busy(m);
1584 pmap_remove_all(m);
1585 vm_page_free(m);
1586 } else if (bp->b_flags & B_DIRECT) {
1587 vm_page_try_to_free(m);
1588 } else if (vm_page_count_severe()) {
1589 vm_page_try_to_cache(m);
1590 }
1591 }
1592 }
1593 vm_page_unlock_queues();
1594 VM_OBJECT_UNLOCK(bp->b_object);
1595 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
1596
1597 if (bp->b_bufsize) {
1598 bufspacewakeup();
1599 bp->b_bufsize = 0;
1600 }
1601 bp->b_npages = 0;
1602 bp->b_flags &= ~B_VMIO;
1603 if (bp->b_vp)
1604 brelvp(bp);
1605 }
1606
1607 /*
1608 * Check to see if a block at a particular lbn is available for a clustered
1609 * write.
1610 */
1611 static int
1612 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1613 {
1614 struct buf *bpa;
1615 int match;
1616
1617 match = 0;
1618
1619 /* If the buf isn't in core skip it */
1620 if ((bpa = gbincore(vp, lblkno)) == NULL)
1621 return (0);
1622
1623 /* If the buf is busy we don't want to wait for it */
1624 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1625 return (0);
1626
1627 /* Only cluster with valid clusterable delayed write buffers */
1628 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1629 (B_DELWRI | B_CLUSTEROK))
1630 goto done;
1631
1632 if (bpa->b_bufsize != size)
1633 goto done;
1634
1635 /*
1636 * Check to see if it is in the expected place on disk and that the
1637 * block has been mapped.
1638 */
1639 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1640 match = 1;
1641 done:
1642 BUF_UNLOCK(bpa);
1643 return (match);
1644 }
1645
1646 /*
1647 * vfs_bio_awrite:
1648 *
1649 * Implement clustered async writes for clearing out B_DELWRI buffers.
1650 * This is much better then the old way of writing only one buffer at
1651 * a time. Note that we may not be presented with the buffers in the
1652 * correct order, so we search for the cluster in both directions.
1653 */
1654 int
1655 vfs_bio_awrite(struct buf * bp)
1656 {
1657 int i;
1658 int j;
1659 daddr_t lblkno = bp->b_lblkno;
1660 struct vnode *vp = bp->b_vp;
1661 int s;
1662 int ncl;
1663 int nwritten;
1664 int size;
1665 int maxcl;
1666
1667 s = splbio();
1668 /*
1669 * right now we support clustered writing only to regular files. If
1670 * we find a clusterable block we could be in the middle of a cluster
1671 * rather then at the beginning.
1672 */
1673 if ((vp->v_type == VREG) &&
1674 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1675 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1676
1677 size = vp->v_mount->mnt_stat.f_iosize;
1678 maxcl = MAXPHYS / size;
1679
1680 VI_LOCK(vp);
1681 for (i = 1; i < maxcl; i++)
1682 if (vfs_bio_clcheck(vp, size, lblkno + i,
1683 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1684 break;
1685
1686 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1687 if (vfs_bio_clcheck(vp, size, lblkno - j,
1688 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1689 break;
1690
1691 VI_UNLOCK(vp);
1692 --j;
1693 ncl = i + j;
1694 /*
1695 * this is a possible cluster write
1696 */
1697 if (ncl != 1) {
1698 BUF_UNLOCK(bp);
1699 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1700 splx(s);
1701 return nwritten;
1702 }
1703 }
1704
1705 bremfree(bp);
1706 bp->b_flags |= B_ASYNC;
1707
1708 splx(s);
1709 /*
1710 * default (old) behavior, writing out only one block
1711 *
1712 * XXX returns b_bufsize instead of b_bcount for nwritten?
1713 */
1714 nwritten = bp->b_bufsize;
1715 (void) BUF_WRITE(bp);
1716
1717 return nwritten;
1718 }
1719
1720 /*
1721 * getnewbuf:
1722 *
1723 * Find and initialize a new buffer header, freeing up existing buffers
1724 * in the bufqueues as necessary. The new buffer is returned locked.
1725 *
1726 * Important: B_INVAL is not set. If the caller wishes to throw the
1727 * buffer away, the caller must set B_INVAL prior to calling brelse().
1728 *
1729 * We block if:
1730 * We have insufficient buffer headers
1731 * We have insufficient buffer space
1732 * buffer_map is too fragmented ( space reservation fails )
1733 * If we have to flush dirty buffers ( but we try to avoid this )
1734 *
1735 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1736 * Instead we ask the buf daemon to do it for us. We attempt to
1737 * avoid piecemeal wakeups of the pageout daemon.
1738 */
1739
1740 static struct buf *
1741 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1742 {
1743 struct buf *bp;
1744 struct buf *nbp;
1745 int defrag = 0;
1746 int nqindex;
1747 static int flushingbufs;
1748
1749 GIANT_REQUIRED;
1750
1751 /*
1752 * We can't afford to block since we might be holding a vnode lock,
1753 * which may prevent system daemons from running. We deal with
1754 * low-memory situations by proactively returning memory and running
1755 * async I/O rather then sync I/O.
1756 */
1757
1758 atomic_add_int(&getnewbufcalls, 1);
1759 atomic_subtract_int(&getnewbufrestarts, 1);
1760 restart:
1761 atomic_add_int(&getnewbufrestarts, 1);
1762
1763 /*
1764 * Setup for scan. If we do not have enough free buffers,
1765 * we setup a degenerate case that immediately fails. Note
1766 * that if we are specially marked process, we are allowed to
1767 * dip into our reserves.
1768 *
1769 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1770 *
1771 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1772 * However, there are a number of cases (defragging, reusing, ...)
1773 * where we cannot backup.
1774 */
1775 mtx_lock(&bqlock);
1776 nqindex = QUEUE_EMPTYKVA;
1777 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1778
1779 if (nbp == NULL) {
1780 /*
1781 * If no EMPTYKVA buffers and we are either
1782 * defragging or reusing, locate a CLEAN buffer
1783 * to free or reuse. If bufspace useage is low
1784 * skip this step so we can allocate a new buffer.
1785 */
1786 if (defrag || bufspace >= lobufspace) {
1787 nqindex = QUEUE_CLEAN;
1788 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1789 }
1790
1791 /*
1792 * If we could not find or were not allowed to reuse a
1793 * CLEAN buffer, check to see if it is ok to use an EMPTY
1794 * buffer. We can only use an EMPTY buffer if allocating
1795 * its KVA would not otherwise run us out of buffer space.
1796 */
1797 if (nbp == NULL && defrag == 0 &&
1798 bufspace + maxsize < hibufspace) {
1799 nqindex = QUEUE_EMPTY;
1800 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1801 }
1802 }
1803
1804 /*
1805 * Run scan, possibly freeing data and/or kva mappings on the fly
1806 * depending.
1807 */
1808
1809 while ((bp = nbp) != NULL) {
1810 int qindex = nqindex;
1811
1812 /*
1813 * Calculate next bp ( we can only use it if we do not block
1814 * or do other fancy things ).
1815 */
1816 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1817 switch(qindex) {
1818 case QUEUE_EMPTY:
1819 nqindex = QUEUE_EMPTYKVA;
1820 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1821 break;
1822 /* FALLTHROUGH */
1823 case QUEUE_EMPTYKVA:
1824 nqindex = QUEUE_CLEAN;
1825 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1826 break;
1827 /* FALLTHROUGH */
1828 case QUEUE_CLEAN:
1829 /*
1830 * nbp is NULL.
1831 */
1832 break;
1833 }
1834 }
1835 if (bp->b_vp) {
1836 VI_LOCK(bp->b_vp);
1837 if (bp->b_vflags & BV_BKGRDINPROG) {
1838 VI_UNLOCK(bp->b_vp);
1839 continue;
1840 }
1841 VI_UNLOCK(bp->b_vp);
1842 }
1843
1844 /*
1845 * Sanity Checks
1846 */
1847 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1848
1849 /*
1850 * Note: we no longer distinguish between VMIO and non-VMIO
1851 * buffers.
1852 */
1853
1854 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1855
1856 /*
1857 * If we are defragging then we need a buffer with
1858 * b_kvasize != 0. XXX this situation should no longer
1859 * occur, if defrag is non-zero the buffer's b_kvasize
1860 * should also be non-zero at this point. XXX
1861 */
1862 if (defrag && bp->b_kvasize == 0) {
1863 printf("Warning: defrag empty buffer %p\n", bp);
1864 continue;
1865 }
1866
1867 /*
1868 * Start freeing the bp. This is somewhat involved. nbp
1869 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1870 */
1871
1872 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1873 panic("getnewbuf: locked buf");
1874 bremfreel(bp);
1875 mtx_unlock(&bqlock);
1876
1877 if (qindex == QUEUE_CLEAN) {
1878 if (bp->b_flags & B_VMIO) {
1879 bp->b_flags &= ~B_ASYNC;
1880 vfs_vmio_release(bp);
1881 }
1882 if (bp->b_vp)
1883 brelvp(bp);
1884 }
1885
1886 /*
1887 * NOTE: nbp is now entirely invalid. We can only restart
1888 * the scan from this point on.
1889 *
1890 * Get the rest of the buffer freed up. b_kva* is still
1891 * valid after this operation.
1892 */
1893
1894 if (bp->b_rcred != NOCRED) {
1895 crfree(bp->b_rcred);
1896 bp->b_rcred = NOCRED;
1897 }
1898 if (bp->b_wcred != NOCRED) {
1899 crfree(bp->b_wcred);
1900 bp->b_wcred = NOCRED;
1901 }
1902 if (LIST_FIRST(&bp->b_dep) != NULL)
1903 buf_deallocate(bp);
1904 if (bp->b_vflags & BV_BKGRDINPROG)
1905 panic("losing buffer 3");
1906
1907 if (bp->b_bufsize)
1908 allocbuf(bp, 0);
1909
1910 bp->b_flags = 0;
1911 bp->b_ioflags = 0;
1912 bp->b_xflags = 0;
1913 bp->b_vflags = 0;
1914 bp->b_dev = NODEV;
1915 bp->b_vp = NULL;
1916 bp->b_blkno = bp->b_lblkno = 0;
1917 bp->b_offset = NOOFFSET;
1918 bp->b_iodone = 0;
1919 bp->b_error = 0;
1920 bp->b_resid = 0;
1921 bp->b_bcount = 0;
1922 bp->b_npages = 0;
1923 bp->b_dirtyoff = bp->b_dirtyend = 0;
1924 bp->b_magic = B_MAGIC_BIO;
1925 bp->b_op = &buf_ops_bio;
1926 bp->b_object = NULL;
1927
1928 LIST_INIT(&bp->b_dep);
1929
1930 /*
1931 * If we are defragging then free the buffer.
1932 */
1933 if (defrag) {
1934 bp->b_flags |= B_INVAL;
1935 bfreekva(bp);
1936 brelse(bp);
1937 defrag = 0;
1938 goto restart;
1939 }
1940
1941 /*
1942 * If we are overcomitted then recover the buffer and its
1943 * KVM space. This occurs in rare situations when multiple
1944 * processes are blocked in getnewbuf() or allocbuf().
1945 */
1946 if (bufspace >= hibufspace)
1947 flushingbufs = 1;
1948 if (flushingbufs && bp->b_kvasize != 0) {
1949 bp->b_flags |= B_INVAL;
1950 bfreekva(bp);
1951 brelse(bp);
1952 goto restart;
1953 }
1954 if (bufspace < lobufspace)
1955 flushingbufs = 0;
1956 break;
1957 }
1958
1959 /*
1960 * If we exhausted our list, sleep as appropriate. We may have to
1961 * wakeup various daemons and write out some dirty buffers.
1962 *
1963 * Generally we are sleeping due to insufficient buffer space.
1964 */
1965
1966 if (bp == NULL) {
1967 int flags;
1968 char *waitmsg;
1969
1970 mtx_unlock(&bqlock);
1971 if (defrag) {
1972 flags = VFS_BIO_NEED_BUFSPACE;
1973 waitmsg = "nbufkv";
1974 } else if (bufspace >= hibufspace) {
1975 waitmsg = "nbufbs";
1976 flags = VFS_BIO_NEED_BUFSPACE;
1977 } else {
1978 waitmsg = "newbuf";
1979 flags = VFS_BIO_NEED_ANY;
1980 }
1981
1982 bd_speedup(); /* heeeelp */
1983
1984 mtx_lock(&nblock);
1985 needsbuffer |= flags;
1986 while (needsbuffer & flags) {
1987 if (msleep(&needsbuffer, &nblock,
1988 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
1989 mtx_unlock(&nblock);
1990 return (NULL);
1991 }
1992 }
1993 mtx_unlock(&nblock);
1994 } else {
1995 /*
1996 * We finally have a valid bp. We aren't quite out of the
1997 * woods, we still have to reserve kva space. In order
1998 * to keep fragmentation sane we only allocate kva in
1999 * BKVASIZE chunks.
2000 */
2001 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2002
2003 if (maxsize != bp->b_kvasize) {
2004 vm_offset_t addr = 0;
2005
2006 bfreekva(bp);
2007
2008 if (vm_map_findspace(buffer_map,
2009 vm_map_min(buffer_map), maxsize, &addr)) {
2010 /*
2011 * Uh oh. Buffer map is to fragmented. We
2012 * must defragment the map.
2013 */
2014 atomic_add_int(&bufdefragcnt, 1);
2015 defrag = 1;
2016 bp->b_flags |= B_INVAL;
2017 brelse(bp);
2018 goto restart;
2019 }
2020 if (addr) {
2021 vm_map_insert(buffer_map, NULL, 0,
2022 addr, addr + maxsize,
2023 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
2024
2025 bp->b_kvabase = (caddr_t) addr;
2026 bp->b_kvasize = maxsize;
2027 atomic_add_int(&bufspace, bp->b_kvasize);
2028 atomic_add_int(&bufreusecnt, 1);
2029 }
2030 }
2031 bp->b_saveaddr = bp->b_kvabase;
2032 bp->b_data = bp->b_saveaddr;
2033 }
2034 return(bp);
2035 }
2036
2037 /*
2038 * buf_daemon:
2039 *
2040 * buffer flushing daemon. Buffers are normally flushed by the
2041 * update daemon but if it cannot keep up this process starts to
2042 * take the load in an attempt to prevent getnewbuf() from blocking.
2043 */
2044
2045 static struct kproc_desc buf_kp = {
2046 "bufdaemon",
2047 buf_daemon,
2048 &bufdaemonproc
2049 };
2050 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
2051
2052 static void
2053 buf_daemon()
2054 {
2055 int s;
2056
2057 mtx_lock(&Giant);
2058
2059 /*
2060 * This process needs to be suspended prior to shutdown sync.
2061 */
2062 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2063 SHUTDOWN_PRI_LAST);
2064
2065 /*
2066 * This process is allowed to take the buffer cache to the limit
2067 */
2068 s = splbio();
2069 mtx_lock(&bdlock);
2070
2071 for (;;) {
2072 bd_request = 0;
2073 mtx_unlock(&bdlock);
2074
2075 kthread_suspend_check(bufdaemonproc);
2076
2077 /*
2078 * Do the flush. Limit the amount of in-transit I/O we
2079 * allow to build up, otherwise we would completely saturate
2080 * the I/O system. Wakeup any waiting processes before we
2081 * normally would so they can run in parallel with our drain.
2082 */
2083 while (numdirtybuffers > lodirtybuffers) {
2084 if (flushbufqueues(0) == 0) {
2085 /*
2086 * Could not find any buffers without rollback
2087 * dependencies, so just write the first one
2088 * in the hopes of eventually making progress.
2089 */
2090 flushbufqueues(1);
2091 break;
2092 }
2093 waitrunningbufspace();
2094 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2095 }
2096
2097 /*
2098 * Only clear bd_request if we have reached our low water
2099 * mark. The buf_daemon normally waits 1 second and
2100 * then incrementally flushes any dirty buffers that have
2101 * built up, within reason.
2102 *
2103 * If we were unable to hit our low water mark and couldn't
2104 * find any flushable buffers, we sleep half a second.
2105 * Otherwise we loop immediately.
2106 */
2107 mtx_lock(&bdlock);
2108 if (numdirtybuffers <= lodirtybuffers) {
2109 /*
2110 * We reached our low water mark, reset the
2111 * request and sleep until we are needed again.
2112 * The sleep is just so the suspend code works.
2113 */
2114 bd_request = 0;
2115 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2116 } else {
2117 /*
2118 * We couldn't find any flushable dirty buffers but
2119 * still have too many dirty buffers, we
2120 * have to sleep and try again. (rare)
2121 */
2122 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2123 }
2124 }
2125 }
2126
2127 /*
2128 * flushbufqueues:
2129 *
2130 * Try to flush a buffer in the dirty queue. We must be careful to
2131 * free up B_INVAL buffers instead of write them, which NFS is
2132 * particularly sensitive to.
2133 */
2134 int flushwithdeps = 0;
2135 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2136 0, "Number of buffers flushed with dependecies that require rollbacks");
2137 static int
2138 flushbufqueues(int flushdeps)
2139 {
2140 struct thread *td = curthread;
2141 struct vnode *vp;
2142 struct mount *mp;
2143 struct buf *bp;
2144 int hasdeps;
2145
2146 mtx_lock(&bqlock);
2147 TAILQ_FOREACH(bp, &bufqueues[QUEUE_DIRTY], b_freelist) {
2148 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2149 continue;
2150 KASSERT((bp->b_flags & B_DELWRI),
2151 ("unexpected clean buffer %p", bp));
2152 VI_LOCK(bp->b_vp);
2153 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
2154 VI_UNLOCK(bp->b_vp);
2155 BUF_UNLOCK(bp);
2156 continue;
2157 }
2158 VI_UNLOCK(bp->b_vp);
2159 if (bp->b_flags & B_INVAL) {
2160 bremfreel(bp);
2161 mtx_unlock(&bqlock);
2162 brelse(bp);
2163 return (1);
2164 }
2165
2166 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) {
2167 if (flushdeps == 0) {
2168 BUF_UNLOCK(bp);
2169 continue;
2170 }
2171 hasdeps = 1;
2172 } else
2173 hasdeps = 0;
2174 /*
2175 * We must hold the lock on a vnode before writing
2176 * one of its buffers. Otherwise we may confuse, or
2177 * in the case of a snapshot vnode, deadlock the
2178 * system.
2179 *
2180 * The lock order here is the reverse of the normal
2181 * of vnode followed by buf lock. This is ok because
2182 * the NOWAIT will prevent deadlock.
2183 */
2184 vp = bp->b_vp;
2185 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2186 BUF_UNLOCK(bp);
2187 continue;
2188 }
2189 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) {
2190 mtx_unlock(&bqlock);
2191 vfs_bio_awrite(bp);
2192 vn_finished_write(mp);
2193 VOP_UNLOCK(vp, 0, td);
2194 flushwithdeps += hasdeps;
2195 return (1);
2196 }
2197 vn_finished_write(mp);
2198 BUF_UNLOCK(bp);
2199 }
2200 mtx_unlock(&bqlock);
2201 return (0);
2202 }
2203
2204 /*
2205 * Check to see if a block is currently memory resident.
2206 */
2207 struct buf *
2208 incore(struct vnode * vp, daddr_t blkno)
2209 {
2210 struct buf *bp;
2211
2212 int s = splbio();
2213 VI_LOCK(vp);
2214 bp = gbincore(vp, blkno);
2215 VI_UNLOCK(vp);
2216 splx(s);
2217 return (bp);
2218 }
2219
2220 /*
2221 * Returns true if no I/O is needed to access the
2222 * associated VM object. This is like incore except
2223 * it also hunts around in the VM system for the data.
2224 */
2225
2226 int
2227 inmem(struct vnode * vp, daddr_t blkno)
2228 {
2229 vm_object_t obj;
2230 vm_offset_t toff, tinc, size;
2231 vm_page_t m;
2232 vm_ooffset_t off;
2233
2234 GIANT_REQUIRED;
2235 ASSERT_VOP_LOCKED(vp, "inmem");
2236
2237 if (incore(vp, blkno))
2238 return 1;
2239 if (vp->v_mount == NULL)
2240 return 0;
2241 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_vflag & VV_OBJBUF) == 0)
2242 return 0;
2243
2244 size = PAGE_SIZE;
2245 if (size > vp->v_mount->mnt_stat.f_iosize)
2246 size = vp->v_mount->mnt_stat.f_iosize;
2247 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2248
2249 VM_OBJECT_LOCK(obj);
2250 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2251 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2252 if (!m)
2253 goto notinmem;
2254 tinc = size;
2255 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2256 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2257 if (vm_page_is_valid(m,
2258 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2259 goto notinmem;
2260 }
2261 VM_OBJECT_UNLOCK(obj);
2262 return 1;
2263
2264 notinmem:
2265 VM_OBJECT_UNLOCK(obj);
2266 return (0);
2267 }
2268
2269 /*
2270 * vfs_setdirty:
2271 *
2272 * Sets the dirty range for a buffer based on the status of the dirty
2273 * bits in the pages comprising the buffer.
2274 *
2275 * The range is limited to the size of the buffer.
2276 *
2277 * This routine is primarily used by NFS, but is generalized for the
2278 * B_VMIO case.
2279 */
2280 static void
2281 vfs_setdirty(struct buf *bp)
2282 {
2283 int i;
2284 vm_object_t object;
2285
2286 GIANT_REQUIRED;
2287 /*
2288 * Degenerate case - empty buffer
2289 */
2290
2291 if (bp->b_bufsize == 0)
2292 return;
2293
2294 /*
2295 * We qualify the scan for modified pages on whether the
2296 * object has been flushed yet. The OBJ_WRITEABLE flag
2297 * is not cleared simply by protecting pages off.
2298 */
2299
2300 if ((bp->b_flags & B_VMIO) == 0)
2301 return;
2302
2303 object = bp->b_pages[0]->object;
2304 VM_OBJECT_LOCK(object);
2305 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
2306 printf("Warning: object %p writeable but not mightbedirty\n", object);
2307 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
2308 printf("Warning: object %p mightbedirty but not writeable\n", object);
2309
2310 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2311 vm_offset_t boffset;
2312 vm_offset_t eoffset;
2313
2314 vm_page_lock_queues();
2315 /*
2316 * test the pages to see if they have been modified directly
2317 * by users through the VM system.
2318 */
2319 for (i = 0; i < bp->b_npages; i++) {
2320 vm_page_flag_clear(bp->b_pages[i], PG_ZERO);
2321 vm_page_test_dirty(bp->b_pages[i]);
2322 }
2323
2324 /*
2325 * Calculate the encompassing dirty range, boffset and eoffset,
2326 * (eoffset - boffset) bytes.
2327 */
2328
2329 for (i = 0; i < bp->b_npages; i++) {
2330 if (bp->b_pages[i]->dirty)
2331 break;
2332 }
2333 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2334
2335 for (i = bp->b_npages - 1; i >= 0; --i) {
2336 if (bp->b_pages[i]->dirty) {
2337 break;
2338 }
2339 }
2340 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2341
2342 vm_page_unlock_queues();
2343 /*
2344 * Fit it to the buffer.
2345 */
2346
2347 if (eoffset > bp->b_bcount)
2348 eoffset = bp->b_bcount;
2349
2350 /*
2351 * If we have a good dirty range, merge with the existing
2352 * dirty range.
2353 */
2354
2355 if (boffset < eoffset) {
2356 if (bp->b_dirtyoff > boffset)
2357 bp->b_dirtyoff = boffset;
2358 if (bp->b_dirtyend < eoffset)
2359 bp->b_dirtyend = eoffset;
2360 }
2361 }
2362 VM_OBJECT_UNLOCK(object);
2363 }
2364
2365 /*
2366 * getblk:
2367 *
2368 * Get a block given a specified block and offset into a file/device.
2369 * The buffers B_DONE bit will be cleared on return, making it almost
2370 * ready for an I/O initiation. B_INVAL may or may not be set on
2371 * return. The caller should clear B_INVAL prior to initiating a
2372 * READ.
2373 *
2374 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2375 * an existing buffer.
2376 *
2377 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2378 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2379 * and then cleared based on the backing VM. If the previous buffer is
2380 * non-0-sized but invalid, B_CACHE will be cleared.
2381 *
2382 * If getblk() must create a new buffer, the new buffer is returned with
2383 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2384 * case it is returned with B_INVAL clear and B_CACHE set based on the
2385 * backing VM.
2386 *
2387 * getblk() also forces a BUF_WRITE() for any B_DELWRI buffer whos
2388 * B_CACHE bit is clear.
2389 *
2390 * What this means, basically, is that the caller should use B_CACHE to
2391 * determine whether the buffer is fully valid or not and should clear
2392 * B_INVAL prior to issuing a read. If the caller intends to validate
2393 * the buffer by loading its data area with something, the caller needs
2394 * to clear B_INVAL. If the caller does this without issuing an I/O,
2395 * the caller should set B_CACHE ( as an optimization ), else the caller
2396 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2397 * a write attempt or if it was a successfull read. If the caller
2398 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2399 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2400 */
2401 struct buf *
2402 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2403 int flags)
2404 {
2405 struct buf *bp;
2406 int s;
2407 int error;
2408 ASSERT_VOP_LOCKED(vp, "getblk");
2409
2410 if (size > MAXBSIZE)
2411 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2412
2413 s = splbio();
2414 loop:
2415 /*
2416 * Block if we are low on buffers. Certain processes are allowed
2417 * to completely exhaust the buffer cache.
2418 *
2419 * If this check ever becomes a bottleneck it may be better to
2420 * move it into the else, when gbincore() fails. At the moment
2421 * it isn't a problem.
2422 *
2423 * XXX remove if 0 sections (clean this up after its proven)
2424 */
2425 if (numfreebuffers == 0) {
2426 if (curthread == PCPU_GET(idlethread))
2427 return NULL;
2428 mtx_lock(&nblock);
2429 needsbuffer |= VFS_BIO_NEED_ANY;
2430 mtx_unlock(&nblock);
2431 }
2432
2433 VI_LOCK(vp);
2434 if ((bp = gbincore(vp, blkno))) {
2435 int lockflags;
2436 /*
2437 * Buffer is in-core. If the buffer is not busy, it must
2438 * be on a queue.
2439 */
2440 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2441
2442 if (flags & GB_LOCK_NOWAIT)
2443 lockflags |= LK_NOWAIT;
2444
2445 error = BUF_TIMELOCK(bp, lockflags,
2446 VI_MTX(vp), "getblk", slpflag, slptimeo);
2447
2448 /*
2449 * If we slept and got the lock we have to restart in case
2450 * the buffer changed identities.
2451 */
2452 if (error == ENOLCK)
2453 goto loop;
2454 /* We timed out or were interrupted. */
2455 else if (error)
2456 return (NULL);
2457
2458 /*
2459 * The buffer is locked. B_CACHE is cleared if the buffer is
2460 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2461 * and for a VMIO buffer B_CACHE is adjusted according to the
2462 * backing VM cache.
2463 */
2464 if (bp->b_flags & B_INVAL)
2465 bp->b_flags &= ~B_CACHE;
2466 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2467 bp->b_flags |= B_CACHE;
2468 bremfree(bp);
2469
2470 /*
2471 * check for size inconsistancies for non-VMIO case.
2472 */
2473
2474 if (bp->b_bcount != size) {
2475 if ((bp->b_flags & B_VMIO) == 0 ||
2476 (size > bp->b_kvasize)) {
2477 if (bp->b_flags & B_DELWRI) {
2478 bp->b_flags |= B_NOCACHE;
2479 BUF_WRITE(bp);
2480 } else {
2481 if ((bp->b_flags & B_VMIO) &&
2482 (LIST_FIRST(&bp->b_dep) == NULL)) {
2483 bp->b_flags |= B_RELBUF;
2484 brelse(bp);
2485 } else {
2486 bp->b_flags |= B_NOCACHE;
2487 BUF_WRITE(bp);
2488 }
2489 }
2490 goto loop;
2491 }
2492 }
2493
2494 /*
2495 * If the size is inconsistant in the VMIO case, we can resize
2496 * the buffer. This might lead to B_CACHE getting set or
2497 * cleared. If the size has not changed, B_CACHE remains
2498 * unchanged from its previous state.
2499 */
2500
2501 if (bp->b_bcount != size)
2502 allocbuf(bp, size);
2503
2504 KASSERT(bp->b_offset != NOOFFSET,
2505 ("getblk: no buffer offset"));
2506
2507 /*
2508 * A buffer with B_DELWRI set and B_CACHE clear must
2509 * be committed before we can return the buffer in
2510 * order to prevent the caller from issuing a read
2511 * ( due to B_CACHE not being set ) and overwriting
2512 * it.
2513 *
2514 * Most callers, including NFS and FFS, need this to
2515 * operate properly either because they assume they
2516 * can issue a read if B_CACHE is not set, or because
2517 * ( for example ) an uncached B_DELWRI might loop due
2518 * to softupdates re-dirtying the buffer. In the latter
2519 * case, B_CACHE is set after the first write completes,
2520 * preventing further loops.
2521 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2522 * above while extending the buffer, we cannot allow the
2523 * buffer to remain with B_CACHE set after the write
2524 * completes or it will represent a corrupt state. To
2525 * deal with this we set B_NOCACHE to scrap the buffer
2526 * after the write.
2527 *
2528 * We might be able to do something fancy, like setting
2529 * B_CACHE in bwrite() except if B_DELWRI is already set,
2530 * so the below call doesn't set B_CACHE, but that gets real
2531 * confusing. This is much easier.
2532 */
2533
2534 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2535 bp->b_flags |= B_NOCACHE;
2536 BUF_WRITE(bp);
2537 goto loop;
2538 }
2539
2540 splx(s);
2541 bp->b_flags &= ~B_DONE;
2542 } else {
2543 int bsize, maxsize, vmio;
2544 off_t offset;
2545
2546 /*
2547 * Buffer is not in-core, create new buffer. The buffer
2548 * returned by getnewbuf() is locked. Note that the returned
2549 * buffer is also considered valid (not marked B_INVAL).
2550 */
2551 VI_UNLOCK(vp);
2552 /*
2553 * If the user does not want us to create the buffer, bail out
2554 * here.
2555 */
2556 if (flags & GB_NOCREAT) {
2557 splx(s);
2558 return NULL;
2559 }
2560 if (vn_isdisk(vp, NULL))
2561 bsize = DEV_BSIZE;
2562 else if (vp->v_mountedhere)
2563 bsize = vp->v_mountedhere->mnt_stat.f_iosize;
2564 else if (vp->v_mount)
2565 bsize = vp->v_mount->mnt_stat.f_iosize;
2566 else
2567 bsize = size;
2568
2569 offset = blkno * bsize;
2570 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) &&
2571 (vp->v_vflag & VV_OBJBUF);
2572 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2573 maxsize = imax(maxsize, bsize);
2574
2575 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) {
2576 if (slpflag || slptimeo) {
2577 splx(s);
2578 return NULL;
2579 }
2580 goto loop;
2581 }
2582
2583 /*
2584 * This code is used to make sure that a buffer is not
2585 * created while the getnewbuf routine is blocked.
2586 * This can be a problem whether the vnode is locked or not.
2587 * If the buffer is created out from under us, we have to
2588 * throw away the one we just created. There is now window
2589 * race because we are safely running at splbio() from the
2590 * point of the duplicate buffer creation through to here,
2591 * and we've locked the buffer.
2592 *
2593 * Note: this must occur before we associate the buffer
2594 * with the vp especially considering limitations in
2595 * the splay tree implementation when dealing with duplicate
2596 * lblkno's.
2597 */
2598 VI_LOCK(vp);
2599 if (gbincore(vp, blkno)) {
2600 VI_UNLOCK(vp);
2601 bp->b_flags |= B_INVAL;
2602 brelse(bp);
2603 goto loop;
2604 }
2605
2606 /*
2607 * Insert the buffer into the hash, so that it can
2608 * be found by incore.
2609 */
2610 bp->b_blkno = bp->b_lblkno = blkno;
2611 bp->b_offset = offset;
2612
2613 bgetvp(vp, bp);
2614 VI_UNLOCK(vp);
2615
2616 /*
2617 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2618 * buffer size starts out as 0, B_CACHE will be set by
2619 * allocbuf() for the VMIO case prior to it testing the
2620 * backing store for validity.
2621 */
2622
2623 if (vmio) {
2624 bp->b_flags |= B_VMIO;
2625 #if defined(VFS_BIO_DEBUG)
2626 if (vp->v_type != VREG)
2627 printf("getblk: vmioing file type %d???\n", vp->v_type);
2628 #endif
2629 VOP_GETVOBJECT(vp, &bp->b_object);
2630 } else {
2631 bp->b_flags &= ~B_VMIO;
2632 bp->b_object = NULL;
2633 }
2634
2635 allocbuf(bp, size);
2636
2637 splx(s);
2638 bp->b_flags &= ~B_DONE;
2639 }
2640 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
2641 return (bp);
2642 }
2643
2644 /*
2645 * Get an empty, disassociated buffer of given size. The buffer is initially
2646 * set to B_INVAL.
2647 */
2648 struct buf *
2649 geteblk(int size)
2650 {
2651 struct buf *bp;
2652 int s;
2653 int maxsize;
2654
2655 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2656
2657 s = splbio();
2658 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
2659 continue;
2660 splx(s);
2661 allocbuf(bp, size);
2662 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2663 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
2664 return (bp);
2665 }
2666
2667
2668 /*
2669 * This code constitutes the buffer memory from either anonymous system
2670 * memory (in the case of non-VMIO operations) or from an associated
2671 * VM object (in the case of VMIO operations). This code is able to
2672 * resize a buffer up or down.
2673 *
2674 * Note that this code is tricky, and has many complications to resolve
2675 * deadlock or inconsistant data situations. Tread lightly!!!
2676 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2677 * the caller. Calling this code willy nilly can result in the loss of data.
2678 *
2679 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2680 * B_CACHE for the non-VMIO case.
2681 */
2682
2683 int
2684 allocbuf(struct buf *bp, int size)
2685 {
2686 int newbsize, mbsize;
2687 int i;
2688
2689 GIANT_REQUIRED;
2690
2691 if (BUF_REFCNT(bp) == 0)
2692 panic("allocbuf: buffer not busy");
2693
2694 if (bp->b_kvasize < size)
2695 panic("allocbuf: buffer too small");
2696
2697 if ((bp->b_flags & B_VMIO) == 0) {
2698 caddr_t origbuf;
2699 int origbufsize;
2700 /*
2701 * Just get anonymous memory from the kernel. Don't
2702 * mess with B_CACHE.
2703 */
2704 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2705 if (bp->b_flags & B_MALLOC)
2706 newbsize = mbsize;
2707 else
2708 newbsize = round_page(size);
2709
2710 if (newbsize < bp->b_bufsize) {
2711 /*
2712 * malloced buffers are not shrunk
2713 */
2714 if (bp->b_flags & B_MALLOC) {
2715 if (newbsize) {
2716 bp->b_bcount = size;
2717 } else {
2718 free(bp->b_data, M_BIOBUF);
2719 if (bp->b_bufsize) {
2720 atomic_subtract_int(
2721 &bufmallocspace,
2722 bp->b_bufsize);
2723 bufspacewakeup();
2724 bp->b_bufsize = 0;
2725 }
2726 bp->b_saveaddr = bp->b_kvabase;
2727 bp->b_data = bp->b_saveaddr;
2728 bp->b_bcount = 0;
2729 bp->b_flags &= ~B_MALLOC;
2730 }
2731 return 1;
2732 }
2733 vm_hold_free_pages(
2734 bp,
2735 (vm_offset_t) bp->b_data + newbsize,
2736 (vm_offset_t) bp->b_data + bp->b_bufsize);
2737 } else if (newbsize > bp->b_bufsize) {
2738 /*
2739 * We only use malloced memory on the first allocation.
2740 * and revert to page-allocated memory when the buffer
2741 * grows.
2742 */
2743 /*
2744 * There is a potential smp race here that could lead
2745 * to bufmallocspace slightly passing the max. It
2746 * is probably extremely rare and not worth worrying
2747 * over.
2748 */
2749 if ( (bufmallocspace < maxbufmallocspace) &&
2750 (bp->b_bufsize == 0) &&
2751 (mbsize <= PAGE_SIZE/2)) {
2752
2753 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2754 bp->b_bufsize = mbsize;
2755 bp->b_bcount = size;
2756 bp->b_flags |= B_MALLOC;
2757 atomic_add_int(&bufmallocspace, mbsize);
2758 return 1;
2759 }
2760 origbuf = NULL;
2761 origbufsize = 0;
2762 /*
2763 * If the buffer is growing on its other-than-first allocation,
2764 * then we revert to the page-allocation scheme.
2765 */
2766 if (bp->b_flags & B_MALLOC) {
2767 origbuf = bp->b_data;
2768 origbufsize = bp->b_bufsize;
2769 bp->b_data = bp->b_kvabase;
2770 if (bp->b_bufsize) {
2771 atomic_subtract_int(&bufmallocspace,
2772 bp->b_bufsize);
2773 bufspacewakeup();
2774 bp->b_bufsize = 0;
2775 }
2776 bp->b_flags &= ~B_MALLOC;
2777 newbsize = round_page(newbsize);
2778 }
2779 vm_hold_load_pages(
2780 bp,
2781 (vm_offset_t) bp->b_data + bp->b_bufsize,
2782 (vm_offset_t) bp->b_data + newbsize);
2783 if (origbuf) {
2784 bcopy(origbuf, bp->b_data, origbufsize);
2785 free(origbuf, M_BIOBUF);
2786 }
2787 }
2788 } else {
2789 int desiredpages;
2790
2791 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2792 desiredpages = (size == 0) ? 0 :
2793 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2794
2795 if (bp->b_flags & B_MALLOC)
2796 panic("allocbuf: VMIO buffer can't be malloced");
2797 /*
2798 * Set B_CACHE initially if buffer is 0 length or will become
2799 * 0-length.
2800 */
2801 if (size == 0 || bp->b_bufsize == 0)
2802 bp->b_flags |= B_CACHE;
2803
2804 if (newbsize < bp->b_bufsize) {
2805 /*
2806 * DEV_BSIZE aligned new buffer size is less then the
2807 * DEV_BSIZE aligned existing buffer size. Figure out
2808 * if we have to remove any pages.
2809 */
2810 if (desiredpages < bp->b_npages) {
2811 vm_page_t m;
2812
2813 vm_page_lock_queues();
2814 for (i = desiredpages; i < bp->b_npages; i++) {
2815 /*
2816 * the page is not freed here -- it
2817 * is the responsibility of
2818 * vnode_pager_setsize
2819 */
2820 m = bp->b_pages[i];
2821 KASSERT(m != bogus_page,
2822 ("allocbuf: bogus page found"));
2823 while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
2824 vm_page_lock_queues();
2825
2826 bp->b_pages[i] = NULL;
2827 vm_page_unwire(m, 0);
2828 }
2829 vm_page_unlock_queues();
2830 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2831 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
2832 bp->b_npages = desiredpages;
2833 }
2834 } else if (size > bp->b_bcount) {
2835 /*
2836 * We are growing the buffer, possibly in a
2837 * byte-granular fashion.
2838 */
2839 struct vnode *vp;
2840 vm_object_t obj;
2841 vm_offset_t toff;
2842 vm_offset_t tinc;
2843
2844 /*
2845 * Step 1, bring in the VM pages from the object,
2846 * allocating them if necessary. We must clear
2847 * B_CACHE if these pages are not valid for the
2848 * range covered by the buffer.
2849 */
2850
2851 vp = bp->b_vp;
2852 obj = bp->b_object;
2853
2854 VM_OBJECT_LOCK(obj);
2855 while (bp->b_npages < desiredpages) {
2856 vm_page_t m;
2857 vm_pindex_t pi;
2858
2859 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
2860 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2861 /*
2862 * note: must allocate system pages
2863 * since blocking here could intefere
2864 * with paging I/O, no matter which
2865 * process we are.
2866 */
2867 m = vm_page_alloc(obj, pi,
2868 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
2869 if (m == NULL) {
2870 atomic_add_int(&vm_pageout_deficit,
2871 desiredpages - bp->b_npages);
2872 VM_OBJECT_UNLOCK(obj);
2873 VM_WAIT;
2874 VM_OBJECT_LOCK(obj);
2875 } else {
2876 vm_page_lock_queues();
2877 vm_page_wakeup(m);
2878 vm_page_unlock_queues();
2879 bp->b_flags &= ~B_CACHE;
2880 bp->b_pages[bp->b_npages] = m;
2881 ++bp->b_npages;
2882 }
2883 continue;
2884 }
2885
2886 /*
2887 * We found a page. If we have to sleep on it,
2888 * retry because it might have gotten freed out
2889 * from under us.
2890 *
2891 * We can only test PG_BUSY here. Blocking on
2892 * m->busy might lead to a deadlock:
2893 *
2894 * vm_fault->getpages->cluster_read->allocbuf
2895 *
2896 */
2897 vm_page_lock_queues();
2898 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
2899 continue;
2900
2901 /*
2902 * We have a good page. Should we wakeup the
2903 * page daemon?
2904 */
2905 if ((curproc != pageproc) &&
2906 ((m->queue - m->pc) == PQ_CACHE) &&
2907 ((cnt.v_free_count + cnt.v_cache_count) <
2908 (cnt.v_free_min + cnt.v_cache_min))) {
2909 pagedaemon_wakeup();
2910 }
2911 vm_page_flag_clear(m, PG_ZERO);
2912 vm_page_wire(m);
2913 vm_page_unlock_queues();
2914 bp->b_pages[bp->b_npages] = m;
2915 ++bp->b_npages;
2916 }
2917
2918 /*
2919 * Step 2. We've loaded the pages into the buffer,
2920 * we have to figure out if we can still have B_CACHE
2921 * set. Note that B_CACHE is set according to the
2922 * byte-granular range ( bcount and size ), new the
2923 * aligned range ( newbsize ).
2924 *
2925 * The VM test is against m->valid, which is DEV_BSIZE
2926 * aligned. Needless to say, the validity of the data
2927 * needs to also be DEV_BSIZE aligned. Note that this
2928 * fails with NFS if the server or some other client
2929 * extends the file's EOF. If our buffer is resized,
2930 * B_CACHE may remain set! XXX
2931 */
2932
2933 toff = bp->b_bcount;
2934 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2935
2936 while ((bp->b_flags & B_CACHE) && toff < size) {
2937 vm_pindex_t pi;
2938
2939 if (tinc > (size - toff))
2940 tinc = size - toff;
2941
2942 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2943 PAGE_SHIFT;
2944
2945 vfs_buf_test_cache(
2946 bp,
2947 bp->b_offset,
2948 toff,
2949 tinc,
2950 bp->b_pages[pi]
2951 );
2952 toff += tinc;
2953 tinc = PAGE_SIZE;
2954 }
2955 VM_OBJECT_UNLOCK(obj);
2956
2957 /*
2958 * Step 3, fixup the KVM pmap. Remember that
2959 * bp->b_data is relative to bp->b_offset, but
2960 * bp->b_offset may be offset into the first page.
2961 */
2962
2963 bp->b_data = (caddr_t)
2964 trunc_page((vm_offset_t)bp->b_data);
2965 pmap_qenter(
2966 (vm_offset_t)bp->b_data,
2967 bp->b_pages,
2968 bp->b_npages
2969 );
2970
2971 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2972 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2973 }
2974 }
2975 if (newbsize < bp->b_bufsize)
2976 bufspacewakeup();
2977 bp->b_bufsize = newbsize; /* actual buffer allocation */
2978 bp->b_bcount = size; /* requested buffer size */
2979 return 1;
2980 }
2981
2982 void
2983 biodone(struct bio *bp)
2984 {
2985 mtx_lock(&bdonelock);
2986 bp->bio_flags |= BIO_DONE;
2987 if (bp->bio_done == NULL)
2988 wakeup(bp);
2989 mtx_unlock(&bdonelock);
2990 if (bp->bio_done != NULL)
2991 bp->bio_done(bp);
2992 }
2993
2994 /*
2995 * Wait for a BIO to finish.
2996 *
2997 * XXX: resort to a timeout for now. The optimal locking (if any) for this
2998 * case is not yet clear.
2999 */
3000 int
3001 biowait(struct bio *bp, const char *wchan)
3002 {
3003
3004 mtx_lock(&bdonelock);
3005 while ((bp->bio_flags & BIO_DONE) == 0)
3006 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
3007 mtx_unlock(&bdonelock);
3008 if (bp->bio_error != 0)
3009 return (bp->bio_error);
3010 if (!(bp->bio_flags & BIO_ERROR))
3011 return (0);
3012 return (EIO);
3013 }
3014
3015 void
3016 biofinish(struct bio *bp, struct devstat *stat, int error)
3017 {
3018
3019 if (error) {
3020 bp->bio_error = error;
3021 bp->bio_flags |= BIO_ERROR;
3022 }
3023 if (stat != NULL)
3024 devstat_end_transaction_bio(stat, bp);
3025 biodone(bp);
3026 }
3027
3028 /*
3029 * bufwait:
3030 *
3031 * Wait for buffer I/O completion, returning error status. The buffer
3032 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3033 * error and cleared.
3034 */
3035 int
3036 bufwait(register struct buf * bp)
3037 {
3038 int s;
3039
3040 s = splbio();
3041 if (bp->b_iocmd == BIO_READ)
3042 bwait(bp, PRIBIO, "biord");
3043 else
3044 bwait(bp, PRIBIO, "biowr");
3045 splx(s);
3046 if (bp->b_flags & B_EINTR) {
3047 bp->b_flags &= ~B_EINTR;
3048 return (EINTR);
3049 }
3050 if (bp->b_ioflags & BIO_ERROR) {
3051 return (bp->b_error ? bp->b_error : EIO);
3052 } else {
3053 return (0);
3054 }
3055 }
3056
3057 /*
3058 * Call back function from struct bio back up to struct buf.
3059 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY().
3060 */
3061 static void
3062 bufdonebio(struct bio *bp)
3063 {
3064
3065 /* Device drivers may or may not hold giant, hold it here. */
3066 mtx_lock(&Giant);
3067 bufdone(bp->bio_caller2);
3068 mtx_unlock(&Giant);
3069 }
3070
3071 void
3072 dev_strategy(struct buf *bp)
3073 {
3074
3075 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
3076 panic("b_iocmd botch");
3077 bp->b_io.bio_done = bufdonebio;
3078 bp->b_io.bio_caller2 = bp;
3079 (*devsw(bp->b_io.bio_dev)->d_strategy)(&bp->b_io);
3080 }
3081
3082 /*
3083 * bufdone:
3084 *
3085 * Finish I/O on a buffer, optionally calling a completion function.
3086 * This is usually called from an interrupt so process blocking is
3087 * not allowed.
3088 *
3089 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3090 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3091 * assuming B_INVAL is clear.
3092 *
3093 * For the VMIO case, we set B_CACHE if the op was a read and no
3094 * read error occured, or if the op was a write. B_CACHE is never
3095 * set if the buffer is invalid or otherwise uncacheable.
3096 *
3097 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3098 * initiator to leave B_INVAL set to brelse the buffer out of existance
3099 * in the biodone routine.
3100 */
3101 void
3102 bufdone(struct buf *bp)
3103 {
3104 int s;
3105 void (*biodone)(struct buf *);
3106
3107 GIANT_REQUIRED;
3108
3109 s = splbio();
3110
3111 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp)));
3112 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3113
3114 bp->b_flags |= B_DONE;
3115 runningbufwakeup(bp);
3116
3117 if (bp->b_iocmd == BIO_DELETE) {
3118 brelse(bp);
3119 splx(s);
3120 return;
3121 }
3122
3123 if (bp->b_iocmd == BIO_WRITE) {
3124 vwakeup(bp);
3125 }
3126
3127 /* call optional completion function if requested */
3128 if (bp->b_iodone != NULL) {
3129 biodone = bp->b_iodone;
3130 bp->b_iodone = NULL;
3131 (*biodone) (bp);
3132 splx(s);
3133 return;
3134 }
3135 if (LIST_FIRST(&bp->b_dep) != NULL)
3136 buf_complete(bp);
3137
3138 if (bp->b_flags & B_VMIO) {
3139 int i;
3140 vm_ooffset_t foff;
3141 vm_page_t m;
3142 vm_object_t obj;
3143 int iosize;
3144 struct vnode *vp = bp->b_vp;
3145
3146 obj = bp->b_object;
3147
3148 #if defined(VFS_BIO_DEBUG)
3149 mp_fixme("usecount and vflag accessed without locks.");
3150 if (vp->v_usecount == 0) {
3151 panic("biodone: zero vnode ref count");
3152 }
3153
3154 if ((vp->v_vflag & VV_OBJBUF) == 0) {
3155 panic("biodone: vnode is not setup for merged cache");
3156 }
3157 #endif
3158
3159 foff = bp->b_offset;
3160 KASSERT(bp->b_offset != NOOFFSET,
3161 ("biodone: no buffer offset"));
3162
3163 VM_OBJECT_LOCK(obj);
3164 #if defined(VFS_BIO_DEBUG)
3165 if (obj->paging_in_progress < bp->b_npages) {
3166 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
3167 obj->paging_in_progress, bp->b_npages);
3168 }
3169 #endif
3170
3171 /*
3172 * Set B_CACHE if the op was a normal read and no error
3173 * occured. B_CACHE is set for writes in the b*write()
3174 * routines.
3175 */
3176 iosize = bp->b_bcount - bp->b_resid;
3177 if (bp->b_iocmd == BIO_READ &&
3178 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3179 !(bp->b_ioflags & BIO_ERROR)) {
3180 bp->b_flags |= B_CACHE;
3181 }
3182 vm_page_lock_queues();
3183 for (i = 0; i < bp->b_npages; i++) {
3184 int bogusflag = 0;
3185 int resid;
3186
3187 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3188 if (resid > iosize)
3189 resid = iosize;
3190
3191 /*
3192 * cleanup bogus pages, restoring the originals
3193 */
3194 m = bp->b_pages[i];
3195 if (m == bogus_page) {
3196 bogusflag = 1;
3197 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3198 if (m == NULL)
3199 panic("biodone: page disappeared!");
3200 bp->b_pages[i] = m;
3201 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3202 }
3203 #if defined(VFS_BIO_DEBUG)
3204 if (OFF_TO_IDX(foff) != m->pindex) {
3205 printf(
3206 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
3207 (intmax_t)foff, (uintmax_t)m->pindex);
3208 }
3209 #endif
3210
3211 /*
3212 * In the write case, the valid and clean bits are
3213 * already changed correctly ( see bdwrite() ), so we
3214 * only need to do this here in the read case.
3215 */
3216 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3217 vfs_page_set_valid(bp, foff, i, m);
3218 }
3219 vm_page_flag_clear(m, PG_ZERO);
3220
3221 /*
3222 * when debugging new filesystems or buffer I/O methods, this
3223 * is the most common error that pops up. if you see this, you
3224 * have not set the page busy flag correctly!!!
3225 */
3226 if (m->busy == 0) {
3227 printf("biodone: page busy < 0, "
3228 "pindex: %d, foff: 0x(%x,%x), "
3229 "resid: %d, index: %d\n",
3230 (int) m->pindex, (int)(foff >> 32),
3231 (int) foff & 0xffffffff, resid, i);
3232 if (!vn_isdisk(vp, NULL))
3233 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
3234 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
3235 (intmax_t) bp->b_lblkno,
3236 bp->b_flags, bp->b_npages);
3237 else
3238 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
3239 (intmax_t) bp->b_lblkno,
3240 bp->b_flags, bp->b_npages);
3241 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
3242 (u_long)m->valid, (u_long)m->dirty,
3243 m->wire_count);
3244 panic("biodone: page busy < 0\n");
3245 }
3246 vm_page_io_finish(m);
3247 vm_object_pip_subtract(obj, 1);
3248 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3249 iosize -= resid;
3250 }
3251 vm_page_unlock_queues();
3252 vm_object_pip_wakeupn(obj, 0);
3253 VM_OBJECT_UNLOCK(obj);
3254 }
3255
3256 /*
3257 * For asynchronous completions, release the buffer now. The brelse
3258 * will do a wakeup there if necessary - so no need to do a wakeup
3259 * here in the async case. The sync case always needs to do a wakeup.
3260 */
3261
3262 if (bp->b_flags & B_ASYNC) {
3263 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3264 brelse(bp);
3265 else
3266 bqrelse(bp);
3267 } else {
3268 bdone(bp);
3269 }
3270 splx(s);
3271 }
3272
3273 /*
3274 * This routine is called in lieu of iodone in the case of
3275 * incomplete I/O. This keeps the busy status for pages
3276 * consistant.
3277 */
3278 void
3279 vfs_unbusy_pages(struct buf * bp)
3280 {
3281 int i;
3282
3283 runningbufwakeup(bp);
3284 if (bp->b_flags & B_VMIO) {
3285 vm_object_t obj;
3286
3287 obj = bp->b_object;
3288 VM_OBJECT_LOCK(obj);
3289 vm_page_lock_queues();
3290 for (i = 0; i < bp->b_npages; i++) {
3291 vm_page_t m = bp->b_pages[i];
3292
3293 if (m == bogus_page) {
3294 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3295 if (!m) {
3296 panic("vfs_unbusy_pages: page missing\n");
3297 }
3298 bp->b_pages[i] = m;
3299 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3300 }
3301 vm_object_pip_subtract(obj, 1);
3302 vm_page_flag_clear(m, PG_ZERO);
3303 vm_page_io_finish(m);
3304 }
3305 vm_page_unlock_queues();
3306 vm_object_pip_wakeupn(obj, 0);
3307 VM_OBJECT_UNLOCK(obj);
3308 }
3309 }
3310
3311 /*
3312 * vfs_page_set_valid:
3313 *
3314 * Set the valid bits in a page based on the supplied offset. The
3315 * range is restricted to the buffer's size.
3316 *
3317 * This routine is typically called after a read completes.
3318 */
3319 static void
3320 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3321 {
3322 vm_ooffset_t soff, eoff;
3323
3324 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
3325 /*
3326 * Start and end offsets in buffer. eoff - soff may not cross a
3327 * page boundry or cross the end of the buffer. The end of the
3328 * buffer, in this case, is our file EOF, not the allocation size
3329 * of the buffer.
3330 */
3331 soff = off;
3332 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3333 if (eoff > bp->b_offset + bp->b_bcount)
3334 eoff = bp->b_offset + bp->b_bcount;
3335
3336 /*
3337 * Set valid range. This is typically the entire buffer and thus the
3338 * entire page.
3339 */
3340 if (eoff > soff) {
3341 vm_page_set_validclean(
3342 m,
3343 (vm_offset_t) (soff & PAGE_MASK),
3344 (vm_offset_t) (eoff - soff)
3345 );
3346 }
3347 }
3348
3349 /*
3350 * This routine is called before a device strategy routine.
3351 * It is used to tell the VM system that paging I/O is in
3352 * progress, and treat the pages associated with the buffer
3353 * almost as being PG_BUSY. Also the object paging_in_progress
3354 * flag is handled to make sure that the object doesn't become
3355 * inconsistant.
3356 *
3357 * Since I/O has not been initiated yet, certain buffer flags
3358 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3359 * and should be ignored.
3360 */
3361 void
3362 vfs_busy_pages(struct buf * bp, int clear_modify)
3363 {
3364 int i, bogus;
3365
3366 if (bp->b_flags & B_VMIO) {
3367 vm_object_t obj;
3368 vm_ooffset_t foff;
3369
3370 obj = bp->b_object;
3371 foff = bp->b_offset;
3372 KASSERT(bp->b_offset != NOOFFSET,
3373 ("vfs_busy_pages: no buffer offset"));
3374 vfs_setdirty(bp);
3375 VM_OBJECT_LOCK(obj);
3376 retry:
3377 vm_page_lock_queues();
3378 for (i = 0; i < bp->b_npages; i++) {
3379 vm_page_t m = bp->b_pages[i];
3380
3381 if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
3382 goto retry;
3383 }
3384 bogus = 0;
3385 for (i = 0; i < bp->b_npages; i++) {
3386 vm_page_t m = bp->b_pages[i];
3387
3388 vm_page_flag_clear(m, PG_ZERO);
3389 if ((bp->b_flags & B_CLUSTER) == 0) {
3390 vm_object_pip_add(obj, 1);
3391 vm_page_io_start(m);
3392 }
3393 /*
3394 * When readying a buffer for a read ( i.e
3395 * clear_modify == 0 ), it is important to do
3396 * bogus_page replacement for valid pages in
3397 * partially instantiated buffers. Partially
3398 * instantiated buffers can, in turn, occur when
3399 * reconstituting a buffer from its VM backing store
3400 * base. We only have to do this if B_CACHE is
3401 * clear ( which causes the I/O to occur in the
3402 * first place ). The replacement prevents the read
3403 * I/O from overwriting potentially dirty VM-backed
3404 * pages. XXX bogus page replacement is, uh, bogus.
3405 * It may not work properly with small-block devices.
3406 * We need to find a better way.
3407 */
3408 pmap_remove_all(m);
3409 if (clear_modify)
3410 vfs_page_set_valid(bp, foff, i, m);
3411 else if (m->valid == VM_PAGE_BITS_ALL &&
3412 (bp->b_flags & B_CACHE) == 0) {
3413 bp->b_pages[i] = bogus_page;
3414 bogus++;
3415 }
3416 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3417 }
3418 vm_page_unlock_queues();
3419 VM_OBJECT_UNLOCK(obj);
3420 if (bogus)
3421 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3422 }
3423 }
3424
3425 /*
3426 * Tell the VM system that the pages associated with this buffer
3427 * are clean. This is used for delayed writes where the data is
3428 * going to go to disk eventually without additional VM intevention.
3429 *
3430 * Note that while we only really need to clean through to b_bcount, we
3431 * just go ahead and clean through to b_bufsize.
3432 */
3433 static void
3434 vfs_clean_pages(struct buf * bp)
3435 {
3436 int i;
3437
3438 if (bp->b_flags & B_VMIO) {
3439 vm_ooffset_t foff;
3440
3441 foff = bp->b_offset;
3442 KASSERT(bp->b_offset != NOOFFSET,
3443 ("vfs_clean_pages: no buffer offset"));
3444 VM_OBJECT_LOCK(bp->b_object);
3445 vm_page_lock_queues();
3446 for (i = 0; i < bp->b_npages; i++) {
3447 vm_page_t m = bp->b_pages[i];
3448 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3449 vm_ooffset_t eoff = noff;
3450
3451 if (eoff > bp->b_offset + bp->b_bufsize)
3452 eoff = bp->b_offset + bp->b_bufsize;
3453 vfs_page_set_valid(bp, foff, i, m);
3454 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3455 foff = noff;
3456 }
3457 vm_page_unlock_queues();
3458 VM_OBJECT_UNLOCK(bp->b_object);
3459 }
3460 }
3461
3462 /*
3463 * vfs_bio_set_validclean:
3464 *
3465 * Set the range within the buffer to valid and clean. The range is
3466 * relative to the beginning of the buffer, b_offset. Note that b_offset
3467 * itself may be offset from the beginning of the first page.
3468 *
3469 */
3470
3471 void
3472 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3473 {
3474 if (bp->b_flags & B_VMIO) {
3475 int i;
3476 int n;
3477
3478 /*
3479 * Fixup base to be relative to beginning of first page.
3480 * Set initial n to be the maximum number of bytes in the
3481 * first page that can be validated.
3482 */
3483
3484 base += (bp->b_offset & PAGE_MASK);
3485 n = PAGE_SIZE - (base & PAGE_MASK);
3486
3487 VM_OBJECT_LOCK(bp->b_object);
3488 vm_page_lock_queues();
3489 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3490 vm_page_t m = bp->b_pages[i];
3491
3492 if (n > size)
3493 n = size;
3494
3495 vm_page_set_validclean(m, base & PAGE_MASK, n);
3496 base += n;
3497 size -= n;
3498 n = PAGE_SIZE;
3499 }
3500 vm_page_unlock_queues();
3501 VM_OBJECT_UNLOCK(bp->b_object);
3502 }
3503 }
3504
3505 /*
3506 * vfs_bio_clrbuf:
3507 *
3508 * clear a buffer. This routine essentially fakes an I/O, so we need
3509 * to clear BIO_ERROR and B_INVAL.
3510 *
3511 * Note that while we only theoretically need to clear through b_bcount,
3512 * we go ahead and clear through b_bufsize.
3513 */
3514
3515 void
3516 vfs_bio_clrbuf(struct buf *bp)
3517 {
3518 int i, mask = 0;
3519 caddr_t sa, ea;
3520
3521 GIANT_REQUIRED;
3522
3523 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) {
3524 bp->b_flags &= ~B_INVAL;
3525 bp->b_ioflags &= ~BIO_ERROR;
3526 VM_OBJECT_LOCK(bp->b_object);
3527 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3528 (bp->b_offset & PAGE_MASK) == 0) {
3529 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3530 if (bp->b_pages[0] != bogus_page)
3531 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3532 if ((bp->b_pages[0]->valid & mask) == mask)
3533 goto unlock;
3534 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
3535 ((bp->b_pages[0]->valid & mask) == 0)) {
3536 bzero(bp->b_data, bp->b_bufsize);
3537 bp->b_pages[0]->valid |= mask;
3538 goto unlock;
3539 }
3540 }
3541 ea = sa = bp->b_data;
3542 for(i=0;i<bp->b_npages;i++,sa=ea) {
3543 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3544 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3545 ea = (caddr_t)(vm_offset_t)ulmin(
3546 (u_long)(vm_offset_t)ea,
3547 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3548 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3549 if (bp->b_pages[i] != bogus_page)
3550 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3551 if ((bp->b_pages[i]->valid & mask) == mask)
3552 continue;
3553 if ((bp->b_pages[i]->valid & mask) == 0) {
3554 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) {
3555 bzero(sa, ea - sa);
3556 }
3557 } else {
3558 for (; sa < ea; sa += DEV_BSIZE, j++) {
3559 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
3560 (bp->b_pages[i]->valid & (1<<j)) == 0)
3561 bzero(sa, DEV_BSIZE);
3562 }
3563 }
3564 bp->b_pages[i]->valid |= mask;
3565 vm_page_lock_queues();
3566 vm_page_flag_clear(bp->b_pages[i], PG_ZERO);
3567 vm_page_unlock_queues();
3568 }
3569 unlock:
3570 VM_OBJECT_UNLOCK(bp->b_object);
3571 bp->b_resid = 0;
3572 } else {
3573 clrbuf(bp);
3574 }
3575 }
3576
3577 /*
3578 * vm_hold_load_pages and vm_hold_free_pages get pages into
3579 * a buffers address space. The pages are anonymous and are
3580 * not associated with a file object.
3581 */
3582 static void
3583 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to)
3584 {
3585 vm_offset_t pg;
3586 vm_page_t p;
3587 int index;
3588
3589 to = round_page(to);
3590 from = round_page(from);
3591 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3592
3593 VM_OBJECT_LOCK(kernel_object);
3594 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3595 tryagain:
3596 /*
3597 * note: must allocate system pages since blocking here
3598 * could intefere with paging I/O, no matter which
3599 * process we are.
3600 */
3601 p = vm_page_alloc(kernel_object,
3602 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3603 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
3604 if (!p) {
3605 atomic_add_int(&vm_pageout_deficit,
3606 (to - pg) >> PAGE_SHIFT);
3607 VM_OBJECT_UNLOCK(kernel_object);
3608 VM_WAIT;
3609 VM_OBJECT_LOCK(kernel_object);
3610 goto tryagain;
3611 }
3612 p->valid = VM_PAGE_BITS_ALL;
3613 pmap_qenter(pg, &p, 1);
3614 bp->b_pages[index] = p;
3615 vm_page_lock_queues();
3616 vm_page_wakeup(p);
3617 vm_page_unlock_queues();
3618 }
3619 VM_OBJECT_UNLOCK(kernel_object);
3620 bp->b_npages = index;
3621 }
3622
3623 /* Return pages associated with this buf to the vm system */
3624 static void
3625 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to)
3626 {
3627 vm_offset_t pg;
3628 vm_page_t p;
3629 int index, newnpages;
3630
3631 GIANT_REQUIRED;
3632
3633 from = round_page(from);
3634 to = round_page(to);
3635 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3636
3637 VM_OBJECT_LOCK(kernel_object);
3638 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3639 p = bp->b_pages[index];
3640 if (p && (index < bp->b_npages)) {
3641 if (p->busy) {
3642 printf(
3643 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3644 (intmax_t)bp->b_blkno,
3645 (intmax_t)bp->b_lblkno);
3646 }
3647 bp->b_pages[index] = NULL;
3648 pmap_qremove(pg, 1);
3649 vm_page_lock_queues();
3650 vm_page_busy(p);
3651 vm_page_unwire(p, 0);
3652 vm_page_free(p);
3653 vm_page_unlock_queues();
3654 }
3655 }
3656 VM_OBJECT_UNLOCK(kernel_object);
3657 bp->b_npages = newnpages;
3658 }
3659
3660 /*
3661 * Map an IO request into kernel virtual address space.
3662 *
3663 * All requests are (re)mapped into kernel VA space.
3664 * Notice that we use b_bufsize for the size of the buffer
3665 * to be mapped. b_bcount might be modified by the driver.
3666 *
3667 * Note that even if the caller determines that the address space should
3668 * be valid, a race or a smaller-file mapped into a larger space may
3669 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3670 * check the return value.
3671 */
3672 int
3673 vmapbuf(struct buf *bp)
3674 {
3675 caddr_t addr, kva;
3676 vm_prot_t prot;
3677 int pidx, i;
3678 struct vm_page *m;
3679 struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
3680
3681 GIANT_REQUIRED;
3682
3683 if (bp->b_bufsize < 0)
3684 return (-1);
3685 prot = (bp->b_iocmd == BIO_READ) ? VM_PROT_READ | VM_PROT_WRITE :
3686 VM_PROT_READ;
3687 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
3688 addr < bp->b_data + bp->b_bufsize;
3689 addr += PAGE_SIZE, pidx++) {
3690 /*
3691 * Do the vm_fault if needed; do the copy-on-write thing
3692 * when reading stuff off device into memory.
3693 *
3694 * NOTE! Must use pmap_extract() because addr may be in
3695 * the userland address space, and kextract is only guarenteed
3696 * to work for the kernland address space (see: sparc64 port).
3697 */
3698 retry:
3699 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
3700 prot) < 0) {
3701 vm_page_lock_queues();
3702 for (i = 0; i < pidx; ++i) {
3703 vm_page_unhold(bp->b_pages[i]);
3704 bp->b_pages[i] = NULL;
3705 }
3706 vm_page_unlock_queues();
3707 return(-1);
3708 }
3709 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
3710 if (m == NULL)
3711 goto retry;
3712 bp->b_pages[pidx] = m;
3713 }
3714 if (pidx > btoc(MAXPHYS))
3715 panic("vmapbuf: mapped more than MAXPHYS");
3716 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3717
3718 kva = bp->b_saveaddr;
3719 bp->b_npages = pidx;
3720 bp->b_saveaddr = bp->b_data;
3721 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3722 return(0);
3723 }
3724
3725 /*
3726 * Free the io map PTEs associated with this IO operation.
3727 * We also invalidate the TLB entries and restore the original b_addr.
3728 */
3729 void
3730 vunmapbuf(struct buf *bp)
3731 {
3732 int pidx;
3733 int npages;
3734
3735 GIANT_REQUIRED;
3736
3737 npages = bp->b_npages;
3738 pmap_qremove(trunc_page((vm_offset_t)bp->b_data),
3739 npages);
3740 vm_page_lock_queues();
3741 for (pidx = 0; pidx < npages; pidx++)
3742 vm_page_unhold(bp->b_pages[pidx]);
3743 vm_page_unlock_queues();
3744
3745 bp->b_data = bp->b_saveaddr;
3746 }
3747
3748 void
3749 bdone(struct buf *bp)
3750 {
3751 mtx_lock(&bdonelock);
3752 bp->b_flags |= B_DONE;
3753 wakeup(bp);
3754 mtx_unlock(&bdonelock);
3755 }
3756
3757 void
3758 bwait(struct buf *bp, u_char pri, const char *wchan)
3759 {
3760 mtx_lock(&bdonelock);
3761 while ((bp->b_flags & B_DONE) == 0)
3762 msleep(bp, &bdonelock, pri, wchan, 0);
3763 mtx_unlock(&bdonelock);
3764 }
3765
3766 #include "opt_ddb.h"
3767 #ifdef DDB
3768 #include <ddb/ddb.h>
3769
3770 /* DDB command to show buffer data */
3771 DB_SHOW_COMMAND(buffer, db_show_buffer)
3772 {
3773 /* get args */
3774 struct buf *bp = (struct buf *)addr;
3775
3776 if (!have_addr) {
3777 db_printf("usage: show buffer <addr>\n");
3778 return;
3779 }
3780
3781 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3782 db_printf(
3783 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
3784 "b_dev = (%d,%d), b_data = %p, b_blkno = %jd\n",
3785 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3786 major(bp->b_dev), minor(bp->b_dev), bp->b_data,
3787 (intmax_t)bp->b_blkno);
3788 if (bp->b_npages) {
3789 int i;
3790 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
3791 for (i = 0; i < bp->b_npages; i++) {
3792 vm_page_t m;
3793 m = bp->b_pages[i];
3794 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3795 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3796 if ((i + 1) < bp->b_npages)
3797 db_printf(",");
3798 }
3799 db_printf("\n");
3800 }
3801 }
3802 #endif /* DDB */
Cache object: 3e2f55b8d08a0048c5d8cc2deb333d69
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