FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_bio.c
1 /*-
2 * Copyright (c) 2004 Poul-Henning Kamp
3 * Copyright (c) 1994,1997 John S. Dyson
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 /*
29 * this file contains a new buffer I/O scheme implementing a coherent
30 * VM object and buffer cache scheme. Pains have been taken to make
31 * sure that the performance degradation associated with schemes such
32 * as this is not realized.
33 *
34 * Author: John S. Dyson
35 * Significant help during the development and debugging phases
36 * had been provided by David Greenman, also of the FreeBSD core team.
37 *
38 * see man buf(9) for more info.
39 */
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD: releng/6.0/sys/kern/vfs_bio.c 151853 2005-10-29 07:00:45Z scottl $");
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/bio.h>
47 #include <sys/conf.h>
48 #include <sys/buf.h>
49 #include <sys/devicestat.h>
50 #include <sys/eventhandler.h>
51 #include <sys/lock.h>
52 #include <sys/malloc.h>
53 #include <sys/mount.h>
54 #include <sys/mutex.h>
55 #include <sys/kernel.h>
56 #include <sys/kthread.h>
57 #include <sys/proc.h>
58 #include <sys/resourcevar.h>
59 #include <sys/sysctl.h>
60 #include <sys/vmmeter.h>
61 #include <sys/vnode.h>
62 #include <geom/geom.h>
63 #include <vm/vm.h>
64 #include <vm/vm_param.h>
65 #include <vm/vm_kern.h>
66 #include <vm/vm_pageout.h>
67 #include <vm/vm_page.h>
68 #include <vm/vm_object.h>
69 #include <vm/vm_extern.h>
70 #include <vm/vm_map.h>
71 #include "opt_directio.h"
72 #include "opt_swap.h"
73
74 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
75
76 struct bio_ops bioops; /* I/O operation notification */
77
78 struct buf_ops buf_ops_bio = {
79 .bop_name = "buf_ops_bio",
80 .bop_write = bufwrite,
81 .bop_strategy = bufstrategy,
82 .bop_sync = bufsync,
83 };
84
85 /*
86 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
87 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
88 */
89 struct buf *buf; /* buffer header pool */
90
91 static struct proc *bufdaemonproc;
92
93 static int inmem(struct vnode *vp, daddr_t blkno);
94 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from,
95 vm_offset_t to);
96 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
97 vm_offset_t to);
98 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
99 int pageno, vm_page_t m);
100 static void vfs_clean_pages(struct buf *bp);
101 static void vfs_setdirty(struct buf *bp);
102 static void vfs_vmio_release(struct buf *bp);
103 static int vfs_bio_clcheck(struct vnode *vp, int size,
104 daddr_t lblkno, daddr_t blkno);
105 static int flushbufqueues(int flushdeps);
106 static void buf_daemon(void);
107 static void bremfreel(struct buf *bp);
108
109 int vmiodirenable = TRUE;
110 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
111 "Use the VM system for directory writes");
112 int runningbufspace;
113 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
114 "Amount of presently outstanding async buffer io");
115 static int bufspace;
116 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
117 "KVA memory used for bufs");
118 static int maxbufspace;
119 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
120 "Maximum allowed value of bufspace (including buf_daemon)");
121 static int bufmallocspace;
122 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
123 "Amount of malloced memory for buffers");
124 static int maxbufmallocspace;
125 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
126 "Maximum amount of malloced memory for buffers");
127 static int lobufspace;
128 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
129 "Minimum amount of buffers we want to have");
130 int hibufspace;
131 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
132 "Maximum allowed value of bufspace (excluding buf_daemon)");
133 static int bufreusecnt;
134 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
135 "Number of times we have reused a buffer");
136 static int buffreekvacnt;
137 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
138 "Number of times we have freed the KVA space from some buffer");
139 static int bufdefragcnt;
140 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
141 "Number of times we have had to repeat buffer allocation to defragment");
142 static int lorunningspace;
143 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
144 "Minimum preferred space used for in-progress I/O");
145 static int hirunningspace;
146 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
147 "Maximum amount of space to use for in-progress I/O");
148 static int dirtybufferflushes;
149 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
150 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
151 static int altbufferflushes;
152 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
153 0, "Number of fsync flushes to limit dirty buffers");
154 static int recursiveflushes;
155 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
156 0, "Number of flushes skipped due to being recursive");
157 static int numdirtybuffers;
158 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
159 "Number of buffers that are dirty (has unwritten changes) at the moment");
160 static int lodirtybuffers;
161 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
162 "How many buffers we want to have free before bufdaemon can sleep");
163 static int hidirtybuffers;
164 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
165 "When the number of dirty buffers is considered severe");
166 static int dirtybufthresh;
167 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
168 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
169 static int numfreebuffers;
170 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
171 "Number of free buffers");
172 static int lofreebuffers;
173 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
174 "XXX Unused");
175 static int hifreebuffers;
176 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
177 "XXX Complicatedly unused");
178 static int getnewbufcalls;
179 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
180 "Number of calls to getnewbuf");
181 static int getnewbufrestarts;
182 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
183 "Number of times getnewbuf has had to restart a buffer aquisition");
184
185 /*
186 * Wakeup point for bufdaemon, as well as indicator of whether it is already
187 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
188 * is idling.
189 */
190 static int bd_request;
191
192 /*
193 * This lock synchronizes access to bd_request.
194 */
195 static struct mtx bdlock;
196
197 /*
198 * bogus page -- for I/O to/from partially complete buffers
199 * this is a temporary solution to the problem, but it is not
200 * really that bad. it would be better to split the buffer
201 * for input in the case of buffers partially already in memory,
202 * but the code is intricate enough already.
203 */
204 vm_page_t bogus_page;
205
206 /*
207 * Synchronization (sleep/wakeup) variable for active buffer space requests.
208 * Set when wait starts, cleared prior to wakeup().
209 * Used in runningbufwakeup() and waitrunningbufspace().
210 */
211 static int runningbufreq;
212
213 /*
214 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
215 * waitrunningbufspace().
216 */
217 static struct mtx rbreqlock;
218
219 /*
220 * Synchronization (sleep/wakeup) variable for buffer requests.
221 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
222 * by and/or.
223 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
224 * getnewbuf(), and getblk().
225 */
226 static int needsbuffer;
227
228 /*
229 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
230 */
231 static struct mtx nblock;
232
233 /*
234 * Lock that protects against bwait()/bdone()/B_DONE races.
235 */
236
237 static struct mtx bdonelock;
238
239 /*
240 * Definitions for the buffer free lists.
241 */
242 #define BUFFER_QUEUES 5 /* number of free buffer queues */
243
244 #define QUEUE_NONE 0 /* on no queue */
245 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
246 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
247 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
248 #define QUEUE_EMPTY 4 /* empty buffer headers */
249
250 /* Queues for free buffers with various properties */
251 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
252
253 /* Lock for the bufqueues */
254 static struct mtx bqlock;
255
256 /*
257 * Single global constant for BUF_WMESG, to avoid getting multiple references.
258 * buf_wmesg is referred from macros.
259 */
260 const char *buf_wmesg = BUF_WMESG;
261
262 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
263 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
264 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
265 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
266
267 #ifdef DIRECTIO
268 extern void ffs_rawread_setup(void);
269 #endif /* DIRECTIO */
270 /*
271 * numdirtywakeup:
272 *
273 * If someone is blocked due to there being too many dirty buffers,
274 * and numdirtybuffers is now reasonable, wake them up.
275 */
276
277 static __inline void
278 numdirtywakeup(int level)
279 {
280
281 if (numdirtybuffers <= level) {
282 mtx_lock(&nblock);
283 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
284 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
285 wakeup(&needsbuffer);
286 }
287 mtx_unlock(&nblock);
288 }
289 }
290
291 /*
292 * bufspacewakeup:
293 *
294 * Called when buffer space is potentially available for recovery.
295 * getnewbuf() will block on this flag when it is unable to free
296 * sufficient buffer space. Buffer space becomes recoverable when
297 * bp's get placed back in the queues.
298 */
299
300 static __inline void
301 bufspacewakeup(void)
302 {
303
304 /*
305 * If someone is waiting for BUF space, wake them up. Even
306 * though we haven't freed the kva space yet, the waiting
307 * process will be able to now.
308 */
309 mtx_lock(&nblock);
310 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
311 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
312 wakeup(&needsbuffer);
313 }
314 mtx_unlock(&nblock);
315 }
316
317 /*
318 * runningbufwakeup() - in-progress I/O accounting.
319 *
320 */
321 void
322 runningbufwakeup(struct buf *bp)
323 {
324
325 if (bp->b_runningbufspace) {
326 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace);
327 bp->b_runningbufspace = 0;
328 mtx_lock(&rbreqlock);
329 if (runningbufreq && runningbufspace <= lorunningspace) {
330 runningbufreq = 0;
331 wakeup(&runningbufreq);
332 }
333 mtx_unlock(&rbreqlock);
334 }
335 }
336
337 /*
338 * bufcountwakeup:
339 *
340 * Called when a buffer has been added to one of the free queues to
341 * account for the buffer and to wakeup anyone waiting for free buffers.
342 * This typically occurs when large amounts of metadata are being handled
343 * by the buffer cache ( else buffer space runs out first, usually ).
344 */
345
346 static __inline void
347 bufcountwakeup(void)
348 {
349
350 atomic_add_int(&numfreebuffers, 1);
351 mtx_lock(&nblock);
352 if (needsbuffer) {
353 needsbuffer &= ~VFS_BIO_NEED_ANY;
354 if (numfreebuffers >= hifreebuffers)
355 needsbuffer &= ~VFS_BIO_NEED_FREE;
356 wakeup(&needsbuffer);
357 }
358 mtx_unlock(&nblock);
359 }
360
361 /*
362 * waitrunningbufspace()
363 *
364 * runningbufspace is a measure of the amount of I/O currently
365 * running. This routine is used in async-write situations to
366 * prevent creating huge backups of pending writes to a device.
367 * Only asynchronous writes are governed by this function.
368 *
369 * Reads will adjust runningbufspace, but will not block based on it.
370 * The read load has a side effect of reducing the allowed write load.
371 *
372 * This does NOT turn an async write into a sync write. It waits
373 * for earlier writes to complete and generally returns before the
374 * caller's write has reached the device.
375 */
376 void
377 waitrunningbufspace(void)
378 {
379
380 mtx_lock(&rbreqlock);
381 while (runningbufspace > hirunningspace) {
382 ++runningbufreq;
383 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
384 }
385 mtx_unlock(&rbreqlock);
386 }
387
388
389 /*
390 * vfs_buf_test_cache:
391 *
392 * Called when a buffer is extended. This function clears the B_CACHE
393 * bit if the newly extended portion of the buffer does not contain
394 * valid data.
395 */
396 static __inline
397 void
398 vfs_buf_test_cache(struct buf *bp,
399 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
400 vm_page_t m)
401 {
402
403 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
404 if (bp->b_flags & B_CACHE) {
405 int base = (foff + off) & PAGE_MASK;
406 if (vm_page_is_valid(m, base, size) == 0)
407 bp->b_flags &= ~B_CACHE;
408 }
409 }
410
411 /* Wake up the buffer deamon if necessary */
412 static __inline
413 void
414 bd_wakeup(int dirtybuflevel)
415 {
416
417 mtx_lock(&bdlock);
418 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
419 bd_request = 1;
420 wakeup(&bd_request);
421 }
422 mtx_unlock(&bdlock);
423 }
424
425 /*
426 * bd_speedup - speedup the buffer cache flushing code
427 */
428
429 static __inline
430 void
431 bd_speedup(void)
432 {
433
434 bd_wakeup(1);
435 }
436
437 /*
438 * Calculating buffer cache scaling values and reserve space for buffer
439 * headers. This is called during low level kernel initialization and
440 * may be called more then once. We CANNOT write to the memory area
441 * being reserved at this time.
442 */
443 caddr_t
444 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
445 {
446
447 /*
448 * physmem_est is in pages. Convert it to kilobytes (assumes
449 * PAGE_SIZE is >= 1K)
450 */
451 physmem_est = physmem_est * (PAGE_SIZE / 1024);
452
453 /*
454 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
455 * For the first 64MB of ram nominally allocate sufficient buffers to
456 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
457 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing
458 * the buffer cache we limit the eventual kva reservation to
459 * maxbcache bytes.
460 *
461 * factor represents the 1/4 x ram conversion.
462 */
463 if (nbuf == 0) {
464 int factor = 4 * BKVASIZE / 1024;
465
466 nbuf = 50;
467 if (physmem_est > 4096)
468 nbuf += min((physmem_est - 4096) / factor,
469 65536 / factor);
470 if (physmem_est > 65536)
471 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
472
473 if (maxbcache && nbuf > maxbcache / BKVASIZE)
474 nbuf = maxbcache / BKVASIZE;
475 }
476
477 #if 0
478 /*
479 * Do not allow the buffer_map to be more then 1/2 the size of the
480 * kernel_map.
481 */
482 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) /
483 (BKVASIZE * 2)) {
484 nbuf = (kernel_map->max_offset - kernel_map->min_offset) /
485 (BKVASIZE * 2);
486 printf("Warning: nbufs capped at %d\n", nbuf);
487 }
488 #endif
489
490 /*
491 * swbufs are used as temporary holders for I/O, such as paging I/O.
492 * We have no less then 16 and no more then 256.
493 */
494 nswbuf = max(min(nbuf/4, 256), 16);
495 #ifdef NSWBUF_MIN
496 if (nswbuf < NSWBUF_MIN)
497 nswbuf = NSWBUF_MIN;
498 #endif
499 #ifdef DIRECTIO
500 ffs_rawread_setup();
501 #endif
502
503 /*
504 * Reserve space for the buffer cache buffers
505 */
506 swbuf = (void *)v;
507 v = (caddr_t)(swbuf + nswbuf);
508 buf = (void *)v;
509 v = (caddr_t)(buf + nbuf);
510
511 return(v);
512 }
513
514 /* Initialize the buffer subsystem. Called before use of any buffers. */
515 void
516 bufinit(void)
517 {
518 struct buf *bp;
519 int i;
520
521 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
522 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
523 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
524 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
525 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF);
526
527 /* next, make a null set of free lists */
528 for (i = 0; i < BUFFER_QUEUES; i++)
529 TAILQ_INIT(&bufqueues[i]);
530
531 /* finally, initialize each buffer header and stick on empty q */
532 for (i = 0; i < nbuf; i++) {
533 bp = &buf[i];
534 bzero(bp, sizeof *bp);
535 bp->b_flags = B_INVAL; /* we're just an empty header */
536 bp->b_rcred = NOCRED;
537 bp->b_wcred = NOCRED;
538 bp->b_qindex = QUEUE_EMPTY;
539 bp->b_vflags = 0;
540 bp->b_xflags = 0;
541 LIST_INIT(&bp->b_dep);
542 BUF_LOCKINIT(bp);
543 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
544 }
545
546 /*
547 * maxbufspace is the absolute maximum amount of buffer space we are
548 * allowed to reserve in KVM and in real terms. The absolute maximum
549 * is nominally used by buf_daemon. hibufspace is the nominal maximum
550 * used by most other processes. The differential is required to
551 * ensure that buf_daemon is able to run when other processes might
552 * be blocked waiting for buffer space.
553 *
554 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
555 * this may result in KVM fragmentation which is not handled optimally
556 * by the system.
557 */
558 maxbufspace = nbuf * BKVASIZE;
559 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
560 lobufspace = hibufspace - MAXBSIZE;
561
562 lorunningspace = 512 * 1024;
563 hirunningspace = 1024 * 1024;
564
565 /*
566 * Limit the amount of malloc memory since it is wired permanently into
567 * the kernel space. Even though this is accounted for in the buffer
568 * allocation, we don't want the malloced region to grow uncontrolled.
569 * The malloc scheme improves memory utilization significantly on average
570 * (small) directories.
571 */
572 maxbufmallocspace = hibufspace / 20;
573
574 /*
575 * Reduce the chance of a deadlock occuring by limiting the number
576 * of delayed-write dirty buffers we allow to stack up.
577 */
578 hidirtybuffers = nbuf / 4 + 20;
579 dirtybufthresh = hidirtybuffers * 9 / 10;
580 numdirtybuffers = 0;
581 /*
582 * To support extreme low-memory systems, make sure hidirtybuffers cannot
583 * eat up all available buffer space. This occurs when our minimum cannot
584 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
585 * BKVASIZE'd (8K) buffers.
586 */
587 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
588 hidirtybuffers >>= 1;
589 }
590 lodirtybuffers = hidirtybuffers / 2;
591
592 /*
593 * Try to keep the number of free buffers in the specified range,
594 * and give special processes (e.g. like buf_daemon) access to an
595 * emergency reserve.
596 */
597 lofreebuffers = nbuf / 18 + 5;
598 hifreebuffers = 2 * lofreebuffers;
599 numfreebuffers = nbuf;
600
601 /*
602 * Maximum number of async ops initiated per buf_daemon loop. This is
603 * somewhat of a hack at the moment, we really need to limit ourselves
604 * based on the number of bytes of I/O in-transit that were initiated
605 * from buf_daemon.
606 */
607
608 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
609 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
610 }
611
612 /*
613 * bfreekva() - free the kva allocation for a buffer.
614 *
615 * Since this call frees up buffer space, we call bufspacewakeup().
616 */
617 static void
618 bfreekva(struct buf *bp)
619 {
620
621 if (bp->b_kvasize) {
622 atomic_add_int(&buffreekvacnt, 1);
623 atomic_subtract_int(&bufspace, bp->b_kvasize);
624 vm_map_lock(buffer_map);
625 vm_map_delete(buffer_map,
626 (vm_offset_t) bp->b_kvabase,
627 (vm_offset_t) bp->b_kvabase + bp->b_kvasize
628 );
629 vm_map_unlock(buffer_map);
630 bp->b_kvasize = 0;
631 bufspacewakeup();
632 }
633 }
634
635 /*
636 * bremfree:
637 *
638 * Mark the buffer for removal from the appropriate free list in brelse.
639 *
640 */
641 void
642 bremfree(struct buf *bp)
643 {
644
645 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
646 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked."));
647 KASSERT((bp->b_flags & B_REMFREE) == 0,
648 ("bremfree: buffer %p already marked for delayed removal.", bp));
649 KASSERT(bp->b_qindex != QUEUE_NONE,
650 ("bremfree: buffer %p not on a queue.", bp));
651
652 bp->b_flags |= B_REMFREE;
653 /* Fixup numfreebuffers count. */
654 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
655 atomic_subtract_int(&numfreebuffers, 1);
656 }
657
658 /*
659 * bremfreef:
660 *
661 * Force an immediate removal from a free list. Used only in nfs when
662 * it abuses the b_freelist pointer.
663 */
664 void
665 bremfreef(struct buf *bp)
666 {
667 mtx_lock(&bqlock);
668 bremfreel(bp);
669 mtx_unlock(&bqlock);
670 }
671
672 /*
673 * bremfreel:
674 *
675 * Removes a buffer from the free list, must be called with the
676 * bqlock held.
677 */
678 static void
679 bremfreel(struct buf *bp)
680 {
681 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
682 bp, bp->b_vp, bp->b_flags);
683 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp));
684 KASSERT(bp->b_qindex != QUEUE_NONE,
685 ("bremfreel: buffer %p not on a queue.", bp));
686 mtx_assert(&bqlock, MA_OWNED);
687
688 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
689 bp->b_qindex = QUEUE_NONE;
690 /*
691 * If this was a delayed bremfree() we only need to remove the buffer
692 * from the queue and return the stats are already done.
693 */
694 if (bp->b_flags & B_REMFREE) {
695 bp->b_flags &= ~B_REMFREE;
696 return;
697 }
698 /*
699 * Fixup numfreebuffers count. If the buffer is invalid or not
700 * delayed-write, the buffer was free and we must decrement
701 * numfreebuffers.
702 */
703 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
704 atomic_subtract_int(&numfreebuffers, 1);
705 }
706
707
708 /*
709 * Get a buffer with the specified data. Look in the cache first. We
710 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
711 * is set, the buffer is valid and we do not have to do anything ( see
712 * getblk() ). This is really just a special case of breadn().
713 */
714 int
715 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
716 struct buf **bpp)
717 {
718
719 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
720 }
721
722 /*
723 * Operates like bread, but also starts asynchronous I/O on
724 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior
725 * to initiating I/O . If B_CACHE is set, the buffer is valid
726 * and we do not have to do anything.
727 */
728 int
729 breadn(struct vnode * vp, daddr_t blkno, int size,
730 daddr_t * rablkno, int *rabsize,
731 int cnt, struct ucred * cred, struct buf **bpp)
732 {
733 struct buf *bp, *rabp;
734 int i;
735 int rv = 0, readwait = 0;
736
737 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
738 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
739
740 /* if not found in cache, do some I/O */
741 if ((bp->b_flags & B_CACHE) == 0) {
742 if (curthread != PCPU_GET(idlethread))
743 curthread->td_proc->p_stats->p_ru.ru_inblock++;
744 bp->b_iocmd = BIO_READ;
745 bp->b_flags &= ~B_INVAL;
746 bp->b_ioflags &= ~BIO_ERROR;
747 if (bp->b_rcred == NOCRED && cred != NOCRED)
748 bp->b_rcred = crhold(cred);
749 vfs_busy_pages(bp, 0);
750 bp->b_iooffset = dbtob(bp->b_blkno);
751 bstrategy(bp);
752 ++readwait;
753 }
754
755 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
756 if (inmem(vp, *rablkno))
757 continue;
758 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
759
760 if ((rabp->b_flags & B_CACHE) == 0) {
761 if (curthread != PCPU_GET(idlethread))
762 curthread->td_proc->p_stats->p_ru.ru_inblock++;
763 rabp->b_flags |= B_ASYNC;
764 rabp->b_flags &= ~B_INVAL;
765 rabp->b_ioflags &= ~BIO_ERROR;
766 rabp->b_iocmd = BIO_READ;
767 if (rabp->b_rcred == NOCRED && cred != NOCRED)
768 rabp->b_rcred = crhold(cred);
769 vfs_busy_pages(rabp, 0);
770 BUF_KERNPROC(rabp);
771 rabp->b_iooffset = dbtob(rabp->b_blkno);
772 bstrategy(rabp);
773 } else {
774 brelse(rabp);
775 }
776 }
777
778 if (readwait) {
779 rv = bufwait(bp);
780 }
781 return (rv);
782 }
783
784 /*
785 * Write, release buffer on completion. (Done by iodone
786 * if async). Do not bother writing anything if the buffer
787 * is invalid.
788 *
789 * Note that we set B_CACHE here, indicating that buffer is
790 * fully valid and thus cacheable. This is true even of NFS
791 * now so we set it generally. This could be set either here
792 * or in biodone() since the I/O is synchronous. We put it
793 * here.
794 */
795 int
796 bufwrite(struct buf *bp)
797 {
798 int oldflags;
799
800 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
801 if (bp->b_flags & B_INVAL) {
802 brelse(bp);
803 return (0);
804 }
805
806 oldflags = bp->b_flags;
807
808 if (BUF_REFCNT(bp) == 0)
809 panic("bufwrite: buffer is not busy???");
810 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
811 ("FFS background buffer should not get here %p", bp));
812
813 /* Mark the buffer clean */
814 bundirty(bp);
815
816 bp->b_flags &= ~B_DONE;
817 bp->b_ioflags &= ~BIO_ERROR;
818 bp->b_flags |= B_CACHE;
819 bp->b_iocmd = BIO_WRITE;
820
821 bufobj_wref(bp->b_bufobj);
822 vfs_busy_pages(bp, 1);
823
824 /*
825 * Normal bwrites pipeline writes
826 */
827 bp->b_runningbufspace = bp->b_bufsize;
828 atomic_add_int(&runningbufspace, bp->b_runningbufspace);
829
830 if (curthread != PCPU_GET(idlethread))
831 curthread->td_proc->p_stats->p_ru.ru_oublock++;
832 if (oldflags & B_ASYNC)
833 BUF_KERNPROC(bp);
834 bp->b_iooffset = dbtob(bp->b_blkno);
835 bstrategy(bp);
836
837 if ((oldflags & B_ASYNC) == 0) {
838 int rtval = bufwait(bp);
839 brelse(bp);
840 return (rtval);
841 } else {
842 /*
843 * don't allow the async write to saturate the I/O
844 * system. We will not deadlock here because
845 * we are blocking waiting for I/O that is already in-progress
846 * to complete. We do not block here if it is the update
847 * or syncer daemon trying to clean up as that can lead
848 * to deadlock.
849 */
850 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0)
851 waitrunningbufspace();
852 }
853
854 return (0);
855 }
856
857 /*
858 * Delayed write. (Buffer is marked dirty). Do not bother writing
859 * anything if the buffer is marked invalid.
860 *
861 * Note that since the buffer must be completely valid, we can safely
862 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
863 * biodone() in order to prevent getblk from writing the buffer
864 * out synchronously.
865 */
866 void
867 bdwrite(struct buf *bp)
868 {
869 struct thread *td = curthread;
870 struct vnode *vp;
871 struct buf *nbp;
872 struct bufobj *bo;
873
874 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
875 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
876 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy"));
877
878 if (bp->b_flags & B_INVAL) {
879 brelse(bp);
880 return;
881 }
882
883 /*
884 * If we have too many dirty buffers, don't create any more.
885 * If we are wildly over our limit, then force a complete
886 * cleanup. Otherwise, just keep the situation from getting
887 * out of control. Note that we have to avoid a recursive
888 * disaster and not try to clean up after our own cleanup!
889 */
890 vp = bp->b_vp;
891 bo = bp->b_bufobj;
892 if ((td->td_pflags & TDP_COWINPROGRESS) == 0) {
893 BO_LOCK(bo);
894 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
895 BO_UNLOCK(bo);
896 (void) VOP_FSYNC(vp, MNT_NOWAIT, td);
897 altbufferflushes++;
898 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
899 /*
900 * Try to find a buffer to flush.
901 */
902 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
903 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
904 BUF_LOCK(nbp,
905 LK_EXCLUSIVE | LK_NOWAIT, NULL))
906 continue;
907 if (bp == nbp)
908 panic("bdwrite: found ourselves");
909 BO_UNLOCK(bo);
910 /* Don't countdeps with the bo lock held. */
911 if (buf_countdeps(nbp, 0)) {
912 BO_LOCK(bo);
913 BUF_UNLOCK(nbp);
914 continue;
915 }
916 if (nbp->b_flags & B_CLUSTEROK) {
917 vfs_bio_awrite(nbp);
918 } else {
919 bremfree(nbp);
920 bawrite(nbp);
921 }
922 dirtybufferflushes++;
923 break;
924 }
925 if (nbp == NULL)
926 BO_UNLOCK(bo);
927 } else
928 BO_UNLOCK(bo);
929 } else
930 recursiveflushes++;
931
932 bdirty(bp);
933 /*
934 * Set B_CACHE, indicating that the buffer is fully valid. This is
935 * true even of NFS now.
936 */
937 bp->b_flags |= B_CACHE;
938
939 /*
940 * This bmap keeps the system from needing to do the bmap later,
941 * perhaps when the system is attempting to do a sync. Since it
942 * is likely that the indirect block -- or whatever other datastructure
943 * that the filesystem needs is still in memory now, it is a good
944 * thing to do this. Note also, that if the pageout daemon is
945 * requesting a sync -- there might not be enough memory to do
946 * the bmap then... So, this is important to do.
947 */
948 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
949 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
950 }
951
952 /*
953 * Set the *dirty* buffer range based upon the VM system dirty pages.
954 */
955 vfs_setdirty(bp);
956
957 /*
958 * We need to do this here to satisfy the vnode_pager and the
959 * pageout daemon, so that it thinks that the pages have been
960 * "cleaned". Note that since the pages are in a delayed write
961 * buffer -- the VFS layer "will" see that the pages get written
962 * out on the next sync, or perhaps the cluster will be completed.
963 */
964 vfs_clean_pages(bp);
965 bqrelse(bp);
966
967 /*
968 * Wakeup the buffer flushing daemon if we have a lot of dirty
969 * buffers (midpoint between our recovery point and our stall
970 * point).
971 */
972 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
973
974 /*
975 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
976 * due to the softdep code.
977 */
978 }
979
980 /*
981 * bdirty:
982 *
983 * Turn buffer into delayed write request. We must clear BIO_READ and
984 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
985 * itself to properly update it in the dirty/clean lists. We mark it
986 * B_DONE to ensure that any asynchronization of the buffer properly
987 * clears B_DONE ( else a panic will occur later ).
988 *
989 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
990 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
991 * should only be called if the buffer is known-good.
992 *
993 * Since the buffer is not on a queue, we do not update the numfreebuffers
994 * count.
995 *
996 * The buffer must be on QUEUE_NONE.
997 */
998 void
999 bdirty(struct buf *bp)
1000 {
1001
1002 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1003 bp, bp->b_vp, bp->b_flags);
1004 KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp));
1005 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1006 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1007 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1008 bp->b_flags &= ~(B_RELBUF);
1009 bp->b_iocmd = BIO_WRITE;
1010
1011 if ((bp->b_flags & B_DELWRI) == 0) {
1012 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1013 reassignbuf(bp);
1014 atomic_add_int(&numdirtybuffers, 1);
1015 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1016 }
1017 }
1018
1019 /*
1020 * bundirty:
1021 *
1022 * Clear B_DELWRI for buffer.
1023 *
1024 * Since the buffer is not on a queue, we do not update the numfreebuffers
1025 * count.
1026 *
1027 * The buffer must be on QUEUE_NONE.
1028 */
1029
1030 void
1031 bundirty(struct buf *bp)
1032 {
1033
1034 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1035 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1036 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1037 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1038 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp));
1039
1040 if (bp->b_flags & B_DELWRI) {
1041 bp->b_flags &= ~B_DELWRI;
1042 reassignbuf(bp);
1043 atomic_subtract_int(&numdirtybuffers, 1);
1044 numdirtywakeup(lodirtybuffers);
1045 }
1046 /*
1047 * Since it is now being written, we can clear its deferred write flag.
1048 */
1049 bp->b_flags &= ~B_DEFERRED;
1050 }
1051
1052 /*
1053 * bawrite:
1054 *
1055 * Asynchronous write. Start output on a buffer, but do not wait for
1056 * it to complete. The buffer is released when the output completes.
1057 *
1058 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1059 * B_INVAL buffers. Not us.
1060 */
1061 void
1062 bawrite(struct buf *bp)
1063 {
1064
1065 bp->b_flags |= B_ASYNC;
1066 (void) bwrite(bp);
1067 }
1068
1069 /*
1070 * bwillwrite:
1071 *
1072 * Called prior to the locking of any vnodes when we are expecting to
1073 * write. We do not want to starve the buffer cache with too many
1074 * dirty buffers so we block here. By blocking prior to the locking
1075 * of any vnodes we attempt to avoid the situation where a locked vnode
1076 * prevents the various system daemons from flushing related buffers.
1077 */
1078
1079 void
1080 bwillwrite(void)
1081 {
1082
1083 if (numdirtybuffers >= hidirtybuffers) {
1084 mtx_lock(&nblock);
1085 while (numdirtybuffers >= hidirtybuffers) {
1086 bd_wakeup(1);
1087 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1088 msleep(&needsbuffer, &nblock,
1089 (PRIBIO + 4), "flswai", 0);
1090 }
1091 mtx_unlock(&nblock);
1092 }
1093 }
1094
1095 /*
1096 * Return true if we have too many dirty buffers.
1097 */
1098 int
1099 buf_dirty_count_severe(void)
1100 {
1101
1102 return(numdirtybuffers >= hidirtybuffers);
1103 }
1104
1105 /*
1106 * brelse:
1107 *
1108 * Release a busy buffer and, if requested, free its resources. The
1109 * buffer will be stashed in the appropriate bufqueue[] allowing it
1110 * to be accessed later as a cache entity or reused for other purposes.
1111 */
1112 void
1113 brelse(struct buf *bp)
1114 {
1115 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1116 bp, bp->b_vp, bp->b_flags);
1117 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1118 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1119
1120 if (bp->b_iocmd == BIO_WRITE &&
1121 (bp->b_ioflags & BIO_ERROR) &&
1122 !(bp->b_flags & B_INVAL)) {
1123 /*
1124 * Failed write, redirty. Must clear BIO_ERROR to prevent
1125 * pages from being scrapped. If B_INVAL is set then
1126 * this case is not run and the next case is run to
1127 * destroy the buffer. B_INVAL can occur if the buffer
1128 * is outside the range supported by the underlying device.
1129 */
1130 bp->b_ioflags &= ~BIO_ERROR;
1131 bdirty(bp);
1132 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1133 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1134 /*
1135 * Either a failed I/O or we were asked to free or not
1136 * cache the buffer.
1137 */
1138 bp->b_flags |= B_INVAL;
1139 if (LIST_FIRST(&bp->b_dep) != NULL)
1140 buf_deallocate(bp);
1141 if (bp->b_flags & B_DELWRI) {
1142 atomic_subtract_int(&numdirtybuffers, 1);
1143 numdirtywakeup(lodirtybuffers);
1144 }
1145 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1146 if ((bp->b_flags & B_VMIO) == 0) {
1147 if (bp->b_bufsize)
1148 allocbuf(bp, 0);
1149 if (bp->b_vp)
1150 brelvp(bp);
1151 }
1152 }
1153
1154 /*
1155 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1156 * is called with B_DELWRI set, the underlying pages may wind up
1157 * getting freed causing a previous write (bdwrite()) to get 'lost'
1158 * because pages associated with a B_DELWRI bp are marked clean.
1159 *
1160 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1161 * if B_DELWRI is set.
1162 *
1163 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1164 * on pages to return pages to the VM page queues.
1165 */
1166 if (bp->b_flags & B_DELWRI)
1167 bp->b_flags &= ~B_RELBUF;
1168 else if (vm_page_count_severe()) {
1169 /*
1170 * XXX This lock may not be necessary since BKGRDINPROG
1171 * cannot be set while we hold the buf lock, it can only be
1172 * cleared if it is already pending.
1173 */
1174 if (bp->b_vp) {
1175 BO_LOCK(bp->b_bufobj);
1176 if (!(bp->b_vflags & BV_BKGRDINPROG))
1177 bp->b_flags |= B_RELBUF;
1178 BO_UNLOCK(bp->b_bufobj);
1179 } else
1180 bp->b_flags |= B_RELBUF;
1181 }
1182
1183 /*
1184 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1185 * constituted, not even NFS buffers now. Two flags effect this. If
1186 * B_INVAL, the struct buf is invalidated but the VM object is kept
1187 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1188 *
1189 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1190 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1191 * buffer is also B_INVAL because it hits the re-dirtying code above.
1192 *
1193 * Normally we can do this whether a buffer is B_DELWRI or not. If
1194 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1195 * the commit state and we cannot afford to lose the buffer. If the
1196 * buffer has a background write in progress, we need to keep it
1197 * around to prevent it from being reconstituted and starting a second
1198 * background write.
1199 */
1200 if ((bp->b_flags & B_VMIO)
1201 && !(bp->b_vp->v_mount != NULL &&
1202 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1203 !vn_isdisk(bp->b_vp, NULL) &&
1204 (bp->b_flags & B_DELWRI))
1205 ) {
1206
1207 int i, j, resid;
1208 vm_page_t m;
1209 off_t foff;
1210 vm_pindex_t poff;
1211 vm_object_t obj;
1212
1213 obj = bp->b_bufobj->bo_object;
1214
1215 /*
1216 * Get the base offset and length of the buffer. Note that
1217 * in the VMIO case if the buffer block size is not
1218 * page-aligned then b_data pointer may not be page-aligned.
1219 * But our b_pages[] array *IS* page aligned.
1220 *
1221 * block sizes less then DEV_BSIZE (usually 512) are not
1222 * supported due to the page granularity bits (m->valid,
1223 * m->dirty, etc...).
1224 *
1225 * See man buf(9) for more information
1226 */
1227 resid = bp->b_bufsize;
1228 foff = bp->b_offset;
1229 VM_OBJECT_LOCK(obj);
1230 for (i = 0; i < bp->b_npages; i++) {
1231 int had_bogus = 0;
1232
1233 m = bp->b_pages[i];
1234
1235 /*
1236 * If we hit a bogus page, fixup *all* the bogus pages
1237 * now.
1238 */
1239 if (m == bogus_page) {
1240 poff = OFF_TO_IDX(bp->b_offset);
1241 had_bogus = 1;
1242
1243 for (j = i; j < bp->b_npages; j++) {
1244 vm_page_t mtmp;
1245 mtmp = bp->b_pages[j];
1246 if (mtmp == bogus_page) {
1247 mtmp = vm_page_lookup(obj, poff + j);
1248 if (!mtmp) {
1249 panic("brelse: page missing\n");
1250 }
1251 bp->b_pages[j] = mtmp;
1252 }
1253 }
1254
1255 if ((bp->b_flags & B_INVAL) == 0) {
1256 pmap_qenter(
1257 trunc_page((vm_offset_t)bp->b_data),
1258 bp->b_pages, bp->b_npages);
1259 }
1260 m = bp->b_pages[i];
1261 }
1262 if ((bp->b_flags & B_NOCACHE) ||
1263 (bp->b_ioflags & BIO_ERROR)) {
1264 int poffset = foff & PAGE_MASK;
1265 int presid = resid > (PAGE_SIZE - poffset) ?
1266 (PAGE_SIZE - poffset) : resid;
1267
1268 KASSERT(presid >= 0, ("brelse: extra page"));
1269 vm_page_lock_queues();
1270 vm_page_set_invalid(m, poffset, presid);
1271 vm_page_unlock_queues();
1272 if (had_bogus)
1273 printf("avoided corruption bug in bogus_page/brelse code\n");
1274 }
1275 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1276 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1277 }
1278 VM_OBJECT_UNLOCK(obj);
1279 if (bp->b_flags & (B_INVAL | B_RELBUF))
1280 vfs_vmio_release(bp);
1281
1282 } else if (bp->b_flags & B_VMIO) {
1283
1284 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1285 vfs_vmio_release(bp);
1286 }
1287
1288 }
1289
1290 if (BUF_REFCNT(bp) > 1) {
1291 /* do not release to free list */
1292 BUF_UNLOCK(bp);
1293 return;
1294 }
1295
1296 /* enqueue */
1297 mtx_lock(&bqlock);
1298 /* Handle delayed bremfree() processing. */
1299 if (bp->b_flags & B_REMFREE)
1300 bremfreel(bp);
1301 if (bp->b_qindex != QUEUE_NONE)
1302 panic("brelse: free buffer onto another queue???");
1303
1304 /* buffers with no memory */
1305 if (bp->b_bufsize == 0) {
1306 bp->b_flags |= B_INVAL;
1307 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1308 if (bp->b_vflags & BV_BKGRDINPROG)
1309 panic("losing buffer 1");
1310 if (bp->b_kvasize) {
1311 bp->b_qindex = QUEUE_EMPTYKVA;
1312 } else {
1313 bp->b_qindex = QUEUE_EMPTY;
1314 }
1315 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1316 /* buffers with junk contents */
1317 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1318 (bp->b_ioflags & BIO_ERROR)) {
1319 bp->b_flags |= B_INVAL;
1320 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1321 if (bp->b_vflags & BV_BKGRDINPROG)
1322 panic("losing buffer 2");
1323 bp->b_qindex = QUEUE_CLEAN;
1324 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1325 /* remaining buffers */
1326 } else {
1327 if (bp->b_flags & B_DELWRI)
1328 bp->b_qindex = QUEUE_DIRTY;
1329 else
1330 bp->b_qindex = QUEUE_CLEAN;
1331 if (bp->b_flags & B_AGE)
1332 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1333 else
1334 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1335 }
1336 mtx_unlock(&bqlock);
1337
1338 /*
1339 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already
1340 * placed the buffer on the correct queue. We must also disassociate
1341 * the device and vnode for a B_INVAL buffer so gbincore() doesn't
1342 * find it.
1343 */
1344 if (bp->b_flags & B_INVAL) {
1345 if (bp->b_flags & B_DELWRI)
1346 bundirty(bp);
1347 if (bp->b_vp)
1348 brelvp(bp);
1349 }
1350
1351 /*
1352 * Fixup numfreebuffers count. The bp is on an appropriate queue
1353 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1354 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1355 * if B_INVAL is set ).
1356 */
1357
1358 if (!(bp->b_flags & B_DELWRI))
1359 bufcountwakeup();
1360
1361 /*
1362 * Something we can maybe free or reuse
1363 */
1364 if (bp->b_bufsize || bp->b_kvasize)
1365 bufspacewakeup();
1366
1367 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1368 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1369 panic("brelse: not dirty");
1370 /* unlock */
1371 BUF_UNLOCK(bp);
1372 }
1373
1374 /*
1375 * Release a buffer back to the appropriate queue but do not try to free
1376 * it. The buffer is expected to be used again soon.
1377 *
1378 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1379 * biodone() to requeue an async I/O on completion. It is also used when
1380 * known good buffers need to be requeued but we think we may need the data
1381 * again soon.
1382 *
1383 * XXX we should be able to leave the B_RELBUF hint set on completion.
1384 */
1385 void
1386 bqrelse(struct buf *bp)
1387 {
1388 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1389 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1390 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1391
1392 if (BUF_REFCNT(bp) > 1) {
1393 /* do not release to free list */
1394 BUF_UNLOCK(bp);
1395 return;
1396 }
1397 mtx_lock(&bqlock);
1398 /* Handle delayed bremfree() processing. */
1399 if (bp->b_flags & B_REMFREE)
1400 bremfreel(bp);
1401 if (bp->b_qindex != QUEUE_NONE)
1402 panic("bqrelse: free buffer onto another queue???");
1403 /* buffers with stale but valid contents */
1404 if (bp->b_flags & B_DELWRI) {
1405 bp->b_qindex = QUEUE_DIRTY;
1406 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1407 } else {
1408 /*
1409 * XXX This lock may not be necessary since BKGRDINPROG
1410 * cannot be set while we hold the buf lock, it can only be
1411 * cleared if it is already pending.
1412 */
1413 BO_LOCK(bp->b_bufobj);
1414 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) {
1415 BO_UNLOCK(bp->b_bufobj);
1416 bp->b_qindex = QUEUE_CLEAN;
1417 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1418 b_freelist);
1419 } else {
1420 /*
1421 * We are too low on memory, we have to try to free
1422 * the buffer (most importantly: the wired pages
1423 * making up its backing store) *now*.
1424 */
1425 BO_UNLOCK(bp->b_bufobj);
1426 mtx_unlock(&bqlock);
1427 brelse(bp);
1428 return;
1429 }
1430 }
1431 mtx_unlock(&bqlock);
1432
1433 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
1434 bufcountwakeup();
1435
1436 /*
1437 * Something we can maybe free or reuse.
1438 */
1439 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1440 bufspacewakeup();
1441
1442 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1443 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1444 panic("bqrelse: not dirty");
1445 /* unlock */
1446 BUF_UNLOCK(bp);
1447 }
1448
1449 /* Give pages used by the bp back to the VM system (where possible) */
1450 static void
1451 vfs_vmio_release(struct buf *bp)
1452 {
1453 int i;
1454 vm_page_t m;
1455
1456 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
1457 vm_page_lock_queues();
1458 for (i = 0; i < bp->b_npages; i++) {
1459 m = bp->b_pages[i];
1460 bp->b_pages[i] = NULL;
1461 /*
1462 * In order to keep page LRU ordering consistent, put
1463 * everything on the inactive queue.
1464 */
1465 vm_page_unwire(m, 0);
1466 /*
1467 * We don't mess with busy pages, it is
1468 * the responsibility of the process that
1469 * busied the pages to deal with them.
1470 */
1471 if ((m->flags & PG_BUSY) || (m->busy != 0))
1472 continue;
1473
1474 if (m->wire_count == 0) {
1475 /*
1476 * Might as well free the page if we can and it has
1477 * no valid data. We also free the page if the
1478 * buffer was used for direct I/O
1479 */
1480 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1481 m->hold_count == 0) {
1482 pmap_remove_all(m);
1483 vm_page_free(m);
1484 } else if (bp->b_flags & B_DIRECT) {
1485 vm_page_try_to_free(m);
1486 } else if (vm_page_count_severe()) {
1487 vm_page_try_to_cache(m);
1488 }
1489 }
1490 }
1491 vm_page_unlock_queues();
1492 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
1493 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
1494
1495 if (bp->b_bufsize) {
1496 bufspacewakeup();
1497 bp->b_bufsize = 0;
1498 }
1499 bp->b_npages = 0;
1500 bp->b_flags &= ~B_VMIO;
1501 if (bp->b_vp)
1502 brelvp(bp);
1503 }
1504
1505 /*
1506 * Check to see if a block at a particular lbn is available for a clustered
1507 * write.
1508 */
1509 static int
1510 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1511 {
1512 struct buf *bpa;
1513 int match;
1514
1515 match = 0;
1516
1517 /* If the buf isn't in core skip it */
1518 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1519 return (0);
1520
1521 /* If the buf is busy we don't want to wait for it */
1522 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1523 return (0);
1524
1525 /* Only cluster with valid clusterable delayed write buffers */
1526 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1527 (B_DELWRI | B_CLUSTEROK))
1528 goto done;
1529
1530 if (bpa->b_bufsize != size)
1531 goto done;
1532
1533 /*
1534 * Check to see if it is in the expected place on disk and that the
1535 * block has been mapped.
1536 */
1537 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1538 match = 1;
1539 done:
1540 BUF_UNLOCK(bpa);
1541 return (match);
1542 }
1543
1544 /*
1545 * vfs_bio_awrite:
1546 *
1547 * Implement clustered async writes for clearing out B_DELWRI buffers.
1548 * This is much better then the old way of writing only one buffer at
1549 * a time. Note that we may not be presented with the buffers in the
1550 * correct order, so we search for the cluster in both directions.
1551 */
1552 int
1553 vfs_bio_awrite(struct buf *bp)
1554 {
1555 int i;
1556 int j;
1557 daddr_t lblkno = bp->b_lblkno;
1558 struct vnode *vp = bp->b_vp;
1559 int ncl;
1560 int nwritten;
1561 int size;
1562 int maxcl;
1563
1564 /*
1565 * right now we support clustered writing only to regular files. If
1566 * we find a clusterable block we could be in the middle of a cluster
1567 * rather then at the beginning.
1568 */
1569 if ((vp->v_type == VREG) &&
1570 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1571 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1572
1573 size = vp->v_mount->mnt_stat.f_iosize;
1574 maxcl = MAXPHYS / size;
1575
1576 VI_LOCK(vp);
1577 for (i = 1; i < maxcl; i++)
1578 if (vfs_bio_clcheck(vp, size, lblkno + i,
1579 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1580 break;
1581
1582 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1583 if (vfs_bio_clcheck(vp, size, lblkno - j,
1584 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1585 break;
1586
1587 VI_UNLOCK(vp);
1588 --j;
1589 ncl = i + j;
1590 /*
1591 * this is a possible cluster write
1592 */
1593 if (ncl != 1) {
1594 BUF_UNLOCK(bp);
1595 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1596 return nwritten;
1597 }
1598 }
1599 bremfree(bp);
1600 bp->b_flags |= B_ASYNC;
1601 /*
1602 * default (old) behavior, writing out only one block
1603 *
1604 * XXX returns b_bufsize instead of b_bcount for nwritten?
1605 */
1606 nwritten = bp->b_bufsize;
1607 (void) bwrite(bp);
1608
1609 return nwritten;
1610 }
1611
1612 /*
1613 * getnewbuf:
1614 *
1615 * Find and initialize a new buffer header, freeing up existing buffers
1616 * in the bufqueues as necessary. The new buffer is returned locked.
1617 *
1618 * Important: B_INVAL is not set. If the caller wishes to throw the
1619 * buffer away, the caller must set B_INVAL prior to calling brelse().
1620 *
1621 * We block if:
1622 * We have insufficient buffer headers
1623 * We have insufficient buffer space
1624 * buffer_map is too fragmented ( space reservation fails )
1625 * If we have to flush dirty buffers ( but we try to avoid this )
1626 *
1627 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1628 * Instead we ask the buf daemon to do it for us. We attempt to
1629 * avoid piecemeal wakeups of the pageout daemon.
1630 */
1631
1632 static struct buf *
1633 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1634 {
1635 struct buf *bp;
1636 struct buf *nbp;
1637 int defrag = 0;
1638 int nqindex;
1639 static int flushingbufs;
1640
1641 /*
1642 * We can't afford to block since we might be holding a vnode lock,
1643 * which may prevent system daemons from running. We deal with
1644 * low-memory situations by proactively returning memory and running
1645 * async I/O rather then sync I/O.
1646 */
1647
1648 atomic_add_int(&getnewbufcalls, 1);
1649 atomic_subtract_int(&getnewbufrestarts, 1);
1650 restart:
1651 atomic_add_int(&getnewbufrestarts, 1);
1652
1653 /*
1654 * Setup for scan. If we do not have enough free buffers,
1655 * we setup a degenerate case that immediately fails. Note
1656 * that if we are specially marked process, we are allowed to
1657 * dip into our reserves.
1658 *
1659 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1660 *
1661 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1662 * However, there are a number of cases (defragging, reusing, ...)
1663 * where we cannot backup.
1664 */
1665 mtx_lock(&bqlock);
1666 nqindex = QUEUE_EMPTYKVA;
1667 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1668
1669 if (nbp == NULL) {
1670 /*
1671 * If no EMPTYKVA buffers and we are either
1672 * defragging or reusing, locate a CLEAN buffer
1673 * to free or reuse. If bufspace useage is low
1674 * skip this step so we can allocate a new buffer.
1675 */
1676 if (defrag || bufspace >= lobufspace) {
1677 nqindex = QUEUE_CLEAN;
1678 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1679 }
1680
1681 /*
1682 * If we could not find or were not allowed to reuse a
1683 * CLEAN buffer, check to see if it is ok to use an EMPTY
1684 * buffer. We can only use an EMPTY buffer if allocating
1685 * its KVA would not otherwise run us out of buffer space.
1686 */
1687 if (nbp == NULL && defrag == 0 &&
1688 bufspace + maxsize < hibufspace) {
1689 nqindex = QUEUE_EMPTY;
1690 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1691 }
1692 }
1693
1694 /*
1695 * Run scan, possibly freeing data and/or kva mappings on the fly
1696 * depending.
1697 */
1698
1699 while ((bp = nbp) != NULL) {
1700 int qindex = nqindex;
1701
1702 /*
1703 * Calculate next bp ( we can only use it if we do not block
1704 * or do other fancy things ).
1705 */
1706 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1707 switch(qindex) {
1708 case QUEUE_EMPTY:
1709 nqindex = QUEUE_EMPTYKVA;
1710 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1711 break;
1712 /* FALLTHROUGH */
1713 case QUEUE_EMPTYKVA:
1714 nqindex = QUEUE_CLEAN;
1715 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1716 break;
1717 /* FALLTHROUGH */
1718 case QUEUE_CLEAN:
1719 /*
1720 * nbp is NULL.
1721 */
1722 break;
1723 }
1724 }
1725 /*
1726 * If we are defragging then we need a buffer with
1727 * b_kvasize != 0. XXX this situation should no longer
1728 * occur, if defrag is non-zero the buffer's b_kvasize
1729 * should also be non-zero at this point. XXX
1730 */
1731 if (defrag && bp->b_kvasize == 0) {
1732 printf("Warning: defrag empty buffer %p\n", bp);
1733 continue;
1734 }
1735
1736 /*
1737 * Start freeing the bp. This is somewhat involved. nbp
1738 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1739 */
1740 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1741 continue;
1742 if (bp->b_vp) {
1743 BO_LOCK(bp->b_bufobj);
1744 if (bp->b_vflags & BV_BKGRDINPROG) {
1745 BO_UNLOCK(bp->b_bufobj);
1746 BUF_UNLOCK(bp);
1747 continue;
1748 }
1749 BO_UNLOCK(bp->b_bufobj);
1750 }
1751 CTR6(KTR_BUF,
1752 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
1753 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
1754 bp->b_kvasize, bp->b_bufsize, qindex);
1755
1756 /*
1757 * Sanity Checks
1758 */
1759 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1760
1761 /*
1762 * Note: we no longer distinguish between VMIO and non-VMIO
1763 * buffers.
1764 */
1765
1766 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1767
1768 bremfreel(bp);
1769 mtx_unlock(&bqlock);
1770
1771 if (qindex == QUEUE_CLEAN) {
1772 if (bp->b_flags & B_VMIO) {
1773 bp->b_flags &= ~B_ASYNC;
1774 vfs_vmio_release(bp);
1775 }
1776 if (bp->b_vp)
1777 brelvp(bp);
1778 }
1779
1780 /*
1781 * NOTE: nbp is now entirely invalid. We can only restart
1782 * the scan from this point on.
1783 *
1784 * Get the rest of the buffer freed up. b_kva* is still
1785 * valid after this operation.
1786 */
1787
1788 if (bp->b_rcred != NOCRED) {
1789 crfree(bp->b_rcred);
1790 bp->b_rcred = NOCRED;
1791 }
1792 if (bp->b_wcred != NOCRED) {
1793 crfree(bp->b_wcred);
1794 bp->b_wcred = NOCRED;
1795 }
1796 if (LIST_FIRST(&bp->b_dep) != NULL)
1797 buf_deallocate(bp);
1798 if (bp->b_vflags & BV_BKGRDINPROG)
1799 panic("losing buffer 3");
1800 KASSERT(bp->b_vp == NULL,
1801 ("bp: %p still has vnode %p. qindex: %d",
1802 bp, bp->b_vp, qindex));
1803 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1804 ("bp: %p still on a buffer list. xflags %X",
1805 bp, bp->b_xflags));
1806
1807 if (bp->b_bufsize)
1808 allocbuf(bp, 0);
1809
1810 bp->b_flags = 0;
1811 bp->b_ioflags = 0;
1812 bp->b_xflags = 0;
1813 bp->b_vflags = 0;
1814 bp->b_vp = NULL;
1815 bp->b_blkno = bp->b_lblkno = 0;
1816 bp->b_offset = NOOFFSET;
1817 bp->b_iodone = 0;
1818 bp->b_error = 0;
1819 bp->b_resid = 0;
1820 bp->b_bcount = 0;
1821 bp->b_npages = 0;
1822 bp->b_dirtyoff = bp->b_dirtyend = 0;
1823 bp->b_bufobj = NULL;
1824
1825 LIST_INIT(&bp->b_dep);
1826
1827 /*
1828 * If we are defragging then free the buffer.
1829 */
1830 if (defrag) {
1831 bp->b_flags |= B_INVAL;
1832 bfreekva(bp);
1833 brelse(bp);
1834 defrag = 0;
1835 goto restart;
1836 }
1837
1838 /*
1839 * If we are overcomitted then recover the buffer and its
1840 * KVM space. This occurs in rare situations when multiple
1841 * processes are blocked in getnewbuf() or allocbuf().
1842 */
1843 if (bufspace >= hibufspace)
1844 flushingbufs = 1;
1845 if (flushingbufs && bp->b_kvasize != 0) {
1846 bp->b_flags |= B_INVAL;
1847 bfreekva(bp);
1848 brelse(bp);
1849 goto restart;
1850 }
1851 if (bufspace < lobufspace)
1852 flushingbufs = 0;
1853 break;
1854 }
1855
1856 /*
1857 * If we exhausted our list, sleep as appropriate. We may have to
1858 * wakeup various daemons and write out some dirty buffers.
1859 *
1860 * Generally we are sleeping due to insufficient buffer space.
1861 */
1862
1863 if (bp == NULL) {
1864 int flags;
1865 char *waitmsg;
1866
1867 mtx_unlock(&bqlock);
1868 if (defrag) {
1869 flags = VFS_BIO_NEED_BUFSPACE;
1870 waitmsg = "nbufkv";
1871 } else if (bufspace >= hibufspace) {
1872 waitmsg = "nbufbs";
1873 flags = VFS_BIO_NEED_BUFSPACE;
1874 } else {
1875 waitmsg = "newbuf";
1876 flags = VFS_BIO_NEED_ANY;
1877 }
1878
1879 bd_speedup(); /* heeeelp */
1880
1881 mtx_lock(&nblock);
1882 needsbuffer |= flags;
1883 while (needsbuffer & flags) {
1884 if (msleep(&needsbuffer, &nblock,
1885 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
1886 mtx_unlock(&nblock);
1887 return (NULL);
1888 }
1889 }
1890 mtx_unlock(&nblock);
1891 } else {
1892 /*
1893 * We finally have a valid bp. We aren't quite out of the
1894 * woods, we still have to reserve kva space. In order
1895 * to keep fragmentation sane we only allocate kva in
1896 * BKVASIZE chunks.
1897 */
1898 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
1899
1900 if (maxsize != bp->b_kvasize) {
1901 vm_offset_t addr = 0;
1902
1903 bfreekva(bp);
1904
1905 vm_map_lock(buffer_map);
1906 if (vm_map_findspace(buffer_map,
1907 vm_map_min(buffer_map), maxsize, &addr)) {
1908 /*
1909 * Uh oh. Buffer map is to fragmented. We
1910 * must defragment the map.
1911 */
1912 atomic_add_int(&bufdefragcnt, 1);
1913 vm_map_unlock(buffer_map);
1914 defrag = 1;
1915 bp->b_flags |= B_INVAL;
1916 brelse(bp);
1917 goto restart;
1918 }
1919 if (addr) {
1920 vm_map_insert(buffer_map, NULL, 0,
1921 addr, addr + maxsize,
1922 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
1923
1924 bp->b_kvabase = (caddr_t) addr;
1925 bp->b_kvasize = maxsize;
1926 atomic_add_int(&bufspace, bp->b_kvasize);
1927 atomic_add_int(&bufreusecnt, 1);
1928 }
1929 vm_map_unlock(buffer_map);
1930 }
1931 bp->b_saveaddr = bp->b_kvabase;
1932 bp->b_data = bp->b_saveaddr;
1933 }
1934 return(bp);
1935 }
1936
1937 /*
1938 * buf_daemon:
1939 *
1940 * buffer flushing daemon. Buffers are normally flushed by the
1941 * update daemon but if it cannot keep up this process starts to
1942 * take the load in an attempt to prevent getnewbuf() from blocking.
1943 */
1944
1945 static struct kproc_desc buf_kp = {
1946 "bufdaemon",
1947 buf_daemon,
1948 &bufdaemonproc
1949 };
1950 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
1951
1952 static void
1953 buf_daemon()
1954 {
1955 mtx_lock(&Giant);
1956
1957 /*
1958 * This process needs to be suspended prior to shutdown sync.
1959 */
1960 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
1961 SHUTDOWN_PRI_LAST);
1962
1963 /*
1964 * This process is allowed to take the buffer cache to the limit
1965 */
1966 curthread->td_pflags |= TDP_NORUNNINGBUF;
1967 mtx_lock(&bdlock);
1968 for (;;) {
1969 bd_request = 0;
1970 mtx_unlock(&bdlock);
1971
1972 kthread_suspend_check(bufdaemonproc);
1973
1974 /*
1975 * Do the flush. Limit the amount of in-transit I/O we
1976 * allow to build up, otherwise we would completely saturate
1977 * the I/O system. Wakeup any waiting processes before we
1978 * normally would so they can run in parallel with our drain.
1979 */
1980 while (numdirtybuffers > lodirtybuffers) {
1981 if (flushbufqueues(0) == 0) {
1982 /*
1983 * Could not find any buffers without rollback
1984 * dependencies, so just write the first one
1985 * in the hopes of eventually making progress.
1986 */
1987 flushbufqueues(1);
1988 break;
1989 }
1990 uio_yield();
1991 }
1992
1993 /*
1994 * Only clear bd_request if we have reached our low water
1995 * mark. The buf_daemon normally waits 1 second and
1996 * then incrementally flushes any dirty buffers that have
1997 * built up, within reason.
1998 *
1999 * If we were unable to hit our low water mark and couldn't
2000 * find any flushable buffers, we sleep half a second.
2001 * Otherwise we loop immediately.
2002 */
2003 mtx_lock(&bdlock);
2004 if (numdirtybuffers <= lodirtybuffers) {
2005 /*
2006 * We reached our low water mark, reset the
2007 * request and sleep until we are needed again.
2008 * The sleep is just so the suspend code works.
2009 */
2010 bd_request = 0;
2011 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2012 } else {
2013 /*
2014 * We couldn't find any flushable dirty buffers but
2015 * still have too many dirty buffers, we
2016 * have to sleep and try again. (rare)
2017 */
2018 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2019 }
2020 }
2021 }
2022
2023 /*
2024 * flushbufqueues:
2025 *
2026 * Try to flush a buffer in the dirty queue. We must be careful to
2027 * free up B_INVAL buffers instead of write them, which NFS is
2028 * particularly sensitive to.
2029 */
2030 static int flushwithdeps = 0;
2031 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2032 0, "Number of buffers flushed with dependecies that require rollbacks");
2033
2034 static int
2035 flushbufqueues(int flushdeps)
2036 {
2037 struct thread *td = curthread;
2038 struct buf sentinel;
2039 struct vnode *vp;
2040 struct mount *mp;
2041 struct buf *bp;
2042 int hasdeps;
2043 int flushed;
2044 int target;
2045
2046 target = numdirtybuffers - lodirtybuffers;
2047 if (flushdeps && target > 2)
2048 target /= 2;
2049 flushed = 0;
2050 bp = NULL;
2051 mtx_lock(&bqlock);
2052 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], &sentinel, b_freelist);
2053 while (flushed != target) {
2054 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]);
2055 if (bp == &sentinel)
2056 break;
2057 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
2058 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
2059
2060 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2061 continue;
2062 BO_LOCK(bp->b_bufobj);
2063 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2064 (bp->b_flags & B_DELWRI) == 0) {
2065 BO_UNLOCK(bp->b_bufobj);
2066 BUF_UNLOCK(bp);
2067 continue;
2068 }
2069 BO_UNLOCK(bp->b_bufobj);
2070 if (bp->b_flags & B_INVAL) {
2071 bremfreel(bp);
2072 mtx_unlock(&bqlock);
2073 brelse(bp);
2074 flushed++;
2075 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2076 mtx_lock(&bqlock);
2077 continue;
2078 }
2079
2080 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) {
2081 if (flushdeps == 0) {
2082 BUF_UNLOCK(bp);
2083 continue;
2084 }
2085 hasdeps = 1;
2086 } else
2087 hasdeps = 0;
2088 /*
2089 * We must hold the lock on a vnode before writing
2090 * one of its buffers. Otherwise we may confuse, or
2091 * in the case of a snapshot vnode, deadlock the
2092 * system.
2093 *
2094 * The lock order here is the reverse of the normal
2095 * of vnode followed by buf lock. This is ok because
2096 * the NOWAIT will prevent deadlock.
2097 */
2098 vp = bp->b_vp;
2099 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2100 BUF_UNLOCK(bp);
2101 continue;
2102 }
2103 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) {
2104 mtx_unlock(&bqlock);
2105 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2106 bp, bp->b_vp, bp->b_flags);
2107 vfs_bio_awrite(bp);
2108 vn_finished_write(mp);
2109 VOP_UNLOCK(vp, 0, td);
2110 flushwithdeps += hasdeps;
2111 flushed++;
2112 waitrunningbufspace();
2113 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2114 mtx_lock(&bqlock);
2115 continue;
2116 }
2117 vn_finished_write(mp);
2118 BUF_UNLOCK(bp);
2119 }
2120 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], &sentinel, b_freelist);
2121 mtx_unlock(&bqlock);
2122 return (flushed);
2123 }
2124
2125 /*
2126 * Check to see if a block is currently memory resident.
2127 */
2128 struct buf *
2129 incore(struct bufobj *bo, daddr_t blkno)
2130 {
2131 struct buf *bp;
2132
2133 BO_LOCK(bo);
2134 bp = gbincore(bo, blkno);
2135 BO_UNLOCK(bo);
2136 return (bp);
2137 }
2138
2139 /*
2140 * Returns true if no I/O is needed to access the
2141 * associated VM object. This is like incore except
2142 * it also hunts around in the VM system for the data.
2143 */
2144
2145 static int
2146 inmem(struct vnode * vp, daddr_t blkno)
2147 {
2148 vm_object_t obj;
2149 vm_offset_t toff, tinc, size;
2150 vm_page_t m;
2151 vm_ooffset_t off;
2152
2153 ASSERT_VOP_LOCKED(vp, "inmem");
2154
2155 if (incore(&vp->v_bufobj, blkno))
2156 return 1;
2157 if (vp->v_mount == NULL)
2158 return 0;
2159 obj = vp->v_object;
2160 if (obj == NULL)
2161 return (0);
2162
2163 size = PAGE_SIZE;
2164 if (size > vp->v_mount->mnt_stat.f_iosize)
2165 size = vp->v_mount->mnt_stat.f_iosize;
2166 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2167
2168 VM_OBJECT_LOCK(obj);
2169 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2170 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2171 if (!m)
2172 goto notinmem;
2173 tinc = size;
2174 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2175 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2176 if (vm_page_is_valid(m,
2177 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2178 goto notinmem;
2179 }
2180 VM_OBJECT_UNLOCK(obj);
2181 return 1;
2182
2183 notinmem:
2184 VM_OBJECT_UNLOCK(obj);
2185 return (0);
2186 }
2187
2188 /*
2189 * vfs_setdirty:
2190 *
2191 * Sets the dirty range for a buffer based on the status of the dirty
2192 * bits in the pages comprising the buffer.
2193 *
2194 * The range is limited to the size of the buffer.
2195 *
2196 * This routine is primarily used by NFS, but is generalized for the
2197 * B_VMIO case.
2198 */
2199 static void
2200 vfs_setdirty(struct buf *bp)
2201 {
2202 int i;
2203 vm_object_t object;
2204
2205 /*
2206 * Degenerate case - empty buffer
2207 */
2208
2209 if (bp->b_bufsize == 0)
2210 return;
2211
2212 /*
2213 * We qualify the scan for modified pages on whether the
2214 * object has been flushed yet. The OBJ_WRITEABLE flag
2215 * is not cleared simply by protecting pages off.
2216 */
2217
2218 if ((bp->b_flags & B_VMIO) == 0)
2219 return;
2220
2221 object = bp->b_pages[0]->object;
2222 VM_OBJECT_LOCK(object);
2223 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
2224 printf("Warning: object %p writeable but not mightbedirty\n", object);
2225 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
2226 printf("Warning: object %p mightbedirty but not writeable\n", object);
2227
2228 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2229 vm_offset_t boffset;
2230 vm_offset_t eoffset;
2231
2232 vm_page_lock_queues();
2233 /*
2234 * test the pages to see if they have been modified directly
2235 * by users through the VM system.
2236 */
2237 for (i = 0; i < bp->b_npages; i++)
2238 vm_page_test_dirty(bp->b_pages[i]);
2239
2240 /*
2241 * Calculate the encompassing dirty range, boffset and eoffset,
2242 * (eoffset - boffset) bytes.
2243 */
2244
2245 for (i = 0; i < bp->b_npages; i++) {
2246 if (bp->b_pages[i]->dirty)
2247 break;
2248 }
2249 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2250
2251 for (i = bp->b_npages - 1; i >= 0; --i) {
2252 if (bp->b_pages[i]->dirty) {
2253 break;
2254 }
2255 }
2256 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2257
2258 vm_page_unlock_queues();
2259 /*
2260 * Fit it to the buffer.
2261 */
2262
2263 if (eoffset > bp->b_bcount)
2264 eoffset = bp->b_bcount;
2265
2266 /*
2267 * If we have a good dirty range, merge with the existing
2268 * dirty range.
2269 */
2270
2271 if (boffset < eoffset) {
2272 if (bp->b_dirtyoff > boffset)
2273 bp->b_dirtyoff = boffset;
2274 if (bp->b_dirtyend < eoffset)
2275 bp->b_dirtyend = eoffset;
2276 }
2277 }
2278 VM_OBJECT_UNLOCK(object);
2279 }
2280
2281 /*
2282 * getblk:
2283 *
2284 * Get a block given a specified block and offset into a file/device.
2285 * The buffers B_DONE bit will be cleared on return, making it almost
2286 * ready for an I/O initiation. B_INVAL may or may not be set on
2287 * return. The caller should clear B_INVAL prior to initiating a
2288 * READ.
2289 *
2290 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2291 * an existing buffer.
2292 *
2293 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2294 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2295 * and then cleared based on the backing VM. If the previous buffer is
2296 * non-0-sized but invalid, B_CACHE will be cleared.
2297 *
2298 * If getblk() must create a new buffer, the new buffer is returned with
2299 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2300 * case it is returned with B_INVAL clear and B_CACHE set based on the
2301 * backing VM.
2302 *
2303 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2304 * B_CACHE bit is clear.
2305 *
2306 * What this means, basically, is that the caller should use B_CACHE to
2307 * determine whether the buffer is fully valid or not and should clear
2308 * B_INVAL prior to issuing a read. If the caller intends to validate
2309 * the buffer by loading its data area with something, the caller needs
2310 * to clear B_INVAL. If the caller does this without issuing an I/O,
2311 * the caller should set B_CACHE ( as an optimization ), else the caller
2312 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2313 * a write attempt or if it was a successfull read. If the caller
2314 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2315 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2316 */
2317 struct buf *
2318 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2319 int flags)
2320 {
2321 struct buf *bp;
2322 struct bufobj *bo;
2323 int error;
2324
2325 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
2326 ASSERT_VOP_LOCKED(vp, "getblk");
2327 if (size > MAXBSIZE)
2328 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2329
2330 bo = &vp->v_bufobj;
2331 loop:
2332 /*
2333 * Block if we are low on buffers. Certain processes are allowed
2334 * to completely exhaust the buffer cache.
2335 *
2336 * If this check ever becomes a bottleneck it may be better to
2337 * move it into the else, when gbincore() fails. At the moment
2338 * it isn't a problem.
2339 *
2340 * XXX remove if 0 sections (clean this up after its proven)
2341 */
2342 if (numfreebuffers == 0) {
2343 if (curthread == PCPU_GET(idlethread))
2344 return NULL;
2345 mtx_lock(&nblock);
2346 needsbuffer |= VFS_BIO_NEED_ANY;
2347 mtx_unlock(&nblock);
2348 }
2349
2350 VI_LOCK(vp);
2351 bp = gbincore(bo, blkno);
2352 if (bp != NULL) {
2353 int lockflags;
2354 /*
2355 * Buffer is in-core. If the buffer is not busy, it must
2356 * be on a queue.
2357 */
2358 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2359
2360 if (flags & GB_LOCK_NOWAIT)
2361 lockflags |= LK_NOWAIT;
2362
2363 error = BUF_TIMELOCK(bp, lockflags,
2364 VI_MTX(vp), "getblk", slpflag, slptimeo);
2365
2366 /*
2367 * If we slept and got the lock we have to restart in case
2368 * the buffer changed identities.
2369 */
2370 if (error == ENOLCK)
2371 goto loop;
2372 /* We timed out or were interrupted. */
2373 else if (error)
2374 return (NULL);
2375
2376 /*
2377 * The buffer is locked. B_CACHE is cleared if the buffer is
2378 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2379 * and for a VMIO buffer B_CACHE is adjusted according to the
2380 * backing VM cache.
2381 */
2382 if (bp->b_flags & B_INVAL)
2383 bp->b_flags &= ~B_CACHE;
2384 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2385 bp->b_flags |= B_CACHE;
2386 bremfree(bp);
2387
2388 /*
2389 * check for size inconsistancies for non-VMIO case.
2390 */
2391
2392 if (bp->b_bcount != size) {
2393 if ((bp->b_flags & B_VMIO) == 0 ||
2394 (size > bp->b_kvasize)) {
2395 if (bp->b_flags & B_DELWRI) {
2396 bp->b_flags |= B_NOCACHE;
2397 bwrite(bp);
2398 } else {
2399 if (LIST_FIRST(&bp->b_dep) == NULL) {
2400 bp->b_flags |= B_RELBUF;
2401 brelse(bp);
2402 } else {
2403 bp->b_flags |= B_NOCACHE;
2404 bwrite(bp);
2405 }
2406 }
2407 goto loop;
2408 }
2409 }
2410
2411 /*
2412 * If the size is inconsistant in the VMIO case, we can resize
2413 * the buffer. This might lead to B_CACHE getting set or
2414 * cleared. If the size has not changed, B_CACHE remains
2415 * unchanged from its previous state.
2416 */
2417
2418 if (bp->b_bcount != size)
2419 allocbuf(bp, size);
2420
2421 KASSERT(bp->b_offset != NOOFFSET,
2422 ("getblk: no buffer offset"));
2423
2424 /*
2425 * A buffer with B_DELWRI set and B_CACHE clear must
2426 * be committed before we can return the buffer in
2427 * order to prevent the caller from issuing a read
2428 * ( due to B_CACHE not being set ) and overwriting
2429 * it.
2430 *
2431 * Most callers, including NFS and FFS, need this to
2432 * operate properly either because they assume they
2433 * can issue a read if B_CACHE is not set, or because
2434 * ( for example ) an uncached B_DELWRI might loop due
2435 * to softupdates re-dirtying the buffer. In the latter
2436 * case, B_CACHE is set after the first write completes,
2437 * preventing further loops.
2438 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2439 * above while extending the buffer, we cannot allow the
2440 * buffer to remain with B_CACHE set after the write
2441 * completes or it will represent a corrupt state. To
2442 * deal with this we set B_NOCACHE to scrap the buffer
2443 * after the write.
2444 *
2445 * We might be able to do something fancy, like setting
2446 * B_CACHE in bwrite() except if B_DELWRI is already set,
2447 * so the below call doesn't set B_CACHE, but that gets real
2448 * confusing. This is much easier.
2449 */
2450
2451 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2452 bp->b_flags |= B_NOCACHE;
2453 bwrite(bp);
2454 goto loop;
2455 }
2456 bp->b_flags &= ~B_DONE;
2457 } else {
2458 int bsize, maxsize, vmio;
2459 off_t offset;
2460
2461 /*
2462 * Buffer is not in-core, create new buffer. The buffer
2463 * returned by getnewbuf() is locked. Note that the returned
2464 * buffer is also considered valid (not marked B_INVAL).
2465 */
2466 VI_UNLOCK(vp);
2467 /*
2468 * If the user does not want us to create the buffer, bail out
2469 * here.
2470 */
2471 if (flags & GB_NOCREAT)
2472 return NULL;
2473 bsize = bo->bo_bsize;
2474 offset = blkno * bsize;
2475 vmio = vp->v_object != NULL;
2476 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2477 maxsize = imax(maxsize, bsize);
2478
2479 bp = getnewbuf(slpflag, slptimeo, size, maxsize);
2480 if (bp == NULL) {
2481 if (slpflag || slptimeo)
2482 return NULL;
2483 goto loop;
2484 }
2485
2486 /*
2487 * This code is used to make sure that a buffer is not
2488 * created while the getnewbuf routine is blocked.
2489 * This can be a problem whether the vnode is locked or not.
2490 * If the buffer is created out from under us, we have to
2491 * throw away the one we just created.
2492 *
2493 * Note: this must occur before we associate the buffer
2494 * with the vp especially considering limitations in
2495 * the splay tree implementation when dealing with duplicate
2496 * lblkno's.
2497 */
2498 BO_LOCK(bo);
2499 if (gbincore(bo, blkno)) {
2500 BO_UNLOCK(bo);
2501 bp->b_flags |= B_INVAL;
2502 brelse(bp);
2503 goto loop;
2504 }
2505
2506 /*
2507 * Insert the buffer into the hash, so that it can
2508 * be found by incore.
2509 */
2510 bp->b_blkno = bp->b_lblkno = blkno;
2511 bp->b_offset = offset;
2512
2513 bgetvp(vp, bp);
2514 BO_UNLOCK(bo);
2515
2516 /*
2517 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2518 * buffer size starts out as 0, B_CACHE will be set by
2519 * allocbuf() for the VMIO case prior to it testing the
2520 * backing store for validity.
2521 */
2522
2523 if (vmio) {
2524 bp->b_flags |= B_VMIO;
2525 #if defined(VFS_BIO_DEBUG)
2526 if (vn_canvmio(vp) != TRUE)
2527 printf("getblk: VMIO on vnode type %d\n",
2528 vp->v_type);
2529 #endif
2530 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
2531 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
2532 bp, vp->v_object, bp->b_bufobj->bo_object));
2533 } else {
2534 bp->b_flags &= ~B_VMIO;
2535 KASSERT(bp->b_bufobj->bo_object == NULL,
2536 ("ARGH! has b_bufobj->bo_object %p %p\n",
2537 bp, bp->b_bufobj->bo_object));
2538 }
2539
2540 allocbuf(bp, size);
2541 bp->b_flags &= ~B_DONE;
2542 }
2543 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
2544 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
2545 KASSERT(bp->b_bufobj == bo,
2546 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
2547 return (bp);
2548 }
2549
2550 /*
2551 * Get an empty, disassociated buffer of given size. The buffer is initially
2552 * set to B_INVAL.
2553 */
2554 struct buf *
2555 geteblk(int size)
2556 {
2557 struct buf *bp;
2558 int maxsize;
2559
2560 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2561 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
2562 continue;
2563 allocbuf(bp, size);
2564 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2565 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
2566 return (bp);
2567 }
2568
2569
2570 /*
2571 * This code constitutes the buffer memory from either anonymous system
2572 * memory (in the case of non-VMIO operations) or from an associated
2573 * VM object (in the case of VMIO operations). This code is able to
2574 * resize a buffer up or down.
2575 *
2576 * Note that this code is tricky, and has many complications to resolve
2577 * deadlock or inconsistant data situations. Tread lightly!!!
2578 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2579 * the caller. Calling this code willy nilly can result in the loss of data.
2580 *
2581 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2582 * B_CACHE for the non-VMIO case.
2583 */
2584
2585 int
2586 allocbuf(struct buf *bp, int size)
2587 {
2588 int newbsize, mbsize;
2589 int i;
2590
2591 if (BUF_REFCNT(bp) == 0)
2592 panic("allocbuf: buffer not busy");
2593
2594 if (bp->b_kvasize < size)
2595 panic("allocbuf: buffer too small");
2596
2597 if ((bp->b_flags & B_VMIO) == 0) {
2598 caddr_t origbuf;
2599 int origbufsize;
2600 /*
2601 * Just get anonymous memory from the kernel. Don't
2602 * mess with B_CACHE.
2603 */
2604 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2605 if (bp->b_flags & B_MALLOC)
2606 newbsize = mbsize;
2607 else
2608 newbsize = round_page(size);
2609
2610 if (newbsize < bp->b_bufsize) {
2611 /*
2612 * malloced buffers are not shrunk
2613 */
2614 if (bp->b_flags & B_MALLOC) {
2615 if (newbsize) {
2616 bp->b_bcount = size;
2617 } else {
2618 free(bp->b_data, M_BIOBUF);
2619 if (bp->b_bufsize) {
2620 atomic_subtract_int(
2621 &bufmallocspace,
2622 bp->b_bufsize);
2623 bufspacewakeup();
2624 bp->b_bufsize = 0;
2625 }
2626 bp->b_saveaddr = bp->b_kvabase;
2627 bp->b_data = bp->b_saveaddr;
2628 bp->b_bcount = 0;
2629 bp->b_flags &= ~B_MALLOC;
2630 }
2631 return 1;
2632 }
2633 vm_hold_free_pages(
2634 bp,
2635 (vm_offset_t) bp->b_data + newbsize,
2636 (vm_offset_t) bp->b_data + bp->b_bufsize);
2637 } else if (newbsize > bp->b_bufsize) {
2638 /*
2639 * We only use malloced memory on the first allocation.
2640 * and revert to page-allocated memory when the buffer
2641 * grows.
2642 */
2643 /*
2644 * There is a potential smp race here that could lead
2645 * to bufmallocspace slightly passing the max. It
2646 * is probably extremely rare and not worth worrying
2647 * over.
2648 */
2649 if ( (bufmallocspace < maxbufmallocspace) &&
2650 (bp->b_bufsize == 0) &&
2651 (mbsize <= PAGE_SIZE/2)) {
2652
2653 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2654 bp->b_bufsize = mbsize;
2655 bp->b_bcount = size;
2656 bp->b_flags |= B_MALLOC;
2657 atomic_add_int(&bufmallocspace, mbsize);
2658 return 1;
2659 }
2660 origbuf = NULL;
2661 origbufsize = 0;
2662 /*
2663 * If the buffer is growing on its other-than-first allocation,
2664 * then we revert to the page-allocation scheme.
2665 */
2666 if (bp->b_flags & B_MALLOC) {
2667 origbuf = bp->b_data;
2668 origbufsize = bp->b_bufsize;
2669 bp->b_data = bp->b_kvabase;
2670 if (bp->b_bufsize) {
2671 atomic_subtract_int(&bufmallocspace,
2672 bp->b_bufsize);
2673 bufspacewakeup();
2674 bp->b_bufsize = 0;
2675 }
2676 bp->b_flags &= ~B_MALLOC;
2677 newbsize = round_page(newbsize);
2678 }
2679 vm_hold_load_pages(
2680 bp,
2681 (vm_offset_t) bp->b_data + bp->b_bufsize,
2682 (vm_offset_t) bp->b_data + newbsize);
2683 if (origbuf) {
2684 bcopy(origbuf, bp->b_data, origbufsize);
2685 free(origbuf, M_BIOBUF);
2686 }
2687 }
2688 } else {
2689 int desiredpages;
2690
2691 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2692 desiredpages = (size == 0) ? 0 :
2693 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2694
2695 if (bp->b_flags & B_MALLOC)
2696 panic("allocbuf: VMIO buffer can't be malloced");
2697 /*
2698 * Set B_CACHE initially if buffer is 0 length or will become
2699 * 0-length.
2700 */
2701 if (size == 0 || bp->b_bufsize == 0)
2702 bp->b_flags |= B_CACHE;
2703
2704 if (newbsize < bp->b_bufsize) {
2705 /*
2706 * DEV_BSIZE aligned new buffer size is less then the
2707 * DEV_BSIZE aligned existing buffer size. Figure out
2708 * if we have to remove any pages.
2709 */
2710 if (desiredpages < bp->b_npages) {
2711 vm_page_t m;
2712
2713 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2714 vm_page_lock_queues();
2715 for (i = desiredpages; i < bp->b_npages; i++) {
2716 /*
2717 * the page is not freed here -- it
2718 * is the responsibility of
2719 * vnode_pager_setsize
2720 */
2721 m = bp->b_pages[i];
2722 KASSERT(m != bogus_page,
2723 ("allocbuf: bogus page found"));
2724 while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
2725 vm_page_lock_queues();
2726
2727 bp->b_pages[i] = NULL;
2728 vm_page_unwire(m, 0);
2729 }
2730 vm_page_unlock_queues();
2731 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2732 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2733 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
2734 bp->b_npages = desiredpages;
2735 }
2736 } else if (size > bp->b_bcount) {
2737 /*
2738 * We are growing the buffer, possibly in a
2739 * byte-granular fashion.
2740 */
2741 struct vnode *vp;
2742 vm_object_t obj;
2743 vm_offset_t toff;
2744 vm_offset_t tinc;
2745
2746 /*
2747 * Step 1, bring in the VM pages from the object,
2748 * allocating them if necessary. We must clear
2749 * B_CACHE if these pages are not valid for the
2750 * range covered by the buffer.
2751 */
2752
2753 vp = bp->b_vp;
2754 obj = bp->b_bufobj->bo_object;
2755
2756 VM_OBJECT_LOCK(obj);
2757 while (bp->b_npages < desiredpages) {
2758 vm_page_t m;
2759 vm_pindex_t pi;
2760
2761 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
2762 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2763 /*
2764 * note: must allocate system pages
2765 * since blocking here could intefere
2766 * with paging I/O, no matter which
2767 * process we are.
2768 */
2769 m = vm_page_alloc(obj, pi,
2770 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
2771 VM_ALLOC_WIRED);
2772 if (m == NULL) {
2773 atomic_add_int(&vm_pageout_deficit,
2774 desiredpages - bp->b_npages);
2775 VM_OBJECT_UNLOCK(obj);
2776 VM_WAIT;
2777 VM_OBJECT_LOCK(obj);
2778 } else {
2779 bp->b_flags &= ~B_CACHE;
2780 bp->b_pages[bp->b_npages] = m;
2781 ++bp->b_npages;
2782 }
2783 continue;
2784 }
2785
2786 /*
2787 * We found a page. If we have to sleep on it,
2788 * retry because it might have gotten freed out
2789 * from under us.
2790 *
2791 * We can only test PG_BUSY here. Blocking on
2792 * m->busy might lead to a deadlock:
2793 *
2794 * vm_fault->getpages->cluster_read->allocbuf
2795 *
2796 */
2797 vm_page_lock_queues();
2798 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
2799 continue;
2800
2801 /*
2802 * We have a good page. Should we wakeup the
2803 * page daemon?
2804 */
2805 if ((curproc != pageproc) &&
2806 ((m->queue - m->pc) == PQ_CACHE) &&
2807 ((cnt.v_free_count + cnt.v_cache_count) <
2808 (cnt.v_free_min + cnt.v_cache_min))) {
2809 pagedaemon_wakeup();
2810 }
2811 vm_page_wire(m);
2812 vm_page_unlock_queues();
2813 bp->b_pages[bp->b_npages] = m;
2814 ++bp->b_npages;
2815 }
2816
2817 /*
2818 * Step 2. We've loaded the pages into the buffer,
2819 * we have to figure out if we can still have B_CACHE
2820 * set. Note that B_CACHE is set according to the
2821 * byte-granular range ( bcount and size ), new the
2822 * aligned range ( newbsize ).
2823 *
2824 * The VM test is against m->valid, which is DEV_BSIZE
2825 * aligned. Needless to say, the validity of the data
2826 * needs to also be DEV_BSIZE aligned. Note that this
2827 * fails with NFS if the server or some other client
2828 * extends the file's EOF. If our buffer is resized,
2829 * B_CACHE may remain set! XXX
2830 */
2831
2832 toff = bp->b_bcount;
2833 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2834
2835 while ((bp->b_flags & B_CACHE) && toff < size) {
2836 vm_pindex_t pi;
2837
2838 if (tinc > (size - toff))
2839 tinc = size - toff;
2840
2841 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2842 PAGE_SHIFT;
2843
2844 vfs_buf_test_cache(
2845 bp,
2846 bp->b_offset,
2847 toff,
2848 tinc,
2849 bp->b_pages[pi]
2850 );
2851 toff += tinc;
2852 tinc = PAGE_SIZE;
2853 }
2854 VM_OBJECT_UNLOCK(obj);
2855
2856 /*
2857 * Step 3, fixup the KVM pmap. Remember that
2858 * bp->b_data is relative to bp->b_offset, but
2859 * bp->b_offset may be offset into the first page.
2860 */
2861
2862 bp->b_data = (caddr_t)
2863 trunc_page((vm_offset_t)bp->b_data);
2864 pmap_qenter(
2865 (vm_offset_t)bp->b_data,
2866 bp->b_pages,
2867 bp->b_npages
2868 );
2869
2870 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2871 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2872 }
2873 }
2874 if (newbsize < bp->b_bufsize)
2875 bufspacewakeup();
2876 bp->b_bufsize = newbsize; /* actual buffer allocation */
2877 bp->b_bcount = size; /* requested buffer size */
2878 return 1;
2879 }
2880
2881 void
2882 biodone(struct bio *bp)
2883 {
2884 void (*done)(struct bio *);
2885
2886 mtx_lock(&bdonelock);
2887 bp->bio_flags |= BIO_DONE;
2888 done = bp->bio_done;
2889 if (done == NULL)
2890 wakeup(bp);
2891 mtx_unlock(&bdonelock);
2892 if (done != NULL)
2893 done(bp);
2894 }
2895
2896 /*
2897 * Wait for a BIO to finish.
2898 *
2899 * XXX: resort to a timeout for now. The optimal locking (if any) for this
2900 * case is not yet clear.
2901 */
2902 int
2903 biowait(struct bio *bp, const char *wchan)
2904 {
2905
2906 mtx_lock(&bdonelock);
2907 while ((bp->bio_flags & BIO_DONE) == 0)
2908 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
2909 mtx_unlock(&bdonelock);
2910 if (bp->bio_error != 0)
2911 return (bp->bio_error);
2912 if (!(bp->bio_flags & BIO_ERROR))
2913 return (0);
2914 return (EIO);
2915 }
2916
2917 void
2918 biofinish(struct bio *bp, struct devstat *stat, int error)
2919 {
2920
2921 if (error) {
2922 bp->bio_error = error;
2923 bp->bio_flags |= BIO_ERROR;
2924 }
2925 if (stat != NULL)
2926 devstat_end_transaction_bio(stat, bp);
2927 biodone(bp);
2928 }
2929
2930 /*
2931 * bufwait:
2932 *
2933 * Wait for buffer I/O completion, returning error status. The buffer
2934 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
2935 * error and cleared.
2936 */
2937 int
2938 bufwait(struct buf *bp)
2939 {
2940 if (bp->b_iocmd == BIO_READ)
2941 bwait(bp, PRIBIO, "biord");
2942 else
2943 bwait(bp, PRIBIO, "biowr");
2944 if (bp->b_flags & B_EINTR) {
2945 bp->b_flags &= ~B_EINTR;
2946 return (EINTR);
2947 }
2948 if (bp->b_ioflags & BIO_ERROR) {
2949 return (bp->b_error ? bp->b_error : EIO);
2950 } else {
2951 return (0);
2952 }
2953 }
2954
2955 /*
2956 * Call back function from struct bio back up to struct buf.
2957 */
2958 static void
2959 bufdonebio(struct bio *bip)
2960 {
2961 struct buf *bp;
2962
2963 bp = bip->bio_caller2;
2964 bp->b_resid = bp->b_bcount - bip->bio_completed;
2965 bp->b_resid = bip->bio_resid; /* XXX: remove */
2966 bp->b_ioflags = bip->bio_flags;
2967 bp->b_error = bip->bio_error;
2968 if (bp->b_error)
2969 bp->b_ioflags |= BIO_ERROR;
2970 bufdone(bp);
2971 g_destroy_bio(bip);
2972 }
2973
2974 void
2975 dev_strategy(struct cdev *dev, struct buf *bp)
2976 {
2977 struct cdevsw *csw;
2978 struct bio *bip;
2979
2980 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
2981 panic("b_iocmd botch");
2982 for (;;) {
2983 bip = g_new_bio();
2984 if (bip != NULL)
2985 break;
2986 /* Try again later */
2987 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
2988 }
2989 bip->bio_cmd = bp->b_iocmd;
2990 bip->bio_offset = bp->b_iooffset;
2991 bip->bio_length = bp->b_bcount;
2992 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
2993 bip->bio_data = bp->b_data;
2994 bip->bio_done = bufdonebio;
2995 bip->bio_caller2 = bp;
2996 bip->bio_dev = dev;
2997 KASSERT(dev->si_refcount > 0,
2998 ("dev_strategy on un-referenced struct cdev *(%s)",
2999 devtoname(dev)));
3000 csw = dev_refthread(dev);
3001 if (csw == NULL) {
3002 bp->b_error = ENXIO;
3003 bp->b_ioflags = BIO_ERROR;
3004 bufdone(bp);
3005 return;
3006 }
3007 (*csw->d_strategy)(bip);
3008 dev_relthread(dev);
3009 }
3010
3011 /*
3012 * bufdone:
3013 *
3014 * Finish I/O on a buffer, optionally calling a completion function.
3015 * This is usually called from an interrupt so process blocking is
3016 * not allowed.
3017 *
3018 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3019 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3020 * assuming B_INVAL is clear.
3021 *
3022 * For the VMIO case, we set B_CACHE if the op was a read and no
3023 * read error occured, or if the op was a write. B_CACHE is never
3024 * set if the buffer is invalid or otherwise uncacheable.
3025 *
3026 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3027 * initiator to leave B_INVAL set to brelse the buffer out of existance
3028 * in the biodone routine.
3029 */
3030 void
3031 bufdone(struct buf *bp)
3032 {
3033 struct bufobj *dropobj;
3034 void (*biodone)(struct buf *);
3035
3036
3037 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3038 dropobj = NULL;
3039
3040 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp)));
3041 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3042
3043 runningbufwakeup(bp);
3044 if (bp->b_iocmd == BIO_WRITE)
3045 dropobj = bp->b_bufobj;
3046 /* call optional completion function if requested */
3047 if (bp->b_iodone != NULL) {
3048 biodone = bp->b_iodone;
3049 bp->b_iodone = NULL;
3050 (*biodone) (bp);
3051 if (dropobj)
3052 bufobj_wdrop(dropobj);
3053 return;
3054 }
3055 if (LIST_FIRST(&bp->b_dep) != NULL)
3056 buf_complete(bp);
3057
3058 if (bp->b_flags & B_VMIO) {
3059 int i;
3060 vm_ooffset_t foff;
3061 vm_page_t m;
3062 vm_object_t obj;
3063 int iosize;
3064 struct vnode *vp = bp->b_vp;
3065
3066 obj = bp->b_bufobj->bo_object;
3067
3068 #if defined(VFS_BIO_DEBUG)
3069 mp_fixme("usecount and vflag accessed without locks.");
3070 if (vp->v_usecount == 0) {
3071 panic("biodone: zero vnode ref count");
3072 }
3073
3074 KASSERT(vp->v_object != NULL,
3075 ("biodone: vnode %p has no vm_object", vp));
3076 #endif
3077
3078 foff = bp->b_offset;
3079 KASSERT(bp->b_offset != NOOFFSET,
3080 ("biodone: no buffer offset"));
3081
3082 VM_OBJECT_LOCK(obj);
3083 #if defined(VFS_BIO_DEBUG)
3084 if (obj->paging_in_progress < bp->b_npages) {
3085 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
3086 obj->paging_in_progress, bp->b_npages);
3087 }
3088 #endif
3089
3090 /*
3091 * Set B_CACHE if the op was a normal read and no error
3092 * occured. B_CACHE is set for writes in the b*write()
3093 * routines.
3094 */
3095 iosize = bp->b_bcount - bp->b_resid;
3096 if (bp->b_iocmd == BIO_READ &&
3097 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3098 !(bp->b_ioflags & BIO_ERROR)) {
3099 bp->b_flags |= B_CACHE;
3100 }
3101 vm_page_lock_queues();
3102 for (i = 0; i < bp->b_npages; i++) {
3103 int bogusflag = 0;
3104 int resid;
3105
3106 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3107 if (resid > iosize)
3108 resid = iosize;
3109
3110 /*
3111 * cleanup bogus pages, restoring the originals
3112 */
3113 m = bp->b_pages[i];
3114 if (m == bogus_page) {
3115 bogusflag = 1;
3116 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3117 if (m == NULL)
3118 panic("biodone: page disappeared!");
3119 bp->b_pages[i] = m;
3120 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3121 }
3122 #if defined(VFS_BIO_DEBUG)
3123 if (OFF_TO_IDX(foff) != m->pindex) {
3124 printf(
3125 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
3126 (intmax_t)foff, (uintmax_t)m->pindex);
3127 }
3128 #endif
3129
3130 /*
3131 * In the write case, the valid and clean bits are
3132 * already changed correctly ( see bdwrite() ), so we
3133 * only need to do this here in the read case.
3134 */
3135 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3136 vfs_page_set_valid(bp, foff, i, m);
3137 }
3138
3139 /*
3140 * when debugging new filesystems or buffer I/O methods, this
3141 * is the most common error that pops up. if you see this, you
3142 * have not set the page busy flag correctly!!!
3143 */
3144 if (m->busy == 0) {
3145 printf("biodone: page busy < 0, "
3146 "pindex: %d, foff: 0x(%x,%x), "
3147 "resid: %d, index: %d\n",
3148 (int) m->pindex, (int)(foff >> 32),
3149 (int) foff & 0xffffffff, resid, i);
3150 if (!vn_isdisk(vp, NULL))
3151 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
3152 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
3153 (intmax_t) bp->b_lblkno,
3154 bp->b_flags, bp->b_npages);
3155 else
3156 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
3157 (intmax_t) bp->b_lblkno,
3158 bp->b_flags, bp->b_npages);
3159 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
3160 (u_long)m->valid, (u_long)m->dirty,
3161 m->wire_count);
3162 panic("biodone: page busy < 0\n");
3163 }
3164 vm_page_io_finish(m);
3165 vm_object_pip_subtract(obj, 1);
3166 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3167 iosize -= resid;
3168 }
3169 vm_page_unlock_queues();
3170 vm_object_pip_wakeupn(obj, 0);
3171 VM_OBJECT_UNLOCK(obj);
3172 }
3173
3174 /*
3175 * For asynchronous completions, release the buffer now. The brelse
3176 * will do a wakeup there if necessary - so no need to do a wakeup
3177 * here in the async case. The sync case always needs to do a wakeup.
3178 */
3179
3180 if (bp->b_flags & B_ASYNC) {
3181 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3182 brelse(bp);
3183 else
3184 bqrelse(bp);
3185 } else
3186 bdone(bp);
3187 if (dropobj)
3188 bufobj_wdrop(dropobj);
3189 }
3190
3191 /*
3192 * This routine is called in lieu of iodone in the case of
3193 * incomplete I/O. This keeps the busy status for pages
3194 * consistant.
3195 */
3196 void
3197 vfs_unbusy_pages(struct buf *bp)
3198 {
3199 int i;
3200 vm_object_t obj;
3201 vm_page_t m;
3202
3203 runningbufwakeup(bp);
3204 if (!(bp->b_flags & B_VMIO))
3205 return;
3206
3207 obj = bp->b_bufobj->bo_object;
3208 VM_OBJECT_LOCK(obj);
3209 vm_page_lock_queues();
3210 for (i = 0; i < bp->b_npages; i++) {
3211 m = bp->b_pages[i];
3212 if (m == bogus_page) {
3213 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3214 if (!m)
3215 panic("vfs_unbusy_pages: page missing\n");
3216 bp->b_pages[i] = m;
3217 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3218 bp->b_pages, bp->b_npages);
3219 }
3220 vm_object_pip_subtract(obj, 1);
3221 vm_page_io_finish(m);
3222 }
3223 vm_page_unlock_queues();
3224 vm_object_pip_wakeupn(obj, 0);
3225 VM_OBJECT_UNLOCK(obj);
3226 }
3227
3228 /*
3229 * vfs_page_set_valid:
3230 *
3231 * Set the valid bits in a page based on the supplied offset. The
3232 * range is restricted to the buffer's size.
3233 *
3234 * This routine is typically called after a read completes.
3235 */
3236 static void
3237 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3238 {
3239 vm_ooffset_t soff, eoff;
3240
3241 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
3242 /*
3243 * Start and end offsets in buffer. eoff - soff may not cross a
3244 * page boundry or cross the end of the buffer. The end of the
3245 * buffer, in this case, is our file EOF, not the allocation size
3246 * of the buffer.
3247 */
3248 soff = off;
3249 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3250 if (eoff > bp->b_offset + bp->b_bcount)
3251 eoff = bp->b_offset + bp->b_bcount;
3252
3253 /*
3254 * Set valid range. This is typically the entire buffer and thus the
3255 * entire page.
3256 */
3257 if (eoff > soff) {
3258 vm_page_set_validclean(
3259 m,
3260 (vm_offset_t) (soff & PAGE_MASK),
3261 (vm_offset_t) (eoff - soff)
3262 );
3263 }
3264 }
3265
3266 /*
3267 * This routine is called before a device strategy routine.
3268 * It is used to tell the VM system that paging I/O is in
3269 * progress, and treat the pages associated with the buffer
3270 * almost as being PG_BUSY. Also the object paging_in_progress
3271 * flag is handled to make sure that the object doesn't become
3272 * inconsistant.
3273 *
3274 * Since I/O has not been initiated yet, certain buffer flags
3275 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3276 * and should be ignored.
3277 */
3278 void
3279 vfs_busy_pages(struct buf *bp, int clear_modify)
3280 {
3281 int i, bogus;
3282 vm_object_t obj;
3283 vm_ooffset_t foff;
3284 vm_page_t m;
3285
3286 if (!(bp->b_flags & B_VMIO))
3287 return;
3288
3289 obj = bp->b_bufobj->bo_object;
3290 foff = bp->b_offset;
3291 KASSERT(bp->b_offset != NOOFFSET,
3292 ("vfs_busy_pages: no buffer offset"));
3293 vfs_setdirty(bp);
3294 VM_OBJECT_LOCK(obj);
3295 retry:
3296 vm_page_lock_queues();
3297 for (i = 0; i < bp->b_npages; i++) {
3298 m = bp->b_pages[i];
3299
3300 if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
3301 goto retry;
3302 }
3303 bogus = 0;
3304 for (i = 0; i < bp->b_npages; i++) {
3305 m = bp->b_pages[i];
3306
3307 if ((bp->b_flags & B_CLUSTER) == 0) {
3308 vm_object_pip_add(obj, 1);
3309 vm_page_io_start(m);
3310 }
3311 /*
3312 * When readying a buffer for a read ( i.e
3313 * clear_modify == 0 ), it is important to do
3314 * bogus_page replacement for valid pages in
3315 * partially instantiated buffers. Partially
3316 * instantiated buffers can, in turn, occur when
3317 * reconstituting a buffer from its VM backing store
3318 * base. We only have to do this if B_CACHE is
3319 * clear ( which causes the I/O to occur in the
3320 * first place ). The replacement prevents the read
3321 * I/O from overwriting potentially dirty VM-backed
3322 * pages. XXX bogus page replacement is, uh, bogus.
3323 * It may not work properly with small-block devices.
3324 * We need to find a better way.
3325 */
3326 pmap_remove_all(m);
3327 if (clear_modify)
3328 vfs_page_set_valid(bp, foff, i, m);
3329 else if (m->valid == VM_PAGE_BITS_ALL &&
3330 (bp->b_flags & B_CACHE) == 0) {
3331 bp->b_pages[i] = bogus_page;
3332 bogus++;
3333 }
3334 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3335 }
3336 vm_page_unlock_queues();
3337 VM_OBJECT_UNLOCK(obj);
3338 if (bogus)
3339 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3340 bp->b_pages, bp->b_npages);
3341 }
3342
3343 /*
3344 * Tell the VM system that the pages associated with this buffer
3345 * are clean. This is used for delayed writes where the data is
3346 * going to go to disk eventually without additional VM intevention.
3347 *
3348 * Note that while we only really need to clean through to b_bcount, we
3349 * just go ahead and clean through to b_bufsize.
3350 */
3351 static void
3352 vfs_clean_pages(struct buf *bp)
3353 {
3354 int i;
3355 vm_ooffset_t foff, noff, eoff;
3356 vm_page_t m;
3357
3358 if (!(bp->b_flags & B_VMIO))
3359 return;
3360
3361 foff = bp->b_offset;
3362 KASSERT(bp->b_offset != NOOFFSET,
3363 ("vfs_clean_pages: no buffer offset"));
3364 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3365 vm_page_lock_queues();
3366 for (i = 0; i < bp->b_npages; i++) {
3367 m = bp->b_pages[i];
3368 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3369 eoff = noff;
3370
3371 if (eoff > bp->b_offset + bp->b_bufsize)
3372 eoff = bp->b_offset + bp->b_bufsize;
3373 vfs_page_set_valid(bp, foff, i, m);
3374 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3375 foff = noff;
3376 }
3377 vm_page_unlock_queues();
3378 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3379 }
3380
3381 /*
3382 * vfs_bio_set_validclean:
3383 *
3384 * Set the range within the buffer to valid and clean. The range is
3385 * relative to the beginning of the buffer, b_offset. Note that b_offset
3386 * itself may be offset from the beginning of the first page.
3387 *
3388 */
3389
3390 void
3391 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3392 {
3393 int i, n;
3394 vm_page_t m;
3395
3396 if (!(bp->b_flags & B_VMIO))
3397 return;
3398 /*
3399 * Fixup base to be relative to beginning of first page.
3400 * Set initial n to be the maximum number of bytes in the
3401 * first page that can be validated.
3402 */
3403
3404 base += (bp->b_offset & PAGE_MASK);
3405 n = PAGE_SIZE - (base & PAGE_MASK);
3406
3407 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3408 vm_page_lock_queues();
3409 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3410 m = bp->b_pages[i];
3411 if (n > size)
3412 n = size;
3413 vm_page_set_validclean(m, base & PAGE_MASK, n);
3414 base += n;
3415 size -= n;
3416 n = PAGE_SIZE;
3417 }
3418 vm_page_unlock_queues();
3419 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3420 }
3421
3422 /*
3423 * vfs_bio_clrbuf:
3424 *
3425 * clear a buffer. This routine essentially fakes an I/O, so we need
3426 * to clear BIO_ERROR and B_INVAL.
3427 *
3428 * Note that while we only theoretically need to clear through b_bcount,
3429 * we go ahead and clear through b_bufsize.
3430 */
3431
3432 void
3433 vfs_bio_clrbuf(struct buf *bp)
3434 {
3435 int i, j, mask = 0;
3436 caddr_t sa, ea;
3437
3438 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
3439 clrbuf(bp);
3440 return;
3441 }
3442
3443 bp->b_flags &= ~B_INVAL;
3444 bp->b_ioflags &= ~BIO_ERROR;
3445 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3446 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3447 (bp->b_offset & PAGE_MASK) == 0) {
3448 if (bp->b_pages[0] == bogus_page)
3449 goto unlock;
3450 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3451 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3452 if ((bp->b_pages[0]->valid & mask) == mask)
3453 goto unlock;
3454 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
3455 ((bp->b_pages[0]->valid & mask) == 0)) {
3456 bzero(bp->b_data, bp->b_bufsize);
3457 bp->b_pages[0]->valid |= mask;
3458 goto unlock;
3459 }
3460 }
3461 ea = sa = bp->b_data;
3462 for(i = 0; i < bp->b_npages; i++, sa = ea) {
3463 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3464 ea = (caddr_t)(vm_offset_t)ulmin(
3465 (u_long)(vm_offset_t)ea,
3466 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3467 if (bp->b_pages[i] == bogus_page)
3468 continue;
3469 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3470 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3471 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3472 if ((bp->b_pages[i]->valid & mask) == mask)
3473 continue;
3474 if ((bp->b_pages[i]->valid & mask) == 0) {
3475 if ((bp->b_pages[i]->flags & PG_ZERO) == 0)
3476 bzero(sa, ea - sa);
3477 } else {
3478 for (; sa < ea; sa += DEV_BSIZE, j++) {
3479 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
3480 (bp->b_pages[i]->valid & (1 << j)) == 0)
3481 bzero(sa, DEV_BSIZE);
3482 }
3483 }
3484 bp->b_pages[i]->valid |= mask;
3485 }
3486 unlock:
3487 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3488 bp->b_resid = 0;
3489 }
3490
3491 /*
3492 * vm_hold_load_pages and vm_hold_free_pages get pages into
3493 * a buffers address space. The pages are anonymous and are
3494 * not associated with a file object.
3495 */
3496 static void
3497 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3498 {
3499 vm_offset_t pg;
3500 vm_page_t p;
3501 int index;
3502
3503 to = round_page(to);
3504 from = round_page(from);
3505 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3506
3507 VM_OBJECT_LOCK(kernel_object);
3508 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3509 tryagain:
3510 /*
3511 * note: must allocate system pages since blocking here
3512 * could intefere with paging I/O, no matter which
3513 * process we are.
3514 */
3515 p = vm_page_alloc(kernel_object,
3516 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3517 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
3518 if (!p) {
3519 atomic_add_int(&vm_pageout_deficit,
3520 (to - pg) >> PAGE_SHIFT);
3521 VM_OBJECT_UNLOCK(kernel_object);
3522 VM_WAIT;
3523 VM_OBJECT_LOCK(kernel_object);
3524 goto tryagain;
3525 }
3526 p->valid = VM_PAGE_BITS_ALL;
3527 pmap_qenter(pg, &p, 1);
3528 bp->b_pages[index] = p;
3529 }
3530 VM_OBJECT_UNLOCK(kernel_object);
3531 bp->b_npages = index;
3532 }
3533
3534 /* Return pages associated with this buf to the vm system */
3535 static void
3536 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3537 {
3538 vm_offset_t pg;
3539 vm_page_t p;
3540 int index, newnpages;
3541
3542 from = round_page(from);
3543 to = round_page(to);
3544 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3545
3546 VM_OBJECT_LOCK(kernel_object);
3547 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3548 p = bp->b_pages[index];
3549 if (p && (index < bp->b_npages)) {
3550 if (p->busy) {
3551 printf(
3552 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3553 (intmax_t)bp->b_blkno,
3554 (intmax_t)bp->b_lblkno);
3555 }
3556 bp->b_pages[index] = NULL;
3557 pmap_qremove(pg, 1);
3558 vm_page_lock_queues();
3559 vm_page_unwire(p, 0);
3560 vm_page_free(p);
3561 vm_page_unlock_queues();
3562 }
3563 }
3564 VM_OBJECT_UNLOCK(kernel_object);
3565 bp->b_npages = newnpages;
3566 }
3567
3568 /*
3569 * Map an IO request into kernel virtual address space.
3570 *
3571 * All requests are (re)mapped into kernel VA space.
3572 * Notice that we use b_bufsize for the size of the buffer
3573 * to be mapped. b_bcount might be modified by the driver.
3574 *
3575 * Note that even if the caller determines that the address space should
3576 * be valid, a race or a smaller-file mapped into a larger space may
3577 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3578 * check the return value.
3579 */
3580 int
3581 vmapbuf(struct buf *bp)
3582 {
3583 caddr_t addr, kva;
3584 vm_prot_t prot;
3585 int pidx, i;
3586 struct vm_page *m;
3587 struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
3588
3589 if (bp->b_bufsize < 0)
3590 return (-1);
3591 prot = VM_PROT_READ;
3592 if (bp->b_iocmd == BIO_READ)
3593 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
3594 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
3595 addr < bp->b_data + bp->b_bufsize;
3596 addr += PAGE_SIZE, pidx++) {
3597 /*
3598 * Do the vm_fault if needed; do the copy-on-write thing
3599 * when reading stuff off device into memory.
3600 *
3601 * NOTE! Must use pmap_extract() because addr may be in
3602 * the userland address space, and kextract is only guarenteed
3603 * to work for the kernland address space (see: sparc64 port).
3604 */
3605 retry:
3606 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
3607 prot) < 0) {
3608 vm_page_lock_queues();
3609 for (i = 0; i < pidx; ++i) {
3610 vm_page_unhold(bp->b_pages[i]);
3611 bp->b_pages[i] = NULL;
3612 }
3613 vm_page_unlock_queues();
3614 return(-1);
3615 }
3616 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
3617 if (m == NULL)
3618 goto retry;
3619 bp->b_pages[pidx] = m;
3620 }
3621 if (pidx > btoc(MAXPHYS))
3622 panic("vmapbuf: mapped more than MAXPHYS");
3623 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3624
3625 kva = bp->b_saveaddr;
3626 bp->b_npages = pidx;
3627 bp->b_saveaddr = bp->b_data;
3628 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3629 return(0);
3630 }
3631
3632 /*
3633 * Free the io map PTEs associated with this IO operation.
3634 * We also invalidate the TLB entries and restore the original b_addr.
3635 */
3636 void
3637 vunmapbuf(struct buf *bp)
3638 {
3639 int pidx;
3640 int npages;
3641
3642 npages = bp->b_npages;
3643 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
3644 vm_page_lock_queues();
3645 for (pidx = 0; pidx < npages; pidx++)
3646 vm_page_unhold(bp->b_pages[pidx]);
3647 vm_page_unlock_queues();
3648
3649 bp->b_data = bp->b_saveaddr;
3650 }
3651
3652 void
3653 bdone(struct buf *bp)
3654 {
3655
3656 mtx_lock(&bdonelock);
3657 bp->b_flags |= B_DONE;
3658 wakeup(bp);
3659 mtx_unlock(&bdonelock);
3660 }
3661
3662 void
3663 bwait(struct buf *bp, u_char pri, const char *wchan)
3664 {
3665
3666 mtx_lock(&bdonelock);
3667 while ((bp->b_flags & B_DONE) == 0)
3668 msleep(bp, &bdonelock, pri, wchan, 0);
3669 mtx_unlock(&bdonelock);
3670 }
3671
3672 int
3673 bufsync(struct bufobj *bo, int waitfor, struct thread *td)
3674 {
3675
3676 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td));
3677 }
3678
3679 void
3680 bufstrategy(struct bufobj *bo, struct buf *bp)
3681 {
3682 int i = 0;
3683 struct vnode *vp;
3684
3685 vp = bp->b_vp;
3686 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
3687 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
3688 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
3689 i = VOP_STRATEGY(vp, bp);
3690 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
3691 }
3692
3693 void
3694 bufobj_wrefl(struct bufobj *bo)
3695 {
3696
3697 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3698 ASSERT_BO_LOCKED(bo);
3699 bo->bo_numoutput++;
3700 }
3701
3702 void
3703 bufobj_wref(struct bufobj *bo)
3704 {
3705
3706 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3707 BO_LOCK(bo);
3708 bo->bo_numoutput++;
3709 BO_UNLOCK(bo);
3710 }
3711
3712 void
3713 bufobj_wdrop(struct bufobj *bo)
3714 {
3715
3716 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
3717 BO_LOCK(bo);
3718 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
3719 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
3720 bo->bo_flag &= ~BO_WWAIT;
3721 wakeup(&bo->bo_numoutput);
3722 }
3723 BO_UNLOCK(bo);
3724 }
3725
3726 int
3727 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
3728 {
3729 int error;
3730
3731 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
3732 ASSERT_BO_LOCKED(bo);
3733 error = 0;
3734 while (bo->bo_numoutput) {
3735 bo->bo_flag |= BO_WWAIT;
3736 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
3737 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
3738 if (error)
3739 break;
3740 }
3741 return (error);
3742 }
3743
3744 #include "opt_ddb.h"
3745 #ifdef DDB
3746 #include <ddb/ddb.h>
3747
3748 /* DDB command to show buffer data */
3749 DB_SHOW_COMMAND(buffer, db_show_buffer)
3750 {
3751 /* get args */
3752 struct buf *bp = (struct buf *)addr;
3753
3754 if (!have_addr) {
3755 db_printf("usage: show buffer <addr>\n");
3756 return;
3757 }
3758
3759 db_printf("buf at %p\n", bp);
3760 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3761 db_printf(
3762 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
3763 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n",
3764 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3765 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno);
3766 db_printf("lockstatus = %d, excl count = %d, excl owner %p\n",
3767 lockstatus(&bp->b_lock, NULL), bp->b_lock.lk_exclusivecount,
3768 bp->b_lock.lk_lockholder);
3769 if (bp->b_npages) {
3770 int i;
3771 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
3772 for (i = 0; i < bp->b_npages; i++) {
3773 vm_page_t m;
3774 m = bp->b_pages[i];
3775 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3776 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3777 if ((i + 1) < bp->b_npages)
3778 db_printf(",");
3779 }
3780 db_printf("\n");
3781 }
3782 }
3783
3784 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
3785 {
3786 struct buf *bp;
3787 int i;
3788
3789 for (i = 0; i < nbuf; i++) {
3790 bp = &buf[i];
3791 if (lockcount(&bp->b_lock)) {
3792 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
3793 db_printf("\n");
3794 }
3795 }
3796 }
3797 #endif /* DDB */
Cache object: 8bb03c5d30b8f14be8a05e49b89e95de
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