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("$FreeBSD$");
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 .bop_bdflush = bufbdflush,
84 };
85
86 /*
87 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
88 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
89 */
90 struct buf *buf; /* buffer header pool */
91
92 static struct proc *bufdaemonproc;
93
94 static int inmem(struct vnode *vp, daddr_t blkno);
95 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from,
96 vm_offset_t to);
97 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
98 vm_offset_t to);
99 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
100 int pageno, vm_page_t m);
101 static void vfs_clean_pages(struct buf *bp);
102 static void vfs_setdirty(struct buf *bp);
103 static void vfs_vmio_release(struct buf *bp);
104 static int vfs_bio_clcheck(struct vnode *vp, int size,
105 daddr_t lblkno, daddr_t blkno);
106 static int flushbufqueues(int flushdeps);
107 static void buf_daemon(void);
108 static void bremfreel(struct buf *bp);
109
110 int vmiodirenable = TRUE;
111 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
112 "Use the VM system for directory writes");
113 int runningbufspace;
114 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
115 "Amount of presently outstanding async buffer io");
116 static int bufspace;
117 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
118 "KVA memory used for bufs");
119 static int maxbufspace;
120 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
121 "Maximum allowed value of bufspace (including buf_daemon)");
122 static int bufmallocspace;
123 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
124 "Amount of malloced memory for buffers");
125 static int maxbufmallocspace;
126 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
127 "Maximum amount of malloced memory for buffers");
128 static int lobufspace;
129 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
130 "Minimum amount of buffers we want to have");
131 int hibufspace;
132 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
133 "Maximum allowed value of bufspace (excluding buf_daemon)");
134 static int bufreusecnt;
135 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
136 "Number of times we have reused a buffer");
137 static int buffreekvacnt;
138 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
139 "Number of times we have freed the KVA space from some buffer");
140 static int bufdefragcnt;
141 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
142 "Number of times we have had to repeat buffer allocation to defragment");
143 static int lorunningspace;
144 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
145 "Minimum preferred space used for in-progress I/O");
146 static int hirunningspace;
147 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
148 "Maximum amount of space to use for in-progress I/O");
149 int dirtybufferflushes;
150 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
151 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
152 int bdwriteskip;
153 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
154 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
155 int altbufferflushes;
156 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
157 0, "Number of fsync flushes to limit dirty buffers");
158 static int recursiveflushes;
159 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
160 0, "Number of flushes skipped due to being recursive");
161 static int numdirtybuffers;
162 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
163 "Number of buffers that are dirty (has unwritten changes) at the moment");
164 static int lodirtybuffers;
165 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
166 "How many buffers we want to have free before bufdaemon can sleep");
167 static int hidirtybuffers;
168 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
169 "When the number of dirty buffers is considered severe");
170 int dirtybufthresh;
171 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
172 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
173 static int numfreebuffers;
174 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
175 "Number of free buffers");
176 static int lofreebuffers;
177 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
178 "XXX Unused");
179 static int hifreebuffers;
180 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
181 "XXX Complicatedly unused");
182 static int getnewbufcalls;
183 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
184 "Number of calls to getnewbuf");
185 static int getnewbufrestarts;
186 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
187 "Number of times getnewbuf has had to restart a buffer aquisition");
188
189 /*
190 * Wakeup point for bufdaemon, as well as indicator of whether it is already
191 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
192 * is idling.
193 */
194 static int bd_request;
195
196 /*
197 * This lock synchronizes access to bd_request.
198 */
199 static struct mtx bdlock;
200
201 /*
202 * bogus page -- for I/O to/from partially complete buffers
203 * this is a temporary solution to the problem, but it is not
204 * really that bad. it would be better to split the buffer
205 * for input in the case of buffers partially already in memory,
206 * but the code is intricate enough already.
207 */
208 vm_page_t bogus_page;
209
210 /*
211 * Synchronization (sleep/wakeup) variable for active buffer space requests.
212 * Set when wait starts, cleared prior to wakeup().
213 * Used in runningbufwakeup() and waitrunningbufspace().
214 */
215 static int runningbufreq;
216
217 /*
218 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
219 * waitrunningbufspace().
220 */
221 static struct mtx rbreqlock;
222
223 /*
224 * Synchronization (sleep/wakeup) variable for buffer requests.
225 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
226 * by and/or.
227 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
228 * getnewbuf(), and getblk().
229 */
230 static int needsbuffer;
231
232 /*
233 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
234 */
235 static struct mtx nblock;
236
237 /*
238 * Lock that protects against bwait()/bdone()/B_DONE races.
239 */
240
241 static struct mtx bdonelock;
242
243 /*
244 * Definitions for the buffer free lists.
245 */
246 #define BUFFER_QUEUES 5 /* number of free buffer queues */
247
248 #define QUEUE_NONE 0 /* on no queue */
249 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
250 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
251 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
252 #define QUEUE_EMPTY 4 /* empty buffer headers */
253
254 /* Queues for free buffers with various properties */
255 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
256
257 /* Lock for the bufqueues */
258 static struct mtx bqlock;
259
260 /*
261 * Single global constant for BUF_WMESG, to avoid getting multiple references.
262 * buf_wmesg is referred from macros.
263 */
264 const char *buf_wmesg = BUF_WMESG;
265
266 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
267 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
268 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
269 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
270
271 #ifdef DIRECTIO
272 extern void ffs_rawread_setup(void);
273 #endif /* DIRECTIO */
274 /*
275 * numdirtywakeup:
276 *
277 * If someone is blocked due to there being too many dirty buffers,
278 * and numdirtybuffers is now reasonable, wake them up.
279 */
280
281 static __inline void
282 numdirtywakeup(int level)
283 {
284
285 if (numdirtybuffers <= level) {
286 mtx_lock(&nblock);
287 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
288 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
289 wakeup(&needsbuffer);
290 }
291 mtx_unlock(&nblock);
292 }
293 }
294
295 /*
296 * bufspacewakeup:
297 *
298 * Called when buffer space is potentially available for recovery.
299 * getnewbuf() will block on this flag when it is unable to free
300 * sufficient buffer space. Buffer space becomes recoverable when
301 * bp's get placed back in the queues.
302 */
303
304 static __inline void
305 bufspacewakeup(void)
306 {
307
308 /*
309 * If someone is waiting for BUF space, wake them up. Even
310 * though we haven't freed the kva space yet, the waiting
311 * process will be able to now.
312 */
313 mtx_lock(&nblock);
314 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
315 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
316 wakeup(&needsbuffer);
317 }
318 mtx_unlock(&nblock);
319 }
320
321 /*
322 * runningbufwakeup() - in-progress I/O accounting.
323 *
324 */
325 void
326 runningbufwakeup(struct buf *bp)
327 {
328
329 if (bp->b_runningbufspace) {
330 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace);
331 bp->b_runningbufspace = 0;
332 mtx_lock(&rbreqlock);
333 if (runningbufreq && runningbufspace <= lorunningspace) {
334 runningbufreq = 0;
335 wakeup(&runningbufreq);
336 }
337 mtx_unlock(&rbreqlock);
338 }
339 }
340
341 /*
342 * bufcountwakeup:
343 *
344 * Called when a buffer has been added to one of the free queues to
345 * account for the buffer and to wakeup anyone waiting for free buffers.
346 * This typically occurs when large amounts of metadata are being handled
347 * by the buffer cache ( else buffer space runs out first, usually ).
348 */
349
350 static __inline void
351 bufcountwakeup(void)
352 {
353
354 atomic_add_int(&numfreebuffers, 1);
355 mtx_lock(&nblock);
356 if (needsbuffer) {
357 needsbuffer &= ~VFS_BIO_NEED_ANY;
358 if (numfreebuffers >= hifreebuffers)
359 needsbuffer &= ~VFS_BIO_NEED_FREE;
360 wakeup(&needsbuffer);
361 }
362 mtx_unlock(&nblock);
363 }
364
365 /*
366 * waitrunningbufspace()
367 *
368 * runningbufspace is a measure of the amount of I/O currently
369 * running. This routine is used in async-write situations to
370 * prevent creating huge backups of pending writes to a device.
371 * Only asynchronous writes are governed by this function.
372 *
373 * Reads will adjust runningbufspace, but will not block based on it.
374 * The read load has a side effect of reducing the allowed write load.
375 *
376 * This does NOT turn an async write into a sync write. It waits
377 * for earlier writes to complete and generally returns before the
378 * caller's write has reached the device.
379 */
380 void
381 waitrunningbufspace(void)
382 {
383
384 mtx_lock(&rbreqlock);
385 while (runningbufspace > hirunningspace) {
386 ++runningbufreq;
387 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
388 }
389 mtx_unlock(&rbreqlock);
390 }
391
392
393 /*
394 * vfs_buf_test_cache:
395 *
396 * Called when a buffer is extended. This function clears the B_CACHE
397 * bit if the newly extended portion of the buffer does not contain
398 * valid data.
399 */
400 static __inline
401 void
402 vfs_buf_test_cache(struct buf *bp,
403 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
404 vm_page_t m)
405 {
406
407 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
408 if (bp->b_flags & B_CACHE) {
409 int base = (foff + off) & PAGE_MASK;
410 if (vm_page_is_valid(m, base, size) == 0)
411 bp->b_flags &= ~B_CACHE;
412 }
413 }
414
415 /* Wake up the buffer deamon if necessary */
416 static __inline
417 void
418 bd_wakeup(int dirtybuflevel)
419 {
420
421 mtx_lock(&bdlock);
422 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
423 bd_request = 1;
424 wakeup(&bd_request);
425 }
426 mtx_unlock(&bdlock);
427 }
428
429 /*
430 * bd_speedup - speedup the buffer cache flushing code
431 */
432
433 static __inline
434 void
435 bd_speedup(void)
436 {
437
438 bd_wakeup(1);
439 }
440
441 /*
442 * Calculating buffer cache scaling values and reserve space for buffer
443 * headers. This is called during low level kernel initialization and
444 * may be called more then once. We CANNOT write to the memory area
445 * being reserved at this time.
446 */
447 caddr_t
448 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
449 {
450
451 /*
452 * physmem_est is in pages. Convert it to kilobytes (assumes
453 * PAGE_SIZE is >= 1K)
454 */
455 physmem_est = physmem_est * (PAGE_SIZE / 1024);
456
457 /*
458 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
459 * For the first 64MB of ram nominally allocate sufficient buffers to
460 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
461 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing
462 * the buffer cache we limit the eventual kva reservation to
463 * maxbcache bytes.
464 *
465 * factor represents the 1/4 x ram conversion.
466 */
467 if (nbuf == 0) {
468 int factor = 4 * BKVASIZE / 1024;
469
470 nbuf = 50;
471 if (physmem_est > 4096)
472 nbuf += min((physmem_est - 4096) / factor,
473 65536 / factor);
474 if (physmem_est > 65536)
475 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
476
477 if (maxbcache && nbuf > maxbcache / BKVASIZE)
478 nbuf = maxbcache / BKVASIZE;
479 }
480
481 #if 0
482 /*
483 * Do not allow the buffer_map to be more then 1/2 the size of the
484 * kernel_map.
485 */
486 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) /
487 (BKVASIZE * 2)) {
488 nbuf = (kernel_map->max_offset - kernel_map->min_offset) /
489 (BKVASIZE * 2);
490 printf("Warning: nbufs capped at %d\n", nbuf);
491 }
492 #endif
493
494 /*
495 * swbufs are used as temporary holders for I/O, such as paging I/O.
496 * We have no less then 16 and no more then 256.
497 */
498 nswbuf = max(min(nbuf/4, 256), 16);
499 #ifdef NSWBUF_MIN
500 if (nswbuf < NSWBUF_MIN)
501 nswbuf = NSWBUF_MIN;
502 #endif
503 #ifdef DIRECTIO
504 ffs_rawread_setup();
505 #endif
506
507 /*
508 * Reserve space for the buffer cache buffers
509 */
510 swbuf = (void *)v;
511 v = (caddr_t)(swbuf + nswbuf);
512 buf = (void *)v;
513 v = (caddr_t)(buf + nbuf);
514
515 return(v);
516 }
517
518 /* Initialize the buffer subsystem. Called before use of any buffers. */
519 void
520 bufinit(void)
521 {
522 struct buf *bp;
523 int i;
524
525 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
526 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
527 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
528 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
529 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF);
530
531 /* next, make a null set of free lists */
532 for (i = 0; i < BUFFER_QUEUES; i++)
533 TAILQ_INIT(&bufqueues[i]);
534
535 /* finally, initialize each buffer header and stick on empty q */
536 for (i = 0; i < nbuf; i++) {
537 bp = &buf[i];
538 bzero(bp, sizeof *bp);
539 bp->b_flags = B_INVAL; /* we're just an empty header */
540 bp->b_rcred = NOCRED;
541 bp->b_wcred = NOCRED;
542 bp->b_qindex = QUEUE_EMPTY;
543 bp->b_vflags = 0;
544 bp->b_xflags = 0;
545 LIST_INIT(&bp->b_dep);
546 BUF_LOCKINIT(bp);
547 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
548 }
549
550 /*
551 * maxbufspace is the absolute maximum amount of buffer space we are
552 * allowed to reserve in KVM and in real terms. The absolute maximum
553 * is nominally used by buf_daemon. hibufspace is the nominal maximum
554 * used by most other processes. The differential is required to
555 * ensure that buf_daemon is able to run when other processes might
556 * be blocked waiting for buffer space.
557 *
558 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
559 * this may result in KVM fragmentation which is not handled optimally
560 * by the system.
561 */
562 maxbufspace = nbuf * BKVASIZE;
563 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
564 lobufspace = hibufspace - MAXBSIZE;
565
566 lorunningspace = 512 * 1024;
567 hirunningspace = 1024 * 1024;
568
569 /*
570 * Limit the amount of malloc memory since it is wired permanently into
571 * the kernel space. Even though this is accounted for in the buffer
572 * allocation, we don't want the malloced region to grow uncontrolled.
573 * The malloc scheme improves memory utilization significantly on average
574 * (small) directories.
575 */
576 maxbufmallocspace = hibufspace / 20;
577
578 /*
579 * Reduce the chance of a deadlock occuring by limiting the number
580 * of delayed-write dirty buffers we allow to stack up.
581 */
582 hidirtybuffers = nbuf / 4 + 20;
583 dirtybufthresh = hidirtybuffers * 9 / 10;
584 numdirtybuffers = 0;
585 /*
586 * To support extreme low-memory systems, make sure hidirtybuffers cannot
587 * eat up all available buffer space. This occurs when our minimum cannot
588 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
589 * BKVASIZE'd (8K) buffers.
590 */
591 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
592 hidirtybuffers >>= 1;
593 }
594 lodirtybuffers = hidirtybuffers / 2;
595
596 /*
597 * Try to keep the number of free buffers in the specified range,
598 * and give special processes (e.g. like buf_daemon) access to an
599 * emergency reserve.
600 */
601 lofreebuffers = nbuf / 18 + 5;
602 hifreebuffers = 2 * lofreebuffers;
603 numfreebuffers = nbuf;
604
605 /*
606 * Maximum number of async ops initiated per buf_daemon loop. This is
607 * somewhat of a hack at the moment, we really need to limit ourselves
608 * based on the number of bytes of I/O in-transit that were initiated
609 * from buf_daemon.
610 */
611
612 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
613 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
614 }
615
616 /*
617 * bfreekva() - free the kva allocation for a buffer.
618 *
619 * Since this call frees up buffer space, we call bufspacewakeup().
620 */
621 static void
622 bfreekva(struct buf *bp)
623 {
624
625 if (bp->b_kvasize) {
626 atomic_add_int(&buffreekvacnt, 1);
627 atomic_subtract_int(&bufspace, bp->b_kvasize);
628 vm_map_lock(buffer_map);
629 vm_map_delete(buffer_map,
630 (vm_offset_t) bp->b_kvabase,
631 (vm_offset_t) bp->b_kvabase + bp->b_kvasize
632 );
633 vm_map_unlock(buffer_map);
634 bp->b_kvasize = 0;
635 bufspacewakeup();
636 }
637 }
638
639 /*
640 * bremfree:
641 *
642 * Mark the buffer for removal from the appropriate free list in brelse.
643 *
644 */
645 void
646 bremfree(struct buf *bp)
647 {
648
649 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
650 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked."));
651 KASSERT((bp->b_flags & B_REMFREE) == 0,
652 ("bremfree: buffer %p already marked for delayed removal.", bp));
653 KASSERT(bp->b_qindex != QUEUE_NONE,
654 ("bremfree: buffer %p not on a queue.", bp));
655
656 bp->b_flags |= B_REMFREE;
657 /* Fixup numfreebuffers count. */
658 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
659 atomic_subtract_int(&numfreebuffers, 1);
660 }
661
662 /*
663 * bremfreef:
664 *
665 * Force an immediate removal from a free list. Used only in nfs when
666 * it abuses the b_freelist pointer.
667 */
668 void
669 bremfreef(struct buf *bp)
670 {
671 mtx_lock(&bqlock);
672 bremfreel(bp);
673 mtx_unlock(&bqlock);
674 }
675
676 /*
677 * bremfreel:
678 *
679 * Removes a buffer from the free list, must be called with the
680 * bqlock held.
681 */
682 static void
683 bremfreel(struct buf *bp)
684 {
685 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
686 bp, bp->b_vp, bp->b_flags);
687 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp));
688 KASSERT(bp->b_qindex != QUEUE_NONE,
689 ("bremfreel: buffer %p not on a queue.", bp));
690 mtx_assert(&bqlock, MA_OWNED);
691
692 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
693 bp->b_qindex = QUEUE_NONE;
694 /*
695 * If this was a delayed bremfree() we only need to remove the buffer
696 * from the queue and return the stats are already done.
697 */
698 if (bp->b_flags & B_REMFREE) {
699 bp->b_flags &= ~B_REMFREE;
700 return;
701 }
702 /*
703 * Fixup numfreebuffers count. If the buffer is invalid or not
704 * delayed-write, the buffer was free and we must decrement
705 * numfreebuffers.
706 */
707 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
708 atomic_subtract_int(&numfreebuffers, 1);
709 }
710
711
712 /*
713 * Get a buffer with the specified data. Look in the cache first. We
714 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
715 * is set, the buffer is valid and we do not have to do anything ( see
716 * getblk() ). This is really just a special case of breadn().
717 */
718 int
719 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
720 struct buf **bpp)
721 {
722
723 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
724 }
725
726 /*
727 * Operates like bread, but also starts asynchronous I/O on
728 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior
729 * to initiating I/O . If B_CACHE is set, the buffer is valid
730 * and we do not have to do anything.
731 */
732 int
733 breadn(struct vnode * vp, daddr_t blkno, int size,
734 daddr_t * rablkno, int *rabsize,
735 int cnt, struct ucred * cred, struct buf **bpp)
736 {
737 struct buf *bp, *rabp;
738 int i;
739 int rv = 0, readwait = 0;
740
741 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
742 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
743
744 /* if not found in cache, do some I/O */
745 if ((bp->b_flags & B_CACHE) == 0) {
746 if (curthread != PCPU_GET(idlethread))
747 curthread->td_proc->p_stats->p_ru.ru_inblock++;
748 bp->b_iocmd = BIO_READ;
749 bp->b_flags &= ~B_INVAL;
750 bp->b_ioflags &= ~BIO_ERROR;
751 if (bp->b_rcred == NOCRED && cred != NOCRED)
752 bp->b_rcred = crhold(cred);
753 vfs_busy_pages(bp, 0);
754 bp->b_iooffset = dbtob(bp->b_blkno);
755 bstrategy(bp);
756 ++readwait;
757 }
758
759 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
760 if (inmem(vp, *rablkno))
761 continue;
762 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
763
764 if ((rabp->b_flags & B_CACHE) == 0) {
765 if (curthread != PCPU_GET(idlethread))
766 curthread->td_proc->p_stats->p_ru.ru_inblock++;
767 rabp->b_flags |= B_ASYNC;
768 rabp->b_flags &= ~B_INVAL;
769 rabp->b_ioflags &= ~BIO_ERROR;
770 rabp->b_iocmd = BIO_READ;
771 if (rabp->b_rcred == NOCRED && cred != NOCRED)
772 rabp->b_rcred = crhold(cred);
773 vfs_busy_pages(rabp, 0);
774 BUF_KERNPROC(rabp);
775 rabp->b_iooffset = dbtob(rabp->b_blkno);
776 bstrategy(rabp);
777 } else {
778 brelse(rabp);
779 }
780 }
781
782 if (readwait) {
783 rv = bufwait(bp);
784 }
785 return (rv);
786 }
787
788 /*
789 * Write, release buffer on completion. (Done by iodone
790 * if async). Do not bother writing anything if the buffer
791 * is invalid.
792 *
793 * Note that we set B_CACHE here, indicating that buffer is
794 * fully valid and thus cacheable. This is true even of NFS
795 * now so we set it generally. This could be set either here
796 * or in biodone() since the I/O is synchronous. We put it
797 * here.
798 */
799 int
800 bufwrite(struct buf *bp)
801 {
802 int oldflags;
803 struct vnode *vp;
804 int vp_md;
805
806 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
807 if (bp->b_flags & B_INVAL) {
808 brelse(bp);
809 return (0);
810 }
811
812 oldflags = bp->b_flags;
813
814 if (BUF_REFCNT(bp) == 0)
815 panic("bufwrite: buffer is not busy???");
816 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
817 ("FFS background buffer should not get here %p", bp));
818
819 vp = bp->b_vp;
820 if (vp)
821 vp_md = vp->v_vflag & VV_MD;
822 else
823 vp_md = 0;
824
825 /* Mark the buffer clean */
826 bundirty(bp);
827
828 bp->b_flags &= ~B_DONE;
829 bp->b_ioflags &= ~BIO_ERROR;
830 bp->b_flags |= B_CACHE;
831 bp->b_iocmd = BIO_WRITE;
832
833 bufobj_wref(bp->b_bufobj);
834 vfs_busy_pages(bp, 1);
835
836 /*
837 * Normal bwrites pipeline writes
838 */
839 bp->b_runningbufspace = bp->b_bufsize;
840 atomic_add_int(&runningbufspace, bp->b_runningbufspace);
841
842 if (curthread != PCPU_GET(idlethread))
843 curthread->td_proc->p_stats->p_ru.ru_oublock++;
844 if (oldflags & B_ASYNC)
845 BUF_KERNPROC(bp);
846 bp->b_iooffset = dbtob(bp->b_blkno);
847 bstrategy(bp);
848
849 if ((oldflags & B_ASYNC) == 0) {
850 int rtval = bufwait(bp);
851 brelse(bp);
852 return (rtval);
853 } else {
854 /*
855 * don't allow the async write to saturate the I/O
856 * system. We will not deadlock here because
857 * we are blocking waiting for I/O that is already in-progress
858 * to complete. We do not block here if it is the update
859 * or syncer daemon trying to clean up as that can lead
860 * to deadlock.
861 */
862 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
863 waitrunningbufspace();
864 }
865
866 return (0);
867 }
868
869 void
870 bufbdflush(struct bufobj *bo, struct buf *bp)
871 {
872 struct buf *nbp;
873
874 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
875 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
876 altbufferflushes++;
877 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
878 BO_LOCK(bo);
879 /*
880 * Try to find a buffer to flush.
881 */
882 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
883 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
884 BUF_LOCK(nbp,
885 LK_EXCLUSIVE | LK_NOWAIT, NULL))
886 continue;
887 if (bp == nbp)
888 panic("bdwrite: found ourselves");
889 BO_UNLOCK(bo);
890 /* Don't countdeps with the bo lock held. */
891 if (buf_countdeps(nbp, 0)) {
892 BO_LOCK(bo);
893 BUF_UNLOCK(nbp);
894 continue;
895 }
896 if (nbp->b_flags & B_CLUSTEROK) {
897 vfs_bio_awrite(nbp);
898 } else {
899 bremfree(nbp);
900 bawrite(nbp);
901 }
902 dirtybufferflushes++;
903 break;
904 }
905 if (nbp == NULL)
906 BO_UNLOCK(bo);
907 }
908 }
909
910 /*
911 * Delayed write. (Buffer is marked dirty). Do not bother writing
912 * anything if the buffer is marked invalid.
913 *
914 * Note that since the buffer must be completely valid, we can safely
915 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
916 * biodone() in order to prevent getblk from writing the buffer
917 * out synchronously.
918 */
919 void
920 bdwrite(struct buf *bp)
921 {
922 struct thread *td = curthread;
923 struct vnode *vp;
924 struct bufobj *bo;
925
926 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
927 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
928 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy"));
929
930 if (bp->b_flags & B_INVAL) {
931 brelse(bp);
932 return;
933 }
934
935 /*
936 * If we have too many dirty buffers, don't create any more.
937 * If we are wildly over our limit, then force a complete
938 * cleanup. Otherwise, just keep the situation from getting
939 * out of control. Note that we have to avoid a recursive
940 * disaster and not try to clean up after our own cleanup!
941 */
942 vp = bp->b_vp;
943 bo = bp->b_bufobj;
944 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
945 td->td_pflags |= TDP_INBDFLUSH;
946 BO_BDFLUSH(bo, bp);
947 td->td_pflags &= ~TDP_INBDFLUSH;
948 } else
949 recursiveflushes++;
950
951 bdirty(bp);
952 /*
953 * Set B_CACHE, indicating that the buffer is fully valid. This is
954 * true even of NFS now.
955 */
956 bp->b_flags |= B_CACHE;
957
958 /*
959 * This bmap keeps the system from needing to do the bmap later,
960 * perhaps when the system is attempting to do a sync. Since it
961 * is likely that the indirect block -- or whatever other datastructure
962 * that the filesystem needs is still in memory now, it is a good
963 * thing to do this. Note also, that if the pageout daemon is
964 * requesting a sync -- there might not be enough memory to do
965 * the bmap then... So, this is important to do.
966 */
967 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
968 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
969 }
970
971 /*
972 * Set the *dirty* buffer range based upon the VM system dirty pages.
973 */
974 vfs_setdirty(bp);
975
976 /*
977 * We need to do this here to satisfy the vnode_pager and the
978 * pageout daemon, so that it thinks that the pages have been
979 * "cleaned". Note that since the pages are in a delayed write
980 * buffer -- the VFS layer "will" see that the pages get written
981 * out on the next sync, or perhaps the cluster will be completed.
982 */
983 vfs_clean_pages(bp);
984 bqrelse(bp);
985
986 /*
987 * Wakeup the buffer flushing daemon if we have a lot of dirty
988 * buffers (midpoint between our recovery point and our stall
989 * point).
990 */
991 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
992
993 /*
994 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
995 * due to the softdep code.
996 */
997 }
998
999 /*
1000 * bdirty:
1001 *
1002 * Turn buffer into delayed write request. We must clear BIO_READ and
1003 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1004 * itself to properly update it in the dirty/clean lists. We mark it
1005 * B_DONE to ensure that any asynchronization of the buffer properly
1006 * clears B_DONE ( else a panic will occur later ).
1007 *
1008 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1009 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1010 * should only be called if the buffer is known-good.
1011 *
1012 * Since the buffer is not on a queue, we do not update the numfreebuffers
1013 * count.
1014 *
1015 * The buffer must be on QUEUE_NONE.
1016 */
1017 void
1018 bdirty(struct buf *bp)
1019 {
1020
1021 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1022 bp, bp->b_vp, bp->b_flags);
1023 KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp));
1024 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1025 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1026 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1027 bp->b_flags &= ~(B_RELBUF);
1028 bp->b_iocmd = BIO_WRITE;
1029
1030 if ((bp->b_flags & B_DELWRI) == 0) {
1031 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1032 reassignbuf(bp);
1033 atomic_add_int(&numdirtybuffers, 1);
1034 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1035 }
1036 }
1037
1038 /*
1039 * bundirty:
1040 *
1041 * Clear B_DELWRI for buffer.
1042 *
1043 * Since the buffer is not on a queue, we do not update the numfreebuffers
1044 * count.
1045 *
1046 * The buffer must be on QUEUE_NONE.
1047 */
1048
1049 void
1050 bundirty(struct buf *bp)
1051 {
1052
1053 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1054 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1055 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1056 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1057 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp));
1058
1059 if (bp->b_flags & B_DELWRI) {
1060 bp->b_flags &= ~B_DELWRI;
1061 reassignbuf(bp);
1062 atomic_subtract_int(&numdirtybuffers, 1);
1063 numdirtywakeup(lodirtybuffers);
1064 }
1065 /*
1066 * Since it is now being written, we can clear its deferred write flag.
1067 */
1068 bp->b_flags &= ~B_DEFERRED;
1069 }
1070
1071 /*
1072 * bawrite:
1073 *
1074 * Asynchronous write. Start output on a buffer, but do not wait for
1075 * it to complete. The buffer is released when the output completes.
1076 *
1077 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1078 * B_INVAL buffers. Not us.
1079 */
1080 void
1081 bawrite(struct buf *bp)
1082 {
1083
1084 bp->b_flags |= B_ASYNC;
1085 (void) bwrite(bp);
1086 }
1087
1088 /*
1089 * bwillwrite:
1090 *
1091 * Called prior to the locking of any vnodes when we are expecting to
1092 * write. We do not want to starve the buffer cache with too many
1093 * dirty buffers so we block here. By blocking prior to the locking
1094 * of any vnodes we attempt to avoid the situation where a locked vnode
1095 * prevents the various system daemons from flushing related buffers.
1096 */
1097
1098 void
1099 bwillwrite(void)
1100 {
1101
1102 if (numdirtybuffers >= hidirtybuffers) {
1103 mtx_lock(&nblock);
1104 while (numdirtybuffers >= hidirtybuffers) {
1105 bd_wakeup(1);
1106 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1107 msleep(&needsbuffer, &nblock,
1108 (PRIBIO + 4), "flswai", 0);
1109 }
1110 mtx_unlock(&nblock);
1111 }
1112 }
1113
1114 /*
1115 * Return true if we have too many dirty buffers.
1116 */
1117 int
1118 buf_dirty_count_severe(void)
1119 {
1120
1121 return(numdirtybuffers >= hidirtybuffers);
1122 }
1123
1124 /*
1125 * brelse:
1126 *
1127 * Release a busy buffer and, if requested, free its resources. The
1128 * buffer will be stashed in the appropriate bufqueue[] allowing it
1129 * to be accessed later as a cache entity or reused for other purposes.
1130 */
1131 void
1132 brelse(struct buf *bp)
1133 {
1134 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1135 bp, bp->b_vp, bp->b_flags);
1136 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1137 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1138
1139 if (bp->b_iocmd == BIO_WRITE &&
1140 (bp->b_ioflags & BIO_ERROR) &&
1141 !(bp->b_flags & B_INVAL)) {
1142 /*
1143 * Failed write, redirty. Must clear BIO_ERROR to prevent
1144 * pages from being scrapped. If B_INVAL is set then
1145 * this case is not run and the next case is run to
1146 * destroy the buffer. B_INVAL can occur if the buffer
1147 * is outside the range supported by the underlying device.
1148 */
1149 bp->b_ioflags &= ~BIO_ERROR;
1150 bdirty(bp);
1151 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1152 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1153 /*
1154 * Either a failed I/O or we were asked to free or not
1155 * cache the buffer.
1156 */
1157 bp->b_flags |= B_INVAL;
1158 if (LIST_FIRST(&bp->b_dep) != NULL)
1159 buf_deallocate(bp);
1160 if (bp->b_flags & B_DELWRI) {
1161 atomic_subtract_int(&numdirtybuffers, 1);
1162 numdirtywakeup(lodirtybuffers);
1163 }
1164 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1165 if ((bp->b_flags & B_VMIO) == 0) {
1166 if (bp->b_bufsize)
1167 allocbuf(bp, 0);
1168 if (bp->b_vp)
1169 brelvp(bp);
1170 }
1171 }
1172
1173 /*
1174 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1175 * is called with B_DELWRI set, the underlying pages may wind up
1176 * getting freed causing a previous write (bdwrite()) to get 'lost'
1177 * because pages associated with a B_DELWRI bp are marked clean.
1178 *
1179 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1180 * if B_DELWRI is set.
1181 *
1182 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1183 * on pages to return pages to the VM page queues.
1184 */
1185 if (bp->b_flags & B_DELWRI)
1186 bp->b_flags &= ~B_RELBUF;
1187 else if (vm_page_count_severe()) {
1188 /*
1189 * XXX This lock may not be necessary since BKGRDINPROG
1190 * cannot be set while we hold the buf lock, it can only be
1191 * cleared if it is already pending.
1192 */
1193 if (bp->b_vp) {
1194 BO_LOCK(bp->b_bufobj);
1195 if (!(bp->b_vflags & BV_BKGRDINPROG))
1196 bp->b_flags |= B_RELBUF;
1197 BO_UNLOCK(bp->b_bufobj);
1198 } else
1199 bp->b_flags |= B_RELBUF;
1200 }
1201
1202 /*
1203 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1204 * constituted, not even NFS buffers now. Two flags effect this. If
1205 * B_INVAL, the struct buf is invalidated but the VM object is kept
1206 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1207 *
1208 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1209 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1210 * buffer is also B_INVAL because it hits the re-dirtying code above.
1211 *
1212 * Normally we can do this whether a buffer is B_DELWRI or not. If
1213 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1214 * the commit state and we cannot afford to lose the buffer. If the
1215 * buffer has a background write in progress, we need to keep it
1216 * around to prevent it from being reconstituted and starting a second
1217 * background write.
1218 */
1219 if ((bp->b_flags & B_VMIO)
1220 && !(bp->b_vp->v_mount != NULL &&
1221 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1222 !vn_isdisk(bp->b_vp, NULL) &&
1223 (bp->b_flags & B_DELWRI))
1224 ) {
1225
1226 int i, j, resid;
1227 vm_page_t m;
1228 off_t foff;
1229 vm_pindex_t poff;
1230 vm_object_t obj;
1231
1232 obj = bp->b_bufobj->bo_object;
1233
1234 /*
1235 * Get the base offset and length of the buffer. Note that
1236 * in the VMIO case if the buffer block size is not
1237 * page-aligned then b_data pointer may not be page-aligned.
1238 * But our b_pages[] array *IS* page aligned.
1239 *
1240 * block sizes less then DEV_BSIZE (usually 512) are not
1241 * supported due to the page granularity bits (m->valid,
1242 * m->dirty, etc...).
1243 *
1244 * See man buf(9) for more information
1245 */
1246 resid = bp->b_bufsize;
1247 foff = bp->b_offset;
1248 VM_OBJECT_LOCK(obj);
1249 for (i = 0; i < bp->b_npages; i++) {
1250 int had_bogus = 0;
1251
1252 m = bp->b_pages[i];
1253
1254 /*
1255 * If we hit a bogus page, fixup *all* the bogus pages
1256 * now.
1257 */
1258 if (m == bogus_page) {
1259 poff = OFF_TO_IDX(bp->b_offset);
1260 had_bogus = 1;
1261
1262 for (j = i; j < bp->b_npages; j++) {
1263 vm_page_t mtmp;
1264 mtmp = bp->b_pages[j];
1265 if (mtmp == bogus_page) {
1266 mtmp = vm_page_lookup(obj, poff + j);
1267 if (!mtmp) {
1268 panic("brelse: page missing\n");
1269 }
1270 bp->b_pages[j] = mtmp;
1271 }
1272 }
1273
1274 if ((bp->b_flags & B_INVAL) == 0) {
1275 pmap_qenter(
1276 trunc_page((vm_offset_t)bp->b_data),
1277 bp->b_pages, bp->b_npages);
1278 }
1279 m = bp->b_pages[i];
1280 }
1281 if ((bp->b_flags & B_NOCACHE) ||
1282 (bp->b_ioflags & BIO_ERROR)) {
1283 int poffset = foff & PAGE_MASK;
1284 int presid = resid > (PAGE_SIZE - poffset) ?
1285 (PAGE_SIZE - poffset) : resid;
1286
1287 KASSERT(presid >= 0, ("brelse: extra page"));
1288 vm_page_lock_queues();
1289 vm_page_set_invalid(m, poffset, presid);
1290 vm_page_unlock_queues();
1291 if (had_bogus)
1292 printf("avoided corruption bug in bogus_page/brelse code\n");
1293 }
1294 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1295 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1296 }
1297 VM_OBJECT_UNLOCK(obj);
1298 if (bp->b_flags & (B_INVAL | B_RELBUF))
1299 vfs_vmio_release(bp);
1300
1301 } else if (bp->b_flags & B_VMIO) {
1302
1303 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1304 vfs_vmio_release(bp);
1305 }
1306
1307 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1308 if (bp->b_bufsize != 0)
1309 allocbuf(bp, 0);
1310 if (bp->b_vp != NULL)
1311 brelvp(bp);
1312 }
1313
1314 if (BUF_REFCNT(bp) > 1) {
1315 /* do not release to free list */
1316 BUF_UNLOCK(bp);
1317 return;
1318 }
1319
1320 /* enqueue */
1321 mtx_lock(&bqlock);
1322 /* Handle delayed bremfree() processing. */
1323 if (bp->b_flags & B_REMFREE)
1324 bremfreel(bp);
1325 if (bp->b_qindex != QUEUE_NONE)
1326 panic("brelse: free buffer onto another queue???");
1327
1328 /* buffers with no memory */
1329 if (bp->b_bufsize == 0) {
1330 bp->b_flags |= B_INVAL;
1331 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1332 if (bp->b_vflags & BV_BKGRDINPROG)
1333 panic("losing buffer 1");
1334 if (bp->b_kvasize) {
1335 bp->b_qindex = QUEUE_EMPTYKVA;
1336 } else {
1337 bp->b_qindex = QUEUE_EMPTY;
1338 }
1339 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1340 /* buffers with junk contents */
1341 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1342 (bp->b_ioflags & BIO_ERROR)) {
1343 bp->b_flags |= B_INVAL;
1344 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1345 if (bp->b_vflags & BV_BKGRDINPROG)
1346 panic("losing buffer 2");
1347 bp->b_qindex = QUEUE_CLEAN;
1348 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1349 /* remaining buffers */
1350 } else {
1351 if (bp->b_flags & B_DELWRI)
1352 bp->b_qindex = QUEUE_DIRTY;
1353 else
1354 bp->b_qindex = QUEUE_CLEAN;
1355 if (bp->b_flags & B_AGE)
1356 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1357 else
1358 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1359 }
1360 mtx_unlock(&bqlock);
1361
1362 /*
1363 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already
1364 * placed the buffer on the correct queue. We must also disassociate
1365 * the device and vnode for a B_INVAL buffer so gbincore() doesn't
1366 * find it.
1367 */
1368 if (bp->b_flags & B_INVAL) {
1369 if (bp->b_flags & B_DELWRI)
1370 bundirty(bp);
1371 if (bp->b_vp)
1372 brelvp(bp);
1373 }
1374
1375 /*
1376 * Fixup numfreebuffers count. The bp is on an appropriate queue
1377 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1378 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1379 * if B_INVAL is set ).
1380 */
1381
1382 if (!(bp->b_flags & B_DELWRI))
1383 bufcountwakeup();
1384
1385 /*
1386 * Something we can maybe free or reuse
1387 */
1388 if (bp->b_bufsize || bp->b_kvasize)
1389 bufspacewakeup();
1390
1391 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1392 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1393 panic("brelse: not dirty");
1394 /* unlock */
1395 BUF_UNLOCK(bp);
1396 }
1397
1398 /*
1399 * Release a buffer back to the appropriate queue but do not try to free
1400 * it. The buffer is expected to be used again soon.
1401 *
1402 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1403 * biodone() to requeue an async I/O on completion. It is also used when
1404 * known good buffers need to be requeued but we think we may need the data
1405 * again soon.
1406 *
1407 * XXX we should be able to leave the B_RELBUF hint set on completion.
1408 */
1409 void
1410 bqrelse(struct buf *bp)
1411 {
1412 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1413 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1414 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1415
1416 if (BUF_REFCNT(bp) > 1) {
1417 /* do not release to free list */
1418 BUF_UNLOCK(bp);
1419 return;
1420 }
1421 mtx_lock(&bqlock);
1422 /* Handle delayed bremfree() processing. */
1423 if (bp->b_flags & B_REMFREE)
1424 bremfreel(bp);
1425 if (bp->b_qindex != QUEUE_NONE)
1426 panic("bqrelse: free buffer onto another queue???");
1427 /* buffers with stale but valid contents */
1428 if (bp->b_flags & B_DELWRI) {
1429 bp->b_qindex = QUEUE_DIRTY;
1430 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1431 } else {
1432 /*
1433 * XXX This lock may not be necessary since BKGRDINPROG
1434 * cannot be set while we hold the buf lock, it can only be
1435 * cleared if it is already pending.
1436 */
1437 BO_LOCK(bp->b_bufobj);
1438 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) {
1439 BO_UNLOCK(bp->b_bufobj);
1440 bp->b_qindex = QUEUE_CLEAN;
1441 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1442 b_freelist);
1443 } else {
1444 /*
1445 * We are too low on memory, we have to try to free
1446 * the buffer (most importantly: the wired pages
1447 * making up its backing store) *now*.
1448 */
1449 BO_UNLOCK(bp->b_bufobj);
1450 mtx_unlock(&bqlock);
1451 brelse(bp);
1452 return;
1453 }
1454 }
1455 mtx_unlock(&bqlock);
1456
1457 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
1458 bufcountwakeup();
1459
1460 /*
1461 * Something we can maybe free or reuse.
1462 */
1463 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1464 bufspacewakeup();
1465
1466 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1467 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1468 panic("bqrelse: not dirty");
1469 /* unlock */
1470 BUF_UNLOCK(bp);
1471 }
1472
1473 /* Give pages used by the bp back to the VM system (where possible) */
1474 static void
1475 vfs_vmio_release(struct buf *bp)
1476 {
1477 int i;
1478 vm_page_t m;
1479
1480 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
1481 vm_page_lock_queues();
1482 for (i = 0; i < bp->b_npages; i++) {
1483 m = bp->b_pages[i];
1484 bp->b_pages[i] = NULL;
1485 /*
1486 * In order to keep page LRU ordering consistent, put
1487 * everything on the inactive queue.
1488 */
1489 vm_page_unwire(m, 0);
1490 /*
1491 * We don't mess with busy pages, it is
1492 * the responsibility of the process that
1493 * busied the pages to deal with them.
1494 */
1495 if ((m->flags & PG_BUSY) || (m->busy != 0))
1496 continue;
1497
1498 if (m->wire_count == 0) {
1499 /*
1500 * Might as well free the page if we can and it has
1501 * no valid data. We also free the page if the
1502 * buffer was used for direct I/O
1503 */
1504 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1505 m->hold_count == 0) {
1506 pmap_remove_all(m);
1507 vm_page_free(m);
1508 } else if (bp->b_flags & B_DIRECT) {
1509 vm_page_try_to_free(m);
1510 } else if (vm_page_count_severe()) {
1511 vm_page_try_to_cache(m);
1512 }
1513 }
1514 }
1515 vm_page_unlock_queues();
1516 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
1517 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
1518
1519 if (bp->b_bufsize) {
1520 bufspacewakeup();
1521 bp->b_bufsize = 0;
1522 }
1523 bp->b_npages = 0;
1524 bp->b_flags &= ~B_VMIO;
1525 if (bp->b_vp)
1526 brelvp(bp);
1527 }
1528
1529 /*
1530 * Check to see if a block at a particular lbn is available for a clustered
1531 * write.
1532 */
1533 static int
1534 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1535 {
1536 struct buf *bpa;
1537 int match;
1538
1539 match = 0;
1540
1541 /* If the buf isn't in core skip it */
1542 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1543 return (0);
1544
1545 /* If the buf is busy we don't want to wait for it */
1546 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1547 return (0);
1548
1549 /* Only cluster with valid clusterable delayed write buffers */
1550 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1551 (B_DELWRI | B_CLUSTEROK))
1552 goto done;
1553
1554 if (bpa->b_bufsize != size)
1555 goto done;
1556
1557 /*
1558 * Check to see if it is in the expected place on disk and that the
1559 * block has been mapped.
1560 */
1561 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1562 match = 1;
1563 done:
1564 BUF_UNLOCK(bpa);
1565 return (match);
1566 }
1567
1568 /*
1569 * vfs_bio_awrite:
1570 *
1571 * Implement clustered async writes for clearing out B_DELWRI buffers.
1572 * This is much better then the old way of writing only one buffer at
1573 * a time. Note that we may not be presented with the buffers in the
1574 * correct order, so we search for the cluster in both directions.
1575 */
1576 int
1577 vfs_bio_awrite(struct buf *bp)
1578 {
1579 int i;
1580 int j;
1581 daddr_t lblkno = bp->b_lblkno;
1582 struct vnode *vp = bp->b_vp;
1583 int ncl;
1584 int nwritten;
1585 int size;
1586 int maxcl;
1587
1588 /*
1589 * right now we support clustered writing only to regular files. If
1590 * we find a clusterable block we could be in the middle of a cluster
1591 * rather then at the beginning.
1592 */
1593 if ((vp->v_type == VREG) &&
1594 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1595 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1596
1597 size = vp->v_mount->mnt_stat.f_iosize;
1598 maxcl = MAXPHYS / size;
1599
1600 VI_LOCK(vp);
1601 for (i = 1; i < maxcl; i++)
1602 if (vfs_bio_clcheck(vp, size, lblkno + i,
1603 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1604 break;
1605
1606 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1607 if (vfs_bio_clcheck(vp, size, lblkno - j,
1608 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1609 break;
1610
1611 VI_UNLOCK(vp);
1612 --j;
1613 ncl = i + j;
1614 /*
1615 * this is a possible cluster write
1616 */
1617 if (ncl != 1) {
1618 BUF_UNLOCK(bp);
1619 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1620 return nwritten;
1621 }
1622 }
1623 bremfree(bp);
1624 bp->b_flags |= B_ASYNC;
1625 /*
1626 * default (old) behavior, writing out only one block
1627 *
1628 * XXX returns b_bufsize instead of b_bcount for nwritten?
1629 */
1630 nwritten = bp->b_bufsize;
1631 (void) bwrite(bp);
1632
1633 return nwritten;
1634 }
1635
1636 /*
1637 * getnewbuf:
1638 *
1639 * Find and initialize a new buffer header, freeing up existing buffers
1640 * in the bufqueues as necessary. The new buffer is returned locked.
1641 *
1642 * Important: B_INVAL is not set. If the caller wishes to throw the
1643 * buffer away, the caller must set B_INVAL prior to calling brelse().
1644 *
1645 * We block if:
1646 * We have insufficient buffer headers
1647 * We have insufficient buffer space
1648 * buffer_map is too fragmented ( space reservation fails )
1649 * If we have to flush dirty buffers ( but we try to avoid this )
1650 *
1651 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1652 * Instead we ask the buf daemon to do it for us. We attempt to
1653 * avoid piecemeal wakeups of the pageout daemon.
1654 */
1655
1656 static struct buf *
1657 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1658 {
1659 struct buf *bp;
1660 struct buf *nbp;
1661 int defrag = 0;
1662 int nqindex;
1663 static int flushingbufs;
1664
1665 /*
1666 * We can't afford to block since we might be holding a vnode lock,
1667 * which may prevent system daemons from running. We deal with
1668 * low-memory situations by proactively returning memory and running
1669 * async I/O rather then sync I/O.
1670 */
1671
1672 atomic_add_int(&getnewbufcalls, 1);
1673 atomic_subtract_int(&getnewbufrestarts, 1);
1674 restart:
1675 atomic_add_int(&getnewbufrestarts, 1);
1676
1677 /*
1678 * Setup for scan. If we do not have enough free buffers,
1679 * we setup a degenerate case that immediately fails. Note
1680 * that if we are specially marked process, we are allowed to
1681 * dip into our reserves.
1682 *
1683 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1684 *
1685 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1686 * However, there are a number of cases (defragging, reusing, ...)
1687 * where we cannot backup.
1688 */
1689 mtx_lock(&bqlock);
1690 nqindex = QUEUE_EMPTYKVA;
1691 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1692
1693 if (nbp == NULL) {
1694 /*
1695 * If no EMPTYKVA buffers and we are either
1696 * defragging or reusing, locate a CLEAN buffer
1697 * to free or reuse. If bufspace useage is low
1698 * skip this step so we can allocate a new buffer.
1699 */
1700 if (defrag || bufspace >= lobufspace) {
1701 nqindex = QUEUE_CLEAN;
1702 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1703 }
1704
1705 /*
1706 * If we could not find or were not allowed to reuse a
1707 * CLEAN buffer, check to see if it is ok to use an EMPTY
1708 * buffer. We can only use an EMPTY buffer if allocating
1709 * its KVA would not otherwise run us out of buffer space.
1710 */
1711 if (nbp == NULL && defrag == 0 &&
1712 bufspace + maxsize < hibufspace) {
1713 nqindex = QUEUE_EMPTY;
1714 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1715 }
1716 }
1717
1718 /*
1719 * Run scan, possibly freeing data and/or kva mappings on the fly
1720 * depending.
1721 */
1722
1723 while ((bp = nbp) != NULL) {
1724 int qindex = nqindex;
1725
1726 /*
1727 * Calculate next bp ( we can only use it if we do not block
1728 * or do other fancy things ).
1729 */
1730 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1731 switch(qindex) {
1732 case QUEUE_EMPTY:
1733 nqindex = QUEUE_EMPTYKVA;
1734 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1735 break;
1736 /* FALLTHROUGH */
1737 case QUEUE_EMPTYKVA:
1738 nqindex = QUEUE_CLEAN;
1739 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1740 break;
1741 /* FALLTHROUGH */
1742 case QUEUE_CLEAN:
1743 /*
1744 * nbp is NULL.
1745 */
1746 break;
1747 }
1748 }
1749 /*
1750 * If we are defragging then we need a buffer with
1751 * b_kvasize != 0. XXX this situation should no longer
1752 * occur, if defrag is non-zero the buffer's b_kvasize
1753 * should also be non-zero at this point. XXX
1754 */
1755 if (defrag && bp->b_kvasize == 0) {
1756 printf("Warning: defrag empty buffer %p\n", bp);
1757 continue;
1758 }
1759
1760 /*
1761 * Start freeing the bp. This is somewhat involved. nbp
1762 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1763 */
1764 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1765 continue;
1766 if (bp->b_vp) {
1767 BO_LOCK(bp->b_bufobj);
1768 if (bp->b_vflags & BV_BKGRDINPROG) {
1769 BO_UNLOCK(bp->b_bufobj);
1770 BUF_UNLOCK(bp);
1771 continue;
1772 }
1773 BO_UNLOCK(bp->b_bufobj);
1774 }
1775 CTR6(KTR_BUF,
1776 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
1777 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
1778 bp->b_kvasize, bp->b_bufsize, qindex);
1779
1780 /*
1781 * Sanity Checks
1782 */
1783 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1784
1785 /*
1786 * Note: we no longer distinguish between VMIO and non-VMIO
1787 * buffers.
1788 */
1789
1790 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1791
1792 bremfreel(bp);
1793 mtx_unlock(&bqlock);
1794
1795 if (qindex == QUEUE_CLEAN) {
1796 if (bp->b_flags & B_VMIO) {
1797 bp->b_flags &= ~B_ASYNC;
1798 vfs_vmio_release(bp);
1799 }
1800 if (bp->b_vp)
1801 brelvp(bp);
1802 }
1803
1804 /*
1805 * NOTE: nbp is now entirely invalid. We can only restart
1806 * the scan from this point on.
1807 *
1808 * Get the rest of the buffer freed up. b_kva* is still
1809 * valid after this operation.
1810 */
1811
1812 if (bp->b_rcred != NOCRED) {
1813 crfree(bp->b_rcred);
1814 bp->b_rcred = NOCRED;
1815 }
1816 if (bp->b_wcred != NOCRED) {
1817 crfree(bp->b_wcred);
1818 bp->b_wcred = NOCRED;
1819 }
1820 if (LIST_FIRST(&bp->b_dep) != NULL)
1821 buf_deallocate(bp);
1822 if (bp->b_vflags & BV_BKGRDINPROG)
1823 panic("losing buffer 3");
1824 KASSERT(bp->b_vp == NULL,
1825 ("bp: %p still has vnode %p. qindex: %d",
1826 bp, bp->b_vp, qindex));
1827 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1828 ("bp: %p still on a buffer list. xflags %X",
1829 bp, bp->b_xflags));
1830
1831 if (bp->b_bufsize)
1832 allocbuf(bp, 0);
1833
1834 bp->b_flags = 0;
1835 bp->b_ioflags = 0;
1836 bp->b_xflags = 0;
1837 bp->b_vflags = 0;
1838 bp->b_vp = NULL;
1839 bp->b_blkno = bp->b_lblkno = 0;
1840 bp->b_offset = NOOFFSET;
1841 bp->b_iodone = 0;
1842 bp->b_error = 0;
1843 bp->b_resid = 0;
1844 bp->b_bcount = 0;
1845 bp->b_npages = 0;
1846 bp->b_dirtyoff = bp->b_dirtyend = 0;
1847 bp->b_bufobj = NULL;
1848
1849 LIST_INIT(&bp->b_dep);
1850
1851 /*
1852 * If we are defragging then free the buffer.
1853 */
1854 if (defrag) {
1855 bp->b_flags |= B_INVAL;
1856 bfreekva(bp);
1857 brelse(bp);
1858 defrag = 0;
1859 goto restart;
1860 }
1861
1862 /*
1863 * Notify any waiters for the buffer lock about
1864 * identity change by freeing the buffer.
1865 */
1866 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) {
1867 bp->b_flags |= B_INVAL;
1868 bfreekva(bp);
1869 brelse(bp);
1870 goto restart;
1871 }
1872
1873 /*
1874 * If we are overcomitted then recover the buffer and its
1875 * KVM space. This occurs in rare situations when multiple
1876 * processes are blocked in getnewbuf() or allocbuf().
1877 */
1878 if (bufspace >= hibufspace)
1879 flushingbufs = 1;
1880 if (flushingbufs && bp->b_kvasize != 0) {
1881 bp->b_flags |= B_INVAL;
1882 bfreekva(bp);
1883 brelse(bp);
1884 goto restart;
1885 }
1886 if (bufspace < lobufspace)
1887 flushingbufs = 0;
1888 break;
1889 }
1890
1891 /*
1892 * If we exhausted our list, sleep as appropriate. We may have to
1893 * wakeup various daemons and write out some dirty buffers.
1894 *
1895 * Generally we are sleeping due to insufficient buffer space.
1896 */
1897
1898 if (bp == NULL) {
1899 int flags;
1900 char *waitmsg;
1901
1902 if (defrag) {
1903 flags = VFS_BIO_NEED_BUFSPACE;
1904 waitmsg = "nbufkv";
1905 } else if (bufspace >= hibufspace) {
1906 waitmsg = "nbufbs";
1907 flags = VFS_BIO_NEED_BUFSPACE;
1908 } else {
1909 waitmsg = "newbuf";
1910 flags = VFS_BIO_NEED_ANY;
1911 }
1912 mtx_lock(&nblock);
1913 needsbuffer |= flags;
1914 mtx_unlock(&nblock);
1915 mtx_unlock(&bqlock);
1916
1917 bd_speedup(); /* heeeelp */
1918
1919 mtx_lock(&nblock);
1920 while (needsbuffer & flags) {
1921 if (msleep(&needsbuffer, &nblock,
1922 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
1923 mtx_unlock(&nblock);
1924 return (NULL);
1925 }
1926 }
1927 mtx_unlock(&nblock);
1928 } else {
1929 /*
1930 * We finally have a valid bp. We aren't quite out of the
1931 * woods, we still have to reserve kva space. In order
1932 * to keep fragmentation sane we only allocate kva in
1933 * BKVASIZE chunks.
1934 */
1935 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
1936
1937 if (maxsize != bp->b_kvasize) {
1938 vm_offset_t addr = 0;
1939
1940 bfreekva(bp);
1941
1942 vm_map_lock(buffer_map);
1943 if (vm_map_findspace(buffer_map,
1944 vm_map_min(buffer_map), maxsize, &addr)) {
1945 /*
1946 * Uh oh. Buffer map is to fragmented. We
1947 * must defragment the map.
1948 */
1949 atomic_add_int(&bufdefragcnt, 1);
1950 vm_map_unlock(buffer_map);
1951 defrag = 1;
1952 bp->b_flags |= B_INVAL;
1953 brelse(bp);
1954 goto restart;
1955 }
1956 if (addr) {
1957 vm_map_insert(buffer_map, NULL, 0,
1958 addr, addr + maxsize,
1959 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
1960
1961 bp->b_kvabase = (caddr_t) addr;
1962 bp->b_kvasize = maxsize;
1963 atomic_add_int(&bufspace, bp->b_kvasize);
1964 atomic_add_int(&bufreusecnt, 1);
1965 }
1966 vm_map_unlock(buffer_map);
1967 }
1968 bp->b_saveaddr = bp->b_kvabase;
1969 bp->b_data = bp->b_saveaddr;
1970 }
1971 return(bp);
1972 }
1973
1974 /*
1975 * buf_daemon:
1976 *
1977 * buffer flushing daemon. Buffers are normally flushed by the
1978 * update daemon but if it cannot keep up this process starts to
1979 * take the load in an attempt to prevent getnewbuf() from blocking.
1980 */
1981
1982 static struct kproc_desc buf_kp = {
1983 "bufdaemon",
1984 buf_daemon,
1985 &bufdaemonproc
1986 };
1987 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
1988
1989 static void
1990 buf_daemon()
1991 {
1992 mtx_lock(&Giant);
1993
1994 /*
1995 * This process needs to be suspended prior to shutdown sync.
1996 */
1997 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
1998 SHUTDOWN_PRI_LAST);
1999
2000 /*
2001 * This process is allowed to take the buffer cache to the limit
2002 */
2003 curthread->td_pflags |= TDP_NORUNNINGBUF;
2004 mtx_lock(&bdlock);
2005 for (;;) {
2006 bd_request = 0;
2007 mtx_unlock(&bdlock);
2008
2009 kthread_suspend_check(bufdaemonproc);
2010
2011 /*
2012 * Do the flush. Limit the amount of in-transit I/O we
2013 * allow to build up, otherwise we would completely saturate
2014 * the I/O system. Wakeup any waiting processes before we
2015 * normally would so they can run in parallel with our drain.
2016 */
2017 while (numdirtybuffers > lodirtybuffers) {
2018 if (flushbufqueues(0) == 0) {
2019 /*
2020 * Could not find any buffers without rollback
2021 * dependencies, so just write the first one
2022 * in the hopes of eventually making progress.
2023 */
2024 flushbufqueues(1);
2025 break;
2026 }
2027 uio_yield();
2028 }
2029
2030 /*
2031 * Only clear bd_request if we have reached our low water
2032 * mark. The buf_daemon normally waits 1 second and
2033 * then incrementally flushes any dirty buffers that have
2034 * built up, within reason.
2035 *
2036 * If we were unable to hit our low water mark and couldn't
2037 * find any flushable buffers, we sleep half a second.
2038 * Otherwise we loop immediately.
2039 */
2040 mtx_lock(&bdlock);
2041 if (numdirtybuffers <= lodirtybuffers) {
2042 /*
2043 * We reached our low water mark, reset the
2044 * request and sleep until we are needed again.
2045 * The sleep is just so the suspend code works.
2046 */
2047 bd_request = 0;
2048 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2049 } else {
2050 /*
2051 * We couldn't find any flushable dirty buffers but
2052 * still have too many dirty buffers, we
2053 * have to sleep and try again. (rare)
2054 */
2055 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2056 }
2057 }
2058 }
2059
2060 /*
2061 * flushbufqueues:
2062 *
2063 * Try to flush a buffer in the dirty queue. We must be careful to
2064 * free up B_INVAL buffers instead of write them, which NFS is
2065 * particularly sensitive to.
2066 */
2067 static int flushwithdeps = 0;
2068 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2069 0, "Number of buffers flushed with dependecies that require rollbacks");
2070
2071 static int
2072 flushbufqueues(int flushdeps)
2073 {
2074 struct thread *td = curthread;
2075 struct buf sentinel;
2076 struct vnode *vp;
2077 struct mount *mp;
2078 struct buf *bp;
2079 int hasdeps;
2080 int flushed;
2081 int target;
2082
2083 target = numdirtybuffers - lodirtybuffers;
2084 if (flushdeps && target > 2)
2085 target /= 2;
2086 flushed = 0;
2087 bp = NULL;
2088 mtx_lock(&bqlock);
2089 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], &sentinel, b_freelist);
2090 while (flushed != target) {
2091 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]);
2092 if (bp == &sentinel)
2093 break;
2094 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
2095 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
2096
2097 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2098 continue;
2099 BO_LOCK(bp->b_bufobj);
2100 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2101 (bp->b_flags & B_DELWRI) == 0) {
2102 BO_UNLOCK(bp->b_bufobj);
2103 BUF_UNLOCK(bp);
2104 continue;
2105 }
2106 BO_UNLOCK(bp->b_bufobj);
2107 if (bp->b_flags & B_INVAL) {
2108 bremfreel(bp);
2109 mtx_unlock(&bqlock);
2110 brelse(bp);
2111 flushed++;
2112 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2113 mtx_lock(&bqlock);
2114 continue;
2115 }
2116
2117 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) {
2118 if (flushdeps == 0) {
2119 BUF_UNLOCK(bp);
2120 continue;
2121 }
2122 hasdeps = 1;
2123 } else
2124 hasdeps = 0;
2125 /*
2126 * We must hold the lock on a vnode before writing
2127 * one of its buffers. Otherwise we may confuse, or
2128 * in the case of a snapshot vnode, deadlock the
2129 * system.
2130 *
2131 * The lock order here is the reverse of the normal
2132 * of vnode followed by buf lock. This is ok because
2133 * the NOWAIT will prevent deadlock.
2134 */
2135 vp = bp->b_vp;
2136 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2137 BUF_UNLOCK(bp);
2138 continue;
2139 }
2140 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) {
2141 mtx_unlock(&bqlock);
2142 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2143 bp, bp->b_vp, bp->b_flags);
2144 vfs_bio_awrite(bp);
2145 vn_finished_write(mp);
2146 VOP_UNLOCK(vp, 0, td);
2147 flushwithdeps += hasdeps;
2148 flushed++;
2149 waitrunningbufspace();
2150 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2151 mtx_lock(&bqlock);
2152 continue;
2153 }
2154 vn_finished_write(mp);
2155 BUF_UNLOCK(bp);
2156 }
2157 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], &sentinel, b_freelist);
2158 mtx_unlock(&bqlock);
2159 return (flushed);
2160 }
2161
2162 /*
2163 * Check to see if a block is currently memory resident.
2164 */
2165 struct buf *
2166 incore(struct bufobj *bo, daddr_t blkno)
2167 {
2168 struct buf *bp;
2169
2170 BO_LOCK(bo);
2171 bp = gbincore(bo, blkno);
2172 BO_UNLOCK(bo);
2173 return (bp);
2174 }
2175
2176 /*
2177 * Returns true if no I/O is needed to access the
2178 * associated VM object. This is like incore except
2179 * it also hunts around in the VM system for the data.
2180 */
2181
2182 static int
2183 inmem(struct vnode * vp, daddr_t blkno)
2184 {
2185 vm_object_t obj;
2186 vm_offset_t toff, tinc, size;
2187 vm_page_t m;
2188 vm_ooffset_t off;
2189
2190 ASSERT_VOP_LOCKED(vp, "inmem");
2191
2192 if (incore(&vp->v_bufobj, blkno))
2193 return 1;
2194 if (vp->v_mount == NULL)
2195 return 0;
2196 obj = vp->v_object;
2197 if (obj == NULL)
2198 return (0);
2199
2200 size = PAGE_SIZE;
2201 if (size > vp->v_mount->mnt_stat.f_iosize)
2202 size = vp->v_mount->mnt_stat.f_iosize;
2203 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2204
2205 VM_OBJECT_LOCK(obj);
2206 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2207 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2208 if (!m)
2209 goto notinmem;
2210 tinc = size;
2211 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2212 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2213 if (vm_page_is_valid(m,
2214 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2215 goto notinmem;
2216 }
2217 VM_OBJECT_UNLOCK(obj);
2218 return 1;
2219
2220 notinmem:
2221 VM_OBJECT_UNLOCK(obj);
2222 return (0);
2223 }
2224
2225 /*
2226 * vfs_setdirty:
2227 *
2228 * Sets the dirty range for a buffer based on the status of the dirty
2229 * bits in the pages comprising the buffer.
2230 *
2231 * The range is limited to the size of the buffer.
2232 *
2233 * This routine is primarily used by NFS, but is generalized for the
2234 * B_VMIO case.
2235 */
2236 static void
2237 vfs_setdirty(struct buf *bp)
2238 {
2239 int i;
2240 vm_object_t object;
2241
2242 /*
2243 * Degenerate case - empty buffer
2244 */
2245
2246 if (bp->b_bufsize == 0)
2247 return;
2248
2249 /*
2250 * We qualify the scan for modified pages on whether the
2251 * object has been flushed yet. The OBJ_WRITEABLE flag
2252 * is not cleared simply by protecting pages off.
2253 */
2254
2255 if ((bp->b_flags & B_VMIO) == 0)
2256 return;
2257
2258 object = bp->b_pages[0]->object;
2259 VM_OBJECT_LOCK(object);
2260 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
2261 printf("Warning: object %p writeable but not mightbedirty\n", object);
2262 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
2263 printf("Warning: object %p mightbedirty but not writeable\n", object);
2264
2265 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2266 vm_offset_t boffset;
2267 vm_offset_t eoffset;
2268
2269 vm_page_lock_queues();
2270 /*
2271 * test the pages to see if they have been modified directly
2272 * by users through the VM system.
2273 */
2274 for (i = 0; i < bp->b_npages; i++)
2275 vm_page_test_dirty(bp->b_pages[i]);
2276
2277 /*
2278 * Calculate the encompassing dirty range, boffset and eoffset,
2279 * (eoffset - boffset) bytes.
2280 */
2281
2282 for (i = 0; i < bp->b_npages; i++) {
2283 if (bp->b_pages[i]->dirty)
2284 break;
2285 }
2286 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2287
2288 for (i = bp->b_npages - 1; i >= 0; --i) {
2289 if (bp->b_pages[i]->dirty) {
2290 break;
2291 }
2292 }
2293 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2294
2295 vm_page_unlock_queues();
2296 /*
2297 * Fit it to the buffer.
2298 */
2299
2300 if (eoffset > bp->b_bcount)
2301 eoffset = bp->b_bcount;
2302
2303 /*
2304 * If we have a good dirty range, merge with the existing
2305 * dirty range.
2306 */
2307
2308 if (boffset < eoffset) {
2309 if (bp->b_dirtyoff > boffset)
2310 bp->b_dirtyoff = boffset;
2311 if (bp->b_dirtyend < eoffset)
2312 bp->b_dirtyend = eoffset;
2313 }
2314 }
2315 VM_OBJECT_UNLOCK(object);
2316 }
2317
2318 /*
2319 * getblk:
2320 *
2321 * Get a block given a specified block and offset into a file/device.
2322 * The buffers B_DONE bit will be cleared on return, making it almost
2323 * ready for an I/O initiation. B_INVAL may or may not be set on
2324 * return. The caller should clear B_INVAL prior to initiating a
2325 * READ.
2326 *
2327 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2328 * an existing buffer.
2329 *
2330 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2331 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2332 * and then cleared based on the backing VM. If the previous buffer is
2333 * non-0-sized but invalid, B_CACHE will be cleared.
2334 *
2335 * If getblk() must create a new buffer, the new buffer is returned with
2336 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2337 * case it is returned with B_INVAL clear and B_CACHE set based on the
2338 * backing VM.
2339 *
2340 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2341 * B_CACHE bit is clear.
2342 *
2343 * What this means, basically, is that the caller should use B_CACHE to
2344 * determine whether the buffer is fully valid or not and should clear
2345 * B_INVAL prior to issuing a read. If the caller intends to validate
2346 * the buffer by loading its data area with something, the caller needs
2347 * to clear B_INVAL. If the caller does this without issuing an I/O,
2348 * the caller should set B_CACHE ( as an optimization ), else the caller
2349 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2350 * a write attempt or if it was a successfull read. If the caller
2351 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2352 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2353 */
2354 struct buf *
2355 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2356 int flags)
2357 {
2358 struct buf *bp;
2359 struct bufobj *bo;
2360 int error;
2361
2362 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
2363 ASSERT_VOP_LOCKED(vp, "getblk");
2364 if (size > MAXBSIZE)
2365 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2366
2367 bo = &vp->v_bufobj;
2368 loop:
2369 /*
2370 * Block if we are low on buffers. Certain processes are allowed
2371 * to completely exhaust the buffer cache.
2372 *
2373 * If this check ever becomes a bottleneck it may be better to
2374 * move it into the else, when gbincore() fails. At the moment
2375 * it isn't a problem.
2376 *
2377 * XXX remove if 0 sections (clean this up after its proven)
2378 */
2379 if (numfreebuffers == 0) {
2380 if (curthread == PCPU_GET(idlethread))
2381 return NULL;
2382 mtx_lock(&nblock);
2383 needsbuffer |= VFS_BIO_NEED_ANY;
2384 mtx_unlock(&nblock);
2385 }
2386
2387 VI_LOCK(vp);
2388 bp = gbincore(bo, blkno);
2389 if (bp != NULL) {
2390 int lockflags;
2391 /*
2392 * Buffer is in-core. If the buffer is not busy, it must
2393 * be on a queue.
2394 */
2395 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2396
2397 if (flags & GB_LOCK_NOWAIT)
2398 lockflags |= LK_NOWAIT;
2399
2400 error = BUF_TIMELOCK(bp, lockflags,
2401 VI_MTX(vp), "getblk", slpflag, slptimeo);
2402
2403 /*
2404 * If we slept and got the lock we have to restart in case
2405 * the buffer changed identities.
2406 */
2407 if (error == ENOLCK)
2408 goto loop;
2409 /* We timed out or were interrupted. */
2410 else if (error)
2411 return (NULL);
2412
2413 /*
2414 * The buffer is locked. B_CACHE is cleared if the buffer is
2415 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2416 * and for a VMIO buffer B_CACHE is adjusted according to the
2417 * backing VM cache.
2418 */
2419 if (bp->b_flags & B_INVAL)
2420 bp->b_flags &= ~B_CACHE;
2421 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2422 bp->b_flags |= B_CACHE;
2423 bremfree(bp);
2424
2425 /*
2426 * check for size inconsistancies for non-VMIO case.
2427 */
2428
2429 if (bp->b_bcount != size) {
2430 if ((bp->b_flags & B_VMIO) == 0 ||
2431 (size > bp->b_kvasize)) {
2432 if (bp->b_flags & B_DELWRI) {
2433 bp->b_flags |= B_NOCACHE;
2434 bwrite(bp);
2435 } else {
2436 if (LIST_FIRST(&bp->b_dep) == NULL) {
2437 bp->b_flags |= B_RELBUF;
2438 brelse(bp);
2439 } else {
2440 bp->b_flags |= B_NOCACHE;
2441 bwrite(bp);
2442 }
2443 }
2444 goto loop;
2445 }
2446 }
2447
2448 /*
2449 * If the size is inconsistant in the VMIO case, we can resize
2450 * the buffer. This might lead to B_CACHE getting set or
2451 * cleared. If the size has not changed, B_CACHE remains
2452 * unchanged from its previous state.
2453 */
2454
2455 if (bp->b_bcount != size)
2456 allocbuf(bp, size);
2457
2458 KASSERT(bp->b_offset != NOOFFSET,
2459 ("getblk: no buffer offset"));
2460
2461 /*
2462 * A buffer with B_DELWRI set and B_CACHE clear must
2463 * be committed before we can return the buffer in
2464 * order to prevent the caller from issuing a read
2465 * ( due to B_CACHE not being set ) and overwriting
2466 * it.
2467 *
2468 * Most callers, including NFS and FFS, need this to
2469 * operate properly either because they assume they
2470 * can issue a read if B_CACHE is not set, or because
2471 * ( for example ) an uncached B_DELWRI might loop due
2472 * to softupdates re-dirtying the buffer. In the latter
2473 * case, B_CACHE is set after the first write completes,
2474 * preventing further loops.
2475 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2476 * above while extending the buffer, we cannot allow the
2477 * buffer to remain with B_CACHE set after the write
2478 * completes or it will represent a corrupt state. To
2479 * deal with this we set B_NOCACHE to scrap the buffer
2480 * after the write.
2481 *
2482 * We might be able to do something fancy, like setting
2483 * B_CACHE in bwrite() except if B_DELWRI is already set,
2484 * so the below call doesn't set B_CACHE, but that gets real
2485 * confusing. This is much easier.
2486 */
2487
2488 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2489 bp->b_flags |= B_NOCACHE;
2490 bwrite(bp);
2491 goto loop;
2492 }
2493 bp->b_flags &= ~B_DONE;
2494 } else {
2495 int bsize, maxsize, vmio;
2496 off_t offset;
2497
2498 /*
2499 * Buffer is not in-core, create new buffer. The buffer
2500 * returned by getnewbuf() is locked. Note that the returned
2501 * buffer is also considered valid (not marked B_INVAL).
2502 */
2503 VI_UNLOCK(vp);
2504 /*
2505 * If the user does not want us to create the buffer, bail out
2506 * here.
2507 */
2508 if (flags & GB_NOCREAT)
2509 return NULL;
2510 bsize = bo->bo_bsize;
2511 offset = blkno * bsize;
2512 vmio = vp->v_object != NULL;
2513 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2514 maxsize = imax(maxsize, bsize);
2515
2516 bp = getnewbuf(slpflag, slptimeo, size, maxsize);
2517 if (bp == NULL) {
2518 if (slpflag || slptimeo)
2519 return NULL;
2520 goto loop;
2521 }
2522
2523 /*
2524 * This code is used to make sure that a buffer is not
2525 * created while the getnewbuf routine is blocked.
2526 * This can be a problem whether the vnode is locked or not.
2527 * If the buffer is created out from under us, we have to
2528 * throw away the one we just created.
2529 *
2530 * Note: this must occur before we associate the buffer
2531 * with the vp especially considering limitations in
2532 * the splay tree implementation when dealing with duplicate
2533 * lblkno's.
2534 */
2535 BO_LOCK(bo);
2536 if (gbincore(bo, blkno)) {
2537 BO_UNLOCK(bo);
2538 bp->b_flags |= B_INVAL;
2539 brelse(bp);
2540 goto loop;
2541 }
2542
2543 /*
2544 * Insert the buffer into the hash, so that it can
2545 * be found by incore.
2546 */
2547 bp->b_blkno = bp->b_lblkno = blkno;
2548 bp->b_offset = offset;
2549
2550 bgetvp(vp, bp);
2551 BO_UNLOCK(bo);
2552
2553 /*
2554 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2555 * buffer size starts out as 0, B_CACHE will be set by
2556 * allocbuf() for the VMIO case prior to it testing the
2557 * backing store for validity.
2558 */
2559
2560 if (vmio) {
2561 bp->b_flags |= B_VMIO;
2562 #if defined(VFS_BIO_DEBUG)
2563 if (vn_canvmio(vp) != TRUE)
2564 printf("getblk: VMIO on vnode type %d\n",
2565 vp->v_type);
2566 #endif
2567 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
2568 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
2569 bp, vp->v_object, bp->b_bufobj->bo_object));
2570 } else {
2571 bp->b_flags &= ~B_VMIO;
2572 KASSERT(bp->b_bufobj->bo_object == NULL,
2573 ("ARGH! has b_bufobj->bo_object %p %p\n",
2574 bp, bp->b_bufobj->bo_object));
2575 }
2576
2577 allocbuf(bp, size);
2578 bp->b_flags &= ~B_DONE;
2579 }
2580 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
2581 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
2582 KASSERT(bp->b_bufobj == bo,
2583 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
2584 return (bp);
2585 }
2586
2587 /*
2588 * Get an empty, disassociated buffer of given size. The buffer is initially
2589 * set to B_INVAL.
2590 */
2591 struct buf *
2592 geteblk(int size)
2593 {
2594 struct buf *bp;
2595 int maxsize;
2596
2597 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2598 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
2599 continue;
2600 allocbuf(bp, size);
2601 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2602 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
2603 return (bp);
2604 }
2605
2606
2607 /*
2608 * This code constitutes the buffer memory from either anonymous system
2609 * memory (in the case of non-VMIO operations) or from an associated
2610 * VM object (in the case of VMIO operations). This code is able to
2611 * resize a buffer up or down.
2612 *
2613 * Note that this code is tricky, and has many complications to resolve
2614 * deadlock or inconsistant data situations. Tread lightly!!!
2615 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2616 * the caller. Calling this code willy nilly can result in the loss of data.
2617 *
2618 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2619 * B_CACHE for the non-VMIO case.
2620 */
2621
2622 int
2623 allocbuf(struct buf *bp, int size)
2624 {
2625 int newbsize, mbsize;
2626 int i;
2627
2628 if (BUF_REFCNT(bp) == 0)
2629 panic("allocbuf: buffer not busy");
2630
2631 if (bp->b_kvasize < size)
2632 panic("allocbuf: buffer too small");
2633
2634 if ((bp->b_flags & B_VMIO) == 0) {
2635 caddr_t origbuf;
2636 int origbufsize;
2637 /*
2638 * Just get anonymous memory from the kernel. Don't
2639 * mess with B_CACHE.
2640 */
2641 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2642 if (bp->b_flags & B_MALLOC)
2643 newbsize = mbsize;
2644 else
2645 newbsize = round_page(size);
2646
2647 if (newbsize < bp->b_bufsize) {
2648 /*
2649 * malloced buffers are not shrunk
2650 */
2651 if (bp->b_flags & B_MALLOC) {
2652 if (newbsize) {
2653 bp->b_bcount = size;
2654 } else {
2655 free(bp->b_data, M_BIOBUF);
2656 if (bp->b_bufsize) {
2657 atomic_subtract_int(
2658 &bufmallocspace,
2659 bp->b_bufsize);
2660 bufspacewakeup();
2661 bp->b_bufsize = 0;
2662 }
2663 bp->b_saveaddr = bp->b_kvabase;
2664 bp->b_data = bp->b_saveaddr;
2665 bp->b_bcount = 0;
2666 bp->b_flags &= ~B_MALLOC;
2667 }
2668 return 1;
2669 }
2670 vm_hold_free_pages(
2671 bp,
2672 (vm_offset_t) bp->b_data + newbsize,
2673 (vm_offset_t) bp->b_data + bp->b_bufsize);
2674 } else if (newbsize > bp->b_bufsize) {
2675 /*
2676 * We only use malloced memory on the first allocation.
2677 * and revert to page-allocated memory when the buffer
2678 * grows.
2679 */
2680 /*
2681 * There is a potential smp race here that could lead
2682 * to bufmallocspace slightly passing the max. It
2683 * is probably extremely rare and not worth worrying
2684 * over.
2685 */
2686 if ( (bufmallocspace < maxbufmallocspace) &&
2687 (bp->b_bufsize == 0) &&
2688 (mbsize <= PAGE_SIZE/2)) {
2689
2690 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2691 bp->b_bufsize = mbsize;
2692 bp->b_bcount = size;
2693 bp->b_flags |= B_MALLOC;
2694 atomic_add_int(&bufmallocspace, mbsize);
2695 return 1;
2696 }
2697 origbuf = NULL;
2698 origbufsize = 0;
2699 /*
2700 * If the buffer is growing on its other-than-first allocation,
2701 * then we revert to the page-allocation scheme.
2702 */
2703 if (bp->b_flags & B_MALLOC) {
2704 origbuf = bp->b_data;
2705 origbufsize = bp->b_bufsize;
2706 bp->b_data = bp->b_kvabase;
2707 if (bp->b_bufsize) {
2708 atomic_subtract_int(&bufmallocspace,
2709 bp->b_bufsize);
2710 bufspacewakeup();
2711 bp->b_bufsize = 0;
2712 }
2713 bp->b_flags &= ~B_MALLOC;
2714 newbsize = round_page(newbsize);
2715 }
2716 vm_hold_load_pages(
2717 bp,
2718 (vm_offset_t) bp->b_data + bp->b_bufsize,
2719 (vm_offset_t) bp->b_data + newbsize);
2720 if (origbuf) {
2721 bcopy(origbuf, bp->b_data, origbufsize);
2722 free(origbuf, M_BIOBUF);
2723 }
2724 }
2725 } else {
2726 int desiredpages;
2727
2728 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2729 desiredpages = (size == 0) ? 0 :
2730 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2731
2732 if (bp->b_flags & B_MALLOC)
2733 panic("allocbuf: VMIO buffer can't be malloced");
2734 /*
2735 * Set B_CACHE initially if buffer is 0 length or will become
2736 * 0-length.
2737 */
2738 if (size == 0 || bp->b_bufsize == 0)
2739 bp->b_flags |= B_CACHE;
2740
2741 if (newbsize < bp->b_bufsize) {
2742 /*
2743 * DEV_BSIZE aligned new buffer size is less then the
2744 * DEV_BSIZE aligned existing buffer size. Figure out
2745 * if we have to remove any pages.
2746 */
2747 if (desiredpages < bp->b_npages) {
2748 vm_page_t m;
2749
2750 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2751 vm_page_lock_queues();
2752 for (i = desiredpages; i < bp->b_npages; i++) {
2753 /*
2754 * the page is not freed here -- it
2755 * is the responsibility of
2756 * vnode_pager_setsize
2757 */
2758 m = bp->b_pages[i];
2759 KASSERT(m != bogus_page,
2760 ("allocbuf: bogus page found"));
2761 while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
2762 vm_page_lock_queues();
2763
2764 bp->b_pages[i] = NULL;
2765 vm_page_unwire(m, 0);
2766 }
2767 vm_page_unlock_queues();
2768 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2769 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2770 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
2771 bp->b_npages = desiredpages;
2772 }
2773 } else if (size > bp->b_bcount) {
2774 /*
2775 * We are growing the buffer, possibly in a
2776 * byte-granular fashion.
2777 */
2778 struct vnode *vp;
2779 vm_object_t obj;
2780 vm_offset_t toff;
2781 vm_offset_t tinc;
2782
2783 /*
2784 * Step 1, bring in the VM pages from the object,
2785 * allocating them if necessary. We must clear
2786 * B_CACHE if these pages are not valid for the
2787 * range covered by the buffer.
2788 */
2789
2790 vp = bp->b_vp;
2791 obj = bp->b_bufobj->bo_object;
2792
2793 VM_OBJECT_LOCK(obj);
2794 while (bp->b_npages < desiredpages) {
2795 vm_page_t m;
2796 vm_pindex_t pi;
2797
2798 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
2799 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2800 /*
2801 * note: must allocate system pages
2802 * since blocking here could intefere
2803 * with paging I/O, no matter which
2804 * process we are.
2805 */
2806 m = vm_page_alloc(obj, pi,
2807 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
2808 VM_ALLOC_WIRED);
2809 if (m == NULL) {
2810 atomic_add_int(&vm_pageout_deficit,
2811 desiredpages - bp->b_npages);
2812 VM_OBJECT_UNLOCK(obj);
2813 VM_WAIT;
2814 VM_OBJECT_LOCK(obj);
2815 } else {
2816 bp->b_flags &= ~B_CACHE;
2817 bp->b_pages[bp->b_npages] = m;
2818 ++bp->b_npages;
2819 }
2820 continue;
2821 }
2822
2823 /*
2824 * We found a page. If we have to sleep on it,
2825 * retry because it might have gotten freed out
2826 * from under us.
2827 *
2828 * We can only test PG_BUSY here. Blocking on
2829 * m->busy might lead to a deadlock:
2830 *
2831 * vm_fault->getpages->cluster_read->allocbuf
2832 *
2833 */
2834 vm_page_lock_queues();
2835 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
2836 continue;
2837
2838 /*
2839 * We have a good page. Should we wakeup the
2840 * page daemon?
2841 */
2842 if ((curproc != pageproc) &&
2843 ((m->queue - m->pc) == PQ_CACHE) &&
2844 ((cnt.v_free_count + cnt.v_cache_count) <
2845 (cnt.v_free_min + cnt.v_cache_min))) {
2846 pagedaemon_wakeup();
2847 }
2848 vm_page_wire(m);
2849 vm_page_unlock_queues();
2850 bp->b_pages[bp->b_npages] = m;
2851 ++bp->b_npages;
2852 }
2853
2854 /*
2855 * Step 2. We've loaded the pages into the buffer,
2856 * we have to figure out if we can still have B_CACHE
2857 * set. Note that B_CACHE is set according to the
2858 * byte-granular range ( bcount and size ), new the
2859 * aligned range ( newbsize ).
2860 *
2861 * The VM test is against m->valid, which is DEV_BSIZE
2862 * aligned. Needless to say, the validity of the data
2863 * needs to also be DEV_BSIZE aligned. Note that this
2864 * fails with NFS if the server or some other client
2865 * extends the file's EOF. If our buffer is resized,
2866 * B_CACHE may remain set! XXX
2867 */
2868
2869 toff = bp->b_bcount;
2870 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2871
2872 while ((bp->b_flags & B_CACHE) && toff < size) {
2873 vm_pindex_t pi;
2874
2875 if (tinc > (size - toff))
2876 tinc = size - toff;
2877
2878 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2879 PAGE_SHIFT;
2880
2881 vfs_buf_test_cache(
2882 bp,
2883 bp->b_offset,
2884 toff,
2885 tinc,
2886 bp->b_pages[pi]
2887 );
2888 toff += tinc;
2889 tinc = PAGE_SIZE;
2890 }
2891 VM_OBJECT_UNLOCK(obj);
2892
2893 /*
2894 * Step 3, fixup the KVM pmap. Remember that
2895 * bp->b_data is relative to bp->b_offset, but
2896 * bp->b_offset may be offset into the first page.
2897 */
2898
2899 bp->b_data = (caddr_t)
2900 trunc_page((vm_offset_t)bp->b_data);
2901 pmap_qenter(
2902 (vm_offset_t)bp->b_data,
2903 bp->b_pages,
2904 bp->b_npages
2905 );
2906
2907 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2908 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2909 }
2910 }
2911 if (newbsize < bp->b_bufsize)
2912 bufspacewakeup();
2913 bp->b_bufsize = newbsize; /* actual buffer allocation */
2914 bp->b_bcount = size; /* requested buffer size */
2915 return 1;
2916 }
2917
2918 void
2919 biodone(struct bio *bp)
2920 {
2921 void (*done)(struct bio *);
2922
2923 mtx_lock(&bdonelock);
2924 bp->bio_flags |= BIO_DONE;
2925 done = bp->bio_done;
2926 if (done == NULL)
2927 wakeup(bp);
2928 mtx_unlock(&bdonelock);
2929 if (done != NULL)
2930 done(bp);
2931 }
2932
2933 /*
2934 * Wait for a BIO to finish.
2935 *
2936 * XXX: resort to a timeout for now. The optimal locking (if any) for this
2937 * case is not yet clear.
2938 */
2939 int
2940 biowait(struct bio *bp, const char *wchan)
2941 {
2942
2943 mtx_lock(&bdonelock);
2944 while ((bp->bio_flags & BIO_DONE) == 0)
2945 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
2946 mtx_unlock(&bdonelock);
2947 if (bp->bio_error != 0)
2948 return (bp->bio_error);
2949 if (!(bp->bio_flags & BIO_ERROR))
2950 return (0);
2951 return (EIO);
2952 }
2953
2954 void
2955 biofinish(struct bio *bp, struct devstat *stat, int error)
2956 {
2957
2958 if (error) {
2959 bp->bio_error = error;
2960 bp->bio_flags |= BIO_ERROR;
2961 }
2962 if (stat != NULL)
2963 devstat_end_transaction_bio(stat, bp);
2964 biodone(bp);
2965 }
2966
2967 /*
2968 * bufwait:
2969 *
2970 * Wait for buffer I/O completion, returning error status. The buffer
2971 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
2972 * error and cleared.
2973 */
2974 int
2975 bufwait(struct buf *bp)
2976 {
2977 if (bp->b_iocmd == BIO_READ)
2978 bwait(bp, PRIBIO, "biord");
2979 else
2980 bwait(bp, PRIBIO, "biowr");
2981 if (bp->b_flags & B_EINTR) {
2982 bp->b_flags &= ~B_EINTR;
2983 return (EINTR);
2984 }
2985 if (bp->b_ioflags & BIO_ERROR) {
2986 return (bp->b_error ? bp->b_error : EIO);
2987 } else {
2988 return (0);
2989 }
2990 }
2991
2992 /*
2993 * Call back function from struct bio back up to struct buf.
2994 */
2995 static void
2996 bufdonebio(struct bio *bip)
2997 {
2998 struct buf *bp;
2999
3000 bp = bip->bio_caller2;
3001 bp->b_resid = bp->b_bcount - bip->bio_completed;
3002 bp->b_resid = bip->bio_resid; /* XXX: remove */
3003 bp->b_ioflags = bip->bio_flags;
3004 bp->b_error = bip->bio_error;
3005 if (bp->b_error)
3006 bp->b_ioflags |= BIO_ERROR;
3007 bufdone(bp);
3008 g_destroy_bio(bip);
3009 }
3010
3011 void
3012 dev_strategy(struct cdev *dev, struct buf *bp)
3013 {
3014 struct cdevsw *csw;
3015 struct bio *bip;
3016
3017 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
3018 panic("b_iocmd botch");
3019 for (;;) {
3020 bip = g_new_bio();
3021 if (bip != NULL)
3022 break;
3023 /* Try again later */
3024 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3025 }
3026 bip->bio_cmd = bp->b_iocmd;
3027 bip->bio_offset = bp->b_iooffset;
3028 bip->bio_length = bp->b_bcount;
3029 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3030 bip->bio_data = bp->b_data;
3031 bip->bio_done = bufdonebio;
3032 bip->bio_caller2 = bp;
3033 bip->bio_dev = dev;
3034 KASSERT(dev->si_refcount > 0,
3035 ("dev_strategy on un-referenced struct cdev *(%s)",
3036 devtoname(dev)));
3037 csw = dev_refthread(dev);
3038 if (csw == NULL) {
3039 g_destroy_bio(bip);
3040 bp->b_error = ENXIO;
3041 bp->b_ioflags = BIO_ERROR;
3042 bufdone(bp);
3043 return;
3044 }
3045 (*csw->d_strategy)(bip);
3046 dev_relthread(dev);
3047 }
3048
3049 /*
3050 * bufdone:
3051 *
3052 * Finish I/O on a buffer, optionally calling a completion function.
3053 * This is usually called from an interrupt so process blocking is
3054 * not allowed.
3055 *
3056 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3057 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3058 * assuming B_INVAL is clear.
3059 *
3060 * For the VMIO case, we set B_CACHE if the op was a read and no
3061 * read error occured, or if the op was a write. B_CACHE is never
3062 * set if the buffer is invalid or otherwise uncacheable.
3063 *
3064 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3065 * initiator to leave B_INVAL set to brelse the buffer out of existance
3066 * in the biodone routine.
3067 */
3068 void
3069 bufdone(struct buf *bp)
3070 {
3071 struct bufobj *dropobj;
3072 void (*biodone)(struct buf *);
3073
3074
3075 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3076 dropobj = NULL;
3077
3078 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp)));
3079 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3080
3081 runningbufwakeup(bp);
3082 if (bp->b_iocmd == BIO_WRITE)
3083 dropobj = bp->b_bufobj;
3084 /* call optional completion function if requested */
3085 if (bp->b_iodone != NULL) {
3086 biodone = bp->b_iodone;
3087 bp->b_iodone = NULL;
3088 (*biodone) (bp);
3089 if (dropobj)
3090 bufobj_wdrop(dropobj);
3091 return;
3092 }
3093 if (LIST_FIRST(&bp->b_dep) != NULL)
3094 buf_complete(bp);
3095
3096 if (bp->b_flags & B_VMIO) {
3097 int i;
3098 vm_ooffset_t foff;
3099 vm_page_t m;
3100 vm_object_t obj;
3101 int iosize;
3102 struct vnode *vp = bp->b_vp;
3103
3104 obj = bp->b_bufobj->bo_object;
3105
3106 #if defined(VFS_BIO_DEBUG)
3107 mp_fixme("usecount and vflag accessed without locks.");
3108 if (vp->v_usecount == 0) {
3109 panic("biodone: zero vnode ref count");
3110 }
3111
3112 KASSERT(vp->v_object != NULL,
3113 ("biodone: vnode %p has no vm_object", vp));
3114 #endif
3115
3116 foff = bp->b_offset;
3117 KASSERT(bp->b_offset != NOOFFSET,
3118 ("biodone: no buffer offset"));
3119
3120 VM_OBJECT_LOCK(obj);
3121 #if defined(VFS_BIO_DEBUG)
3122 if (obj->paging_in_progress < bp->b_npages) {
3123 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
3124 obj->paging_in_progress, bp->b_npages);
3125 }
3126 #endif
3127
3128 /*
3129 * Set B_CACHE if the op was a normal read and no error
3130 * occured. B_CACHE is set for writes in the b*write()
3131 * routines.
3132 */
3133 iosize = bp->b_bcount - bp->b_resid;
3134 if (bp->b_iocmd == BIO_READ &&
3135 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3136 !(bp->b_ioflags & BIO_ERROR)) {
3137 bp->b_flags |= B_CACHE;
3138 }
3139 vm_page_lock_queues();
3140 for (i = 0; i < bp->b_npages; i++) {
3141 int bogusflag = 0;
3142 int resid;
3143
3144 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3145 if (resid > iosize)
3146 resid = iosize;
3147
3148 /*
3149 * cleanup bogus pages, restoring the originals
3150 */
3151 m = bp->b_pages[i];
3152 if (m == bogus_page) {
3153 bogusflag = 1;
3154 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3155 if (m == NULL)
3156 panic("biodone: page disappeared!");
3157 bp->b_pages[i] = m;
3158 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3159 }
3160 #if defined(VFS_BIO_DEBUG)
3161 if (OFF_TO_IDX(foff) != m->pindex) {
3162 printf(
3163 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
3164 (intmax_t)foff, (uintmax_t)m->pindex);
3165 }
3166 #endif
3167
3168 /*
3169 * In the write case, the valid and clean bits are
3170 * already changed correctly ( see bdwrite() ), so we
3171 * only need to do this here in the read case.
3172 */
3173 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3174 vfs_page_set_valid(bp, foff, i, m);
3175 }
3176
3177 /*
3178 * when debugging new filesystems or buffer I/O methods, this
3179 * is the most common error that pops up. if you see this, you
3180 * have not set the page busy flag correctly!!!
3181 */
3182 if (m->busy == 0) {
3183 printf("biodone: page busy < 0, "
3184 "pindex: %d, foff: 0x(%x,%x), "
3185 "resid: %d, index: %d\n",
3186 (int) m->pindex, (int)(foff >> 32),
3187 (int) foff & 0xffffffff, resid, i);
3188 if (!vn_isdisk(vp, NULL))
3189 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
3190 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
3191 (intmax_t) bp->b_lblkno,
3192 bp->b_flags, bp->b_npages);
3193 else
3194 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
3195 (intmax_t) bp->b_lblkno,
3196 bp->b_flags, bp->b_npages);
3197 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
3198 (u_long)m->valid, (u_long)m->dirty,
3199 m->wire_count);
3200 panic("biodone: page busy < 0\n");
3201 }
3202 vm_page_io_finish(m);
3203 vm_object_pip_subtract(obj, 1);
3204 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3205 iosize -= resid;
3206 }
3207 vm_page_unlock_queues();
3208 vm_object_pip_wakeupn(obj, 0);
3209 VM_OBJECT_UNLOCK(obj);
3210 }
3211
3212 /*
3213 * For asynchronous completions, release the buffer now. The brelse
3214 * will do a wakeup there if necessary - so no need to do a wakeup
3215 * here in the async case. The sync case always needs to do a wakeup.
3216 */
3217
3218 if (bp->b_flags & B_ASYNC) {
3219 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3220 brelse(bp);
3221 else
3222 bqrelse(bp);
3223 } else
3224 bdone(bp);
3225 if (dropobj)
3226 bufobj_wdrop(dropobj);
3227 }
3228
3229 /*
3230 * This routine is called in lieu of iodone in the case of
3231 * incomplete I/O. This keeps the busy status for pages
3232 * consistant.
3233 */
3234 void
3235 vfs_unbusy_pages(struct buf *bp)
3236 {
3237 int i;
3238 vm_object_t obj;
3239 vm_page_t m;
3240
3241 runningbufwakeup(bp);
3242 if (!(bp->b_flags & B_VMIO))
3243 return;
3244
3245 obj = bp->b_bufobj->bo_object;
3246 VM_OBJECT_LOCK(obj);
3247 vm_page_lock_queues();
3248 for (i = 0; i < bp->b_npages; i++) {
3249 m = bp->b_pages[i];
3250 if (m == bogus_page) {
3251 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3252 if (!m)
3253 panic("vfs_unbusy_pages: page missing\n");
3254 bp->b_pages[i] = m;
3255 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3256 bp->b_pages, bp->b_npages);
3257 }
3258 vm_object_pip_subtract(obj, 1);
3259 vm_page_io_finish(m);
3260 }
3261 vm_page_unlock_queues();
3262 vm_object_pip_wakeupn(obj, 0);
3263 VM_OBJECT_UNLOCK(obj);
3264 }
3265
3266 /*
3267 * vfs_page_set_valid:
3268 *
3269 * Set the valid bits in a page based on the supplied offset. The
3270 * range is restricted to the buffer's size.
3271 *
3272 * This routine is typically called after a read completes.
3273 */
3274 static void
3275 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3276 {
3277 vm_ooffset_t soff, eoff;
3278
3279 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
3280 /*
3281 * Start and end offsets in buffer. eoff - soff may not cross a
3282 * page boundry or cross the end of the buffer. The end of the
3283 * buffer, in this case, is our file EOF, not the allocation size
3284 * of the buffer.
3285 */
3286 soff = off;
3287 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3288 if (eoff > bp->b_offset + bp->b_bcount)
3289 eoff = bp->b_offset + bp->b_bcount;
3290
3291 /*
3292 * Set valid range. This is typically the entire buffer and thus the
3293 * entire page.
3294 */
3295 if (eoff > soff) {
3296 vm_page_set_validclean(
3297 m,
3298 (vm_offset_t) (soff & PAGE_MASK),
3299 (vm_offset_t) (eoff - soff)
3300 );
3301 }
3302 }
3303
3304 /*
3305 * This routine is called before a device strategy routine.
3306 * It is used to tell the VM system that paging I/O is in
3307 * progress, and treat the pages associated with the buffer
3308 * almost as being PG_BUSY. Also the object paging_in_progress
3309 * flag is handled to make sure that the object doesn't become
3310 * inconsistant.
3311 *
3312 * Since I/O has not been initiated yet, certain buffer flags
3313 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3314 * and should be ignored.
3315 */
3316 void
3317 vfs_busy_pages(struct buf *bp, int clear_modify)
3318 {
3319 int i, bogus;
3320 vm_object_t obj;
3321 vm_ooffset_t foff;
3322 vm_page_t m;
3323
3324 if (!(bp->b_flags & B_VMIO))
3325 return;
3326
3327 obj = bp->b_bufobj->bo_object;
3328 foff = bp->b_offset;
3329 KASSERT(bp->b_offset != NOOFFSET,
3330 ("vfs_busy_pages: no buffer offset"));
3331 vfs_setdirty(bp);
3332 VM_OBJECT_LOCK(obj);
3333 retry:
3334 vm_page_lock_queues();
3335 for (i = 0; i < bp->b_npages; i++) {
3336 m = bp->b_pages[i];
3337
3338 if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
3339 goto retry;
3340 }
3341 bogus = 0;
3342 for (i = 0; i < bp->b_npages; i++) {
3343 m = bp->b_pages[i];
3344
3345 if ((bp->b_flags & B_CLUSTER) == 0) {
3346 vm_object_pip_add(obj, 1);
3347 vm_page_io_start(m);
3348 }
3349 /*
3350 * When readying a buffer for a read ( i.e
3351 * clear_modify == 0 ), it is important to do
3352 * bogus_page replacement for valid pages in
3353 * partially instantiated buffers. Partially
3354 * instantiated buffers can, in turn, occur when
3355 * reconstituting a buffer from its VM backing store
3356 * base. We only have to do this if B_CACHE is
3357 * clear ( which causes the I/O to occur in the
3358 * first place ). The replacement prevents the read
3359 * I/O from overwriting potentially dirty VM-backed
3360 * pages. XXX bogus page replacement is, uh, bogus.
3361 * It may not work properly with small-block devices.
3362 * We need to find a better way.
3363 */
3364 pmap_remove_all(m);
3365 if (clear_modify)
3366 vfs_page_set_valid(bp, foff, i, m);
3367 else if (m->valid == VM_PAGE_BITS_ALL &&
3368 (bp->b_flags & B_CACHE) == 0) {
3369 bp->b_pages[i] = bogus_page;
3370 bogus++;
3371 }
3372 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3373 }
3374 vm_page_unlock_queues();
3375 VM_OBJECT_UNLOCK(obj);
3376 if (bogus)
3377 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3378 bp->b_pages, bp->b_npages);
3379 }
3380
3381 /*
3382 * Tell the VM system that the pages associated with this buffer
3383 * are clean. This is used for delayed writes where the data is
3384 * going to go to disk eventually without additional VM intevention.
3385 *
3386 * Note that while we only really need to clean through to b_bcount, we
3387 * just go ahead and clean through to b_bufsize.
3388 */
3389 static void
3390 vfs_clean_pages(struct buf *bp)
3391 {
3392 int i;
3393 vm_ooffset_t foff, noff, eoff;
3394 vm_page_t m;
3395
3396 if (!(bp->b_flags & B_VMIO))
3397 return;
3398
3399 foff = bp->b_offset;
3400 KASSERT(bp->b_offset != NOOFFSET,
3401 ("vfs_clean_pages: no buffer offset"));
3402 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3403 vm_page_lock_queues();
3404 for (i = 0; i < bp->b_npages; i++) {
3405 m = bp->b_pages[i];
3406 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3407 eoff = noff;
3408
3409 if (eoff > bp->b_offset + bp->b_bufsize)
3410 eoff = bp->b_offset + bp->b_bufsize;
3411 vfs_page_set_valid(bp, foff, i, m);
3412 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3413 foff = noff;
3414 }
3415 vm_page_unlock_queues();
3416 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3417 }
3418
3419 /*
3420 * vfs_bio_set_validclean:
3421 *
3422 * Set the range within the buffer to valid and clean. The range is
3423 * relative to the beginning of the buffer, b_offset. Note that b_offset
3424 * itself may be offset from the beginning of the first page.
3425 *
3426 */
3427
3428 void
3429 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3430 {
3431 int i, n;
3432 vm_page_t m;
3433
3434 if (!(bp->b_flags & B_VMIO))
3435 return;
3436 /*
3437 * Fixup base to be relative to beginning of first page.
3438 * Set initial n to be the maximum number of bytes in the
3439 * first page that can be validated.
3440 */
3441
3442 base += (bp->b_offset & PAGE_MASK);
3443 n = PAGE_SIZE - (base & PAGE_MASK);
3444
3445 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3446 vm_page_lock_queues();
3447 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3448 m = bp->b_pages[i];
3449 if (n > size)
3450 n = size;
3451 vm_page_set_validclean(m, base & PAGE_MASK, n);
3452 base += n;
3453 size -= n;
3454 n = PAGE_SIZE;
3455 }
3456 vm_page_unlock_queues();
3457 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3458 }
3459
3460 /*
3461 * vfs_bio_clrbuf:
3462 *
3463 * clear a buffer. This routine essentially fakes an I/O, so we need
3464 * to clear BIO_ERROR and B_INVAL.
3465 *
3466 * Note that while we only theoretically need to clear through b_bcount,
3467 * we go ahead and clear through b_bufsize.
3468 */
3469
3470 void
3471 vfs_bio_clrbuf(struct buf *bp)
3472 {
3473 int i, j, mask = 0;
3474 caddr_t sa, ea;
3475
3476 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
3477 clrbuf(bp);
3478 return;
3479 }
3480
3481 bp->b_flags &= ~B_INVAL;
3482 bp->b_ioflags &= ~BIO_ERROR;
3483 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3484 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3485 (bp->b_offset & PAGE_MASK) == 0) {
3486 if (bp->b_pages[0] == bogus_page)
3487 goto unlock;
3488 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3489 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3490 if ((bp->b_pages[0]->valid & mask) == mask)
3491 goto unlock;
3492 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
3493 ((bp->b_pages[0]->valid & mask) == 0)) {
3494 bzero(bp->b_data, bp->b_bufsize);
3495 bp->b_pages[0]->valid |= mask;
3496 goto unlock;
3497 }
3498 }
3499 ea = sa = bp->b_data;
3500 for(i = 0; i < bp->b_npages; i++, sa = ea) {
3501 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3502 ea = (caddr_t)(vm_offset_t)ulmin(
3503 (u_long)(vm_offset_t)ea,
3504 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3505 if (bp->b_pages[i] == bogus_page)
3506 continue;
3507 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3508 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3509 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3510 if ((bp->b_pages[i]->valid & mask) == mask)
3511 continue;
3512 if ((bp->b_pages[i]->valid & mask) == 0) {
3513 if ((bp->b_pages[i]->flags & PG_ZERO) == 0)
3514 bzero(sa, ea - sa);
3515 } else {
3516 for (; sa < ea; sa += DEV_BSIZE, j++) {
3517 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
3518 (bp->b_pages[i]->valid & (1 << j)) == 0)
3519 bzero(sa, DEV_BSIZE);
3520 }
3521 }
3522 bp->b_pages[i]->valid |= mask;
3523 }
3524 unlock:
3525 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3526 bp->b_resid = 0;
3527 }
3528
3529 /*
3530 * vm_hold_load_pages and vm_hold_free_pages get pages into
3531 * a buffers address space. The pages are anonymous and are
3532 * not associated with a file object.
3533 */
3534 static void
3535 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3536 {
3537 vm_offset_t pg;
3538 vm_page_t p;
3539 int index;
3540
3541 to = round_page(to);
3542 from = round_page(from);
3543 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3544
3545 VM_OBJECT_LOCK(kernel_object);
3546 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3547 tryagain:
3548 /*
3549 * note: must allocate system pages since blocking here
3550 * could intefere with paging I/O, no matter which
3551 * process we are.
3552 */
3553 p = vm_page_alloc(kernel_object,
3554 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3555 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
3556 if (!p) {
3557 atomic_add_int(&vm_pageout_deficit,
3558 (to - pg) >> PAGE_SHIFT);
3559 VM_OBJECT_UNLOCK(kernel_object);
3560 VM_WAIT;
3561 VM_OBJECT_LOCK(kernel_object);
3562 goto tryagain;
3563 }
3564 p->valid = VM_PAGE_BITS_ALL;
3565 pmap_qenter(pg, &p, 1);
3566 bp->b_pages[index] = p;
3567 }
3568 VM_OBJECT_UNLOCK(kernel_object);
3569 bp->b_npages = index;
3570 }
3571
3572 /* Return pages associated with this buf to the vm system */
3573 static void
3574 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3575 {
3576 vm_offset_t pg;
3577 vm_page_t p;
3578 int index, newnpages;
3579
3580 from = round_page(from);
3581 to = round_page(to);
3582 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3583
3584 VM_OBJECT_LOCK(kernel_object);
3585 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3586 p = bp->b_pages[index];
3587 if (p && (index < bp->b_npages)) {
3588 if (p->busy) {
3589 printf(
3590 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3591 (intmax_t)bp->b_blkno,
3592 (intmax_t)bp->b_lblkno);
3593 }
3594 bp->b_pages[index] = NULL;
3595 pmap_qremove(pg, 1);
3596 vm_page_lock_queues();
3597 vm_page_unwire(p, 0);
3598 vm_page_free(p);
3599 vm_page_unlock_queues();
3600 }
3601 }
3602 VM_OBJECT_UNLOCK(kernel_object);
3603 bp->b_npages = newnpages;
3604 }
3605
3606 /*
3607 * Map an IO request into kernel virtual address space.
3608 *
3609 * All requests are (re)mapped into kernel VA space.
3610 * Notice that we use b_bufsize for the size of the buffer
3611 * to be mapped. b_bcount might be modified by the driver.
3612 *
3613 * Note that even if the caller determines that the address space should
3614 * be valid, a race or a smaller-file mapped into a larger space may
3615 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3616 * check the return value.
3617 */
3618 int
3619 vmapbuf(struct buf *bp)
3620 {
3621 caddr_t addr, kva;
3622 vm_prot_t prot;
3623 int pidx, i;
3624 struct vm_page *m;
3625 struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
3626
3627 if (bp->b_bufsize < 0)
3628 return (-1);
3629 prot = VM_PROT_READ;
3630 if (bp->b_iocmd == BIO_READ)
3631 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
3632 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
3633 addr < bp->b_data + bp->b_bufsize;
3634 addr += PAGE_SIZE, pidx++) {
3635 /*
3636 * Do the vm_fault if needed; do the copy-on-write thing
3637 * when reading stuff off device into memory.
3638 *
3639 * NOTE! Must use pmap_extract() because addr may be in
3640 * the userland address space, and kextract is only guarenteed
3641 * to work for the kernland address space (see: sparc64 port).
3642 */
3643 retry:
3644 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
3645 prot) < 0) {
3646 vm_page_lock_queues();
3647 for (i = 0; i < pidx; ++i) {
3648 vm_page_unhold(bp->b_pages[i]);
3649 bp->b_pages[i] = NULL;
3650 }
3651 vm_page_unlock_queues();
3652 return(-1);
3653 }
3654 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
3655 if (m == NULL)
3656 goto retry;
3657 bp->b_pages[pidx] = m;
3658 }
3659 if (pidx > btoc(MAXPHYS))
3660 panic("vmapbuf: mapped more than MAXPHYS");
3661 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3662
3663 kva = bp->b_saveaddr;
3664 bp->b_npages = pidx;
3665 bp->b_saveaddr = bp->b_data;
3666 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3667 return(0);
3668 }
3669
3670 /*
3671 * Free the io map PTEs associated with this IO operation.
3672 * We also invalidate the TLB entries and restore the original b_addr.
3673 */
3674 void
3675 vunmapbuf(struct buf *bp)
3676 {
3677 int pidx;
3678 int npages;
3679
3680 npages = bp->b_npages;
3681 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
3682 vm_page_lock_queues();
3683 for (pidx = 0; pidx < npages; pidx++)
3684 vm_page_unhold(bp->b_pages[pidx]);
3685 vm_page_unlock_queues();
3686
3687 bp->b_data = bp->b_saveaddr;
3688 }
3689
3690 void
3691 bdone(struct buf *bp)
3692 {
3693
3694 mtx_lock(&bdonelock);
3695 bp->b_flags |= B_DONE;
3696 wakeup(bp);
3697 mtx_unlock(&bdonelock);
3698 }
3699
3700 void
3701 bwait(struct buf *bp, u_char pri, const char *wchan)
3702 {
3703
3704 mtx_lock(&bdonelock);
3705 while ((bp->b_flags & B_DONE) == 0)
3706 msleep(bp, &bdonelock, pri, wchan, 0);
3707 mtx_unlock(&bdonelock);
3708 }
3709
3710 int
3711 bufsync(struct bufobj *bo, int waitfor, struct thread *td)
3712 {
3713
3714 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td));
3715 }
3716
3717 void
3718 bufstrategy(struct bufobj *bo, struct buf *bp)
3719 {
3720 int i = 0;
3721 struct vnode *vp;
3722
3723 vp = bp->b_vp;
3724 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
3725 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
3726 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
3727 i = VOP_STRATEGY(vp, bp);
3728 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
3729 }
3730
3731 void
3732 bufobj_wrefl(struct bufobj *bo)
3733 {
3734
3735 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3736 ASSERT_BO_LOCKED(bo);
3737 bo->bo_numoutput++;
3738 }
3739
3740 void
3741 bufobj_wref(struct bufobj *bo)
3742 {
3743
3744 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3745 BO_LOCK(bo);
3746 bo->bo_numoutput++;
3747 BO_UNLOCK(bo);
3748 }
3749
3750 void
3751 bufobj_wdrop(struct bufobj *bo)
3752 {
3753
3754 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
3755 BO_LOCK(bo);
3756 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
3757 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
3758 bo->bo_flag &= ~BO_WWAIT;
3759 wakeup(&bo->bo_numoutput);
3760 }
3761 BO_UNLOCK(bo);
3762 }
3763
3764 int
3765 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
3766 {
3767 int error;
3768
3769 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
3770 ASSERT_BO_LOCKED(bo);
3771 error = 0;
3772 while (bo->bo_numoutput) {
3773 bo->bo_flag |= BO_WWAIT;
3774 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
3775 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
3776 if (error)
3777 break;
3778 }
3779 return (error);
3780 }
3781
3782 #include "opt_ddb.h"
3783 #ifdef DDB
3784 #include <ddb/ddb.h>
3785
3786 /* DDB command to show buffer data */
3787 DB_SHOW_COMMAND(buffer, db_show_buffer)
3788 {
3789 /* get args */
3790 struct buf *bp = (struct buf *)addr;
3791
3792 if (!have_addr) {
3793 db_printf("usage: show buffer <addr>\n");
3794 return;
3795 }
3796
3797 db_printf("buf at %p\n", bp);
3798 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3799 db_printf(
3800 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
3801 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n",
3802 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3803 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno);
3804 if (bp->b_npages) {
3805 int i;
3806 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
3807 for (i = 0; i < bp->b_npages; i++) {
3808 vm_page_t m;
3809 m = bp->b_pages[i];
3810 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3811 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3812 if ((i + 1) < bp->b_npages)
3813 db_printf(",");
3814 }
3815 db_printf("\n");
3816 }
3817 lockmgr_printinfo(&bp->b_lock);
3818 }
3819
3820 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
3821 {
3822 struct buf *bp;
3823 int i;
3824
3825 for (i = 0; i < nbuf; i++) {
3826 bp = &buf[i];
3827 if (lockcount(&bp->b_lock)) {
3828 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
3829 db_printf("\n");
3830 }
3831 }
3832 }
3833 #endif /* DDB */
Cache object: 2f8a386a8e1d3b085a391eeeca65acf8
|