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 * Copyright (c) 2013 The FreeBSD Foundation
5 * All rights reserved.
6 *
7 * Portions of this software were developed by Konstantin Belousov
8 * under sponsorship from the FreeBSD Foundation.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 /*
33 * this file contains a new buffer I/O scheme implementing a coherent
34 * VM object and buffer cache scheme. Pains have been taken to make
35 * sure that the performance degradation associated with schemes such
36 * as this is not realized.
37 *
38 * Author: John S. Dyson
39 * Significant help during the development and debugging phases
40 * had been provided by David Greenman, also of the FreeBSD core team.
41 *
42 * see man buf(9) for more info.
43 */
44
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD: releng/10.0/sys/kern/vfs_bio.c 256213 2013-10-09 18:45:01Z kib $");
47
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/bio.h>
51 #include <sys/conf.h>
52 #include <sys/buf.h>
53 #include <sys/devicestat.h>
54 #include <sys/eventhandler.h>
55 #include <sys/fail.h>
56 #include <sys/limits.h>
57 #include <sys/lock.h>
58 #include <sys/malloc.h>
59 #include <sys/mount.h>
60 #include <sys/mutex.h>
61 #include <sys/kernel.h>
62 #include <sys/kthread.h>
63 #include <sys/proc.h>
64 #include <sys/resourcevar.h>
65 #include <sys/rwlock.h>
66 #include <sys/sysctl.h>
67 #include <sys/vmem.h>
68 #include <sys/vmmeter.h>
69 #include <sys/vnode.h>
70 #include <geom/geom.h>
71 #include <vm/vm.h>
72 #include <vm/vm_param.h>
73 #include <vm/vm_kern.h>
74 #include <vm/vm_pageout.h>
75 #include <vm/vm_page.h>
76 #include <vm/vm_object.h>
77 #include <vm/vm_extern.h>
78 #include <vm/vm_map.h>
79 #include "opt_compat.h"
80 #include "opt_directio.h"
81 #include "opt_swap.h"
82
83 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
84
85 struct bio_ops bioops; /* I/O operation notification */
86
87 struct buf_ops buf_ops_bio = {
88 .bop_name = "buf_ops_bio",
89 .bop_write = bufwrite,
90 .bop_strategy = bufstrategy,
91 .bop_sync = bufsync,
92 .bop_bdflush = bufbdflush,
93 };
94
95 /*
96 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
97 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
98 */
99 struct buf *buf; /* buffer header pool */
100 caddr_t unmapped_buf;
101
102 static struct proc *bufdaemonproc;
103
104 static int inmem(struct vnode *vp, daddr_t blkno);
105 static void vm_hold_free_pages(struct buf *bp, int newbsize);
106 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
107 vm_offset_t to);
108 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
109 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
110 vm_page_t m);
111 static void vfs_clean_pages_dirty_buf(struct buf *bp);
112 static void vfs_setdirty_locked_object(struct buf *bp);
113 static void vfs_vmio_release(struct buf *bp);
114 static int vfs_bio_clcheck(struct vnode *vp, int size,
115 daddr_t lblkno, daddr_t blkno);
116 static int buf_flush(int);
117 static int flushbufqueues(int, int);
118 static void buf_daemon(void);
119 static void bremfreel(struct buf *bp);
120 static __inline void bd_wakeup(void);
121 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
122 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
123 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
124 #endif
125
126 int vmiodirenable = TRUE;
127 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
128 "Use the VM system for directory writes");
129 long runningbufspace;
130 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
131 "Amount of presently outstanding async buffer io");
132 static long bufspace;
133 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
134 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
135 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
136 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
137 #else
138 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
139 "Virtual memory used for buffers");
140 #endif
141 static long unmapped_bufspace;
142 SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD,
143 &unmapped_bufspace, 0,
144 "Amount of unmapped buffers, inclusive in the bufspace");
145 static long maxbufspace;
146 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
147 "Maximum allowed value of bufspace (including buf_daemon)");
148 static long bufmallocspace;
149 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
150 "Amount of malloced memory for buffers");
151 static long maxbufmallocspace;
152 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
153 "Maximum amount of malloced memory for buffers");
154 static long lobufspace;
155 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
156 "Minimum amount of buffers we want to have");
157 long hibufspace;
158 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
159 "Maximum allowed value of bufspace (excluding buf_daemon)");
160 static int bufreusecnt;
161 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
162 "Number of times we have reused a buffer");
163 static int buffreekvacnt;
164 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
165 "Number of times we have freed the KVA space from some buffer");
166 static int bufdefragcnt;
167 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
168 "Number of times we have had to repeat buffer allocation to defragment");
169 static long lorunningspace;
170 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
171 "Minimum preferred space used for in-progress I/O");
172 static long hirunningspace;
173 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
174 "Maximum amount of space to use for in-progress I/O");
175 int dirtybufferflushes;
176 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
177 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
178 int bdwriteskip;
179 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
180 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
181 int altbufferflushes;
182 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
183 0, "Number of fsync flushes to limit dirty buffers");
184 static int recursiveflushes;
185 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
186 0, "Number of flushes skipped due to being recursive");
187 static int numdirtybuffers;
188 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
189 "Number of buffers that are dirty (has unwritten changes) at the moment");
190 static int lodirtybuffers;
191 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
192 "How many buffers we want to have free before bufdaemon can sleep");
193 static int hidirtybuffers;
194 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
195 "When the number of dirty buffers is considered severe");
196 int dirtybufthresh;
197 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
198 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
199 static int numfreebuffers;
200 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
201 "Number of free buffers");
202 static int lofreebuffers;
203 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
204 "XXX Unused");
205 static int hifreebuffers;
206 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
207 "XXX Complicatedly unused");
208 static int getnewbufcalls;
209 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
210 "Number of calls to getnewbuf");
211 static int getnewbufrestarts;
212 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
213 "Number of times getnewbuf has had to restart a buffer aquisition");
214 static int mappingrestarts;
215 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0,
216 "Number of times getblk has had to restart a buffer mapping for "
217 "unmapped buffer");
218 static int flushbufqtarget = 100;
219 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
220 "Amount of work to do in flushbufqueues when helping bufdaemon");
221 static long notbufdflushes;
222 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0,
223 "Number of dirty buffer flushes done by the bufdaemon helpers");
224 static long barrierwrites;
225 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
226 "Number of barrier writes");
227 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
228 &unmapped_buf_allowed, 0,
229 "Permit the use of the unmapped i/o");
230
231 /*
232 * Lock for the non-dirty bufqueues
233 */
234 static struct mtx_padalign bqclean;
235
236 /*
237 * Lock for the dirty queue.
238 */
239 static struct mtx_padalign bqdirty;
240
241 /*
242 * This lock synchronizes access to bd_request.
243 */
244 static struct mtx_padalign bdlock;
245
246 /*
247 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
248 * waitrunningbufspace().
249 */
250 static struct mtx_padalign rbreqlock;
251
252 /*
253 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
254 */
255 static struct mtx_padalign nblock;
256
257 /*
258 * Lock that protects bdirtywait.
259 */
260 static struct mtx_padalign bdirtylock;
261
262 /*
263 * Wakeup point for bufdaemon, as well as indicator of whether it is already
264 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
265 * is idling.
266 */
267 static int bd_request;
268
269 /*
270 * Request for the buf daemon to write more buffers than is indicated by
271 * lodirtybuf. This may be necessary to push out excess dependencies or
272 * defragment the address space where a simple count of the number of dirty
273 * buffers is insufficient to characterize the demand for flushing them.
274 */
275 static int bd_speedupreq;
276
277 /*
278 * bogus page -- for I/O to/from partially complete buffers
279 * this is a temporary solution to the problem, but it is not
280 * really that bad. it would be better to split the buffer
281 * for input in the case of buffers partially already in memory,
282 * but the code is intricate enough already.
283 */
284 vm_page_t bogus_page;
285
286 /*
287 * Synchronization (sleep/wakeup) variable for active buffer space requests.
288 * Set when wait starts, cleared prior to wakeup().
289 * Used in runningbufwakeup() and waitrunningbufspace().
290 */
291 static int runningbufreq;
292
293 /*
294 * Synchronization (sleep/wakeup) variable for buffer requests.
295 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
296 * by and/or.
297 * Used in numdirtywakeup(), bufspacewakeup(), bufcountadd(), bwillwrite(),
298 * getnewbuf(), and getblk().
299 */
300 static int needsbuffer;
301
302 /*
303 * Synchronization for bwillwrite() waiters.
304 */
305 static int bdirtywait;
306
307 /*
308 * Definitions for the buffer free lists.
309 */
310 #define BUFFER_QUEUES 5 /* number of free buffer queues */
311
312 #define QUEUE_NONE 0 /* on no queue */
313 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
314 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
315 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
316 #define QUEUE_EMPTY 4 /* empty buffer headers */
317 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
318
319 /* Queues for free buffers with various properties */
320 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
321 #ifdef INVARIANTS
322 static int bq_len[BUFFER_QUEUES];
323 #endif
324
325 /*
326 * Single global constant for BUF_WMESG, to avoid getting multiple references.
327 * buf_wmesg is referred from macros.
328 */
329 const char *buf_wmesg = BUF_WMESG;
330
331 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
332 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
333 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
334
335 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
336 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
337 static int
338 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
339 {
340 long lvalue;
341 int ivalue;
342
343 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
344 return (sysctl_handle_long(oidp, arg1, arg2, req));
345 lvalue = *(long *)arg1;
346 if (lvalue > INT_MAX)
347 /* On overflow, still write out a long to trigger ENOMEM. */
348 return (sysctl_handle_long(oidp, &lvalue, 0, req));
349 ivalue = lvalue;
350 return (sysctl_handle_int(oidp, &ivalue, 0, req));
351 }
352 #endif
353
354 #ifdef DIRECTIO
355 extern void ffs_rawread_setup(void);
356 #endif /* DIRECTIO */
357
358 /*
359 * bqlock:
360 *
361 * Return the appropriate queue lock based on the index.
362 */
363 static inline struct mtx *
364 bqlock(int qindex)
365 {
366
367 if (qindex == QUEUE_DIRTY)
368 return (struct mtx *)(&bqdirty);
369 return (struct mtx *)(&bqclean);
370 }
371
372 /*
373 * bdirtywakeup:
374 *
375 * Wakeup any bwillwrite() waiters.
376 */
377 static void
378 bdirtywakeup(void)
379 {
380 mtx_lock(&bdirtylock);
381 if (bdirtywait) {
382 bdirtywait = 0;
383 wakeup(&bdirtywait);
384 }
385 mtx_unlock(&bdirtylock);
386 }
387
388 /*
389 * bdirtysub:
390 *
391 * Decrement the numdirtybuffers count by one and wakeup any
392 * threads blocked in bwillwrite().
393 */
394 static void
395 bdirtysub(void)
396 {
397
398 if (atomic_fetchadd_int(&numdirtybuffers, -1) ==
399 (lodirtybuffers + hidirtybuffers) / 2)
400 bdirtywakeup();
401 }
402
403 /*
404 * bdirtyadd:
405 *
406 * Increment the numdirtybuffers count by one and wakeup the buf
407 * daemon if needed.
408 */
409 static void
410 bdirtyadd(void)
411 {
412
413 /*
414 * Only do the wakeup once as we cross the boundary. The
415 * buf daemon will keep running until the condition clears.
416 */
417 if (atomic_fetchadd_int(&numdirtybuffers, 1) ==
418 (lodirtybuffers + hidirtybuffers) / 2)
419 bd_wakeup();
420 }
421
422 /*
423 * bufspacewakeup:
424 *
425 * Called when buffer space is potentially available for recovery.
426 * getnewbuf() will block on this flag when it is unable to free
427 * sufficient buffer space. Buffer space becomes recoverable when
428 * bp's get placed back in the queues.
429 */
430
431 static __inline void
432 bufspacewakeup(void)
433 {
434
435 /*
436 * If someone is waiting for BUF space, wake them up. Even
437 * though we haven't freed the kva space yet, the waiting
438 * process will be able to now.
439 */
440 mtx_lock(&nblock);
441 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
442 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
443 wakeup(&needsbuffer);
444 }
445 mtx_unlock(&nblock);
446 }
447
448 /*
449 * runningwakeup:
450 *
451 * Wake up processes that are waiting on asynchronous writes to fall
452 * below lorunningspace.
453 */
454 static void
455 runningwakeup(void)
456 {
457
458 mtx_lock(&rbreqlock);
459 if (runningbufreq) {
460 runningbufreq = 0;
461 wakeup(&runningbufreq);
462 }
463 mtx_unlock(&rbreqlock);
464 }
465
466 /*
467 * runningbufwakeup:
468 *
469 * Decrement the outstanding write count according.
470 */
471 void
472 runningbufwakeup(struct buf *bp)
473 {
474 long space, bspace;
475
476 bspace = bp->b_runningbufspace;
477 if (bspace == 0)
478 return;
479 space = atomic_fetchadd_long(&runningbufspace, -bspace);
480 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
481 space, bspace));
482 bp->b_runningbufspace = 0;
483 /*
484 * Only acquire the lock and wakeup on the transition from exceeding
485 * the threshold to falling below it.
486 */
487 if (space < lorunningspace)
488 return;
489 if (space - bspace > lorunningspace)
490 return;
491 runningwakeup();
492 }
493
494 /*
495 * bufcountadd:
496 *
497 * Called when a buffer has been added to one of the free queues to
498 * account for the buffer and to wakeup anyone waiting for free buffers.
499 * This typically occurs when large amounts of metadata are being handled
500 * by the buffer cache ( else buffer space runs out first, usually ).
501 */
502 static __inline void
503 bufcountadd(struct buf *bp)
504 {
505 int old;
506
507 KASSERT((bp->b_flags & B_INFREECNT) == 0,
508 ("buf %p already counted as free", bp));
509 bp->b_flags |= B_INFREECNT;
510 old = atomic_fetchadd_int(&numfreebuffers, 1);
511 KASSERT(old >= 0 && old < nbuf,
512 ("numfreebuffers climbed to %d", old + 1));
513 mtx_lock(&nblock);
514 if (needsbuffer) {
515 needsbuffer &= ~VFS_BIO_NEED_ANY;
516 if (numfreebuffers >= hifreebuffers)
517 needsbuffer &= ~VFS_BIO_NEED_FREE;
518 wakeup(&needsbuffer);
519 }
520 mtx_unlock(&nblock);
521 }
522
523 /*
524 * bufcountsub:
525 *
526 * Decrement the numfreebuffers count as needed.
527 */
528 static void
529 bufcountsub(struct buf *bp)
530 {
531 int old;
532
533 /*
534 * Fixup numfreebuffers count. If the buffer is invalid or not
535 * delayed-write, the buffer was free and we must decrement
536 * numfreebuffers.
537 */
538 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
539 KASSERT((bp->b_flags & B_INFREECNT) != 0,
540 ("buf %p not counted in numfreebuffers", bp));
541 bp->b_flags &= ~B_INFREECNT;
542 old = atomic_fetchadd_int(&numfreebuffers, -1);
543 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
544 }
545 }
546
547 /*
548 * waitrunningbufspace()
549 *
550 * runningbufspace is a measure of the amount of I/O currently
551 * running. This routine is used in async-write situations to
552 * prevent creating huge backups of pending writes to a device.
553 * Only asynchronous writes are governed by this function.
554 *
555 * This does NOT turn an async write into a sync write. It waits
556 * for earlier writes to complete and generally returns before the
557 * caller's write has reached the device.
558 */
559 void
560 waitrunningbufspace(void)
561 {
562
563 mtx_lock(&rbreqlock);
564 while (runningbufspace > hirunningspace) {
565 runningbufreq = 1;
566 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
567 }
568 mtx_unlock(&rbreqlock);
569 }
570
571
572 /*
573 * vfs_buf_test_cache:
574 *
575 * Called when a buffer is extended. This function clears the B_CACHE
576 * bit if the newly extended portion of the buffer does not contain
577 * valid data.
578 */
579 static __inline
580 void
581 vfs_buf_test_cache(struct buf *bp,
582 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
583 vm_page_t m)
584 {
585
586 VM_OBJECT_ASSERT_LOCKED(m->object);
587 if (bp->b_flags & B_CACHE) {
588 int base = (foff + off) & PAGE_MASK;
589 if (vm_page_is_valid(m, base, size) == 0)
590 bp->b_flags &= ~B_CACHE;
591 }
592 }
593
594 /* Wake up the buffer daemon if necessary */
595 static __inline void
596 bd_wakeup(void)
597 {
598
599 mtx_lock(&bdlock);
600 if (bd_request == 0) {
601 bd_request = 1;
602 wakeup(&bd_request);
603 }
604 mtx_unlock(&bdlock);
605 }
606
607 /*
608 * bd_speedup - speedup the buffer cache flushing code
609 */
610 void
611 bd_speedup(void)
612 {
613 int needwake;
614
615 mtx_lock(&bdlock);
616 needwake = 0;
617 if (bd_speedupreq == 0 || bd_request == 0)
618 needwake = 1;
619 bd_speedupreq = 1;
620 bd_request = 1;
621 if (needwake)
622 wakeup(&bd_request);
623 mtx_unlock(&bdlock);
624 }
625
626 #ifdef __i386__
627 #define TRANSIENT_DENOM 5
628 #else
629 #define TRANSIENT_DENOM 10
630 #endif
631
632 /*
633 * Calculating buffer cache scaling values and reserve space for buffer
634 * headers. This is called during low level kernel initialization and
635 * may be called more then once. We CANNOT write to the memory area
636 * being reserved at this time.
637 */
638 caddr_t
639 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
640 {
641 int tuned_nbuf;
642 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
643
644 /*
645 * physmem_est is in pages. Convert it to kilobytes (assumes
646 * PAGE_SIZE is >= 1K)
647 */
648 physmem_est = physmem_est * (PAGE_SIZE / 1024);
649
650 /*
651 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
652 * For the first 64MB of ram nominally allocate sufficient buffers to
653 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
654 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
655 * the buffer cache we limit the eventual kva reservation to
656 * maxbcache bytes.
657 *
658 * factor represents the 1/4 x ram conversion.
659 */
660 if (nbuf == 0) {
661 int factor = 4 * BKVASIZE / 1024;
662
663 nbuf = 50;
664 if (physmem_est > 4096)
665 nbuf += min((physmem_est - 4096) / factor,
666 65536 / factor);
667 if (physmem_est > 65536)
668 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
669 32 * 1024 * 1024 / (factor * 5));
670
671 if (maxbcache && nbuf > maxbcache / BKVASIZE)
672 nbuf = maxbcache / BKVASIZE;
673 tuned_nbuf = 1;
674 } else
675 tuned_nbuf = 0;
676
677 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
678 maxbuf = (LONG_MAX / 3) / BKVASIZE;
679 if (nbuf > maxbuf) {
680 if (!tuned_nbuf)
681 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
682 maxbuf);
683 nbuf = maxbuf;
684 }
685
686 /*
687 * Ideal allocation size for the transient bio submap if 10%
688 * of the maximal space buffer map. This roughly corresponds
689 * to the amount of the buffer mapped for typical UFS load.
690 *
691 * Clip the buffer map to reserve space for the transient
692 * BIOs, if its extent is bigger than 90% (80% on i386) of the
693 * maximum buffer map extent on the platform.
694 *
695 * The fall-back to the maxbuf in case of maxbcache unset,
696 * allows to not trim the buffer KVA for the architectures
697 * with ample KVA space.
698 */
699 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
700 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
701 buf_sz = (long)nbuf * BKVASIZE;
702 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
703 (TRANSIENT_DENOM - 1)) {
704 /*
705 * There is more KVA than memory. Do not
706 * adjust buffer map size, and assign the rest
707 * of maxbuf to transient map.
708 */
709 biotmap_sz = maxbuf_sz - buf_sz;
710 } else {
711 /*
712 * Buffer map spans all KVA we could afford on
713 * this platform. Give 10% (20% on i386) of
714 * the buffer map to the transient bio map.
715 */
716 biotmap_sz = buf_sz / TRANSIENT_DENOM;
717 buf_sz -= biotmap_sz;
718 }
719 if (biotmap_sz / INT_MAX > MAXPHYS)
720 bio_transient_maxcnt = INT_MAX;
721 else
722 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
723 /*
724 * Artifically limit to 1024 simultaneous in-flight I/Os
725 * using the transient mapping.
726 */
727 if (bio_transient_maxcnt > 1024)
728 bio_transient_maxcnt = 1024;
729 if (tuned_nbuf)
730 nbuf = buf_sz / BKVASIZE;
731 }
732
733 /*
734 * swbufs are used as temporary holders for I/O, such as paging I/O.
735 * We have no less then 16 and no more then 256.
736 */
737 nswbuf = max(min(nbuf/4, 256), 16);
738 #ifdef NSWBUF_MIN
739 if (nswbuf < NSWBUF_MIN)
740 nswbuf = NSWBUF_MIN;
741 #endif
742 #ifdef DIRECTIO
743 ffs_rawread_setup();
744 #endif
745
746 /*
747 * Reserve space for the buffer cache buffers
748 */
749 swbuf = (void *)v;
750 v = (caddr_t)(swbuf + nswbuf);
751 buf = (void *)v;
752 v = (caddr_t)(buf + nbuf);
753
754 return(v);
755 }
756
757 /* Initialize the buffer subsystem. Called before use of any buffers. */
758 void
759 bufinit(void)
760 {
761 struct buf *bp;
762 int i;
763
764 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF);
765 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF);
766 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
767 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
768 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
769 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
770
771 /* next, make a null set of free lists */
772 for (i = 0; i < BUFFER_QUEUES; i++)
773 TAILQ_INIT(&bufqueues[i]);
774
775 /* finally, initialize each buffer header and stick on empty q */
776 for (i = 0; i < nbuf; i++) {
777 bp = &buf[i];
778 bzero(bp, sizeof *bp);
779 bp->b_flags = B_INVAL | B_INFREECNT;
780 bp->b_rcred = NOCRED;
781 bp->b_wcred = NOCRED;
782 bp->b_qindex = QUEUE_EMPTY;
783 bp->b_xflags = 0;
784 LIST_INIT(&bp->b_dep);
785 BUF_LOCKINIT(bp);
786 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
787 #ifdef INVARIANTS
788 bq_len[QUEUE_EMPTY]++;
789 #endif
790 }
791
792 /*
793 * maxbufspace is the absolute maximum amount of buffer space we are
794 * allowed to reserve in KVM and in real terms. The absolute maximum
795 * is nominally used by buf_daemon. hibufspace is the nominal maximum
796 * used by most other processes. The differential is required to
797 * ensure that buf_daemon is able to run when other processes might
798 * be blocked waiting for buffer space.
799 *
800 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
801 * this may result in KVM fragmentation which is not handled optimally
802 * by the system.
803 */
804 maxbufspace = (long)nbuf * BKVASIZE;
805 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
806 lobufspace = hibufspace - MAXBSIZE;
807
808 /*
809 * Note: The 16 MiB upper limit for hirunningspace was chosen
810 * arbitrarily and may need further tuning. It corresponds to
811 * 128 outstanding write IO requests (if IO size is 128 KiB),
812 * which fits with many RAID controllers' tagged queuing limits.
813 * The lower 1 MiB limit is the historical upper limit for
814 * hirunningspace.
815 */
816 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE),
817 16 * 1024 * 1024), 1024 * 1024);
818 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE);
819
820 /*
821 * Limit the amount of malloc memory since it is wired permanently into
822 * the kernel space. Even though this is accounted for in the buffer
823 * allocation, we don't want the malloced region to grow uncontrolled.
824 * The malloc scheme improves memory utilization significantly on average
825 * (small) directories.
826 */
827 maxbufmallocspace = hibufspace / 20;
828
829 /*
830 * Reduce the chance of a deadlock occuring by limiting the number
831 * of delayed-write dirty buffers we allow to stack up.
832 */
833 hidirtybuffers = nbuf / 4 + 20;
834 dirtybufthresh = hidirtybuffers * 9 / 10;
835 numdirtybuffers = 0;
836 /*
837 * To support extreme low-memory systems, make sure hidirtybuffers cannot
838 * eat up all available buffer space. This occurs when our minimum cannot
839 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
840 * BKVASIZE'd buffers.
841 */
842 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
843 hidirtybuffers >>= 1;
844 }
845 lodirtybuffers = hidirtybuffers / 2;
846
847 /*
848 * Try to keep the number of free buffers in the specified range,
849 * and give special processes (e.g. like buf_daemon) access to an
850 * emergency reserve.
851 */
852 lofreebuffers = nbuf / 18 + 5;
853 hifreebuffers = 2 * lofreebuffers;
854 numfreebuffers = nbuf;
855
856 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
857 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
858 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
859 }
860
861 #ifdef INVARIANTS
862 static inline void
863 vfs_buf_check_mapped(struct buf *bp)
864 {
865
866 KASSERT((bp->b_flags & B_UNMAPPED) == 0,
867 ("mapped buf %p %x", bp, bp->b_flags));
868 KASSERT(bp->b_kvabase != unmapped_buf,
869 ("mapped buf: b_kvabase was not updated %p", bp));
870 KASSERT(bp->b_data != unmapped_buf,
871 ("mapped buf: b_data was not updated %p", bp));
872 }
873
874 static inline void
875 vfs_buf_check_unmapped(struct buf *bp)
876 {
877
878 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED,
879 ("unmapped buf %p %x", bp, bp->b_flags));
880 KASSERT(bp->b_kvabase == unmapped_buf,
881 ("unmapped buf: corrupted b_kvabase %p", bp));
882 KASSERT(bp->b_data == unmapped_buf,
883 ("unmapped buf: corrupted b_data %p", bp));
884 }
885
886 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
887 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
888 #else
889 #define BUF_CHECK_MAPPED(bp) do {} while (0)
890 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
891 #endif
892
893 static void
894 bpmap_qenter(struct buf *bp)
895 {
896
897 BUF_CHECK_MAPPED(bp);
898
899 /*
900 * bp->b_data is relative to bp->b_offset, but
901 * bp->b_offset may be offset into the first page.
902 */
903 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
904 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
905 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
906 (vm_offset_t)(bp->b_offset & PAGE_MASK));
907 }
908
909 /*
910 * bfreekva() - free the kva allocation for a buffer.
911 *
912 * Since this call frees up buffer space, we call bufspacewakeup().
913 */
914 static void
915 bfreekva(struct buf *bp)
916 {
917
918 if (bp->b_kvasize == 0)
919 return;
920
921 atomic_add_int(&buffreekvacnt, 1);
922 atomic_subtract_long(&bufspace, bp->b_kvasize);
923 if ((bp->b_flags & B_UNMAPPED) == 0) {
924 BUF_CHECK_MAPPED(bp);
925 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase,
926 bp->b_kvasize);
927 } else {
928 BUF_CHECK_UNMAPPED(bp);
929 if ((bp->b_flags & B_KVAALLOC) != 0) {
930 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc,
931 bp->b_kvasize);
932 }
933 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
934 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
935 }
936 bp->b_kvasize = 0;
937 bufspacewakeup();
938 }
939
940 /*
941 * binsfree:
942 *
943 * Insert the buffer into the appropriate free list.
944 */
945 static void
946 binsfree(struct buf *bp, int qindex)
947 {
948 struct mtx *olock, *nlock;
949
950 BUF_ASSERT_XLOCKED(bp);
951
952 olock = bqlock(bp->b_qindex);
953 nlock = bqlock(qindex);
954 mtx_lock(olock);
955 /* Handle delayed bremfree() processing. */
956 if (bp->b_flags & B_REMFREE)
957 bremfreel(bp);
958
959 if (bp->b_qindex != QUEUE_NONE)
960 panic("binsfree: free buffer onto another queue???");
961
962 bp->b_qindex = qindex;
963 if (olock != nlock) {
964 mtx_unlock(olock);
965 mtx_lock(nlock);
966 }
967 if (bp->b_flags & B_AGE)
968 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
969 else
970 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
971 #ifdef INVARIANTS
972 bq_len[bp->b_qindex]++;
973 #endif
974 mtx_unlock(nlock);
975
976 /*
977 * Something we can maybe free or reuse.
978 */
979 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
980 bufspacewakeup();
981
982 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
983 bufcountadd(bp);
984 }
985
986 /*
987 * bremfree:
988 *
989 * Mark the buffer for removal from the appropriate free list.
990 *
991 */
992 void
993 bremfree(struct buf *bp)
994 {
995
996 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
997 KASSERT((bp->b_flags & B_REMFREE) == 0,
998 ("bremfree: buffer %p already marked for delayed removal.", bp));
999 KASSERT(bp->b_qindex != QUEUE_NONE,
1000 ("bremfree: buffer %p not on a queue.", bp));
1001 BUF_ASSERT_XLOCKED(bp);
1002
1003 bp->b_flags |= B_REMFREE;
1004 bufcountsub(bp);
1005 }
1006
1007 /*
1008 * bremfreef:
1009 *
1010 * Force an immediate removal from a free list. Used only in nfs when
1011 * it abuses the b_freelist pointer.
1012 */
1013 void
1014 bremfreef(struct buf *bp)
1015 {
1016 struct mtx *qlock;
1017
1018 qlock = bqlock(bp->b_qindex);
1019 mtx_lock(qlock);
1020 bremfreel(bp);
1021 mtx_unlock(qlock);
1022 }
1023
1024 /*
1025 * bremfreel:
1026 *
1027 * Removes a buffer from the free list, must be called with the
1028 * correct qlock held.
1029 */
1030 static void
1031 bremfreel(struct buf *bp)
1032 {
1033
1034 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
1035 bp, bp->b_vp, bp->b_flags);
1036 KASSERT(bp->b_qindex != QUEUE_NONE,
1037 ("bremfreel: buffer %p not on a queue.", bp));
1038 BUF_ASSERT_XLOCKED(bp);
1039 mtx_assert(bqlock(bp->b_qindex), MA_OWNED);
1040
1041 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
1042 #ifdef INVARIANTS
1043 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow",
1044 bp->b_qindex));
1045 bq_len[bp->b_qindex]--;
1046 #endif
1047 bp->b_qindex = QUEUE_NONE;
1048 /*
1049 * If this was a delayed bremfree() we only need to remove the buffer
1050 * from the queue and return the stats are already done.
1051 */
1052 if (bp->b_flags & B_REMFREE) {
1053 bp->b_flags &= ~B_REMFREE;
1054 return;
1055 }
1056 bufcountsub(bp);
1057 }
1058
1059 /*
1060 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
1061 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
1062 * the buffer is valid and we do not have to do anything.
1063 */
1064 void
1065 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
1066 int cnt, struct ucred * cred)
1067 {
1068 struct buf *rabp;
1069 int i;
1070
1071 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
1072 if (inmem(vp, *rablkno))
1073 continue;
1074 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
1075
1076 if ((rabp->b_flags & B_CACHE) == 0) {
1077 if (!TD_IS_IDLETHREAD(curthread))
1078 curthread->td_ru.ru_inblock++;
1079 rabp->b_flags |= B_ASYNC;
1080 rabp->b_flags &= ~B_INVAL;
1081 rabp->b_ioflags &= ~BIO_ERROR;
1082 rabp->b_iocmd = BIO_READ;
1083 if (rabp->b_rcred == NOCRED && cred != NOCRED)
1084 rabp->b_rcred = crhold(cred);
1085 vfs_busy_pages(rabp, 0);
1086 BUF_KERNPROC(rabp);
1087 rabp->b_iooffset = dbtob(rabp->b_blkno);
1088 bstrategy(rabp);
1089 } else {
1090 brelse(rabp);
1091 }
1092 }
1093 }
1094
1095 /*
1096 * Entry point for bread() and breadn() via #defines in sys/buf.h.
1097 *
1098 * Get a buffer with the specified data. Look in the cache first. We
1099 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
1100 * is set, the buffer is valid and we do not have to do anything, see
1101 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
1102 */
1103 int
1104 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
1105 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp)
1106 {
1107 struct buf *bp;
1108 int rv = 0, readwait = 0;
1109
1110 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
1111 /*
1112 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
1113 */
1114 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
1115 if (bp == NULL)
1116 return (EBUSY);
1117
1118 /* if not found in cache, do some I/O */
1119 if ((bp->b_flags & B_CACHE) == 0) {
1120 if (!TD_IS_IDLETHREAD(curthread))
1121 curthread->td_ru.ru_inblock++;
1122 bp->b_iocmd = BIO_READ;
1123 bp->b_flags &= ~B_INVAL;
1124 bp->b_ioflags &= ~BIO_ERROR;
1125 if (bp->b_rcred == NOCRED && cred != NOCRED)
1126 bp->b_rcred = crhold(cred);
1127 vfs_busy_pages(bp, 0);
1128 bp->b_iooffset = dbtob(bp->b_blkno);
1129 bstrategy(bp);
1130 ++readwait;
1131 }
1132
1133 breada(vp, rablkno, rabsize, cnt, cred);
1134
1135 if (readwait) {
1136 rv = bufwait(bp);
1137 }
1138 return (rv);
1139 }
1140
1141 /*
1142 * Write, release buffer on completion. (Done by iodone
1143 * if async). Do not bother writing anything if the buffer
1144 * is invalid.
1145 *
1146 * Note that we set B_CACHE here, indicating that buffer is
1147 * fully valid and thus cacheable. This is true even of NFS
1148 * now so we set it generally. This could be set either here
1149 * or in biodone() since the I/O is synchronous. We put it
1150 * here.
1151 */
1152 int
1153 bufwrite(struct buf *bp)
1154 {
1155 int oldflags;
1156 struct vnode *vp;
1157 long space;
1158 int vp_md;
1159
1160 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1161 if (bp->b_flags & B_INVAL) {
1162 brelse(bp);
1163 return (0);
1164 }
1165
1166 if (bp->b_flags & B_BARRIER)
1167 barrierwrites++;
1168
1169 oldflags = bp->b_flags;
1170
1171 BUF_ASSERT_HELD(bp);
1172
1173 if (bp->b_pin_count > 0)
1174 bunpin_wait(bp);
1175
1176 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
1177 ("FFS background buffer should not get here %p", bp));
1178
1179 vp = bp->b_vp;
1180 if (vp)
1181 vp_md = vp->v_vflag & VV_MD;
1182 else
1183 vp_md = 0;
1184
1185 /*
1186 * Mark the buffer clean. Increment the bufobj write count
1187 * before bundirty() call, to prevent other thread from seeing
1188 * empty dirty list and zero counter for writes in progress,
1189 * falsely indicating that the bufobj is clean.
1190 */
1191 bufobj_wref(bp->b_bufobj);
1192 bundirty(bp);
1193
1194 bp->b_flags &= ~B_DONE;
1195 bp->b_ioflags &= ~BIO_ERROR;
1196 bp->b_flags |= B_CACHE;
1197 bp->b_iocmd = BIO_WRITE;
1198
1199 vfs_busy_pages(bp, 1);
1200
1201 /*
1202 * Normal bwrites pipeline writes
1203 */
1204 bp->b_runningbufspace = bp->b_bufsize;
1205 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
1206
1207 if (!TD_IS_IDLETHREAD(curthread))
1208 curthread->td_ru.ru_oublock++;
1209 if (oldflags & B_ASYNC)
1210 BUF_KERNPROC(bp);
1211 bp->b_iooffset = dbtob(bp->b_blkno);
1212 bstrategy(bp);
1213
1214 if ((oldflags & B_ASYNC) == 0) {
1215 int rtval = bufwait(bp);
1216 brelse(bp);
1217 return (rtval);
1218 } else if (space > hirunningspace) {
1219 /*
1220 * don't allow the async write to saturate the I/O
1221 * system. We will not deadlock here because
1222 * we are blocking waiting for I/O that is already in-progress
1223 * to complete. We do not block here if it is the update
1224 * or syncer daemon trying to clean up as that can lead
1225 * to deadlock.
1226 */
1227 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
1228 waitrunningbufspace();
1229 }
1230
1231 return (0);
1232 }
1233
1234 void
1235 bufbdflush(struct bufobj *bo, struct buf *bp)
1236 {
1237 struct buf *nbp;
1238
1239 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
1240 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
1241 altbufferflushes++;
1242 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
1243 BO_LOCK(bo);
1244 /*
1245 * Try to find a buffer to flush.
1246 */
1247 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
1248 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
1249 BUF_LOCK(nbp,
1250 LK_EXCLUSIVE | LK_NOWAIT, NULL))
1251 continue;
1252 if (bp == nbp)
1253 panic("bdwrite: found ourselves");
1254 BO_UNLOCK(bo);
1255 /* Don't countdeps with the bo lock held. */
1256 if (buf_countdeps(nbp, 0)) {
1257 BO_LOCK(bo);
1258 BUF_UNLOCK(nbp);
1259 continue;
1260 }
1261 if (nbp->b_flags & B_CLUSTEROK) {
1262 vfs_bio_awrite(nbp);
1263 } else {
1264 bremfree(nbp);
1265 bawrite(nbp);
1266 }
1267 dirtybufferflushes++;
1268 break;
1269 }
1270 if (nbp == NULL)
1271 BO_UNLOCK(bo);
1272 }
1273 }
1274
1275 /*
1276 * Delayed write. (Buffer is marked dirty). Do not bother writing
1277 * anything if the buffer is marked invalid.
1278 *
1279 * Note that since the buffer must be completely valid, we can safely
1280 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
1281 * biodone() in order to prevent getblk from writing the buffer
1282 * out synchronously.
1283 */
1284 void
1285 bdwrite(struct buf *bp)
1286 {
1287 struct thread *td = curthread;
1288 struct vnode *vp;
1289 struct bufobj *bo;
1290
1291 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1292 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1293 KASSERT((bp->b_flags & B_BARRIER) == 0,
1294 ("Barrier request in delayed write %p", bp));
1295 BUF_ASSERT_HELD(bp);
1296
1297 if (bp->b_flags & B_INVAL) {
1298 brelse(bp);
1299 return;
1300 }
1301
1302 /*
1303 * If we have too many dirty buffers, don't create any more.
1304 * If we are wildly over our limit, then force a complete
1305 * cleanup. Otherwise, just keep the situation from getting
1306 * out of control. Note that we have to avoid a recursive
1307 * disaster and not try to clean up after our own cleanup!
1308 */
1309 vp = bp->b_vp;
1310 bo = bp->b_bufobj;
1311 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
1312 td->td_pflags |= TDP_INBDFLUSH;
1313 BO_BDFLUSH(bo, bp);
1314 td->td_pflags &= ~TDP_INBDFLUSH;
1315 } else
1316 recursiveflushes++;
1317
1318 bdirty(bp);
1319 /*
1320 * Set B_CACHE, indicating that the buffer is fully valid. This is
1321 * true even of NFS now.
1322 */
1323 bp->b_flags |= B_CACHE;
1324
1325 /*
1326 * This bmap keeps the system from needing to do the bmap later,
1327 * perhaps when the system is attempting to do a sync. Since it
1328 * is likely that the indirect block -- or whatever other datastructure
1329 * that the filesystem needs is still in memory now, it is a good
1330 * thing to do this. Note also, that if the pageout daemon is
1331 * requesting a sync -- there might not be enough memory to do
1332 * the bmap then... So, this is important to do.
1333 */
1334 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1335 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1336 }
1337
1338 /*
1339 * Set the *dirty* buffer range based upon the VM system dirty
1340 * pages.
1341 *
1342 * Mark the buffer pages as clean. We need to do this here to
1343 * satisfy the vnode_pager and the pageout daemon, so that it
1344 * thinks that the pages have been "cleaned". Note that since
1345 * the pages are in a delayed write buffer -- the VFS layer
1346 * "will" see that the pages get written out on the next sync,
1347 * or perhaps the cluster will be completed.
1348 */
1349 vfs_clean_pages_dirty_buf(bp);
1350 bqrelse(bp);
1351
1352 /*
1353 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1354 * due to the softdep code.
1355 */
1356 }
1357
1358 /*
1359 * bdirty:
1360 *
1361 * Turn buffer into delayed write request. We must clear BIO_READ and
1362 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1363 * itself to properly update it in the dirty/clean lists. We mark it
1364 * B_DONE to ensure that any asynchronization of the buffer properly
1365 * clears B_DONE ( else a panic will occur later ).
1366 *
1367 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1368 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1369 * should only be called if the buffer is known-good.
1370 *
1371 * Since the buffer is not on a queue, we do not update the numfreebuffers
1372 * count.
1373 *
1374 * The buffer must be on QUEUE_NONE.
1375 */
1376 void
1377 bdirty(struct buf *bp)
1378 {
1379
1380 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1381 bp, bp->b_vp, bp->b_flags);
1382 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1383 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1384 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1385 BUF_ASSERT_HELD(bp);
1386 bp->b_flags &= ~(B_RELBUF);
1387 bp->b_iocmd = BIO_WRITE;
1388
1389 if ((bp->b_flags & B_DELWRI) == 0) {
1390 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1391 reassignbuf(bp);
1392 bdirtyadd();
1393 }
1394 }
1395
1396 /*
1397 * bundirty:
1398 *
1399 * Clear B_DELWRI for buffer.
1400 *
1401 * Since the buffer is not on a queue, we do not update the numfreebuffers
1402 * count.
1403 *
1404 * The buffer must be on QUEUE_NONE.
1405 */
1406
1407 void
1408 bundirty(struct buf *bp)
1409 {
1410
1411 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1412 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1413 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1414 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1415 BUF_ASSERT_HELD(bp);
1416
1417 if (bp->b_flags & B_DELWRI) {
1418 bp->b_flags &= ~B_DELWRI;
1419 reassignbuf(bp);
1420 bdirtysub();
1421 }
1422 /*
1423 * Since it is now being written, we can clear its deferred write flag.
1424 */
1425 bp->b_flags &= ~B_DEFERRED;
1426 }
1427
1428 /*
1429 * bawrite:
1430 *
1431 * Asynchronous write. Start output on a buffer, but do not wait for
1432 * it to complete. The buffer is released when the output completes.
1433 *
1434 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1435 * B_INVAL buffers. Not us.
1436 */
1437 void
1438 bawrite(struct buf *bp)
1439 {
1440
1441 bp->b_flags |= B_ASYNC;
1442 (void) bwrite(bp);
1443 }
1444
1445 /*
1446 * babarrierwrite:
1447 *
1448 * Asynchronous barrier write. Start output on a buffer, but do not
1449 * wait for it to complete. Place a write barrier after this write so
1450 * that this buffer and all buffers written before it are committed to
1451 * the disk before any buffers written after this write are committed
1452 * to the disk. The buffer is released when the output completes.
1453 */
1454 void
1455 babarrierwrite(struct buf *bp)
1456 {
1457
1458 bp->b_flags |= B_ASYNC | B_BARRIER;
1459 (void) bwrite(bp);
1460 }
1461
1462 /*
1463 * bbarrierwrite:
1464 *
1465 * Synchronous barrier write. Start output on a buffer and wait for
1466 * it to complete. Place a write barrier after this write so that
1467 * this buffer and all buffers written before it are committed to
1468 * the disk before any buffers written after this write are committed
1469 * to the disk. The buffer is released when the output completes.
1470 */
1471 int
1472 bbarrierwrite(struct buf *bp)
1473 {
1474
1475 bp->b_flags |= B_BARRIER;
1476 return (bwrite(bp));
1477 }
1478
1479 /*
1480 * bwillwrite:
1481 *
1482 * Called prior to the locking of any vnodes when we are expecting to
1483 * write. We do not want to starve the buffer cache with too many
1484 * dirty buffers so we block here. By blocking prior to the locking
1485 * of any vnodes we attempt to avoid the situation where a locked vnode
1486 * prevents the various system daemons from flushing related buffers.
1487 */
1488 void
1489 bwillwrite(void)
1490 {
1491
1492 if (numdirtybuffers >= hidirtybuffers) {
1493 mtx_lock(&bdirtylock);
1494 while (numdirtybuffers >= hidirtybuffers) {
1495 bdirtywait = 1;
1496 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
1497 "flswai", 0);
1498 }
1499 mtx_unlock(&bdirtylock);
1500 }
1501 }
1502
1503 /*
1504 * Return true if we have too many dirty buffers.
1505 */
1506 int
1507 buf_dirty_count_severe(void)
1508 {
1509
1510 return(numdirtybuffers >= hidirtybuffers);
1511 }
1512
1513 static __noinline int
1514 buf_vm_page_count_severe(void)
1515 {
1516
1517 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1);
1518
1519 return vm_page_count_severe();
1520 }
1521
1522 /*
1523 * brelse:
1524 *
1525 * Release a busy buffer and, if requested, free its resources. The
1526 * buffer will be stashed in the appropriate bufqueue[] allowing it
1527 * to be accessed later as a cache entity or reused for other purposes.
1528 */
1529 void
1530 brelse(struct buf *bp)
1531 {
1532 int qindex;
1533
1534 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1535 bp, bp->b_vp, bp->b_flags);
1536 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1537 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1538
1539 if (BUF_LOCKRECURSED(bp)) {
1540 /*
1541 * Do not process, in particular, do not handle the
1542 * B_INVAL/B_RELBUF and do not release to free list.
1543 */
1544 BUF_UNLOCK(bp);
1545 return;
1546 }
1547
1548 if (bp->b_flags & B_MANAGED) {
1549 bqrelse(bp);
1550 return;
1551 }
1552
1553 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
1554 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) {
1555 /*
1556 * Failed write, redirty. Must clear BIO_ERROR to prevent
1557 * pages from being scrapped. If the error is anything
1558 * other than an I/O error (EIO), assume that retrying
1559 * is futile.
1560 */
1561 bp->b_ioflags &= ~BIO_ERROR;
1562 bdirty(bp);
1563 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1564 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1565 /*
1566 * Either a failed I/O or we were asked to free or not
1567 * cache the buffer.
1568 */
1569 bp->b_flags |= B_INVAL;
1570 if (!LIST_EMPTY(&bp->b_dep))
1571 buf_deallocate(bp);
1572 if (bp->b_flags & B_DELWRI)
1573 bdirtysub();
1574 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1575 if ((bp->b_flags & B_VMIO) == 0) {
1576 if (bp->b_bufsize)
1577 allocbuf(bp, 0);
1578 if (bp->b_vp)
1579 brelvp(bp);
1580 }
1581 }
1582
1583 /*
1584 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1585 * is called with B_DELWRI set, the underlying pages may wind up
1586 * getting freed causing a previous write (bdwrite()) to get 'lost'
1587 * because pages associated with a B_DELWRI bp are marked clean.
1588 *
1589 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1590 * if B_DELWRI is set.
1591 *
1592 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1593 * on pages to return pages to the VM page queues.
1594 */
1595 if (bp->b_flags & B_DELWRI)
1596 bp->b_flags &= ~B_RELBUF;
1597 else if (buf_vm_page_count_severe()) {
1598 /*
1599 * BKGRDINPROG can only be set with the buf and bufobj
1600 * locks both held. We tolerate a race to clear it here.
1601 */
1602 if (!(bp->b_vflags & BV_BKGRDINPROG))
1603 bp->b_flags |= B_RELBUF;
1604 }
1605
1606 /*
1607 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1608 * constituted, not even NFS buffers now. Two flags effect this. If
1609 * B_INVAL, the struct buf is invalidated but the VM object is kept
1610 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1611 *
1612 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1613 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1614 * buffer is also B_INVAL because it hits the re-dirtying code above.
1615 *
1616 * Normally we can do this whether a buffer is B_DELWRI or not. If
1617 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1618 * the commit state and we cannot afford to lose the buffer. If the
1619 * buffer has a background write in progress, we need to keep it
1620 * around to prevent it from being reconstituted and starting a second
1621 * background write.
1622 */
1623 if ((bp->b_flags & B_VMIO)
1624 && !(bp->b_vp->v_mount != NULL &&
1625 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1626 !vn_isdisk(bp->b_vp, NULL) &&
1627 (bp->b_flags & B_DELWRI))
1628 ) {
1629
1630 int i, j, resid;
1631 vm_page_t m;
1632 off_t foff;
1633 vm_pindex_t poff;
1634 vm_object_t obj;
1635
1636 obj = bp->b_bufobj->bo_object;
1637
1638 /*
1639 * Get the base offset and length of the buffer. Note that
1640 * in the VMIO case if the buffer block size is not
1641 * page-aligned then b_data pointer may not be page-aligned.
1642 * But our b_pages[] array *IS* page aligned.
1643 *
1644 * block sizes less then DEV_BSIZE (usually 512) are not
1645 * supported due to the page granularity bits (m->valid,
1646 * m->dirty, etc...).
1647 *
1648 * See man buf(9) for more information
1649 */
1650 resid = bp->b_bufsize;
1651 foff = bp->b_offset;
1652 for (i = 0; i < bp->b_npages; i++) {
1653 int had_bogus = 0;
1654
1655 m = bp->b_pages[i];
1656
1657 /*
1658 * If we hit a bogus page, fixup *all* the bogus pages
1659 * now.
1660 */
1661 if (m == bogus_page) {
1662 poff = OFF_TO_IDX(bp->b_offset);
1663 had_bogus = 1;
1664
1665 VM_OBJECT_RLOCK(obj);
1666 for (j = i; j < bp->b_npages; j++) {
1667 vm_page_t mtmp;
1668 mtmp = bp->b_pages[j];
1669 if (mtmp == bogus_page) {
1670 mtmp = vm_page_lookup(obj, poff + j);
1671 if (!mtmp) {
1672 panic("brelse: page missing\n");
1673 }
1674 bp->b_pages[j] = mtmp;
1675 }
1676 }
1677 VM_OBJECT_RUNLOCK(obj);
1678
1679 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) {
1680 BUF_CHECK_MAPPED(bp);
1681 pmap_qenter(
1682 trunc_page((vm_offset_t)bp->b_data),
1683 bp->b_pages, bp->b_npages);
1684 }
1685 m = bp->b_pages[i];
1686 }
1687 if ((bp->b_flags & B_NOCACHE) ||
1688 (bp->b_ioflags & BIO_ERROR &&
1689 bp->b_iocmd == BIO_READ)) {
1690 int poffset = foff & PAGE_MASK;
1691 int presid = resid > (PAGE_SIZE - poffset) ?
1692 (PAGE_SIZE - poffset) : resid;
1693
1694 KASSERT(presid >= 0, ("brelse: extra page"));
1695 VM_OBJECT_WLOCK(obj);
1696 while (vm_page_xbusied(m)) {
1697 vm_page_lock(m);
1698 VM_OBJECT_WUNLOCK(obj);
1699 vm_page_busy_sleep(m, "mbncsh");
1700 VM_OBJECT_WLOCK(obj);
1701 }
1702 if (pmap_page_wired_mappings(m) == 0)
1703 vm_page_set_invalid(m, poffset, presid);
1704 VM_OBJECT_WUNLOCK(obj);
1705 if (had_bogus)
1706 printf("avoided corruption bug in bogus_page/brelse code\n");
1707 }
1708 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1709 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1710 }
1711 if (bp->b_flags & (B_INVAL | B_RELBUF))
1712 vfs_vmio_release(bp);
1713
1714 } else if (bp->b_flags & B_VMIO) {
1715
1716 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1717 vfs_vmio_release(bp);
1718 }
1719
1720 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1721 if (bp->b_bufsize != 0)
1722 allocbuf(bp, 0);
1723 if (bp->b_vp != NULL)
1724 brelvp(bp);
1725 }
1726
1727 /*
1728 * If the buffer has junk contents signal it and eventually
1729 * clean up B_DELWRI and diassociate the vnode so that gbincore()
1730 * doesn't find it.
1731 */
1732 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
1733 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
1734 bp->b_flags |= B_INVAL;
1735 if (bp->b_flags & B_INVAL) {
1736 if (bp->b_flags & B_DELWRI)
1737 bundirty(bp);
1738 if (bp->b_vp)
1739 brelvp(bp);
1740 }
1741
1742 /* buffers with no memory */
1743 if (bp->b_bufsize == 0) {
1744 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1745 if (bp->b_vflags & BV_BKGRDINPROG)
1746 panic("losing buffer 1");
1747 if (bp->b_kvasize)
1748 qindex = QUEUE_EMPTYKVA;
1749 else
1750 qindex = QUEUE_EMPTY;
1751 bp->b_flags |= B_AGE;
1752 /* buffers with junk contents */
1753 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1754 (bp->b_ioflags & BIO_ERROR)) {
1755 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1756 if (bp->b_vflags & BV_BKGRDINPROG)
1757 panic("losing buffer 2");
1758 qindex = QUEUE_CLEAN;
1759 bp->b_flags |= B_AGE;
1760 /* remaining buffers */
1761 } else if (bp->b_flags & B_DELWRI)
1762 qindex = QUEUE_DIRTY;
1763 else
1764 qindex = QUEUE_CLEAN;
1765
1766 binsfree(bp, qindex);
1767
1768 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1769 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1770 panic("brelse: not dirty");
1771 /* unlock */
1772 BUF_UNLOCK(bp);
1773 }
1774
1775 /*
1776 * Release a buffer back to the appropriate queue but do not try to free
1777 * it. The buffer is expected to be used again soon.
1778 *
1779 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1780 * biodone() to requeue an async I/O on completion. It is also used when
1781 * known good buffers need to be requeued but we think we may need the data
1782 * again soon.
1783 *
1784 * XXX we should be able to leave the B_RELBUF hint set on completion.
1785 */
1786 void
1787 bqrelse(struct buf *bp)
1788 {
1789 int qindex;
1790
1791 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1792 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1793 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1794
1795 if (BUF_LOCKRECURSED(bp)) {
1796 /* do not release to free list */
1797 BUF_UNLOCK(bp);
1798 return;
1799 }
1800 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1801
1802 if (bp->b_flags & B_MANAGED) {
1803 if (bp->b_flags & B_REMFREE)
1804 bremfreef(bp);
1805 goto out;
1806 }
1807
1808 /* buffers with stale but valid contents */
1809 if (bp->b_flags & B_DELWRI) {
1810 qindex = QUEUE_DIRTY;
1811 } else {
1812 if ((bp->b_flags & B_DELWRI) == 0 &&
1813 (bp->b_xflags & BX_VNDIRTY))
1814 panic("bqrelse: not dirty");
1815 /*
1816 * BKGRDINPROG can only be set with the buf and bufobj
1817 * locks both held. We tolerate a race to clear it here.
1818 */
1819 if (buf_vm_page_count_severe() &&
1820 (bp->b_vflags & BV_BKGRDINPROG) == 0) {
1821 /*
1822 * We are too low on memory, we have to try to free
1823 * the buffer (most importantly: the wired pages
1824 * making up its backing store) *now*.
1825 */
1826 brelse(bp);
1827 return;
1828 }
1829 qindex = QUEUE_CLEAN;
1830 }
1831 binsfree(bp, qindex);
1832
1833 out:
1834 /* unlock */
1835 BUF_UNLOCK(bp);
1836 }
1837
1838 /* Give pages used by the bp back to the VM system (where possible) */
1839 static void
1840 vfs_vmio_release(struct buf *bp)
1841 {
1842 int i;
1843 vm_page_t m;
1844
1845 if ((bp->b_flags & B_UNMAPPED) == 0) {
1846 BUF_CHECK_MAPPED(bp);
1847 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
1848 } else
1849 BUF_CHECK_UNMAPPED(bp);
1850 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
1851 for (i = 0; i < bp->b_npages; i++) {
1852 m = bp->b_pages[i];
1853 bp->b_pages[i] = NULL;
1854 /*
1855 * In order to keep page LRU ordering consistent, put
1856 * everything on the inactive queue.
1857 */
1858 vm_page_lock(m);
1859 vm_page_unwire(m, 0);
1860
1861 /*
1862 * Might as well free the page if we can and it has
1863 * no valid data. We also free the page if the
1864 * buffer was used for direct I/O
1865 */
1866 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) {
1867 if (m->wire_count == 0 && !vm_page_busied(m))
1868 vm_page_free(m);
1869 } else if (bp->b_flags & B_DIRECT)
1870 vm_page_try_to_free(m);
1871 else if (buf_vm_page_count_severe())
1872 vm_page_try_to_cache(m);
1873 vm_page_unlock(m);
1874 }
1875 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
1876
1877 if (bp->b_bufsize) {
1878 bufspacewakeup();
1879 bp->b_bufsize = 0;
1880 }
1881 bp->b_npages = 0;
1882 bp->b_flags &= ~B_VMIO;
1883 if (bp->b_vp)
1884 brelvp(bp);
1885 }
1886
1887 /*
1888 * Check to see if a block at a particular lbn is available for a clustered
1889 * write.
1890 */
1891 static int
1892 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1893 {
1894 struct buf *bpa;
1895 int match;
1896
1897 match = 0;
1898
1899 /* If the buf isn't in core skip it */
1900 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1901 return (0);
1902
1903 /* If the buf is busy we don't want to wait for it */
1904 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1905 return (0);
1906
1907 /* Only cluster with valid clusterable delayed write buffers */
1908 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1909 (B_DELWRI | B_CLUSTEROK))
1910 goto done;
1911
1912 if (bpa->b_bufsize != size)
1913 goto done;
1914
1915 /*
1916 * Check to see if it is in the expected place on disk and that the
1917 * block has been mapped.
1918 */
1919 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1920 match = 1;
1921 done:
1922 BUF_UNLOCK(bpa);
1923 return (match);
1924 }
1925
1926 /*
1927 * vfs_bio_awrite:
1928 *
1929 * Implement clustered async writes for clearing out B_DELWRI buffers.
1930 * This is much better then the old way of writing only one buffer at
1931 * a time. Note that we may not be presented with the buffers in the
1932 * correct order, so we search for the cluster in both directions.
1933 */
1934 int
1935 vfs_bio_awrite(struct buf *bp)
1936 {
1937 struct bufobj *bo;
1938 int i;
1939 int j;
1940 daddr_t lblkno = bp->b_lblkno;
1941 struct vnode *vp = bp->b_vp;
1942 int ncl;
1943 int nwritten;
1944 int size;
1945 int maxcl;
1946 int gbflags;
1947
1948 bo = &vp->v_bufobj;
1949 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0;
1950 /*
1951 * right now we support clustered writing only to regular files. If
1952 * we find a clusterable block we could be in the middle of a cluster
1953 * rather then at the beginning.
1954 */
1955 if ((vp->v_type == VREG) &&
1956 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1957 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1958
1959 size = vp->v_mount->mnt_stat.f_iosize;
1960 maxcl = MAXPHYS / size;
1961
1962 BO_RLOCK(bo);
1963 for (i = 1; i < maxcl; i++)
1964 if (vfs_bio_clcheck(vp, size, lblkno + i,
1965 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1966 break;
1967
1968 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1969 if (vfs_bio_clcheck(vp, size, lblkno - j,
1970 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1971 break;
1972 BO_RUNLOCK(bo);
1973 --j;
1974 ncl = i + j;
1975 /*
1976 * this is a possible cluster write
1977 */
1978 if (ncl != 1) {
1979 BUF_UNLOCK(bp);
1980 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
1981 gbflags);
1982 return (nwritten);
1983 }
1984 }
1985 bremfree(bp);
1986 bp->b_flags |= B_ASYNC;
1987 /*
1988 * default (old) behavior, writing out only one block
1989 *
1990 * XXX returns b_bufsize instead of b_bcount for nwritten?
1991 */
1992 nwritten = bp->b_bufsize;
1993 (void) bwrite(bp);
1994
1995 return (nwritten);
1996 }
1997
1998 static void
1999 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags)
2000 {
2001
2002 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 &&
2003 bp->b_kvasize == 0, ("call bfreekva(%p)", bp));
2004 if ((gbflags & GB_UNMAPPED) == 0) {
2005 bp->b_kvabase = (caddr_t)addr;
2006 } else if ((gbflags & GB_KVAALLOC) != 0) {
2007 KASSERT((gbflags & GB_UNMAPPED) != 0,
2008 ("GB_KVAALLOC without GB_UNMAPPED"));
2009 bp->b_kvaalloc = (caddr_t)addr;
2010 bp->b_flags |= B_UNMAPPED | B_KVAALLOC;
2011 atomic_add_long(&unmapped_bufspace, bp->b_kvasize);
2012 }
2013 bp->b_kvasize = maxsize;
2014 }
2015
2016 /*
2017 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if
2018 * needed.
2019 */
2020 static int
2021 allocbufkva(struct buf *bp, int maxsize, int gbflags)
2022 {
2023 vm_offset_t addr;
2024
2025 bfreekva(bp);
2026 addr = 0;
2027
2028 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) {
2029 /*
2030 * Buffer map is too fragmented. Request the caller
2031 * to defragment the map.
2032 */
2033 atomic_add_int(&bufdefragcnt, 1);
2034 return (1);
2035 }
2036 setbufkva(bp, addr, maxsize, gbflags);
2037 atomic_add_long(&bufspace, bp->b_kvasize);
2038 return (0);
2039 }
2040
2041 /*
2042 * Ask the bufdaemon for help, or act as bufdaemon itself, when a
2043 * locked vnode is supplied.
2044 */
2045 static void
2046 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo,
2047 int defrag)
2048 {
2049 struct thread *td;
2050 char *waitmsg;
2051 int cnt, error, flags, norunbuf, wait;
2052
2053 mtx_assert(&bqclean, MA_OWNED);
2054
2055 if (defrag) {
2056 flags = VFS_BIO_NEED_BUFSPACE;
2057 waitmsg = "nbufkv";
2058 } else if (bufspace >= hibufspace) {
2059 waitmsg = "nbufbs";
2060 flags = VFS_BIO_NEED_BUFSPACE;
2061 } else {
2062 waitmsg = "newbuf";
2063 flags = VFS_BIO_NEED_ANY;
2064 }
2065 mtx_lock(&nblock);
2066 needsbuffer |= flags;
2067 mtx_unlock(&nblock);
2068 mtx_unlock(&bqclean);
2069
2070 bd_speedup(); /* heeeelp */
2071 if ((gbflags & GB_NOWAIT_BD) != 0)
2072 return;
2073
2074 td = curthread;
2075 cnt = 0;
2076 wait = MNT_NOWAIT;
2077 mtx_lock(&nblock);
2078 while (needsbuffer & flags) {
2079 if (vp != NULL && vp->v_type != VCHR &&
2080 (td->td_pflags & TDP_BUFNEED) == 0) {
2081 mtx_unlock(&nblock);
2082
2083 /*
2084 * getblk() is called with a vnode locked, and
2085 * some majority of the dirty buffers may as
2086 * well belong to the vnode. Flushing the
2087 * buffers there would make a progress that
2088 * cannot be achieved by the buf_daemon, that
2089 * cannot lock the vnode.
2090 */
2091 if (cnt++ > 2)
2092 wait = MNT_WAIT;
2093 ASSERT_VOP_LOCKED(vp, "bufd_helper");
2094 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
2095 vn_lock(vp, LK_TRYUPGRADE);
2096 if (error == 0) {
2097 /* play bufdaemon */
2098 norunbuf = curthread_pflags_set(TDP_BUFNEED |
2099 TDP_NORUNNINGBUF);
2100 VOP_FSYNC(vp, wait, td);
2101 atomic_add_long(¬bufdflushes, 1);
2102 curthread_pflags_restore(norunbuf);
2103 }
2104 mtx_lock(&nblock);
2105 if ((needsbuffer & flags) == 0)
2106 break;
2107 }
2108 if (msleep(&needsbuffer, &nblock, (PRIBIO + 4) | slpflag,
2109 waitmsg, slptimeo))
2110 break;
2111 }
2112 mtx_unlock(&nblock);
2113 }
2114
2115 static void
2116 getnewbuf_reuse_bp(struct buf *bp, int qindex)
2117 {
2118
2119 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
2120 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
2121 bp->b_kvasize, bp->b_bufsize, qindex);
2122 mtx_assert(&bqclean, MA_NOTOWNED);
2123
2124 /*
2125 * Note: we no longer distinguish between VMIO and non-VMIO
2126 * buffers.
2127 */
2128 KASSERT((bp->b_flags & B_DELWRI) == 0,
2129 ("delwri buffer %p found in queue %d", bp, qindex));
2130
2131 if (qindex == QUEUE_CLEAN) {
2132 if (bp->b_flags & B_VMIO) {
2133 bp->b_flags &= ~B_ASYNC;
2134 vfs_vmio_release(bp);
2135 }
2136 if (bp->b_vp != NULL)
2137 brelvp(bp);
2138 }
2139
2140 /*
2141 * Get the rest of the buffer freed up. b_kva* is still valid
2142 * after this operation.
2143 */
2144
2145 if (bp->b_rcred != NOCRED) {
2146 crfree(bp->b_rcred);
2147 bp->b_rcred = NOCRED;
2148 }
2149 if (bp->b_wcred != NOCRED) {
2150 crfree(bp->b_wcred);
2151 bp->b_wcred = NOCRED;
2152 }
2153 if (!LIST_EMPTY(&bp->b_dep))
2154 buf_deallocate(bp);
2155 if (bp->b_vflags & BV_BKGRDINPROG)
2156 panic("losing buffer 3");
2157 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d",
2158 bp, bp->b_vp, qindex));
2159 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
2160 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
2161
2162 if (bp->b_bufsize)
2163 allocbuf(bp, 0);
2164
2165 bp->b_flags &= B_UNMAPPED | B_KVAALLOC;
2166 bp->b_ioflags = 0;
2167 bp->b_xflags = 0;
2168 KASSERT((bp->b_flags & B_INFREECNT) == 0,
2169 ("buf %p still counted as free?", bp));
2170 bp->b_vflags = 0;
2171 bp->b_vp = NULL;
2172 bp->b_blkno = bp->b_lblkno = 0;
2173 bp->b_offset = NOOFFSET;
2174 bp->b_iodone = 0;
2175 bp->b_error = 0;
2176 bp->b_resid = 0;
2177 bp->b_bcount = 0;
2178 bp->b_npages = 0;
2179 bp->b_dirtyoff = bp->b_dirtyend = 0;
2180 bp->b_bufobj = NULL;
2181 bp->b_pin_count = 0;
2182 bp->b_fsprivate1 = NULL;
2183 bp->b_fsprivate2 = NULL;
2184 bp->b_fsprivate3 = NULL;
2185
2186 LIST_INIT(&bp->b_dep);
2187 }
2188
2189 static int flushingbufs;
2190
2191 static struct buf *
2192 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata)
2193 {
2194 struct buf *bp, *nbp;
2195 int nqindex, qindex, pass;
2196
2197 KASSERT(!unmapped || !defrag, ("both unmapped and defrag"));
2198
2199 pass = 1;
2200 restart:
2201 atomic_add_int(&getnewbufrestarts, 1);
2202
2203 /*
2204 * Setup for scan. If we do not have enough free buffers,
2205 * we setup a degenerate case that immediately fails. Note
2206 * that if we are specially marked process, we are allowed to
2207 * dip into our reserves.
2208 *
2209 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
2210 * for the allocation of the mapped buffer. For unmapped, the
2211 * easiest is to start with EMPTY outright.
2212 *
2213 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
2214 * However, there are a number of cases (defragging, reusing, ...)
2215 * where we cannot backup.
2216 */
2217 nbp = NULL;
2218 mtx_lock(&bqclean);
2219 if (!defrag && unmapped) {
2220 nqindex = QUEUE_EMPTY;
2221 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
2222 }
2223 if (nbp == NULL) {
2224 nqindex = QUEUE_EMPTYKVA;
2225 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
2226 }
2227
2228 /*
2229 * If no EMPTYKVA buffers and we are either defragging or
2230 * reusing, locate a CLEAN buffer to free or reuse. If
2231 * bufspace useage is low skip this step so we can allocate a
2232 * new buffer.
2233 */
2234 if (nbp == NULL && (defrag || bufspace >= lobufspace)) {
2235 nqindex = QUEUE_CLEAN;
2236 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2237 }
2238
2239 /*
2240 * If we could not find or were not allowed to reuse a CLEAN
2241 * buffer, check to see if it is ok to use an EMPTY buffer.
2242 * We can only use an EMPTY buffer if allocating its KVA would
2243 * not otherwise run us out of buffer space. No KVA is needed
2244 * for the unmapped allocation.
2245 */
2246 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace ||
2247 metadata)) {
2248 nqindex = QUEUE_EMPTY;
2249 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
2250 }
2251
2252 /*
2253 * All available buffers might be clean, retry ignoring the
2254 * lobufspace as the last resort.
2255 */
2256 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) {
2257 nqindex = QUEUE_CLEAN;
2258 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2259 }
2260
2261 /*
2262 * Run scan, possibly freeing data and/or kva mappings on the fly
2263 * depending.
2264 */
2265 while ((bp = nbp) != NULL) {
2266 qindex = nqindex;
2267
2268 /*
2269 * Calculate next bp (we can only use it if we do not
2270 * block or do other fancy things).
2271 */
2272 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
2273 switch (qindex) {
2274 case QUEUE_EMPTY:
2275 nqindex = QUEUE_EMPTYKVA;
2276 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
2277 if (nbp != NULL)
2278 break;
2279 /* FALLTHROUGH */
2280 case QUEUE_EMPTYKVA:
2281 nqindex = QUEUE_CLEAN;
2282 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2283 if (nbp != NULL)
2284 break;
2285 /* FALLTHROUGH */
2286 case QUEUE_CLEAN:
2287 if (metadata && pass == 1) {
2288 pass = 2;
2289 nqindex = QUEUE_EMPTY;
2290 nbp = TAILQ_FIRST(
2291 &bufqueues[QUEUE_EMPTY]);
2292 }
2293 /*
2294 * nbp is NULL.
2295 */
2296 break;
2297 }
2298 }
2299 /*
2300 * If we are defragging then we need a buffer with
2301 * b_kvasize != 0. XXX this situation should no longer
2302 * occur, if defrag is non-zero the buffer's b_kvasize
2303 * should also be non-zero at this point. XXX
2304 */
2305 if (defrag && bp->b_kvasize == 0) {
2306 printf("Warning: defrag empty buffer %p\n", bp);
2307 continue;
2308 }
2309
2310 /*
2311 * Start freeing the bp. This is somewhat involved. nbp
2312 * remains valid only for QUEUE_EMPTY[KVA] bp's.
2313 */
2314 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2315 continue;
2316 /*
2317 * BKGRDINPROG can only be set with the buf and bufobj
2318 * locks both held. We tolerate a race to clear it here.
2319 */
2320 if (bp->b_vflags & BV_BKGRDINPROG) {
2321 BUF_UNLOCK(bp);
2322 continue;
2323 }
2324
2325 KASSERT(bp->b_qindex == qindex,
2326 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
2327
2328 bremfreel(bp);
2329 mtx_unlock(&bqclean);
2330 /*
2331 * NOTE: nbp is now entirely invalid. We can only restart
2332 * the scan from this point on.
2333 */
2334
2335 getnewbuf_reuse_bp(bp, qindex);
2336 mtx_assert(&bqclean, MA_NOTOWNED);
2337
2338 /*
2339 * If we are defragging then free the buffer.
2340 */
2341 if (defrag) {
2342 bp->b_flags |= B_INVAL;
2343 bfreekva(bp);
2344 brelse(bp);
2345 defrag = 0;
2346 goto restart;
2347 }
2348
2349 /*
2350 * Notify any waiters for the buffer lock about
2351 * identity change by freeing the buffer.
2352 */
2353 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
2354 bp->b_flags |= B_INVAL;
2355 bfreekva(bp);
2356 brelse(bp);
2357 goto restart;
2358 }
2359
2360 if (metadata)
2361 break;
2362
2363 /*
2364 * If we are overcomitted then recover the buffer and its
2365 * KVM space. This occurs in rare situations when multiple
2366 * processes are blocked in getnewbuf() or allocbuf().
2367 */
2368 if (bufspace >= hibufspace)
2369 flushingbufs = 1;
2370 if (flushingbufs && bp->b_kvasize != 0) {
2371 bp->b_flags |= B_INVAL;
2372 bfreekva(bp);
2373 brelse(bp);
2374 goto restart;
2375 }
2376 if (bufspace < lobufspace)
2377 flushingbufs = 0;
2378 break;
2379 }
2380 return (bp);
2381 }
2382
2383 /*
2384 * getnewbuf:
2385 *
2386 * Find and initialize a new buffer header, freeing up existing buffers
2387 * in the bufqueues as necessary. The new buffer is returned locked.
2388 *
2389 * Important: B_INVAL is not set. If the caller wishes to throw the
2390 * buffer away, the caller must set B_INVAL prior to calling brelse().
2391 *
2392 * We block if:
2393 * We have insufficient buffer headers
2394 * We have insufficient buffer space
2395 * buffer_arena is too fragmented ( space reservation fails )
2396 * If we have to flush dirty buffers ( but we try to avoid this )
2397 */
2398 static struct buf *
2399 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
2400 int gbflags)
2401 {
2402 struct buf *bp;
2403 int defrag, metadata;
2404
2405 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
2406 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
2407 if (!unmapped_buf_allowed)
2408 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
2409
2410 defrag = 0;
2411 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
2412 vp->v_type == VCHR)
2413 metadata = 1;
2414 else
2415 metadata = 0;
2416 /*
2417 * We can't afford to block since we might be holding a vnode lock,
2418 * which may prevent system daemons from running. We deal with
2419 * low-memory situations by proactively returning memory and running
2420 * async I/O rather then sync I/O.
2421 */
2422 atomic_add_int(&getnewbufcalls, 1);
2423 atomic_subtract_int(&getnewbufrestarts, 1);
2424 restart:
2425 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED |
2426 GB_KVAALLOC)) == GB_UNMAPPED, metadata);
2427 if (bp != NULL)
2428 defrag = 0;
2429
2430 /*
2431 * If we exhausted our list, sleep as appropriate. We may have to
2432 * wakeup various daemons and write out some dirty buffers.
2433 *
2434 * Generally we are sleeping due to insufficient buffer space.
2435 */
2436 if (bp == NULL) {
2437 mtx_assert(&bqclean, MA_OWNED);
2438 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag);
2439 mtx_assert(&bqclean, MA_NOTOWNED);
2440 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) {
2441 mtx_assert(&bqclean, MA_NOTOWNED);
2442
2443 bfreekva(bp);
2444 bp->b_flags |= B_UNMAPPED;
2445 bp->b_kvabase = bp->b_data = unmapped_buf;
2446 bp->b_kvasize = maxsize;
2447 atomic_add_long(&bufspace, bp->b_kvasize);
2448 atomic_add_long(&unmapped_bufspace, bp->b_kvasize);
2449 atomic_add_int(&bufreusecnt, 1);
2450 } else {
2451 mtx_assert(&bqclean, MA_NOTOWNED);
2452
2453 /*
2454 * We finally have a valid bp. We aren't quite out of the
2455 * woods, we still have to reserve kva space. In order
2456 * to keep fragmentation sane we only allocate kva in
2457 * BKVASIZE chunks.
2458 */
2459 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2460
2461 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED |
2462 B_KVAALLOC)) == B_UNMAPPED) {
2463 if (allocbufkva(bp, maxsize, gbflags)) {
2464 defrag = 1;
2465 bp->b_flags |= B_INVAL;
2466 brelse(bp);
2467 goto restart;
2468 }
2469 atomic_add_int(&bufreusecnt, 1);
2470 } else if ((bp->b_flags & B_KVAALLOC) != 0 &&
2471 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) {
2472 /*
2473 * If the reused buffer has KVA allocated,
2474 * reassign b_kvaalloc to b_kvabase.
2475 */
2476 bp->b_kvabase = bp->b_kvaalloc;
2477 bp->b_flags &= ~B_KVAALLOC;
2478 atomic_subtract_long(&unmapped_bufspace,
2479 bp->b_kvasize);
2480 atomic_add_int(&bufreusecnt, 1);
2481 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 &&
2482 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED |
2483 GB_KVAALLOC)) {
2484 /*
2485 * The case of reused buffer already have KVA
2486 * mapped, but the request is for unmapped
2487 * buffer with KVA allocated.
2488 */
2489 bp->b_kvaalloc = bp->b_kvabase;
2490 bp->b_data = bp->b_kvabase = unmapped_buf;
2491 bp->b_flags |= B_UNMAPPED | B_KVAALLOC;
2492 atomic_add_long(&unmapped_bufspace,
2493 bp->b_kvasize);
2494 atomic_add_int(&bufreusecnt, 1);
2495 }
2496 if ((gbflags & GB_UNMAPPED) == 0) {
2497 bp->b_saveaddr = bp->b_kvabase;
2498 bp->b_data = bp->b_saveaddr;
2499 bp->b_flags &= ~B_UNMAPPED;
2500 BUF_CHECK_MAPPED(bp);
2501 }
2502 }
2503 return (bp);
2504 }
2505
2506 /*
2507 * buf_daemon:
2508 *
2509 * buffer flushing daemon. Buffers are normally flushed by the
2510 * update daemon but if it cannot keep up this process starts to
2511 * take the load in an attempt to prevent getnewbuf() from blocking.
2512 */
2513
2514 static struct kproc_desc buf_kp = {
2515 "bufdaemon",
2516 buf_daemon,
2517 &bufdaemonproc
2518 };
2519 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2520
2521 static int
2522 buf_flush(int target)
2523 {
2524 int flushed;
2525
2526 flushed = flushbufqueues(target, 0);
2527 if (flushed == 0) {
2528 /*
2529 * Could not find any buffers without rollback
2530 * dependencies, so just write the first one
2531 * in the hopes of eventually making progress.
2532 */
2533 flushed = flushbufqueues(target, 1);
2534 }
2535 return (flushed);
2536 }
2537
2538 static void
2539 buf_daemon()
2540 {
2541 int lodirty;
2542
2543 /*
2544 * This process needs to be suspended prior to shutdown sync.
2545 */
2546 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2547 SHUTDOWN_PRI_LAST);
2548
2549 /*
2550 * This process is allowed to take the buffer cache to the limit
2551 */
2552 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
2553 mtx_lock(&bdlock);
2554 for (;;) {
2555 bd_request = 0;
2556 mtx_unlock(&bdlock);
2557
2558 kproc_suspend_check(bufdaemonproc);
2559 lodirty = lodirtybuffers;
2560 if (bd_speedupreq) {
2561 lodirty = numdirtybuffers / 2;
2562 bd_speedupreq = 0;
2563 }
2564 /*
2565 * Do the flush. Limit the amount of in-transit I/O we
2566 * allow to build up, otherwise we would completely saturate
2567 * the I/O system.
2568 */
2569 while (numdirtybuffers > lodirty) {
2570 if (buf_flush(numdirtybuffers - lodirty) == 0)
2571 break;
2572 kern_yield(PRI_USER);
2573 }
2574
2575 /*
2576 * Only clear bd_request if we have reached our low water
2577 * mark. The buf_daemon normally waits 1 second and
2578 * then incrementally flushes any dirty buffers that have
2579 * built up, within reason.
2580 *
2581 * If we were unable to hit our low water mark and couldn't
2582 * find any flushable buffers, we sleep for a short period
2583 * to avoid endless loops on unlockable buffers.
2584 */
2585 mtx_lock(&bdlock);
2586 if (numdirtybuffers <= lodirtybuffers) {
2587 /*
2588 * We reached our low water mark, reset the
2589 * request and sleep until we are needed again.
2590 * The sleep is just so the suspend code works.
2591 */
2592 bd_request = 0;
2593 /*
2594 * Do an extra wakeup in case dirty threshold
2595 * changed via sysctl and the explicit transition
2596 * out of shortfall was missed.
2597 */
2598 bdirtywakeup();
2599 if (runningbufspace <= lorunningspace)
2600 runningwakeup();
2601 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2602 } else {
2603 /*
2604 * We couldn't find any flushable dirty buffers but
2605 * still have too many dirty buffers, we
2606 * have to sleep and try again. (rare)
2607 */
2608 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2609 }
2610 }
2611 }
2612
2613 /*
2614 * flushbufqueues:
2615 *
2616 * Try to flush a buffer in the dirty queue. We must be careful to
2617 * free up B_INVAL buffers instead of write them, which NFS is
2618 * particularly sensitive to.
2619 */
2620 static int flushwithdeps = 0;
2621 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2622 0, "Number of buffers flushed with dependecies that require rollbacks");
2623
2624 static int
2625 flushbufqueues(int target, int flushdeps)
2626 {
2627 struct buf *sentinel;
2628 struct vnode *vp;
2629 struct mount *mp;
2630 struct buf *bp;
2631 int hasdeps;
2632 int flushed;
2633 int queue;
2634 int error;
2635
2636 flushed = 0;
2637 queue = QUEUE_DIRTY;
2638 bp = NULL;
2639 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
2640 sentinel->b_qindex = QUEUE_SENTINEL;
2641 mtx_lock(&bqdirty);
2642 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
2643 mtx_unlock(&bqdirty);
2644 while (flushed != target) {
2645 maybe_yield();
2646 mtx_lock(&bqdirty);
2647 bp = TAILQ_NEXT(sentinel, b_freelist);
2648 if (bp != NULL) {
2649 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2650 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
2651 b_freelist);
2652 } else {
2653 mtx_unlock(&bqdirty);
2654 break;
2655 }
2656 KASSERT(bp->b_qindex != QUEUE_SENTINEL,
2657 ("parallel calls to flushbufqueues() bp %p", bp));
2658 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
2659 mtx_unlock(&bqdirty);
2660 if (error != 0)
2661 continue;
2662 if (bp->b_pin_count > 0) {
2663 BUF_UNLOCK(bp);
2664 continue;
2665 }
2666 /*
2667 * BKGRDINPROG can only be set with the buf and bufobj
2668 * locks both held. We tolerate a race to clear it here.
2669 */
2670 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2671 (bp->b_flags & B_DELWRI) == 0) {
2672 BUF_UNLOCK(bp);
2673 continue;
2674 }
2675 if (bp->b_flags & B_INVAL) {
2676 bremfreef(bp);
2677 brelse(bp);
2678 flushed++;
2679 continue;
2680 }
2681
2682 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
2683 if (flushdeps == 0) {
2684 BUF_UNLOCK(bp);
2685 continue;
2686 }
2687 hasdeps = 1;
2688 } else
2689 hasdeps = 0;
2690 /*
2691 * We must hold the lock on a vnode before writing
2692 * one of its buffers. Otherwise we may confuse, or
2693 * in the case of a snapshot vnode, deadlock the
2694 * system.
2695 *
2696 * The lock order here is the reverse of the normal
2697 * of vnode followed by buf lock. This is ok because
2698 * the NOWAIT will prevent deadlock.
2699 */
2700 vp = bp->b_vp;
2701 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2702 BUF_UNLOCK(bp);
2703 continue;
2704 }
2705 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
2706 if (error == 0) {
2707 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2708 bp, bp->b_vp, bp->b_flags);
2709 vfs_bio_awrite(bp);
2710 vn_finished_write(mp);
2711 VOP_UNLOCK(vp, 0);
2712 flushwithdeps += hasdeps;
2713 flushed++;
2714 if (runningbufspace > hirunningspace)
2715 waitrunningbufspace();
2716 continue;
2717 }
2718 vn_finished_write(mp);
2719 BUF_UNLOCK(bp);
2720 }
2721 mtx_lock(&bqdirty);
2722 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2723 mtx_unlock(&bqdirty);
2724 free(sentinel, M_TEMP);
2725 return (flushed);
2726 }
2727
2728 /*
2729 * Check to see if a block is currently memory resident.
2730 */
2731 struct buf *
2732 incore(struct bufobj *bo, daddr_t blkno)
2733 {
2734 struct buf *bp;
2735
2736 BO_RLOCK(bo);
2737 bp = gbincore(bo, blkno);
2738 BO_RUNLOCK(bo);
2739 return (bp);
2740 }
2741
2742 /*
2743 * Returns true if no I/O is needed to access the
2744 * associated VM object. This is like incore except
2745 * it also hunts around in the VM system for the data.
2746 */
2747
2748 static int
2749 inmem(struct vnode * vp, daddr_t blkno)
2750 {
2751 vm_object_t obj;
2752 vm_offset_t toff, tinc, size;
2753 vm_page_t m;
2754 vm_ooffset_t off;
2755
2756 ASSERT_VOP_LOCKED(vp, "inmem");
2757
2758 if (incore(&vp->v_bufobj, blkno))
2759 return 1;
2760 if (vp->v_mount == NULL)
2761 return 0;
2762 obj = vp->v_object;
2763 if (obj == NULL)
2764 return (0);
2765
2766 size = PAGE_SIZE;
2767 if (size > vp->v_mount->mnt_stat.f_iosize)
2768 size = vp->v_mount->mnt_stat.f_iosize;
2769 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2770
2771 VM_OBJECT_RLOCK(obj);
2772 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2773 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2774 if (!m)
2775 goto notinmem;
2776 tinc = size;
2777 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2778 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2779 if (vm_page_is_valid(m,
2780 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2781 goto notinmem;
2782 }
2783 VM_OBJECT_RUNLOCK(obj);
2784 return 1;
2785
2786 notinmem:
2787 VM_OBJECT_RUNLOCK(obj);
2788 return (0);
2789 }
2790
2791 /*
2792 * Set the dirty range for a buffer based on the status of the dirty
2793 * bits in the pages comprising the buffer. The range is limited
2794 * to the size of the buffer.
2795 *
2796 * Tell the VM system that the pages associated with this buffer
2797 * are clean. This is used for delayed writes where the data is
2798 * going to go to disk eventually without additional VM intevention.
2799 *
2800 * Note that while we only really need to clean through to b_bcount, we
2801 * just go ahead and clean through to b_bufsize.
2802 */
2803 static void
2804 vfs_clean_pages_dirty_buf(struct buf *bp)
2805 {
2806 vm_ooffset_t foff, noff, eoff;
2807 vm_page_t m;
2808 int i;
2809
2810 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
2811 return;
2812
2813 foff = bp->b_offset;
2814 KASSERT(bp->b_offset != NOOFFSET,
2815 ("vfs_clean_pages_dirty_buf: no buffer offset"));
2816
2817 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
2818 vfs_drain_busy_pages(bp);
2819 vfs_setdirty_locked_object(bp);
2820 for (i = 0; i < bp->b_npages; i++) {
2821 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2822 eoff = noff;
2823 if (eoff > bp->b_offset + bp->b_bufsize)
2824 eoff = bp->b_offset + bp->b_bufsize;
2825 m = bp->b_pages[i];
2826 vfs_page_set_validclean(bp, foff, m);
2827 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
2828 foff = noff;
2829 }
2830 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
2831 }
2832
2833 static void
2834 vfs_setdirty_locked_object(struct buf *bp)
2835 {
2836 vm_object_t object;
2837 int i;
2838
2839 object = bp->b_bufobj->bo_object;
2840 VM_OBJECT_ASSERT_WLOCKED(object);
2841
2842 /*
2843 * We qualify the scan for modified pages on whether the
2844 * object has been flushed yet.
2845 */
2846 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
2847 vm_offset_t boffset;
2848 vm_offset_t eoffset;
2849
2850 /*
2851 * test the pages to see if they have been modified directly
2852 * by users through the VM system.
2853 */
2854 for (i = 0; i < bp->b_npages; i++)
2855 vm_page_test_dirty(bp->b_pages[i]);
2856
2857 /*
2858 * Calculate the encompassing dirty range, boffset and eoffset,
2859 * (eoffset - boffset) bytes.
2860 */
2861
2862 for (i = 0; i < bp->b_npages; i++) {
2863 if (bp->b_pages[i]->dirty)
2864 break;
2865 }
2866 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2867
2868 for (i = bp->b_npages - 1; i >= 0; --i) {
2869 if (bp->b_pages[i]->dirty) {
2870 break;
2871 }
2872 }
2873 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2874
2875 /*
2876 * Fit it to the buffer.
2877 */
2878
2879 if (eoffset > bp->b_bcount)
2880 eoffset = bp->b_bcount;
2881
2882 /*
2883 * If we have a good dirty range, merge with the existing
2884 * dirty range.
2885 */
2886
2887 if (boffset < eoffset) {
2888 if (bp->b_dirtyoff > boffset)
2889 bp->b_dirtyoff = boffset;
2890 if (bp->b_dirtyend < eoffset)
2891 bp->b_dirtyend = eoffset;
2892 }
2893 }
2894 }
2895
2896 /*
2897 * Allocate the KVA mapping for an existing buffer. It handles the
2898 * cases of both B_UNMAPPED buffer, and buffer with the preallocated
2899 * KVA which is not mapped (B_KVAALLOC).
2900 */
2901 static void
2902 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
2903 {
2904 struct buf *scratch_bp;
2905 int bsize, maxsize, need_mapping, need_kva;
2906 off_t offset;
2907
2908 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 &&
2909 (gbflags & GB_UNMAPPED) == 0;
2910 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED &&
2911 (gbflags & GB_KVAALLOC) != 0;
2912 if (!need_mapping && !need_kva)
2913 return;
2914
2915 BUF_CHECK_UNMAPPED(bp);
2916
2917 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) {
2918 /*
2919 * Buffer is not mapped, but the KVA was already
2920 * reserved at the time of the instantiation. Use the
2921 * allocated space.
2922 */
2923 bp->b_flags &= ~B_KVAALLOC;
2924 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0"));
2925 bp->b_kvabase = bp->b_kvaalloc;
2926 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
2927 goto has_addr;
2928 }
2929
2930 /*
2931 * Calculate the amount of the address space we would reserve
2932 * if the buffer was mapped.
2933 */
2934 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
2935 offset = blkno * bsize;
2936 maxsize = size + (offset & PAGE_MASK);
2937 maxsize = imax(maxsize, bsize);
2938
2939 mapping_loop:
2940 if (allocbufkva(bp, maxsize, gbflags)) {
2941 /*
2942 * Request defragmentation. getnewbuf() returns us the
2943 * allocated space by the scratch buffer KVA.
2944 */
2945 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags |
2946 (GB_UNMAPPED | GB_KVAALLOC));
2947 if (scratch_bp == NULL) {
2948 if ((gbflags & GB_NOWAIT_BD) != 0) {
2949 /*
2950 * XXXKIB: defragmentation cannot
2951 * succeed, not sure what else to do.
2952 */
2953 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp);
2954 }
2955 atomic_add_int(&mappingrestarts, 1);
2956 goto mapping_loop;
2957 }
2958 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0,
2959 ("scratch bp !B_KVAALLOC %p", scratch_bp));
2960 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc,
2961 scratch_bp->b_kvasize, gbflags);
2962
2963 /* Get rid of the scratch buffer. */
2964 scratch_bp->b_kvasize = 0;
2965 scratch_bp->b_flags |= B_INVAL;
2966 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
2967 brelse(scratch_bp);
2968 }
2969 if (!need_mapping)
2970 return;
2971
2972 has_addr:
2973 bp->b_saveaddr = bp->b_kvabase;
2974 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */
2975 bp->b_flags &= ~B_UNMAPPED;
2976 BUF_CHECK_MAPPED(bp);
2977 bpmap_qenter(bp);
2978 }
2979
2980 /*
2981 * getblk:
2982 *
2983 * Get a block given a specified block and offset into a file/device.
2984 * The buffers B_DONE bit will be cleared on return, making it almost
2985 * ready for an I/O initiation. B_INVAL may or may not be set on
2986 * return. The caller should clear B_INVAL prior to initiating a
2987 * READ.
2988 *
2989 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2990 * an existing buffer.
2991 *
2992 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2993 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2994 * and then cleared based on the backing VM. If the previous buffer is
2995 * non-0-sized but invalid, B_CACHE will be cleared.
2996 *
2997 * If getblk() must create a new buffer, the new buffer is returned with
2998 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2999 * case it is returned with B_INVAL clear and B_CACHE set based on the
3000 * backing VM.
3001 *
3002 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3003 * B_CACHE bit is clear.
3004 *
3005 * What this means, basically, is that the caller should use B_CACHE to
3006 * determine whether the buffer is fully valid or not and should clear
3007 * B_INVAL prior to issuing a read. If the caller intends to validate
3008 * the buffer by loading its data area with something, the caller needs
3009 * to clear B_INVAL. If the caller does this without issuing an I/O,
3010 * the caller should set B_CACHE ( as an optimization ), else the caller
3011 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3012 * a write attempt or if it was a successfull read. If the caller
3013 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3014 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3015 */
3016 struct buf *
3017 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3018 int flags)
3019 {
3020 struct buf *bp;
3021 struct bufobj *bo;
3022 int bsize, error, maxsize, vmio;
3023 off_t offset;
3024
3025 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3026 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3027 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3028 ASSERT_VOP_LOCKED(vp, "getblk");
3029 if (size > MAXBSIZE)
3030 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
3031 if (!unmapped_buf_allowed)
3032 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3033
3034 bo = &vp->v_bufobj;
3035 loop:
3036 BO_RLOCK(bo);
3037 bp = gbincore(bo, blkno);
3038 if (bp != NULL) {
3039 int lockflags;
3040 /*
3041 * Buffer is in-core. If the buffer is not busy nor managed,
3042 * it must be on a queue.
3043 */
3044 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3045
3046 if (flags & GB_LOCK_NOWAIT)
3047 lockflags |= LK_NOWAIT;
3048
3049 error = BUF_TIMELOCK(bp, lockflags,
3050 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3051
3052 /*
3053 * If we slept and got the lock we have to restart in case
3054 * the buffer changed identities.
3055 */
3056 if (error == ENOLCK)
3057 goto loop;
3058 /* We timed out or were interrupted. */
3059 else if (error)
3060 return (NULL);
3061 /* If recursed, assume caller knows the rules. */
3062 else if (BUF_LOCKRECURSED(bp))
3063 goto end;
3064
3065 /*
3066 * The buffer is locked. B_CACHE is cleared if the buffer is
3067 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3068 * and for a VMIO buffer B_CACHE is adjusted according to the
3069 * backing VM cache.
3070 */
3071 if (bp->b_flags & B_INVAL)
3072 bp->b_flags &= ~B_CACHE;
3073 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3074 bp->b_flags |= B_CACHE;
3075 if (bp->b_flags & B_MANAGED)
3076 MPASS(bp->b_qindex == QUEUE_NONE);
3077 else
3078 bremfree(bp);
3079
3080 /*
3081 * check for size inconsistencies for non-VMIO case.
3082 */
3083 if (bp->b_bcount != size) {
3084 if ((bp->b_flags & B_VMIO) == 0 ||
3085 (size > bp->b_kvasize)) {
3086 if (bp->b_flags & B_DELWRI) {
3087 /*
3088 * If buffer is pinned and caller does
3089 * not want sleep waiting for it to be
3090 * unpinned, bail out
3091 * */
3092 if (bp->b_pin_count > 0) {
3093 if (flags & GB_LOCK_NOWAIT) {
3094 bqrelse(bp);
3095 return (NULL);
3096 } else {
3097 bunpin_wait(bp);
3098 }
3099 }
3100 bp->b_flags |= B_NOCACHE;
3101 bwrite(bp);
3102 } else {
3103 if (LIST_EMPTY(&bp->b_dep)) {
3104 bp->b_flags |= B_RELBUF;
3105 brelse(bp);
3106 } else {
3107 bp->b_flags |= B_NOCACHE;
3108 bwrite(bp);
3109 }
3110 }
3111 goto loop;
3112 }
3113 }
3114
3115 /*
3116 * Handle the case of unmapped buffer which should
3117 * become mapped, or the buffer for which KVA
3118 * reservation is requested.
3119 */
3120 bp_unmapped_get_kva(bp, blkno, size, flags);
3121
3122 /*
3123 * If the size is inconsistant in the VMIO case, we can resize
3124 * the buffer. This might lead to B_CACHE getting set or
3125 * cleared. If the size has not changed, B_CACHE remains
3126 * unchanged from its previous state.
3127 */
3128 if (bp->b_bcount != size)
3129 allocbuf(bp, size);
3130
3131 KASSERT(bp->b_offset != NOOFFSET,
3132 ("getblk: no buffer offset"));
3133
3134 /*
3135 * A buffer with B_DELWRI set and B_CACHE clear must
3136 * be committed before we can return the buffer in
3137 * order to prevent the caller from issuing a read
3138 * ( due to B_CACHE not being set ) and overwriting
3139 * it.
3140 *
3141 * Most callers, including NFS and FFS, need this to
3142 * operate properly either because they assume they
3143 * can issue a read if B_CACHE is not set, or because
3144 * ( for example ) an uncached B_DELWRI might loop due
3145 * to softupdates re-dirtying the buffer. In the latter
3146 * case, B_CACHE is set after the first write completes,
3147 * preventing further loops.
3148 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3149 * above while extending the buffer, we cannot allow the
3150 * buffer to remain with B_CACHE set after the write
3151 * completes or it will represent a corrupt state. To
3152 * deal with this we set B_NOCACHE to scrap the buffer
3153 * after the write.
3154 *
3155 * We might be able to do something fancy, like setting
3156 * B_CACHE in bwrite() except if B_DELWRI is already set,
3157 * so the below call doesn't set B_CACHE, but that gets real
3158 * confusing. This is much easier.
3159 */
3160
3161 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3162 bp->b_flags |= B_NOCACHE;
3163 bwrite(bp);
3164 goto loop;
3165 }
3166 bp->b_flags &= ~B_DONE;
3167 } else {
3168 /*
3169 * Buffer is not in-core, create new buffer. The buffer
3170 * returned by getnewbuf() is locked. Note that the returned
3171 * buffer is also considered valid (not marked B_INVAL).
3172 */
3173 BO_RUNLOCK(bo);
3174 /*
3175 * If the user does not want us to create the buffer, bail out
3176 * here.
3177 */
3178 if (flags & GB_NOCREAT)
3179 return NULL;
3180 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread))
3181 return NULL;
3182
3183 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
3184 offset = blkno * bsize;
3185 vmio = vp->v_object != NULL;
3186 if (vmio) {
3187 maxsize = size + (offset & PAGE_MASK);
3188 } else {
3189 maxsize = size;
3190 /* Do not allow non-VMIO notmapped buffers. */
3191 flags &= ~GB_UNMAPPED;
3192 }
3193 maxsize = imax(maxsize, bsize);
3194
3195 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags);
3196 if (bp == NULL) {
3197 if (slpflag || slptimeo)
3198 return NULL;
3199 goto loop;
3200 }
3201
3202 /*
3203 * This code is used to make sure that a buffer is not
3204 * created while the getnewbuf routine is blocked.
3205 * This can be a problem whether the vnode is locked or not.
3206 * If the buffer is created out from under us, we have to
3207 * throw away the one we just created.
3208 *
3209 * Note: this must occur before we associate the buffer
3210 * with the vp especially considering limitations in
3211 * the splay tree implementation when dealing with duplicate
3212 * lblkno's.
3213 */
3214 BO_LOCK(bo);
3215 if (gbincore(bo, blkno)) {
3216 BO_UNLOCK(bo);
3217 bp->b_flags |= B_INVAL;
3218 brelse(bp);
3219 goto loop;
3220 }
3221
3222 /*
3223 * Insert the buffer into the hash, so that it can
3224 * be found by incore.
3225 */
3226 bp->b_blkno = bp->b_lblkno = blkno;
3227 bp->b_offset = offset;
3228 bgetvp(vp, bp);
3229 BO_UNLOCK(bo);
3230
3231 /*
3232 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
3233 * buffer size starts out as 0, B_CACHE will be set by
3234 * allocbuf() for the VMIO case prior to it testing the
3235 * backing store for validity.
3236 */
3237
3238 if (vmio) {
3239 bp->b_flags |= B_VMIO;
3240 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
3241 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
3242 bp, vp->v_object, bp->b_bufobj->bo_object));
3243 } else {
3244 bp->b_flags &= ~B_VMIO;
3245 KASSERT(bp->b_bufobj->bo_object == NULL,
3246 ("ARGH! has b_bufobj->bo_object %p %p\n",
3247 bp, bp->b_bufobj->bo_object));
3248 BUF_CHECK_MAPPED(bp);
3249 }
3250
3251 allocbuf(bp, size);
3252 bp->b_flags &= ~B_DONE;
3253 }
3254 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
3255 BUF_ASSERT_HELD(bp);
3256 end:
3257 KASSERT(bp->b_bufobj == bo,
3258 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
3259 return (bp);
3260 }
3261
3262 /*
3263 * Get an empty, disassociated buffer of given size. The buffer is initially
3264 * set to B_INVAL.
3265 */
3266 struct buf *
3267 geteblk(int size, int flags)
3268 {
3269 struct buf *bp;
3270 int maxsize;
3271
3272 maxsize = (size + BKVAMASK) & ~BKVAMASK;
3273 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) {
3274 if ((flags & GB_NOWAIT_BD) &&
3275 (curthread->td_pflags & TDP_BUFNEED) != 0)
3276 return (NULL);
3277 }
3278 allocbuf(bp, size);
3279 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
3280 BUF_ASSERT_HELD(bp);
3281 return (bp);
3282 }
3283
3284
3285 /*
3286 * This code constitutes the buffer memory from either anonymous system
3287 * memory (in the case of non-VMIO operations) or from an associated
3288 * VM object (in the case of VMIO operations). This code is able to
3289 * resize a buffer up or down.
3290 *
3291 * Note that this code is tricky, and has many complications to resolve
3292 * deadlock or inconsistant data situations. Tread lightly!!!
3293 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3294 * the caller. Calling this code willy nilly can result in the loss of data.
3295 *
3296 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3297 * B_CACHE for the non-VMIO case.
3298 */
3299
3300 int
3301 allocbuf(struct buf *bp, int size)
3302 {
3303 int newbsize, mbsize;
3304 int i;
3305
3306 BUF_ASSERT_HELD(bp);
3307
3308 if (bp->b_kvasize < size)
3309 panic("allocbuf: buffer too small");
3310
3311 if ((bp->b_flags & B_VMIO) == 0) {
3312 caddr_t origbuf;
3313 int origbufsize;
3314 /*
3315 * Just get anonymous memory from the kernel. Don't
3316 * mess with B_CACHE.
3317 */
3318 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3319 if (bp->b_flags & B_MALLOC)
3320 newbsize = mbsize;
3321 else
3322 newbsize = round_page(size);
3323
3324 if (newbsize < bp->b_bufsize) {
3325 /*
3326 * malloced buffers are not shrunk
3327 */
3328 if (bp->b_flags & B_MALLOC) {
3329 if (newbsize) {
3330 bp->b_bcount = size;
3331 } else {
3332 free(bp->b_data, M_BIOBUF);
3333 if (bp->b_bufsize) {
3334 atomic_subtract_long(
3335 &bufmallocspace,
3336 bp->b_bufsize);
3337 bufspacewakeup();
3338 bp->b_bufsize = 0;
3339 }
3340 bp->b_saveaddr = bp->b_kvabase;
3341 bp->b_data = bp->b_saveaddr;
3342 bp->b_bcount = 0;
3343 bp->b_flags &= ~B_MALLOC;
3344 }
3345 return 1;
3346 }
3347 vm_hold_free_pages(bp, newbsize);
3348 } else if (newbsize > bp->b_bufsize) {
3349 /*
3350 * We only use malloced memory on the first allocation.
3351 * and revert to page-allocated memory when the buffer
3352 * grows.
3353 */
3354 /*
3355 * There is a potential smp race here that could lead
3356 * to bufmallocspace slightly passing the max. It
3357 * is probably extremely rare and not worth worrying
3358 * over.
3359 */
3360 if ( (bufmallocspace < maxbufmallocspace) &&
3361 (bp->b_bufsize == 0) &&
3362 (mbsize <= PAGE_SIZE/2)) {
3363
3364 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
3365 bp->b_bufsize = mbsize;
3366 bp->b_bcount = size;
3367 bp->b_flags |= B_MALLOC;
3368 atomic_add_long(&bufmallocspace, mbsize);
3369 return 1;
3370 }
3371 origbuf = NULL;
3372 origbufsize = 0;
3373 /*
3374 * If the buffer is growing on its other-than-first allocation,
3375 * then we revert to the page-allocation scheme.
3376 */
3377 if (bp->b_flags & B_MALLOC) {
3378 origbuf = bp->b_data;
3379 origbufsize = bp->b_bufsize;
3380 bp->b_data = bp->b_kvabase;
3381 if (bp->b_bufsize) {
3382 atomic_subtract_long(&bufmallocspace,
3383 bp->b_bufsize);
3384 bufspacewakeup();
3385 bp->b_bufsize = 0;
3386 }
3387 bp->b_flags &= ~B_MALLOC;
3388 newbsize = round_page(newbsize);
3389 }
3390 vm_hold_load_pages(
3391 bp,
3392 (vm_offset_t) bp->b_data + bp->b_bufsize,
3393 (vm_offset_t) bp->b_data + newbsize);
3394 if (origbuf) {
3395 bcopy(origbuf, bp->b_data, origbufsize);
3396 free(origbuf, M_BIOBUF);
3397 }
3398 }
3399 } else {
3400 int desiredpages;
3401
3402 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3403 desiredpages = (size == 0) ? 0 :
3404 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
3405
3406 if (bp->b_flags & B_MALLOC)
3407 panic("allocbuf: VMIO buffer can't be malloced");
3408 /*
3409 * Set B_CACHE initially if buffer is 0 length or will become
3410 * 0-length.
3411 */
3412 if (size == 0 || bp->b_bufsize == 0)
3413 bp->b_flags |= B_CACHE;
3414
3415 if (newbsize < bp->b_bufsize) {
3416 /*
3417 * DEV_BSIZE aligned new buffer size is less then the
3418 * DEV_BSIZE aligned existing buffer size. Figure out
3419 * if we have to remove any pages.
3420 */
3421 if (desiredpages < bp->b_npages) {
3422 vm_page_t m;
3423
3424 if ((bp->b_flags & B_UNMAPPED) == 0) {
3425 BUF_CHECK_MAPPED(bp);
3426 pmap_qremove((vm_offset_t)trunc_page(
3427 (vm_offset_t)bp->b_data) +
3428 (desiredpages << PAGE_SHIFT),
3429 (bp->b_npages - desiredpages));
3430 } else
3431 BUF_CHECK_UNMAPPED(bp);
3432 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3433 for (i = desiredpages; i < bp->b_npages; i++) {
3434 /*
3435 * the page is not freed here -- it
3436 * is the responsibility of
3437 * vnode_pager_setsize
3438 */
3439 m = bp->b_pages[i];
3440 KASSERT(m != bogus_page,
3441 ("allocbuf: bogus page found"));
3442 while (vm_page_sleep_if_busy(m,
3443 "biodep"))
3444 continue;
3445
3446 bp->b_pages[i] = NULL;
3447 vm_page_lock(m);
3448 vm_page_unwire(m, 0);
3449 vm_page_unlock(m);
3450 }
3451 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3452 bp->b_npages = desiredpages;
3453 }
3454 } else if (size > bp->b_bcount) {
3455 /*
3456 * We are growing the buffer, possibly in a
3457 * byte-granular fashion.
3458 */
3459 vm_object_t obj;
3460 vm_offset_t toff;
3461 vm_offset_t tinc;
3462
3463 /*
3464 * Step 1, bring in the VM pages from the object,
3465 * allocating them if necessary. We must clear
3466 * B_CACHE if these pages are not valid for the
3467 * range covered by the buffer.
3468 */
3469
3470 obj = bp->b_bufobj->bo_object;
3471
3472 VM_OBJECT_WLOCK(obj);
3473 while (bp->b_npages < desiredpages) {
3474 vm_page_t m;
3475
3476 /*
3477 * We must allocate system pages since blocking
3478 * here could interfere with paging I/O, no
3479 * matter which process we are.
3480 *
3481 * Only exclusive busy can be tested here.
3482 * Blocking on shared busy might lead to
3483 * deadlocks once allocbuf() is called after
3484 * pages are vfs_busy_pages().
3485 */
3486 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
3487 bp->b_npages, VM_ALLOC_NOBUSY |
3488 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
3489 VM_ALLOC_IGN_SBUSY |
3490 VM_ALLOC_COUNT(desiredpages - bp->b_npages));
3491 if (m->valid == 0)
3492 bp->b_flags &= ~B_CACHE;
3493 bp->b_pages[bp->b_npages] = m;
3494 ++bp->b_npages;
3495 }
3496
3497 /*
3498 * Step 2. We've loaded the pages into the buffer,
3499 * we have to figure out if we can still have B_CACHE
3500 * set. Note that B_CACHE is set according to the
3501 * byte-granular range ( bcount and size ), new the
3502 * aligned range ( newbsize ).
3503 *
3504 * The VM test is against m->valid, which is DEV_BSIZE
3505 * aligned. Needless to say, the validity of the data
3506 * needs to also be DEV_BSIZE aligned. Note that this
3507 * fails with NFS if the server or some other client
3508 * extends the file's EOF. If our buffer is resized,
3509 * B_CACHE may remain set! XXX
3510 */
3511
3512 toff = bp->b_bcount;
3513 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3514
3515 while ((bp->b_flags & B_CACHE) && toff < size) {
3516 vm_pindex_t pi;
3517
3518 if (tinc > (size - toff))
3519 tinc = size - toff;
3520
3521 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
3522 PAGE_SHIFT;
3523
3524 vfs_buf_test_cache(
3525 bp,
3526 bp->b_offset,
3527 toff,
3528 tinc,
3529 bp->b_pages[pi]
3530 );
3531 toff += tinc;
3532 tinc = PAGE_SIZE;
3533 }
3534 VM_OBJECT_WUNLOCK(obj);
3535
3536 /*
3537 * Step 3, fixup the KVM pmap.
3538 */
3539 if ((bp->b_flags & B_UNMAPPED) == 0)
3540 bpmap_qenter(bp);
3541 else
3542 BUF_CHECK_UNMAPPED(bp);
3543 }
3544 }
3545 if (newbsize < bp->b_bufsize)
3546 bufspacewakeup();
3547 bp->b_bufsize = newbsize; /* actual buffer allocation */
3548 bp->b_bcount = size; /* requested buffer size */
3549 return 1;
3550 }
3551
3552 extern int inflight_transient_maps;
3553
3554 void
3555 biodone(struct bio *bp)
3556 {
3557 struct mtx *mtxp;
3558 void (*done)(struct bio *);
3559 vm_offset_t start, end;
3560 int transient;
3561
3562 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3563 mtx_lock(mtxp);
3564 bp->bio_flags |= BIO_DONE;
3565 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
3566 start = trunc_page((vm_offset_t)bp->bio_data);
3567 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
3568 transient = 1;
3569 } else {
3570 transient = 0;
3571 start = end = 0;
3572 }
3573 done = bp->bio_done;
3574 if (done == NULL)
3575 wakeup(bp);
3576 mtx_unlock(mtxp);
3577 if (done != NULL)
3578 done(bp);
3579 if (transient) {
3580 pmap_qremove(start, OFF_TO_IDX(end - start));
3581 vmem_free(transient_arena, start, end - start);
3582 atomic_add_int(&inflight_transient_maps, -1);
3583 }
3584 }
3585
3586 /*
3587 * Wait for a BIO to finish.
3588 *
3589 * XXX: resort to a timeout for now. The optimal locking (if any) for this
3590 * case is not yet clear.
3591 */
3592 int
3593 biowait(struct bio *bp, const char *wchan)
3594 {
3595 struct mtx *mtxp;
3596
3597 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3598 mtx_lock(mtxp);
3599 while ((bp->bio_flags & BIO_DONE) == 0)
3600 msleep(bp, mtxp, PRIBIO, wchan, hz / 10);
3601 mtx_unlock(mtxp);
3602 if (bp->bio_error != 0)
3603 return (bp->bio_error);
3604 if (!(bp->bio_flags & BIO_ERROR))
3605 return (0);
3606 return (EIO);
3607 }
3608
3609 void
3610 biofinish(struct bio *bp, struct devstat *stat, int error)
3611 {
3612
3613 if (error) {
3614 bp->bio_error = error;
3615 bp->bio_flags |= BIO_ERROR;
3616 }
3617 if (stat != NULL)
3618 devstat_end_transaction_bio(stat, bp);
3619 biodone(bp);
3620 }
3621
3622 /*
3623 * bufwait:
3624 *
3625 * Wait for buffer I/O completion, returning error status. The buffer
3626 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3627 * error and cleared.
3628 */
3629 int
3630 bufwait(struct buf *bp)
3631 {
3632 if (bp->b_iocmd == BIO_READ)
3633 bwait(bp, PRIBIO, "biord");
3634 else
3635 bwait(bp, PRIBIO, "biowr");
3636 if (bp->b_flags & B_EINTR) {
3637 bp->b_flags &= ~B_EINTR;
3638 return (EINTR);
3639 }
3640 if (bp->b_ioflags & BIO_ERROR) {
3641 return (bp->b_error ? bp->b_error : EIO);
3642 } else {
3643 return (0);
3644 }
3645 }
3646
3647 /*
3648 * Call back function from struct bio back up to struct buf.
3649 */
3650 static void
3651 bufdonebio(struct bio *bip)
3652 {
3653 struct buf *bp;
3654
3655 bp = bip->bio_caller2;
3656 bp->b_resid = bp->b_bcount - bip->bio_completed;
3657 bp->b_resid = bip->bio_resid; /* XXX: remove */
3658 bp->b_ioflags = bip->bio_flags;
3659 bp->b_error = bip->bio_error;
3660 if (bp->b_error)
3661 bp->b_ioflags |= BIO_ERROR;
3662 bufdone(bp);
3663 g_destroy_bio(bip);
3664 }
3665
3666 void
3667 dev_strategy(struct cdev *dev, struct buf *bp)
3668 {
3669 struct cdevsw *csw;
3670 int ref;
3671
3672 KASSERT(dev->si_refcount > 0,
3673 ("dev_strategy on un-referenced struct cdev *(%s) %p",
3674 devtoname(dev), dev));
3675
3676 csw = dev_refthread(dev, &ref);
3677 dev_strategy_csw(dev, csw, bp);
3678 dev_relthread(dev, ref);
3679 }
3680
3681 void
3682 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp)
3683 {
3684 struct bio *bip;
3685
3686 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE,
3687 ("b_iocmd botch"));
3688 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) ||
3689 dev->si_threadcount > 0,
3690 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev),
3691 dev));
3692 if (csw == NULL) {
3693 bp->b_error = ENXIO;
3694 bp->b_ioflags = BIO_ERROR;
3695 bufdone(bp);
3696 return;
3697 }
3698 for (;;) {
3699 bip = g_new_bio();
3700 if (bip != NULL)
3701 break;
3702 /* Try again later */
3703 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3704 }
3705 bip->bio_cmd = bp->b_iocmd;
3706 bip->bio_offset = bp->b_iooffset;
3707 bip->bio_length = bp->b_bcount;
3708 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3709 bdata2bio(bp, bip);
3710 bip->bio_done = bufdonebio;
3711 bip->bio_caller2 = bp;
3712 bip->bio_dev = dev;
3713 (*csw->d_strategy)(bip);
3714 }
3715
3716 /*
3717 * bufdone:
3718 *
3719 * Finish I/O on a buffer, optionally calling a completion function.
3720 * This is usually called from an interrupt so process blocking is
3721 * not allowed.
3722 *
3723 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3724 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3725 * assuming B_INVAL is clear.
3726 *
3727 * For the VMIO case, we set B_CACHE if the op was a read and no
3728 * read error occured, or if the op was a write. B_CACHE is never
3729 * set if the buffer is invalid or otherwise uncacheable.
3730 *
3731 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3732 * initiator to leave B_INVAL set to brelse the buffer out of existance
3733 * in the biodone routine.
3734 */
3735 void
3736 bufdone(struct buf *bp)
3737 {
3738 struct bufobj *dropobj;
3739 void (*biodone)(struct buf *);
3740
3741 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3742 dropobj = NULL;
3743
3744 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3745 BUF_ASSERT_HELD(bp);
3746
3747 runningbufwakeup(bp);
3748 if (bp->b_iocmd == BIO_WRITE)
3749 dropobj = bp->b_bufobj;
3750 /* call optional completion function if requested */
3751 if (bp->b_iodone != NULL) {
3752 biodone = bp->b_iodone;
3753 bp->b_iodone = NULL;
3754 (*biodone) (bp);
3755 if (dropobj)
3756 bufobj_wdrop(dropobj);
3757 return;
3758 }
3759
3760 bufdone_finish(bp);
3761
3762 if (dropobj)
3763 bufobj_wdrop(dropobj);
3764 }
3765
3766 void
3767 bufdone_finish(struct buf *bp)
3768 {
3769 BUF_ASSERT_HELD(bp);
3770
3771 if (!LIST_EMPTY(&bp->b_dep))
3772 buf_complete(bp);
3773
3774 if (bp->b_flags & B_VMIO) {
3775 vm_ooffset_t foff;
3776 vm_page_t m;
3777 vm_object_t obj;
3778 struct vnode *vp;
3779 int bogus, i, iosize;
3780
3781 obj = bp->b_bufobj->bo_object;
3782 KASSERT(obj->paging_in_progress >= bp->b_npages,
3783 ("biodone_finish: paging in progress(%d) < b_npages(%d)",
3784 obj->paging_in_progress, bp->b_npages));
3785
3786 vp = bp->b_vp;
3787 KASSERT(vp->v_holdcnt > 0,
3788 ("biodone_finish: vnode %p has zero hold count", vp));
3789 KASSERT(vp->v_object != NULL,
3790 ("biodone_finish: vnode %p has no vm_object", vp));
3791
3792 foff = bp->b_offset;
3793 KASSERT(bp->b_offset != NOOFFSET,
3794 ("biodone_finish: bp %p has no buffer offset", bp));
3795
3796 /*
3797 * Set B_CACHE if the op was a normal read and no error
3798 * occured. B_CACHE is set for writes in the b*write()
3799 * routines.
3800 */
3801 iosize = bp->b_bcount - bp->b_resid;
3802 if (bp->b_iocmd == BIO_READ &&
3803 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3804 !(bp->b_ioflags & BIO_ERROR)) {
3805 bp->b_flags |= B_CACHE;
3806 }
3807 bogus = 0;
3808 VM_OBJECT_WLOCK(obj);
3809 for (i = 0; i < bp->b_npages; i++) {
3810 int bogusflag = 0;
3811 int resid;
3812
3813 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3814 if (resid > iosize)
3815 resid = iosize;
3816
3817 /*
3818 * cleanup bogus pages, restoring the originals
3819 */
3820 m = bp->b_pages[i];
3821 if (m == bogus_page) {
3822 bogus = bogusflag = 1;
3823 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3824 if (m == NULL)
3825 panic("biodone: page disappeared!");
3826 bp->b_pages[i] = m;
3827 }
3828 KASSERT(OFF_TO_IDX(foff) == m->pindex,
3829 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch",
3830 (intmax_t)foff, (uintmax_t)m->pindex));
3831
3832 /*
3833 * In the write case, the valid and clean bits are
3834 * already changed correctly ( see bdwrite() ), so we
3835 * only need to do this here in the read case.
3836 */
3837 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3838 KASSERT((m->dirty & vm_page_bits(foff &
3839 PAGE_MASK, resid)) == 0, ("bufdone_finish:"
3840 " page %p has unexpected dirty bits", m));
3841 vfs_page_set_valid(bp, foff, m);
3842 }
3843
3844 vm_page_sunbusy(m);
3845 vm_object_pip_subtract(obj, 1);
3846 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3847 iosize -= resid;
3848 }
3849 vm_object_pip_wakeupn(obj, 0);
3850 VM_OBJECT_WUNLOCK(obj);
3851 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) {
3852 BUF_CHECK_MAPPED(bp);
3853 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3854 bp->b_pages, bp->b_npages);
3855 }
3856 }
3857
3858 /*
3859 * For asynchronous completions, release the buffer now. The brelse
3860 * will do a wakeup there if necessary - so no need to do a wakeup
3861 * here in the async case. The sync case always needs to do a wakeup.
3862 */
3863
3864 if (bp->b_flags & B_ASYNC) {
3865 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3866 brelse(bp);
3867 else
3868 bqrelse(bp);
3869 } else
3870 bdone(bp);
3871 }
3872
3873 /*
3874 * This routine is called in lieu of iodone in the case of
3875 * incomplete I/O. This keeps the busy status for pages
3876 * consistant.
3877 */
3878 void
3879 vfs_unbusy_pages(struct buf *bp)
3880 {
3881 int i;
3882 vm_object_t obj;
3883 vm_page_t m;
3884
3885 runningbufwakeup(bp);
3886 if (!(bp->b_flags & B_VMIO))
3887 return;
3888
3889 obj = bp->b_bufobj->bo_object;
3890 VM_OBJECT_WLOCK(obj);
3891 for (i = 0; i < bp->b_npages; i++) {
3892 m = bp->b_pages[i];
3893 if (m == bogus_page) {
3894 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3895 if (!m)
3896 panic("vfs_unbusy_pages: page missing\n");
3897 bp->b_pages[i] = m;
3898 if ((bp->b_flags & B_UNMAPPED) == 0) {
3899 BUF_CHECK_MAPPED(bp);
3900 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3901 bp->b_pages, bp->b_npages);
3902 } else
3903 BUF_CHECK_UNMAPPED(bp);
3904 }
3905 vm_object_pip_subtract(obj, 1);
3906 vm_page_sunbusy(m);
3907 }
3908 vm_object_pip_wakeupn(obj, 0);
3909 VM_OBJECT_WUNLOCK(obj);
3910 }
3911
3912 /*
3913 * vfs_page_set_valid:
3914 *
3915 * Set the valid bits in a page based on the supplied offset. The
3916 * range is restricted to the buffer's size.
3917 *
3918 * This routine is typically called after a read completes.
3919 */
3920 static void
3921 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3922 {
3923 vm_ooffset_t eoff;
3924
3925 /*
3926 * Compute the end offset, eoff, such that [off, eoff) does not span a
3927 * page boundary and eoff is not greater than the end of the buffer.
3928 * The end of the buffer, in this case, is our file EOF, not the
3929 * allocation size of the buffer.
3930 */
3931 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
3932 if (eoff > bp->b_offset + bp->b_bcount)
3933 eoff = bp->b_offset + bp->b_bcount;
3934
3935 /*
3936 * Set valid range. This is typically the entire buffer and thus the
3937 * entire page.
3938 */
3939 if (eoff > off)
3940 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
3941 }
3942
3943 /*
3944 * vfs_page_set_validclean:
3945 *
3946 * Set the valid bits and clear the dirty bits in a page based on the
3947 * supplied offset. The range is restricted to the buffer's size.
3948 */
3949 static void
3950 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3951 {
3952 vm_ooffset_t soff, eoff;
3953
3954 /*
3955 * Start and end offsets in buffer. eoff - soff may not cross a
3956 * page boundry or cross the end of the buffer. The end of the
3957 * buffer, in this case, is our file EOF, not the allocation size
3958 * of the buffer.
3959 */
3960 soff = off;
3961 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3962 if (eoff > bp->b_offset + bp->b_bcount)
3963 eoff = bp->b_offset + bp->b_bcount;
3964
3965 /*
3966 * Set valid range. This is typically the entire buffer and thus the
3967 * entire page.
3968 */
3969 if (eoff > soff) {
3970 vm_page_set_validclean(
3971 m,
3972 (vm_offset_t) (soff & PAGE_MASK),
3973 (vm_offset_t) (eoff - soff)
3974 );
3975 }
3976 }
3977
3978 /*
3979 * Ensure that all buffer pages are not exclusive busied. If any page is
3980 * exclusive busy, drain it.
3981 */
3982 void
3983 vfs_drain_busy_pages(struct buf *bp)
3984 {
3985 vm_page_t m;
3986 int i, last_busied;
3987
3988 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
3989 last_busied = 0;
3990 for (i = 0; i < bp->b_npages; i++) {
3991 m = bp->b_pages[i];
3992 if (vm_page_xbusied(m)) {
3993 for (; last_busied < i; last_busied++)
3994 vm_page_sbusy(bp->b_pages[last_busied]);
3995 while (vm_page_xbusied(m)) {
3996 vm_page_lock(m);
3997 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3998 vm_page_busy_sleep(m, "vbpage");
3999 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4000 }
4001 }
4002 }
4003 for (i = 0; i < last_busied; i++)
4004 vm_page_sunbusy(bp->b_pages[i]);
4005 }
4006
4007 /*
4008 * This routine is called before a device strategy routine.
4009 * It is used to tell the VM system that paging I/O is in
4010 * progress, and treat the pages associated with the buffer
4011 * almost as being exclusive busy. Also the object paging_in_progress
4012 * flag is handled to make sure that the object doesn't become
4013 * inconsistant.
4014 *
4015 * Since I/O has not been initiated yet, certain buffer flags
4016 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
4017 * and should be ignored.
4018 */
4019 void
4020 vfs_busy_pages(struct buf *bp, int clear_modify)
4021 {
4022 int i, bogus;
4023 vm_object_t obj;
4024 vm_ooffset_t foff;
4025 vm_page_t m;
4026
4027 if (!(bp->b_flags & B_VMIO))
4028 return;
4029
4030 obj = bp->b_bufobj->bo_object;
4031 foff = bp->b_offset;
4032 KASSERT(bp->b_offset != NOOFFSET,
4033 ("vfs_busy_pages: no buffer offset"));
4034 VM_OBJECT_WLOCK(obj);
4035 vfs_drain_busy_pages(bp);
4036 if (bp->b_bufsize != 0)
4037 vfs_setdirty_locked_object(bp);
4038 bogus = 0;
4039 for (i = 0; i < bp->b_npages; i++) {
4040 m = bp->b_pages[i];
4041
4042 if ((bp->b_flags & B_CLUSTER) == 0) {
4043 vm_object_pip_add(obj, 1);
4044 vm_page_sbusy(m);
4045 }
4046 /*
4047 * When readying a buffer for a read ( i.e
4048 * clear_modify == 0 ), it is important to do
4049 * bogus_page replacement for valid pages in
4050 * partially instantiated buffers. Partially
4051 * instantiated buffers can, in turn, occur when
4052 * reconstituting a buffer from its VM backing store
4053 * base. We only have to do this if B_CACHE is
4054 * clear ( which causes the I/O to occur in the
4055 * first place ). The replacement prevents the read
4056 * I/O from overwriting potentially dirty VM-backed
4057 * pages. XXX bogus page replacement is, uh, bogus.
4058 * It may not work properly with small-block devices.
4059 * We need to find a better way.
4060 */
4061 if (clear_modify) {
4062 pmap_remove_write(m);
4063 vfs_page_set_validclean(bp, foff, m);
4064 } else if (m->valid == VM_PAGE_BITS_ALL &&
4065 (bp->b_flags & B_CACHE) == 0) {
4066 bp->b_pages[i] = bogus_page;
4067 bogus++;
4068 }
4069 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4070 }
4071 VM_OBJECT_WUNLOCK(obj);
4072 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) {
4073 BUF_CHECK_MAPPED(bp);
4074 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4075 bp->b_pages, bp->b_npages);
4076 }
4077 }
4078
4079 /*
4080 * vfs_bio_set_valid:
4081 *
4082 * Set the range within the buffer to valid. The range is
4083 * relative to the beginning of the buffer, b_offset. Note that
4084 * b_offset itself may be offset from the beginning of the first
4085 * page.
4086 */
4087 void
4088 vfs_bio_set_valid(struct buf *bp, int base, int size)
4089 {
4090 int i, n;
4091 vm_page_t m;
4092
4093 if (!(bp->b_flags & B_VMIO))
4094 return;
4095
4096 /*
4097 * Fixup base to be relative to beginning of first page.
4098 * Set initial n to be the maximum number of bytes in the
4099 * first page that can be validated.
4100 */
4101 base += (bp->b_offset & PAGE_MASK);
4102 n = PAGE_SIZE - (base & PAGE_MASK);
4103
4104 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4105 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4106 m = bp->b_pages[i];
4107 if (n > size)
4108 n = size;
4109 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4110 base += n;
4111 size -= n;
4112 n = PAGE_SIZE;
4113 }
4114 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4115 }
4116
4117 /*
4118 * vfs_bio_clrbuf:
4119 *
4120 * If the specified buffer is a non-VMIO buffer, clear the entire
4121 * buffer. If the specified buffer is a VMIO buffer, clear and
4122 * validate only the previously invalid portions of the buffer.
4123 * This routine essentially fakes an I/O, so we need to clear
4124 * BIO_ERROR and B_INVAL.
4125 *
4126 * Note that while we only theoretically need to clear through b_bcount,
4127 * we go ahead and clear through b_bufsize.
4128 */
4129 void
4130 vfs_bio_clrbuf(struct buf *bp)
4131 {
4132 int i, j, mask, sa, ea, slide;
4133
4134 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4135 clrbuf(bp);
4136 return;
4137 }
4138 bp->b_flags &= ~B_INVAL;
4139 bp->b_ioflags &= ~BIO_ERROR;
4140 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4141 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4142 (bp->b_offset & PAGE_MASK) == 0) {
4143 if (bp->b_pages[0] == bogus_page)
4144 goto unlock;
4145 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4146 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4147 if ((bp->b_pages[0]->valid & mask) == mask)
4148 goto unlock;
4149 if ((bp->b_pages[0]->valid & mask) == 0) {
4150 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4151 bp->b_pages[0]->valid |= mask;
4152 goto unlock;
4153 }
4154 }
4155 sa = bp->b_offset & PAGE_MASK;
4156 slide = 0;
4157 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4158 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4159 ea = slide & PAGE_MASK;
4160 if (ea == 0)
4161 ea = PAGE_SIZE;
4162 if (bp->b_pages[i] == bogus_page)
4163 continue;
4164 j = sa / DEV_BSIZE;
4165 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4166 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4167 if ((bp->b_pages[i]->valid & mask) == mask)
4168 continue;
4169 if ((bp->b_pages[i]->valid & mask) == 0)
4170 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4171 else {
4172 for (; sa < ea; sa += DEV_BSIZE, j++) {
4173 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4174 pmap_zero_page_area(bp->b_pages[i],
4175 sa, DEV_BSIZE);
4176 }
4177 }
4178 }
4179 bp->b_pages[i]->valid |= mask;
4180 }
4181 unlock:
4182 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4183 bp->b_resid = 0;
4184 }
4185
4186 void
4187 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4188 {
4189 vm_page_t m;
4190 int i, n;
4191
4192 if ((bp->b_flags & B_UNMAPPED) == 0) {
4193 BUF_CHECK_MAPPED(bp);
4194 bzero(bp->b_data + base, size);
4195 } else {
4196 BUF_CHECK_UNMAPPED(bp);
4197 n = PAGE_SIZE - (base & PAGE_MASK);
4198 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4199 m = bp->b_pages[i];
4200 if (n > size)
4201 n = size;
4202 pmap_zero_page_area(m, base & PAGE_MASK, n);
4203 base += n;
4204 size -= n;
4205 n = PAGE_SIZE;
4206 }
4207 }
4208 }
4209
4210 /*
4211 * vm_hold_load_pages and vm_hold_free_pages get pages into
4212 * a buffers address space. The pages are anonymous and are
4213 * not associated with a file object.
4214 */
4215 static void
4216 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4217 {
4218 vm_offset_t pg;
4219 vm_page_t p;
4220 int index;
4221
4222 BUF_CHECK_MAPPED(bp);
4223
4224 to = round_page(to);
4225 from = round_page(from);
4226 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4227
4228 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4229 tryagain:
4230 /*
4231 * note: must allocate system pages since blocking here
4232 * could interfere with paging I/O, no matter which
4233 * process we are.
4234 */
4235 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4236 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
4237 if (p == NULL) {
4238 VM_WAIT;
4239 goto tryagain;
4240 }
4241 pmap_qenter(pg, &p, 1);
4242 bp->b_pages[index] = p;
4243 }
4244 bp->b_npages = index;
4245 }
4246
4247 /* Return pages associated with this buf to the vm system */
4248 static void
4249 vm_hold_free_pages(struct buf *bp, int newbsize)
4250 {
4251 vm_offset_t from;
4252 vm_page_t p;
4253 int index, newnpages;
4254
4255 BUF_CHECK_MAPPED(bp);
4256
4257 from = round_page((vm_offset_t)bp->b_data + newbsize);
4258 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4259 if (bp->b_npages > newnpages)
4260 pmap_qremove(from, bp->b_npages - newnpages);
4261 for (index = newnpages; index < bp->b_npages; index++) {
4262 p = bp->b_pages[index];
4263 bp->b_pages[index] = NULL;
4264 if (vm_page_sbusied(p))
4265 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
4266 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
4267 p->wire_count--;
4268 vm_page_free(p);
4269 atomic_subtract_int(&cnt.v_wire_count, 1);
4270 }
4271 bp->b_npages = newnpages;
4272 }
4273
4274 /*
4275 * Map an IO request into kernel virtual address space.
4276 *
4277 * All requests are (re)mapped into kernel VA space.
4278 * Notice that we use b_bufsize for the size of the buffer
4279 * to be mapped. b_bcount might be modified by the driver.
4280 *
4281 * Note that even if the caller determines that the address space should
4282 * be valid, a race or a smaller-file mapped into a larger space may
4283 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4284 * check the return value.
4285 */
4286 int
4287 vmapbuf(struct buf *bp, int mapbuf)
4288 {
4289 caddr_t kva;
4290 vm_prot_t prot;
4291 int pidx;
4292
4293 if (bp->b_bufsize < 0)
4294 return (-1);
4295 prot = VM_PROT_READ;
4296 if (bp->b_iocmd == BIO_READ)
4297 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4298 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4299 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4300 btoc(MAXPHYS))) < 0)
4301 return (-1);
4302 bp->b_npages = pidx;
4303 if (mapbuf || !unmapped_buf_allowed) {
4304 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
4305 kva = bp->b_saveaddr;
4306 bp->b_saveaddr = bp->b_data;
4307 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK);
4308 bp->b_flags &= ~B_UNMAPPED;
4309 } else {
4310 bp->b_flags |= B_UNMAPPED;
4311 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4312 bp->b_saveaddr = bp->b_data;
4313 bp->b_data = unmapped_buf;
4314 }
4315 return(0);
4316 }
4317
4318 /*
4319 * Free the io map PTEs associated with this IO operation.
4320 * We also invalidate the TLB entries and restore the original b_addr.
4321 */
4322 void
4323 vunmapbuf(struct buf *bp)
4324 {
4325 int npages;
4326
4327 npages = bp->b_npages;
4328 if (bp->b_flags & B_UNMAPPED)
4329 bp->b_flags &= ~B_UNMAPPED;
4330 else
4331 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4332 vm_page_unhold_pages(bp->b_pages, npages);
4333
4334 bp->b_data = bp->b_saveaddr;
4335 }
4336
4337 void
4338 bdone(struct buf *bp)
4339 {
4340 struct mtx *mtxp;
4341
4342 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4343 mtx_lock(mtxp);
4344 bp->b_flags |= B_DONE;
4345 wakeup(bp);
4346 mtx_unlock(mtxp);
4347 }
4348
4349 void
4350 bwait(struct buf *bp, u_char pri, const char *wchan)
4351 {
4352 struct mtx *mtxp;
4353
4354 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4355 mtx_lock(mtxp);
4356 while ((bp->b_flags & B_DONE) == 0)
4357 msleep(bp, mtxp, pri, wchan, 0);
4358 mtx_unlock(mtxp);
4359 }
4360
4361 int
4362 bufsync(struct bufobj *bo, int waitfor)
4363 {
4364
4365 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
4366 }
4367
4368 void
4369 bufstrategy(struct bufobj *bo, struct buf *bp)
4370 {
4371 int i = 0;
4372 struct vnode *vp;
4373
4374 vp = bp->b_vp;
4375 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4376 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4377 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4378 i = VOP_STRATEGY(vp, bp);
4379 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4380 }
4381
4382 void
4383 bufobj_wrefl(struct bufobj *bo)
4384 {
4385
4386 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4387 ASSERT_BO_WLOCKED(bo);
4388 bo->bo_numoutput++;
4389 }
4390
4391 void
4392 bufobj_wref(struct bufobj *bo)
4393 {
4394
4395 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4396 BO_LOCK(bo);
4397 bo->bo_numoutput++;
4398 BO_UNLOCK(bo);
4399 }
4400
4401 void
4402 bufobj_wdrop(struct bufobj *bo)
4403 {
4404
4405 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
4406 BO_LOCK(bo);
4407 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
4408 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
4409 bo->bo_flag &= ~BO_WWAIT;
4410 wakeup(&bo->bo_numoutput);
4411 }
4412 BO_UNLOCK(bo);
4413 }
4414
4415 int
4416 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
4417 {
4418 int error;
4419
4420 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
4421 ASSERT_BO_WLOCKED(bo);
4422 error = 0;
4423 while (bo->bo_numoutput) {
4424 bo->bo_flag |= BO_WWAIT;
4425 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
4426 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
4427 if (error)
4428 break;
4429 }
4430 return (error);
4431 }
4432
4433 void
4434 bpin(struct buf *bp)
4435 {
4436 struct mtx *mtxp;
4437
4438 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4439 mtx_lock(mtxp);
4440 bp->b_pin_count++;
4441 mtx_unlock(mtxp);
4442 }
4443
4444 void
4445 bunpin(struct buf *bp)
4446 {
4447 struct mtx *mtxp;
4448
4449 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4450 mtx_lock(mtxp);
4451 if (--bp->b_pin_count == 0)
4452 wakeup(bp);
4453 mtx_unlock(mtxp);
4454 }
4455
4456 void
4457 bunpin_wait(struct buf *bp)
4458 {
4459 struct mtx *mtxp;
4460
4461 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4462 mtx_lock(mtxp);
4463 while (bp->b_pin_count > 0)
4464 msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
4465 mtx_unlock(mtxp);
4466 }
4467
4468 /*
4469 * Set bio_data or bio_ma for struct bio from the struct buf.
4470 */
4471 void
4472 bdata2bio(struct buf *bp, struct bio *bip)
4473 {
4474
4475 if ((bp->b_flags & B_UNMAPPED) != 0) {
4476 KASSERT(unmapped_buf_allowed, ("unmapped"));
4477 bip->bio_ma = bp->b_pages;
4478 bip->bio_ma_n = bp->b_npages;
4479 bip->bio_data = unmapped_buf;
4480 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
4481 bip->bio_flags |= BIO_UNMAPPED;
4482 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
4483 PAGE_SIZE == bp->b_npages,
4484 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
4485 (long long)bip->bio_length, bip->bio_ma_n));
4486 } else {
4487 bip->bio_data = bp->b_data;
4488 bip->bio_ma = NULL;
4489 }
4490 }
4491
4492 #include "opt_ddb.h"
4493 #ifdef DDB
4494 #include <ddb/ddb.h>
4495
4496 /* DDB command to show buffer data */
4497 DB_SHOW_COMMAND(buffer, db_show_buffer)
4498 {
4499 /* get args */
4500 struct buf *bp = (struct buf *)addr;
4501
4502 if (!have_addr) {
4503 db_printf("usage: show buffer <addr>\n");
4504 return;
4505 }
4506
4507 db_printf("buf at %p\n", bp);
4508 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
4509 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
4510 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
4511 db_printf(
4512 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
4513 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
4514 "b_dep = %p\n",
4515 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4516 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4517 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
4518 if (bp->b_npages) {
4519 int i;
4520 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4521 for (i = 0; i < bp->b_npages; i++) {
4522 vm_page_t m;
4523 m = bp->b_pages[i];
4524 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4525 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4526 if ((i + 1) < bp->b_npages)
4527 db_printf(",");
4528 }
4529 db_printf("\n");
4530 }
4531 db_printf(" ");
4532 BUF_LOCKPRINTINFO(bp);
4533 }
4534
4535 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4536 {
4537 struct buf *bp;
4538 int i;
4539
4540 for (i = 0; i < nbuf; i++) {
4541 bp = &buf[i];
4542 if (BUF_ISLOCKED(bp)) {
4543 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4544 db_printf("\n");
4545 }
4546 }
4547 }
4548
4549 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
4550 {
4551 struct vnode *vp;
4552 struct buf *bp;
4553
4554 if (!have_addr) {
4555 db_printf("usage: show vnodebufs <addr>\n");
4556 return;
4557 }
4558 vp = (struct vnode *)addr;
4559 db_printf("Clean buffers:\n");
4560 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
4561 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4562 db_printf("\n");
4563 }
4564 db_printf("Dirty buffers:\n");
4565 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
4566 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4567 db_printf("\n");
4568 }
4569 }
4570
4571 DB_COMMAND(countfreebufs, db_coundfreebufs)
4572 {
4573 struct buf *bp;
4574 int i, used = 0, nfree = 0;
4575
4576 if (have_addr) {
4577 db_printf("usage: countfreebufs\n");
4578 return;
4579 }
4580
4581 for (i = 0; i < nbuf; i++) {
4582 bp = &buf[i];
4583 if ((bp->b_flags & B_INFREECNT) != 0)
4584 nfree++;
4585 else
4586 used++;
4587 }
4588
4589 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
4590 nfree + used);
4591 db_printf("numfreebuffers is %d\n", numfreebuffers);
4592 }
4593 #endif /* DDB */
Cache object: 397f652073f6d218ee63d9e9dd707460
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