FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_bio.c
1 /*-
2 * Copyright (c) 2004 Poul-Henning Kamp
3 * Copyright (c) 1994,1997 John S. Dyson
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 /*
29 * this file contains a new buffer I/O scheme implementing a coherent
30 * VM object and buffer cache scheme. Pains have been taken to make
31 * sure that the performance degradation associated with schemes such
32 * as this is not realized.
33 *
34 * Author: John S. Dyson
35 * Significant help during the development and debugging phases
36 * had been provided by David Greenman, also of the FreeBSD core team.
37 *
38 * see man buf(9) for more info.
39 */
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD: releng/9.0/sys/kern/vfs_bio.c 225448 2011-09-08 12:56:26Z attilio $");
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/bio.h>
47 #include <sys/conf.h>
48 #include <sys/buf.h>
49 #include <sys/devicestat.h>
50 #include <sys/eventhandler.h>
51 #include <sys/fail.h>
52 #include <sys/limits.h>
53 #include <sys/lock.h>
54 #include <sys/malloc.h>
55 #include <sys/mount.h>
56 #include <sys/mutex.h>
57 #include <sys/kernel.h>
58 #include <sys/kthread.h>
59 #include <sys/proc.h>
60 #include <sys/resourcevar.h>
61 #include <sys/sysctl.h>
62 #include <sys/vmmeter.h>
63 #include <sys/vnode.h>
64 #include <geom/geom.h>
65 #include <vm/vm.h>
66 #include <vm/vm_param.h>
67 #include <vm/vm_kern.h>
68 #include <vm/vm_pageout.h>
69 #include <vm/vm_page.h>
70 #include <vm/vm_object.h>
71 #include <vm/vm_extern.h>
72 #include <vm/vm_map.h>
73 #include "opt_compat.h"
74 #include "opt_directio.h"
75 #include "opt_swap.h"
76
77 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
78
79 struct bio_ops bioops; /* I/O operation notification */
80
81 struct buf_ops buf_ops_bio = {
82 .bop_name = "buf_ops_bio",
83 .bop_write = bufwrite,
84 .bop_strategy = bufstrategy,
85 .bop_sync = bufsync,
86 .bop_bdflush = bufbdflush,
87 };
88
89 /*
90 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
91 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
92 */
93 struct buf *buf; /* buffer header pool */
94
95 static struct proc *bufdaemonproc;
96
97 static int inmem(struct vnode *vp, daddr_t blkno);
98 static void vm_hold_free_pages(struct buf *bp, int newbsize);
99 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
100 vm_offset_t to);
101 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
102 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
103 vm_page_t m);
104 static void vfs_drain_busy_pages(struct buf *bp);
105 static void vfs_clean_pages_dirty_buf(struct buf *bp);
106 static void vfs_setdirty_locked_object(struct buf *bp);
107 static void vfs_vmio_release(struct buf *bp);
108 static int vfs_bio_clcheck(struct vnode *vp, int size,
109 daddr_t lblkno, daddr_t blkno);
110 static int buf_do_flush(struct vnode *vp);
111 static int flushbufqueues(struct vnode *, int, int);
112 static void buf_daemon(void);
113 static void bremfreel(struct buf *bp);
114 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
115 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
116 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
117 #endif
118
119 int vmiodirenable = TRUE;
120 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
121 "Use the VM system for directory writes");
122 long runningbufspace;
123 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
124 "Amount of presently outstanding async buffer io");
125 static long bufspace;
126 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
127 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
128 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
129 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
130 #else
131 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
132 "Virtual memory used for buffers");
133 #endif
134 static long maxbufspace;
135 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
136 "Maximum allowed value of bufspace (including buf_daemon)");
137 static long bufmallocspace;
138 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
139 "Amount of malloced memory for buffers");
140 static long maxbufmallocspace;
141 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
142 "Maximum amount of malloced memory for buffers");
143 static long lobufspace;
144 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
145 "Minimum amount of buffers we want to have");
146 long hibufspace;
147 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
148 "Maximum allowed value of bufspace (excluding buf_daemon)");
149 static int bufreusecnt;
150 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
151 "Number of times we have reused a buffer");
152 static int buffreekvacnt;
153 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
154 "Number of times we have freed the KVA space from some buffer");
155 static int bufdefragcnt;
156 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
157 "Number of times we have had to repeat buffer allocation to defragment");
158 static long lorunningspace;
159 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
160 "Minimum preferred space used for in-progress I/O");
161 static long hirunningspace;
162 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
163 "Maximum amount of space to use for in-progress I/O");
164 int dirtybufferflushes;
165 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
166 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
167 int bdwriteskip;
168 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
169 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
170 int altbufferflushes;
171 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
172 0, "Number of fsync flushes to limit dirty buffers");
173 static int recursiveflushes;
174 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
175 0, "Number of flushes skipped due to being recursive");
176 static int numdirtybuffers;
177 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
178 "Number of buffers that are dirty (has unwritten changes) at the moment");
179 static int lodirtybuffers;
180 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
181 "How many buffers we want to have free before bufdaemon can sleep");
182 static int hidirtybuffers;
183 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
184 "When the number of dirty buffers is considered severe");
185 int dirtybufthresh;
186 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
187 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
188 static int numfreebuffers;
189 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
190 "Number of free buffers");
191 static int lofreebuffers;
192 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
193 "XXX Unused");
194 static int hifreebuffers;
195 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
196 "XXX Complicatedly unused");
197 static int getnewbufcalls;
198 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
199 "Number of calls to getnewbuf");
200 static int getnewbufrestarts;
201 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
202 "Number of times getnewbuf has had to restart a buffer aquisition");
203 static int flushbufqtarget = 100;
204 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
205 "Amount of work to do in flushbufqueues when helping bufdaemon");
206 static long notbufdflashes;
207 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0,
208 "Number of dirty buffer flushes done by the bufdaemon helpers");
209
210 /*
211 * Wakeup point for bufdaemon, as well as indicator of whether it is already
212 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
213 * is idling.
214 */
215 static int bd_request;
216
217 /*
218 * Request for the buf daemon to write more buffers than is indicated by
219 * lodirtybuf. This may be necessary to push out excess dependencies or
220 * defragment the address space where a simple count of the number of dirty
221 * buffers is insufficient to characterize the demand for flushing them.
222 */
223 static int bd_speedupreq;
224
225 /*
226 * This lock synchronizes access to bd_request.
227 */
228 static struct mtx bdlock;
229
230 /*
231 * bogus page -- for I/O to/from partially complete buffers
232 * this is a temporary solution to the problem, but it is not
233 * really that bad. it would be better to split the buffer
234 * for input in the case of buffers partially already in memory,
235 * but the code is intricate enough already.
236 */
237 vm_page_t bogus_page;
238
239 /*
240 * Synchronization (sleep/wakeup) variable for active buffer space requests.
241 * Set when wait starts, cleared prior to wakeup().
242 * Used in runningbufwakeup() and waitrunningbufspace().
243 */
244 static int runningbufreq;
245
246 /*
247 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
248 * waitrunningbufspace().
249 */
250 static struct mtx rbreqlock;
251
252 /*
253 * Synchronization (sleep/wakeup) variable for buffer requests.
254 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
255 * by and/or.
256 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
257 * getnewbuf(), and getblk().
258 */
259 static int needsbuffer;
260
261 /*
262 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
263 */
264 static struct mtx nblock;
265
266 /*
267 * Definitions for the buffer free lists.
268 */
269 #define BUFFER_QUEUES 6 /* number of free buffer queues */
270
271 #define QUEUE_NONE 0 /* on no queue */
272 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
273 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
274 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */
275 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
276 #define QUEUE_EMPTY 5 /* empty buffer headers */
277 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
278
279 /* Queues for free buffers with various properties */
280 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
281
282 /* Lock for the bufqueues */
283 static struct mtx bqlock;
284
285 /*
286 * Single global constant for BUF_WMESG, to avoid getting multiple references.
287 * buf_wmesg is referred from macros.
288 */
289 const char *buf_wmesg = BUF_WMESG;
290
291 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
292 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
293 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
294 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
295
296 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
297 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
298 static int
299 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
300 {
301 long lvalue;
302 int ivalue;
303
304 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
305 return (sysctl_handle_long(oidp, arg1, arg2, req));
306 lvalue = *(long *)arg1;
307 if (lvalue > INT_MAX)
308 /* On overflow, still write out a long to trigger ENOMEM. */
309 return (sysctl_handle_long(oidp, &lvalue, 0, req));
310 ivalue = lvalue;
311 return (sysctl_handle_int(oidp, &ivalue, 0, req));
312 }
313 #endif
314
315 #ifdef DIRECTIO
316 extern void ffs_rawread_setup(void);
317 #endif /* DIRECTIO */
318 /*
319 * numdirtywakeup:
320 *
321 * If someone is blocked due to there being too many dirty buffers,
322 * and numdirtybuffers is now reasonable, wake them up.
323 */
324
325 static __inline void
326 numdirtywakeup(int level)
327 {
328
329 if (numdirtybuffers <= level) {
330 mtx_lock(&nblock);
331 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
332 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
333 wakeup(&needsbuffer);
334 }
335 mtx_unlock(&nblock);
336 }
337 }
338
339 /*
340 * bufspacewakeup:
341 *
342 * Called when buffer space is potentially available for recovery.
343 * getnewbuf() will block on this flag when it is unable to free
344 * sufficient buffer space. Buffer space becomes recoverable when
345 * bp's get placed back in the queues.
346 */
347
348 static __inline void
349 bufspacewakeup(void)
350 {
351
352 /*
353 * If someone is waiting for BUF space, wake them up. Even
354 * though we haven't freed the kva space yet, the waiting
355 * process will be able to now.
356 */
357 mtx_lock(&nblock);
358 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
359 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
360 wakeup(&needsbuffer);
361 }
362 mtx_unlock(&nblock);
363 }
364
365 /*
366 * runningbufwakeup() - in-progress I/O accounting.
367 *
368 */
369 void
370 runningbufwakeup(struct buf *bp)
371 {
372
373 if (bp->b_runningbufspace) {
374 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace);
375 bp->b_runningbufspace = 0;
376 mtx_lock(&rbreqlock);
377 if (runningbufreq && runningbufspace <= lorunningspace) {
378 runningbufreq = 0;
379 wakeup(&runningbufreq);
380 }
381 mtx_unlock(&rbreqlock);
382 }
383 }
384
385 /*
386 * bufcountwakeup:
387 *
388 * Called when a buffer has been added to one of the free queues to
389 * account for the buffer and to wakeup anyone waiting for free buffers.
390 * This typically occurs when large amounts of metadata are being handled
391 * by the buffer cache ( else buffer space runs out first, usually ).
392 */
393
394 static __inline void
395 bufcountwakeup(struct buf *bp)
396 {
397 int old;
398
399 KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
400 ("buf %p already counted as free", bp));
401 if (bp->b_bufobj != NULL)
402 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
403 bp->b_vflags |= BV_INFREECNT;
404 old = atomic_fetchadd_int(&numfreebuffers, 1);
405 KASSERT(old >= 0 && old < nbuf,
406 ("numfreebuffers climbed to %d", old + 1));
407 mtx_lock(&nblock);
408 if (needsbuffer) {
409 needsbuffer &= ~VFS_BIO_NEED_ANY;
410 if (numfreebuffers >= hifreebuffers)
411 needsbuffer &= ~VFS_BIO_NEED_FREE;
412 wakeup(&needsbuffer);
413 }
414 mtx_unlock(&nblock);
415 }
416
417 /*
418 * waitrunningbufspace()
419 *
420 * runningbufspace is a measure of the amount of I/O currently
421 * running. This routine is used in async-write situations to
422 * prevent creating huge backups of pending writes to a device.
423 * Only asynchronous writes are governed by this function.
424 *
425 * Reads will adjust runningbufspace, but will not block based on it.
426 * The read load has a side effect of reducing the allowed write load.
427 *
428 * This does NOT turn an async write into a sync write. It waits
429 * for earlier writes to complete and generally returns before the
430 * caller's write has reached the device.
431 */
432 void
433 waitrunningbufspace(void)
434 {
435
436 mtx_lock(&rbreqlock);
437 while (runningbufspace > hirunningspace) {
438 ++runningbufreq;
439 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
440 }
441 mtx_unlock(&rbreqlock);
442 }
443
444
445 /*
446 * vfs_buf_test_cache:
447 *
448 * Called when a buffer is extended. This function clears the B_CACHE
449 * bit if the newly extended portion of the buffer does not contain
450 * valid data.
451 */
452 static __inline
453 void
454 vfs_buf_test_cache(struct buf *bp,
455 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
456 vm_page_t m)
457 {
458
459 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
460 if (bp->b_flags & B_CACHE) {
461 int base = (foff + off) & PAGE_MASK;
462 if (vm_page_is_valid(m, base, size) == 0)
463 bp->b_flags &= ~B_CACHE;
464 }
465 }
466
467 /* Wake up the buffer daemon if necessary */
468 static __inline
469 void
470 bd_wakeup(int dirtybuflevel)
471 {
472
473 mtx_lock(&bdlock);
474 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
475 bd_request = 1;
476 wakeup(&bd_request);
477 }
478 mtx_unlock(&bdlock);
479 }
480
481 /*
482 * bd_speedup - speedup the buffer cache flushing code
483 */
484
485 void
486 bd_speedup(void)
487 {
488 int needwake;
489
490 mtx_lock(&bdlock);
491 needwake = 0;
492 if (bd_speedupreq == 0 || bd_request == 0)
493 needwake = 1;
494 bd_speedupreq = 1;
495 bd_request = 1;
496 if (needwake)
497 wakeup(&bd_request);
498 mtx_unlock(&bdlock);
499 }
500
501 /*
502 * Calculating buffer cache scaling values and reserve space for buffer
503 * headers. This is called during low level kernel initialization and
504 * may be called more then once. We CANNOT write to the memory area
505 * being reserved at this time.
506 */
507 caddr_t
508 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
509 {
510 int tuned_nbuf;
511 long maxbuf;
512
513 /*
514 * physmem_est is in pages. Convert it to kilobytes (assumes
515 * PAGE_SIZE is >= 1K)
516 */
517 physmem_est = physmem_est * (PAGE_SIZE / 1024);
518
519 /*
520 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
521 * For the first 64MB of ram nominally allocate sufficient buffers to
522 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
523 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
524 * the buffer cache we limit the eventual kva reservation to
525 * maxbcache bytes.
526 *
527 * factor represents the 1/4 x ram conversion.
528 */
529 if (nbuf == 0) {
530 int factor = 4 * BKVASIZE / 1024;
531
532 nbuf = 50;
533 if (physmem_est > 4096)
534 nbuf += min((physmem_est - 4096) / factor,
535 65536 / factor);
536 if (physmem_est > 65536)
537 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
538
539 if (maxbcache && nbuf > maxbcache / BKVASIZE)
540 nbuf = maxbcache / BKVASIZE;
541 tuned_nbuf = 1;
542 } else
543 tuned_nbuf = 0;
544
545 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
546 maxbuf = (LONG_MAX / 3) / BKVASIZE;
547 if (nbuf > maxbuf) {
548 if (!tuned_nbuf)
549 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
550 maxbuf);
551 nbuf = maxbuf;
552 }
553
554 /*
555 * swbufs are used as temporary holders for I/O, such as paging I/O.
556 * We have no less then 16 and no more then 256.
557 */
558 nswbuf = max(min(nbuf/4, 256), 16);
559 #ifdef NSWBUF_MIN
560 if (nswbuf < NSWBUF_MIN)
561 nswbuf = NSWBUF_MIN;
562 #endif
563 #ifdef DIRECTIO
564 ffs_rawread_setup();
565 #endif
566
567 /*
568 * Reserve space for the buffer cache buffers
569 */
570 swbuf = (void *)v;
571 v = (caddr_t)(swbuf + nswbuf);
572 buf = (void *)v;
573 v = (caddr_t)(buf + nbuf);
574
575 return(v);
576 }
577
578 /* Initialize the buffer subsystem. Called before use of any buffers. */
579 void
580 bufinit(void)
581 {
582 struct buf *bp;
583 int i;
584
585 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
586 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
587 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
588 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
589
590 /* next, make a null set of free lists */
591 for (i = 0; i < BUFFER_QUEUES; i++)
592 TAILQ_INIT(&bufqueues[i]);
593
594 /* finally, initialize each buffer header and stick on empty q */
595 for (i = 0; i < nbuf; i++) {
596 bp = &buf[i];
597 bzero(bp, sizeof *bp);
598 bp->b_flags = B_INVAL; /* we're just an empty header */
599 bp->b_rcred = NOCRED;
600 bp->b_wcred = NOCRED;
601 bp->b_qindex = QUEUE_EMPTY;
602 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */
603 bp->b_xflags = 0;
604 LIST_INIT(&bp->b_dep);
605 BUF_LOCKINIT(bp);
606 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
607 }
608
609 /*
610 * maxbufspace is the absolute maximum amount of buffer space we are
611 * allowed to reserve in KVM and in real terms. The absolute maximum
612 * is nominally used by buf_daemon. hibufspace is the nominal maximum
613 * used by most other processes. The differential is required to
614 * ensure that buf_daemon is able to run when other processes might
615 * be blocked waiting for buffer space.
616 *
617 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
618 * this may result in KVM fragmentation which is not handled optimally
619 * by the system.
620 */
621 maxbufspace = (long)nbuf * BKVASIZE;
622 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
623 lobufspace = hibufspace - MAXBSIZE;
624
625 /*
626 * Note: The 16 MiB upper limit for hirunningspace was chosen
627 * arbitrarily and may need further tuning. It corresponds to
628 * 128 outstanding write IO requests (if IO size is 128 KiB),
629 * which fits with many RAID controllers' tagged queuing limits.
630 * The lower 1 MiB limit is the historical upper limit for
631 * hirunningspace.
632 */
633 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE),
634 16 * 1024 * 1024), 1024 * 1024);
635 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE);
636
637 /*
638 * Limit the amount of malloc memory since it is wired permanently into
639 * the kernel space. Even though this is accounted for in the buffer
640 * allocation, we don't want the malloced region to grow uncontrolled.
641 * The malloc scheme improves memory utilization significantly on average
642 * (small) directories.
643 */
644 maxbufmallocspace = hibufspace / 20;
645
646 /*
647 * Reduce the chance of a deadlock occuring by limiting the number
648 * of delayed-write dirty buffers we allow to stack up.
649 */
650 hidirtybuffers = nbuf / 4 + 20;
651 dirtybufthresh = hidirtybuffers * 9 / 10;
652 numdirtybuffers = 0;
653 /*
654 * To support extreme low-memory systems, make sure hidirtybuffers cannot
655 * eat up all available buffer space. This occurs when our minimum cannot
656 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
657 * BKVASIZE'd buffers.
658 */
659 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
660 hidirtybuffers >>= 1;
661 }
662 lodirtybuffers = hidirtybuffers / 2;
663
664 /*
665 * Try to keep the number of free buffers in the specified range,
666 * and give special processes (e.g. like buf_daemon) access to an
667 * emergency reserve.
668 */
669 lofreebuffers = nbuf / 18 + 5;
670 hifreebuffers = 2 * lofreebuffers;
671 numfreebuffers = nbuf;
672
673 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
674 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
675 }
676
677 /*
678 * bfreekva() - free the kva allocation for a buffer.
679 *
680 * Since this call frees up buffer space, we call bufspacewakeup().
681 */
682 static void
683 bfreekva(struct buf *bp)
684 {
685
686 if (bp->b_kvasize) {
687 atomic_add_int(&buffreekvacnt, 1);
688 atomic_subtract_long(&bufspace, bp->b_kvasize);
689 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase,
690 (vm_offset_t) bp->b_kvabase + bp->b_kvasize);
691 bp->b_kvasize = 0;
692 bufspacewakeup();
693 }
694 }
695
696 /*
697 * bremfree:
698 *
699 * Mark the buffer for removal from the appropriate free list in brelse.
700 *
701 */
702 void
703 bremfree(struct buf *bp)
704 {
705 int old;
706
707 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
708 KASSERT((bp->b_flags & B_REMFREE) == 0,
709 ("bremfree: buffer %p already marked for delayed removal.", bp));
710 KASSERT(bp->b_qindex != QUEUE_NONE,
711 ("bremfree: buffer %p not on a queue.", bp));
712 BUF_ASSERT_HELD(bp);
713
714 bp->b_flags |= B_REMFREE;
715 /* Fixup numfreebuffers count. */
716 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
717 KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
718 ("buf %p not counted in numfreebuffers", bp));
719 if (bp->b_bufobj != NULL)
720 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
721 bp->b_vflags &= ~BV_INFREECNT;
722 old = atomic_fetchadd_int(&numfreebuffers, -1);
723 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
724 }
725 }
726
727 /*
728 * bremfreef:
729 *
730 * Force an immediate removal from a free list. Used only in nfs when
731 * it abuses the b_freelist pointer.
732 */
733 void
734 bremfreef(struct buf *bp)
735 {
736 mtx_lock(&bqlock);
737 bremfreel(bp);
738 mtx_unlock(&bqlock);
739 }
740
741 /*
742 * bremfreel:
743 *
744 * Removes a buffer from the free list, must be called with the
745 * bqlock held.
746 */
747 static void
748 bremfreel(struct buf *bp)
749 {
750 int old;
751
752 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
753 bp, bp->b_vp, bp->b_flags);
754 KASSERT(bp->b_qindex != QUEUE_NONE,
755 ("bremfreel: buffer %p not on a queue.", bp));
756 BUF_ASSERT_HELD(bp);
757 mtx_assert(&bqlock, MA_OWNED);
758
759 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
760 bp->b_qindex = QUEUE_NONE;
761 /*
762 * If this was a delayed bremfree() we only need to remove the buffer
763 * from the queue and return the stats are already done.
764 */
765 if (bp->b_flags & B_REMFREE) {
766 bp->b_flags &= ~B_REMFREE;
767 return;
768 }
769 /*
770 * Fixup numfreebuffers count. If the buffer is invalid or not
771 * delayed-write, the buffer was free and we must decrement
772 * numfreebuffers.
773 */
774 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
775 KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
776 ("buf %p not counted in numfreebuffers", bp));
777 if (bp->b_bufobj != NULL)
778 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
779 bp->b_vflags &= ~BV_INFREECNT;
780 old = atomic_fetchadd_int(&numfreebuffers, -1);
781 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
782 }
783 }
784
785
786 /*
787 * Get a buffer with the specified data. Look in the cache first. We
788 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
789 * is set, the buffer is valid and we do not have to do anything ( see
790 * getblk() ). This is really just a special case of breadn().
791 */
792 int
793 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
794 struct buf **bpp)
795 {
796
797 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
798 }
799
800 /*
801 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
802 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
803 * the buffer is valid and we do not have to do anything.
804 */
805 void
806 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
807 int cnt, struct ucred * cred)
808 {
809 struct buf *rabp;
810 int i;
811
812 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
813 if (inmem(vp, *rablkno))
814 continue;
815 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
816
817 if ((rabp->b_flags & B_CACHE) == 0) {
818 if (!TD_IS_IDLETHREAD(curthread))
819 curthread->td_ru.ru_inblock++;
820 rabp->b_flags |= B_ASYNC;
821 rabp->b_flags &= ~B_INVAL;
822 rabp->b_ioflags &= ~BIO_ERROR;
823 rabp->b_iocmd = BIO_READ;
824 if (rabp->b_rcred == NOCRED && cred != NOCRED)
825 rabp->b_rcred = crhold(cred);
826 vfs_busy_pages(rabp, 0);
827 BUF_KERNPROC(rabp);
828 rabp->b_iooffset = dbtob(rabp->b_blkno);
829 bstrategy(rabp);
830 } else {
831 brelse(rabp);
832 }
833 }
834 }
835
836 /*
837 * Operates like bread, but also starts asynchronous I/O on
838 * read-ahead blocks.
839 */
840 int
841 breadn(struct vnode * vp, daddr_t blkno, int size,
842 daddr_t * rablkno, int *rabsize,
843 int cnt, struct ucred * cred, struct buf **bpp)
844 {
845 struct buf *bp;
846 int rv = 0, readwait = 0;
847
848 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
849 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
850
851 /* if not found in cache, do some I/O */
852 if ((bp->b_flags & B_CACHE) == 0) {
853 if (!TD_IS_IDLETHREAD(curthread))
854 curthread->td_ru.ru_inblock++;
855 bp->b_iocmd = BIO_READ;
856 bp->b_flags &= ~B_INVAL;
857 bp->b_ioflags &= ~BIO_ERROR;
858 if (bp->b_rcred == NOCRED && cred != NOCRED)
859 bp->b_rcred = crhold(cred);
860 vfs_busy_pages(bp, 0);
861 bp->b_iooffset = dbtob(bp->b_blkno);
862 bstrategy(bp);
863 ++readwait;
864 }
865
866 breada(vp, rablkno, rabsize, cnt, cred);
867
868 if (readwait) {
869 rv = bufwait(bp);
870 }
871 return (rv);
872 }
873
874 /*
875 * Write, release buffer on completion. (Done by iodone
876 * if async). Do not bother writing anything if the buffer
877 * is invalid.
878 *
879 * Note that we set B_CACHE here, indicating that buffer is
880 * fully valid and thus cacheable. This is true even of NFS
881 * now so we set it generally. This could be set either here
882 * or in biodone() since the I/O is synchronous. We put it
883 * here.
884 */
885 int
886 bufwrite(struct buf *bp)
887 {
888 int oldflags;
889 struct vnode *vp;
890 int vp_md;
891
892 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
893 if (bp->b_flags & B_INVAL) {
894 brelse(bp);
895 return (0);
896 }
897
898 oldflags = bp->b_flags;
899
900 BUF_ASSERT_HELD(bp);
901
902 if (bp->b_pin_count > 0)
903 bunpin_wait(bp);
904
905 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
906 ("FFS background buffer should not get here %p", bp));
907
908 vp = bp->b_vp;
909 if (vp)
910 vp_md = vp->v_vflag & VV_MD;
911 else
912 vp_md = 0;
913
914 /* Mark the buffer clean */
915 bundirty(bp);
916
917 bp->b_flags &= ~B_DONE;
918 bp->b_ioflags &= ~BIO_ERROR;
919 bp->b_flags |= B_CACHE;
920 bp->b_iocmd = BIO_WRITE;
921
922 bufobj_wref(bp->b_bufobj);
923 vfs_busy_pages(bp, 1);
924
925 /*
926 * Normal bwrites pipeline writes
927 */
928 bp->b_runningbufspace = bp->b_bufsize;
929 atomic_add_long(&runningbufspace, bp->b_runningbufspace);
930
931 if (!TD_IS_IDLETHREAD(curthread))
932 curthread->td_ru.ru_oublock++;
933 if (oldflags & B_ASYNC)
934 BUF_KERNPROC(bp);
935 bp->b_iooffset = dbtob(bp->b_blkno);
936 bstrategy(bp);
937
938 if ((oldflags & B_ASYNC) == 0) {
939 int rtval = bufwait(bp);
940 brelse(bp);
941 return (rtval);
942 } else {
943 /*
944 * don't allow the async write to saturate the I/O
945 * system. We will not deadlock here because
946 * we are blocking waiting for I/O that is already in-progress
947 * to complete. We do not block here if it is the update
948 * or syncer daemon trying to clean up as that can lead
949 * to deadlock.
950 */
951 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
952 waitrunningbufspace();
953 }
954
955 return (0);
956 }
957
958 void
959 bufbdflush(struct bufobj *bo, struct buf *bp)
960 {
961 struct buf *nbp;
962
963 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
964 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
965 altbufferflushes++;
966 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
967 BO_LOCK(bo);
968 /*
969 * Try to find a buffer to flush.
970 */
971 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
972 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
973 BUF_LOCK(nbp,
974 LK_EXCLUSIVE | LK_NOWAIT, NULL))
975 continue;
976 if (bp == nbp)
977 panic("bdwrite: found ourselves");
978 BO_UNLOCK(bo);
979 /* Don't countdeps with the bo lock held. */
980 if (buf_countdeps(nbp, 0)) {
981 BO_LOCK(bo);
982 BUF_UNLOCK(nbp);
983 continue;
984 }
985 if (nbp->b_flags & B_CLUSTEROK) {
986 vfs_bio_awrite(nbp);
987 } else {
988 bremfree(nbp);
989 bawrite(nbp);
990 }
991 dirtybufferflushes++;
992 break;
993 }
994 if (nbp == NULL)
995 BO_UNLOCK(bo);
996 }
997 }
998
999 /*
1000 * Delayed write. (Buffer is marked dirty). Do not bother writing
1001 * anything if the buffer is marked invalid.
1002 *
1003 * Note that since the buffer must be completely valid, we can safely
1004 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
1005 * biodone() in order to prevent getblk from writing the buffer
1006 * out synchronously.
1007 */
1008 void
1009 bdwrite(struct buf *bp)
1010 {
1011 struct thread *td = curthread;
1012 struct vnode *vp;
1013 struct bufobj *bo;
1014
1015 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1016 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1017 BUF_ASSERT_HELD(bp);
1018
1019 if (bp->b_flags & B_INVAL) {
1020 brelse(bp);
1021 return;
1022 }
1023
1024 /*
1025 * If we have too many dirty buffers, don't create any more.
1026 * If we are wildly over our limit, then force a complete
1027 * cleanup. Otherwise, just keep the situation from getting
1028 * out of control. Note that we have to avoid a recursive
1029 * disaster and not try to clean up after our own cleanup!
1030 */
1031 vp = bp->b_vp;
1032 bo = bp->b_bufobj;
1033 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
1034 td->td_pflags |= TDP_INBDFLUSH;
1035 BO_BDFLUSH(bo, bp);
1036 td->td_pflags &= ~TDP_INBDFLUSH;
1037 } else
1038 recursiveflushes++;
1039
1040 bdirty(bp);
1041 /*
1042 * Set B_CACHE, indicating that the buffer is fully valid. This is
1043 * true even of NFS now.
1044 */
1045 bp->b_flags |= B_CACHE;
1046
1047 /*
1048 * This bmap keeps the system from needing to do the bmap later,
1049 * perhaps when the system is attempting to do a sync. Since it
1050 * is likely that the indirect block -- or whatever other datastructure
1051 * that the filesystem needs is still in memory now, it is a good
1052 * thing to do this. Note also, that if the pageout daemon is
1053 * requesting a sync -- there might not be enough memory to do
1054 * the bmap then... So, this is important to do.
1055 */
1056 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1057 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1058 }
1059
1060 /*
1061 * Set the *dirty* buffer range based upon the VM system dirty
1062 * pages.
1063 *
1064 * Mark the buffer pages as clean. We need to do this here to
1065 * satisfy the vnode_pager and the pageout daemon, so that it
1066 * thinks that the pages have been "cleaned". Note that since
1067 * the pages are in a delayed write buffer -- the VFS layer
1068 * "will" see that the pages get written out on the next sync,
1069 * or perhaps the cluster will be completed.
1070 */
1071 vfs_clean_pages_dirty_buf(bp);
1072 bqrelse(bp);
1073
1074 /*
1075 * Wakeup the buffer flushing daemon if we have a lot of dirty
1076 * buffers (midpoint between our recovery point and our stall
1077 * point).
1078 */
1079 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1080
1081 /*
1082 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1083 * due to the softdep code.
1084 */
1085 }
1086
1087 /*
1088 * bdirty:
1089 *
1090 * Turn buffer into delayed write request. We must clear BIO_READ and
1091 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1092 * itself to properly update it in the dirty/clean lists. We mark it
1093 * B_DONE to ensure that any asynchronization of the buffer properly
1094 * clears B_DONE ( else a panic will occur later ).
1095 *
1096 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1097 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1098 * should only be called if the buffer is known-good.
1099 *
1100 * Since the buffer is not on a queue, we do not update the numfreebuffers
1101 * count.
1102 *
1103 * The buffer must be on QUEUE_NONE.
1104 */
1105 void
1106 bdirty(struct buf *bp)
1107 {
1108
1109 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1110 bp, bp->b_vp, bp->b_flags);
1111 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1112 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1113 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1114 BUF_ASSERT_HELD(bp);
1115 bp->b_flags &= ~(B_RELBUF);
1116 bp->b_iocmd = BIO_WRITE;
1117
1118 if ((bp->b_flags & B_DELWRI) == 0) {
1119 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1120 reassignbuf(bp);
1121 atomic_add_int(&numdirtybuffers, 1);
1122 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1123 }
1124 }
1125
1126 /*
1127 * bundirty:
1128 *
1129 * Clear B_DELWRI for buffer.
1130 *
1131 * Since the buffer is not on a queue, we do not update the numfreebuffers
1132 * count.
1133 *
1134 * The buffer must be on QUEUE_NONE.
1135 */
1136
1137 void
1138 bundirty(struct buf *bp)
1139 {
1140
1141 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1142 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1143 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1144 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1145 BUF_ASSERT_HELD(bp);
1146
1147 if (bp->b_flags & B_DELWRI) {
1148 bp->b_flags &= ~B_DELWRI;
1149 reassignbuf(bp);
1150 atomic_subtract_int(&numdirtybuffers, 1);
1151 numdirtywakeup(lodirtybuffers);
1152 }
1153 /*
1154 * Since it is now being written, we can clear its deferred write flag.
1155 */
1156 bp->b_flags &= ~B_DEFERRED;
1157 }
1158
1159 /*
1160 * bawrite:
1161 *
1162 * Asynchronous write. Start output on a buffer, but do not wait for
1163 * it to complete. The buffer is released when the output completes.
1164 *
1165 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1166 * B_INVAL buffers. Not us.
1167 */
1168 void
1169 bawrite(struct buf *bp)
1170 {
1171
1172 bp->b_flags |= B_ASYNC;
1173 (void) bwrite(bp);
1174 }
1175
1176 /*
1177 * bwillwrite:
1178 *
1179 * Called prior to the locking of any vnodes when we are expecting to
1180 * write. We do not want to starve the buffer cache with too many
1181 * dirty buffers so we block here. By blocking prior to the locking
1182 * of any vnodes we attempt to avoid the situation where a locked vnode
1183 * prevents the various system daemons from flushing related buffers.
1184 */
1185
1186 void
1187 bwillwrite(void)
1188 {
1189
1190 if (numdirtybuffers >= hidirtybuffers) {
1191 mtx_lock(&nblock);
1192 while (numdirtybuffers >= hidirtybuffers) {
1193 bd_wakeup(1);
1194 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1195 msleep(&needsbuffer, &nblock,
1196 (PRIBIO + 4), "flswai", 0);
1197 }
1198 mtx_unlock(&nblock);
1199 }
1200 }
1201
1202 /*
1203 * Return true if we have too many dirty buffers.
1204 */
1205 int
1206 buf_dirty_count_severe(void)
1207 {
1208
1209 return(numdirtybuffers >= hidirtybuffers);
1210 }
1211
1212 static __noinline int
1213 buf_vm_page_count_severe(void)
1214 {
1215
1216 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1);
1217
1218 return vm_page_count_severe();
1219 }
1220
1221 /*
1222 * brelse:
1223 *
1224 * Release a busy buffer and, if requested, free its resources. The
1225 * buffer will be stashed in the appropriate bufqueue[] allowing it
1226 * to be accessed later as a cache entity or reused for other purposes.
1227 */
1228 void
1229 brelse(struct buf *bp)
1230 {
1231 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1232 bp, bp->b_vp, bp->b_flags);
1233 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1234 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1235
1236 if (bp->b_flags & B_MANAGED) {
1237 bqrelse(bp);
1238 return;
1239 }
1240
1241 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
1242 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) {
1243 /*
1244 * Failed write, redirty. Must clear BIO_ERROR to prevent
1245 * pages from being scrapped. If the error is anything
1246 * other than an I/O error (EIO), assume that retrying
1247 * is futile.
1248 */
1249 bp->b_ioflags &= ~BIO_ERROR;
1250 bdirty(bp);
1251 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1252 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1253 /*
1254 * Either a failed I/O or we were asked to free or not
1255 * cache the buffer.
1256 */
1257 bp->b_flags |= B_INVAL;
1258 if (!LIST_EMPTY(&bp->b_dep))
1259 buf_deallocate(bp);
1260 if (bp->b_flags & B_DELWRI) {
1261 atomic_subtract_int(&numdirtybuffers, 1);
1262 numdirtywakeup(lodirtybuffers);
1263 }
1264 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1265 if ((bp->b_flags & B_VMIO) == 0) {
1266 if (bp->b_bufsize)
1267 allocbuf(bp, 0);
1268 if (bp->b_vp)
1269 brelvp(bp);
1270 }
1271 }
1272
1273 /*
1274 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1275 * is called with B_DELWRI set, the underlying pages may wind up
1276 * getting freed causing a previous write (bdwrite()) to get 'lost'
1277 * because pages associated with a B_DELWRI bp are marked clean.
1278 *
1279 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1280 * if B_DELWRI is set.
1281 *
1282 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1283 * on pages to return pages to the VM page queues.
1284 */
1285 if (bp->b_flags & B_DELWRI)
1286 bp->b_flags &= ~B_RELBUF;
1287 else if (buf_vm_page_count_severe()) {
1288 /*
1289 * The locking of the BO_LOCK is not necessary since
1290 * BKGRDINPROG cannot be set while we hold the buf
1291 * lock, it can only be cleared if it is already
1292 * pending.
1293 */
1294 if (bp->b_vp) {
1295 if (!(bp->b_vflags & BV_BKGRDINPROG))
1296 bp->b_flags |= B_RELBUF;
1297 } else
1298 bp->b_flags |= B_RELBUF;
1299 }
1300
1301 /*
1302 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1303 * constituted, not even NFS buffers now. Two flags effect this. If
1304 * B_INVAL, the struct buf is invalidated but the VM object is kept
1305 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1306 *
1307 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1308 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1309 * buffer is also B_INVAL because it hits the re-dirtying code above.
1310 *
1311 * Normally we can do this whether a buffer is B_DELWRI or not. If
1312 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1313 * the commit state and we cannot afford to lose the buffer. If the
1314 * buffer has a background write in progress, we need to keep it
1315 * around to prevent it from being reconstituted and starting a second
1316 * background write.
1317 */
1318 if ((bp->b_flags & B_VMIO)
1319 && !(bp->b_vp->v_mount != NULL &&
1320 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1321 !vn_isdisk(bp->b_vp, NULL) &&
1322 (bp->b_flags & B_DELWRI))
1323 ) {
1324
1325 int i, j, resid;
1326 vm_page_t m;
1327 off_t foff;
1328 vm_pindex_t poff;
1329 vm_object_t obj;
1330
1331 obj = bp->b_bufobj->bo_object;
1332
1333 /*
1334 * Get the base offset and length of the buffer. Note that
1335 * in the VMIO case if the buffer block size is not
1336 * page-aligned then b_data pointer may not be page-aligned.
1337 * But our b_pages[] array *IS* page aligned.
1338 *
1339 * block sizes less then DEV_BSIZE (usually 512) are not
1340 * supported due to the page granularity bits (m->valid,
1341 * m->dirty, etc...).
1342 *
1343 * See man buf(9) for more information
1344 */
1345 resid = bp->b_bufsize;
1346 foff = bp->b_offset;
1347 VM_OBJECT_LOCK(obj);
1348 for (i = 0; i < bp->b_npages; i++) {
1349 int had_bogus = 0;
1350
1351 m = bp->b_pages[i];
1352
1353 /*
1354 * If we hit a bogus page, fixup *all* the bogus pages
1355 * now.
1356 */
1357 if (m == bogus_page) {
1358 poff = OFF_TO_IDX(bp->b_offset);
1359 had_bogus = 1;
1360
1361 for (j = i; j < bp->b_npages; j++) {
1362 vm_page_t mtmp;
1363 mtmp = bp->b_pages[j];
1364 if (mtmp == bogus_page) {
1365 mtmp = vm_page_lookup(obj, poff + j);
1366 if (!mtmp) {
1367 panic("brelse: page missing\n");
1368 }
1369 bp->b_pages[j] = mtmp;
1370 }
1371 }
1372
1373 if ((bp->b_flags & B_INVAL) == 0) {
1374 pmap_qenter(
1375 trunc_page((vm_offset_t)bp->b_data),
1376 bp->b_pages, bp->b_npages);
1377 }
1378 m = bp->b_pages[i];
1379 }
1380 if ((bp->b_flags & B_NOCACHE) ||
1381 (bp->b_ioflags & BIO_ERROR &&
1382 bp->b_iocmd == BIO_READ)) {
1383 int poffset = foff & PAGE_MASK;
1384 int presid = resid > (PAGE_SIZE - poffset) ?
1385 (PAGE_SIZE - poffset) : resid;
1386
1387 KASSERT(presid >= 0, ("brelse: extra page"));
1388 vm_page_set_invalid(m, poffset, presid);
1389 if (had_bogus)
1390 printf("avoided corruption bug in bogus_page/brelse code\n");
1391 }
1392 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1393 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1394 }
1395 VM_OBJECT_UNLOCK(obj);
1396 if (bp->b_flags & (B_INVAL | B_RELBUF))
1397 vfs_vmio_release(bp);
1398
1399 } else if (bp->b_flags & B_VMIO) {
1400
1401 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1402 vfs_vmio_release(bp);
1403 }
1404
1405 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1406 if (bp->b_bufsize != 0)
1407 allocbuf(bp, 0);
1408 if (bp->b_vp != NULL)
1409 brelvp(bp);
1410 }
1411
1412 if (BUF_LOCKRECURSED(bp)) {
1413 /* do not release to free list */
1414 BUF_UNLOCK(bp);
1415 return;
1416 }
1417
1418 /* enqueue */
1419 mtx_lock(&bqlock);
1420 /* Handle delayed bremfree() processing. */
1421 if (bp->b_flags & B_REMFREE) {
1422 struct bufobj *bo;
1423
1424 bo = bp->b_bufobj;
1425 if (bo != NULL)
1426 BO_LOCK(bo);
1427 bremfreel(bp);
1428 if (bo != NULL)
1429 BO_UNLOCK(bo);
1430 }
1431 if (bp->b_qindex != QUEUE_NONE)
1432 panic("brelse: free buffer onto another queue???");
1433
1434 /*
1435 * If the buffer has junk contents signal it and eventually
1436 * clean up B_DELWRI and diassociate the vnode so that gbincore()
1437 * doesn't find it.
1438 */
1439 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
1440 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
1441 bp->b_flags |= B_INVAL;
1442 if (bp->b_flags & B_INVAL) {
1443 if (bp->b_flags & B_DELWRI)
1444 bundirty(bp);
1445 if (bp->b_vp)
1446 brelvp(bp);
1447 }
1448
1449 /* buffers with no memory */
1450 if (bp->b_bufsize == 0) {
1451 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1452 if (bp->b_vflags & BV_BKGRDINPROG)
1453 panic("losing buffer 1");
1454 if (bp->b_kvasize) {
1455 bp->b_qindex = QUEUE_EMPTYKVA;
1456 } else {
1457 bp->b_qindex = QUEUE_EMPTY;
1458 }
1459 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1460 /* buffers with junk contents */
1461 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1462 (bp->b_ioflags & BIO_ERROR)) {
1463 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1464 if (bp->b_vflags & BV_BKGRDINPROG)
1465 panic("losing buffer 2");
1466 bp->b_qindex = QUEUE_CLEAN;
1467 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1468 /* remaining buffers */
1469 } else {
1470 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) ==
1471 (B_DELWRI|B_NEEDSGIANT))
1472 bp->b_qindex = QUEUE_DIRTY_GIANT;
1473 else if (bp->b_flags & B_DELWRI)
1474 bp->b_qindex = QUEUE_DIRTY;
1475 else
1476 bp->b_qindex = QUEUE_CLEAN;
1477 if (bp->b_flags & B_AGE)
1478 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1479 else
1480 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1481 }
1482 mtx_unlock(&bqlock);
1483
1484 /*
1485 * Fixup numfreebuffers count. The bp is on an appropriate queue
1486 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1487 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1488 * if B_INVAL is set ).
1489 */
1490
1491 if (!(bp->b_flags & B_DELWRI)) {
1492 struct bufobj *bo;
1493
1494 bo = bp->b_bufobj;
1495 if (bo != NULL)
1496 BO_LOCK(bo);
1497 bufcountwakeup(bp);
1498 if (bo != NULL)
1499 BO_UNLOCK(bo);
1500 }
1501
1502 /*
1503 * Something we can maybe free or reuse
1504 */
1505 if (bp->b_bufsize || bp->b_kvasize)
1506 bufspacewakeup();
1507
1508 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1509 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1510 panic("brelse: not dirty");
1511 /* unlock */
1512 BUF_UNLOCK(bp);
1513 }
1514
1515 /*
1516 * Release a buffer back to the appropriate queue but do not try to free
1517 * it. The buffer is expected to be used again soon.
1518 *
1519 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1520 * biodone() to requeue an async I/O on completion. It is also used when
1521 * known good buffers need to be requeued but we think we may need the data
1522 * again soon.
1523 *
1524 * XXX we should be able to leave the B_RELBUF hint set on completion.
1525 */
1526 void
1527 bqrelse(struct buf *bp)
1528 {
1529 struct bufobj *bo;
1530
1531 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1532 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1533 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1534
1535 if (BUF_LOCKRECURSED(bp)) {
1536 /* do not release to free list */
1537 BUF_UNLOCK(bp);
1538 return;
1539 }
1540
1541 bo = bp->b_bufobj;
1542 if (bp->b_flags & B_MANAGED) {
1543 if (bp->b_flags & B_REMFREE) {
1544 mtx_lock(&bqlock);
1545 if (bo != NULL)
1546 BO_LOCK(bo);
1547 bremfreel(bp);
1548 if (bo != NULL)
1549 BO_UNLOCK(bo);
1550 mtx_unlock(&bqlock);
1551 }
1552 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1553 BUF_UNLOCK(bp);
1554 return;
1555 }
1556
1557 mtx_lock(&bqlock);
1558 /* Handle delayed bremfree() processing. */
1559 if (bp->b_flags & B_REMFREE) {
1560 if (bo != NULL)
1561 BO_LOCK(bo);
1562 bremfreel(bp);
1563 if (bo != NULL)
1564 BO_UNLOCK(bo);
1565 }
1566 if (bp->b_qindex != QUEUE_NONE)
1567 panic("bqrelse: free buffer onto another queue???");
1568 /* buffers with stale but valid contents */
1569 if (bp->b_flags & B_DELWRI) {
1570 if (bp->b_flags & B_NEEDSGIANT)
1571 bp->b_qindex = QUEUE_DIRTY_GIANT;
1572 else
1573 bp->b_qindex = QUEUE_DIRTY;
1574 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1575 } else {
1576 /*
1577 * The locking of the BO_LOCK for checking of the
1578 * BV_BKGRDINPROG is not necessary since the
1579 * BV_BKGRDINPROG cannot be set while we hold the buf
1580 * lock, it can only be cleared if it is already
1581 * pending.
1582 */
1583 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) {
1584 bp->b_qindex = QUEUE_CLEAN;
1585 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1586 b_freelist);
1587 } else {
1588 /*
1589 * We are too low on memory, we have to try to free
1590 * the buffer (most importantly: the wired pages
1591 * making up its backing store) *now*.
1592 */
1593 mtx_unlock(&bqlock);
1594 brelse(bp);
1595 return;
1596 }
1597 }
1598 mtx_unlock(&bqlock);
1599
1600 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) {
1601 if (bo != NULL)
1602 BO_LOCK(bo);
1603 bufcountwakeup(bp);
1604 if (bo != NULL)
1605 BO_UNLOCK(bo);
1606 }
1607
1608 /*
1609 * Something we can maybe free or reuse.
1610 */
1611 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1612 bufspacewakeup();
1613
1614 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1615 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1616 panic("bqrelse: not dirty");
1617 /* unlock */
1618 BUF_UNLOCK(bp);
1619 }
1620
1621 /* Give pages used by the bp back to the VM system (where possible) */
1622 static void
1623 vfs_vmio_release(struct buf *bp)
1624 {
1625 int i;
1626 vm_page_t m;
1627
1628 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
1629 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
1630 for (i = 0; i < bp->b_npages; i++) {
1631 m = bp->b_pages[i];
1632 bp->b_pages[i] = NULL;
1633 /*
1634 * In order to keep page LRU ordering consistent, put
1635 * everything on the inactive queue.
1636 */
1637 vm_page_lock(m);
1638 vm_page_unwire(m, 0);
1639 /*
1640 * We don't mess with busy pages, it is
1641 * the responsibility of the process that
1642 * busied the pages to deal with them.
1643 */
1644 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 &&
1645 m->wire_count == 0) {
1646 /*
1647 * Might as well free the page if we can and it has
1648 * no valid data. We also free the page if the
1649 * buffer was used for direct I/O
1650 */
1651 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) {
1652 vm_page_free(m);
1653 } else if (bp->b_flags & B_DIRECT) {
1654 vm_page_try_to_free(m);
1655 } else if (buf_vm_page_count_severe()) {
1656 vm_page_try_to_cache(m);
1657 }
1658 }
1659 vm_page_unlock(m);
1660 }
1661 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
1662
1663 if (bp->b_bufsize) {
1664 bufspacewakeup();
1665 bp->b_bufsize = 0;
1666 }
1667 bp->b_npages = 0;
1668 bp->b_flags &= ~B_VMIO;
1669 if (bp->b_vp)
1670 brelvp(bp);
1671 }
1672
1673 /*
1674 * Check to see if a block at a particular lbn is available for a clustered
1675 * write.
1676 */
1677 static int
1678 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1679 {
1680 struct buf *bpa;
1681 int match;
1682
1683 match = 0;
1684
1685 /* If the buf isn't in core skip it */
1686 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1687 return (0);
1688
1689 /* If the buf is busy we don't want to wait for it */
1690 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1691 return (0);
1692
1693 /* Only cluster with valid clusterable delayed write buffers */
1694 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1695 (B_DELWRI | B_CLUSTEROK))
1696 goto done;
1697
1698 if (bpa->b_bufsize != size)
1699 goto done;
1700
1701 /*
1702 * Check to see if it is in the expected place on disk and that the
1703 * block has been mapped.
1704 */
1705 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1706 match = 1;
1707 done:
1708 BUF_UNLOCK(bpa);
1709 return (match);
1710 }
1711
1712 /*
1713 * vfs_bio_awrite:
1714 *
1715 * Implement clustered async writes for clearing out B_DELWRI buffers.
1716 * This is much better then the old way of writing only one buffer at
1717 * a time. Note that we may not be presented with the buffers in the
1718 * correct order, so we search for the cluster in both directions.
1719 */
1720 int
1721 vfs_bio_awrite(struct buf *bp)
1722 {
1723 struct bufobj *bo;
1724 int i;
1725 int j;
1726 daddr_t lblkno = bp->b_lblkno;
1727 struct vnode *vp = bp->b_vp;
1728 int ncl;
1729 int nwritten;
1730 int size;
1731 int maxcl;
1732
1733 bo = &vp->v_bufobj;
1734 /*
1735 * right now we support clustered writing only to regular files. If
1736 * we find a clusterable block we could be in the middle of a cluster
1737 * rather then at the beginning.
1738 */
1739 if ((vp->v_type == VREG) &&
1740 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1741 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1742
1743 size = vp->v_mount->mnt_stat.f_iosize;
1744 maxcl = MAXPHYS / size;
1745
1746 BO_LOCK(bo);
1747 for (i = 1; i < maxcl; i++)
1748 if (vfs_bio_clcheck(vp, size, lblkno + i,
1749 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1750 break;
1751
1752 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1753 if (vfs_bio_clcheck(vp, size, lblkno - j,
1754 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1755 break;
1756 BO_UNLOCK(bo);
1757 --j;
1758 ncl = i + j;
1759 /*
1760 * this is a possible cluster write
1761 */
1762 if (ncl != 1) {
1763 BUF_UNLOCK(bp);
1764 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1765 return nwritten;
1766 }
1767 }
1768 bremfree(bp);
1769 bp->b_flags |= B_ASYNC;
1770 /*
1771 * default (old) behavior, writing out only one block
1772 *
1773 * XXX returns b_bufsize instead of b_bcount for nwritten?
1774 */
1775 nwritten = bp->b_bufsize;
1776 (void) bwrite(bp);
1777
1778 return nwritten;
1779 }
1780
1781 /*
1782 * getnewbuf:
1783 *
1784 * Find and initialize a new buffer header, freeing up existing buffers
1785 * in the bufqueues as necessary. The new buffer is returned locked.
1786 *
1787 * Important: B_INVAL is not set. If the caller wishes to throw the
1788 * buffer away, the caller must set B_INVAL prior to calling brelse().
1789 *
1790 * We block if:
1791 * We have insufficient buffer headers
1792 * We have insufficient buffer space
1793 * buffer_map is too fragmented ( space reservation fails )
1794 * If we have to flush dirty buffers ( but we try to avoid this )
1795 *
1796 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1797 * Instead we ask the buf daemon to do it for us. We attempt to
1798 * avoid piecemeal wakeups of the pageout daemon.
1799 */
1800
1801 static struct buf *
1802 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
1803 int gbflags)
1804 {
1805 struct thread *td;
1806 struct buf *bp;
1807 struct buf *nbp;
1808 int defrag = 0;
1809 int nqindex;
1810 static int flushingbufs;
1811
1812 td = curthread;
1813 /*
1814 * We can't afford to block since we might be holding a vnode lock,
1815 * which may prevent system daemons from running. We deal with
1816 * low-memory situations by proactively returning memory and running
1817 * async I/O rather then sync I/O.
1818 */
1819 atomic_add_int(&getnewbufcalls, 1);
1820 atomic_subtract_int(&getnewbufrestarts, 1);
1821 restart:
1822 atomic_add_int(&getnewbufrestarts, 1);
1823
1824 /*
1825 * Setup for scan. If we do not have enough free buffers,
1826 * we setup a degenerate case that immediately fails. Note
1827 * that if we are specially marked process, we are allowed to
1828 * dip into our reserves.
1829 *
1830 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1831 *
1832 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1833 * However, there are a number of cases (defragging, reusing, ...)
1834 * where we cannot backup.
1835 */
1836 mtx_lock(&bqlock);
1837 nqindex = QUEUE_EMPTYKVA;
1838 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1839
1840 if (nbp == NULL) {
1841 /*
1842 * If no EMPTYKVA buffers and we are either
1843 * defragging or reusing, locate a CLEAN buffer
1844 * to free or reuse. If bufspace useage is low
1845 * skip this step so we can allocate a new buffer.
1846 */
1847 if (defrag || bufspace >= lobufspace) {
1848 nqindex = QUEUE_CLEAN;
1849 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1850 }
1851
1852 /*
1853 * If we could not find or were not allowed to reuse a
1854 * CLEAN buffer, check to see if it is ok to use an EMPTY
1855 * buffer. We can only use an EMPTY buffer if allocating
1856 * its KVA would not otherwise run us out of buffer space.
1857 */
1858 if (nbp == NULL && defrag == 0 &&
1859 bufspace + maxsize < hibufspace) {
1860 nqindex = QUEUE_EMPTY;
1861 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1862 }
1863 }
1864
1865 /*
1866 * Run scan, possibly freeing data and/or kva mappings on the fly
1867 * depending.
1868 */
1869
1870 while ((bp = nbp) != NULL) {
1871 int qindex = nqindex;
1872
1873 /*
1874 * Calculate next bp ( we can only use it if we do not block
1875 * or do other fancy things ).
1876 */
1877 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1878 switch(qindex) {
1879 case QUEUE_EMPTY:
1880 nqindex = QUEUE_EMPTYKVA;
1881 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1882 break;
1883 /* FALLTHROUGH */
1884 case QUEUE_EMPTYKVA:
1885 nqindex = QUEUE_CLEAN;
1886 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1887 break;
1888 /* FALLTHROUGH */
1889 case QUEUE_CLEAN:
1890 /*
1891 * nbp is NULL.
1892 */
1893 break;
1894 }
1895 }
1896 /*
1897 * If we are defragging then we need a buffer with
1898 * b_kvasize != 0. XXX this situation should no longer
1899 * occur, if defrag is non-zero the buffer's b_kvasize
1900 * should also be non-zero at this point. XXX
1901 */
1902 if (defrag && bp->b_kvasize == 0) {
1903 printf("Warning: defrag empty buffer %p\n", bp);
1904 continue;
1905 }
1906
1907 /*
1908 * Start freeing the bp. This is somewhat involved. nbp
1909 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1910 */
1911 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1912 continue;
1913 if (bp->b_vp) {
1914 BO_LOCK(bp->b_bufobj);
1915 if (bp->b_vflags & BV_BKGRDINPROG) {
1916 BO_UNLOCK(bp->b_bufobj);
1917 BUF_UNLOCK(bp);
1918 continue;
1919 }
1920 BO_UNLOCK(bp->b_bufobj);
1921 }
1922 CTR6(KTR_BUF,
1923 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
1924 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
1925 bp->b_kvasize, bp->b_bufsize, qindex);
1926
1927 /*
1928 * Sanity Checks
1929 */
1930 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1931
1932 /*
1933 * Note: we no longer distinguish between VMIO and non-VMIO
1934 * buffers.
1935 */
1936
1937 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1938
1939 if (bp->b_bufobj != NULL)
1940 BO_LOCK(bp->b_bufobj);
1941 bremfreel(bp);
1942 if (bp->b_bufobj != NULL)
1943 BO_UNLOCK(bp->b_bufobj);
1944 mtx_unlock(&bqlock);
1945
1946 if (qindex == QUEUE_CLEAN) {
1947 if (bp->b_flags & B_VMIO) {
1948 bp->b_flags &= ~B_ASYNC;
1949 vfs_vmio_release(bp);
1950 }
1951 if (bp->b_vp)
1952 brelvp(bp);
1953 }
1954
1955 /*
1956 * NOTE: nbp is now entirely invalid. We can only restart
1957 * the scan from this point on.
1958 *
1959 * Get the rest of the buffer freed up. b_kva* is still
1960 * valid after this operation.
1961 */
1962
1963 if (bp->b_rcred != NOCRED) {
1964 crfree(bp->b_rcred);
1965 bp->b_rcred = NOCRED;
1966 }
1967 if (bp->b_wcred != NOCRED) {
1968 crfree(bp->b_wcred);
1969 bp->b_wcred = NOCRED;
1970 }
1971 if (!LIST_EMPTY(&bp->b_dep))
1972 buf_deallocate(bp);
1973 if (bp->b_vflags & BV_BKGRDINPROG)
1974 panic("losing buffer 3");
1975 KASSERT(bp->b_vp == NULL,
1976 ("bp: %p still has vnode %p. qindex: %d",
1977 bp, bp->b_vp, qindex));
1978 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1979 ("bp: %p still on a buffer list. xflags %X",
1980 bp, bp->b_xflags));
1981
1982 if (bp->b_bufsize)
1983 allocbuf(bp, 0);
1984
1985 bp->b_flags = 0;
1986 bp->b_ioflags = 0;
1987 bp->b_xflags = 0;
1988 KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
1989 ("buf %p still counted as free?", bp));
1990 bp->b_vflags = 0;
1991 bp->b_vp = NULL;
1992 bp->b_blkno = bp->b_lblkno = 0;
1993 bp->b_offset = NOOFFSET;
1994 bp->b_iodone = 0;
1995 bp->b_error = 0;
1996 bp->b_resid = 0;
1997 bp->b_bcount = 0;
1998 bp->b_npages = 0;
1999 bp->b_dirtyoff = bp->b_dirtyend = 0;
2000 bp->b_bufobj = NULL;
2001 bp->b_pin_count = 0;
2002 bp->b_fsprivate1 = NULL;
2003 bp->b_fsprivate2 = NULL;
2004 bp->b_fsprivate3 = NULL;
2005
2006 LIST_INIT(&bp->b_dep);
2007
2008 /*
2009 * If we are defragging then free the buffer.
2010 */
2011 if (defrag) {
2012 bp->b_flags |= B_INVAL;
2013 bfreekva(bp);
2014 brelse(bp);
2015 defrag = 0;
2016 goto restart;
2017 }
2018
2019 /*
2020 * Notify any waiters for the buffer lock about
2021 * identity change by freeing the buffer.
2022 */
2023 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
2024 bp->b_flags |= B_INVAL;
2025 bfreekva(bp);
2026 brelse(bp);
2027 goto restart;
2028 }
2029
2030 /*
2031 * If we are overcomitted then recover the buffer and its
2032 * KVM space. This occurs in rare situations when multiple
2033 * processes are blocked in getnewbuf() or allocbuf().
2034 */
2035 if (bufspace >= hibufspace)
2036 flushingbufs = 1;
2037 if (flushingbufs && bp->b_kvasize != 0) {
2038 bp->b_flags |= B_INVAL;
2039 bfreekva(bp);
2040 brelse(bp);
2041 goto restart;
2042 }
2043 if (bufspace < lobufspace)
2044 flushingbufs = 0;
2045 break;
2046 }
2047
2048 /*
2049 * If we exhausted our list, sleep as appropriate. We may have to
2050 * wakeup various daemons and write out some dirty buffers.
2051 *
2052 * Generally we are sleeping due to insufficient buffer space.
2053 */
2054
2055 if (bp == NULL) {
2056 int flags, norunbuf;
2057 char *waitmsg;
2058 int fl;
2059
2060 if (defrag) {
2061 flags = VFS_BIO_NEED_BUFSPACE;
2062 waitmsg = "nbufkv";
2063 } else if (bufspace >= hibufspace) {
2064 waitmsg = "nbufbs";
2065 flags = VFS_BIO_NEED_BUFSPACE;
2066 } else {
2067 waitmsg = "newbuf";
2068 flags = VFS_BIO_NEED_ANY;
2069 }
2070 mtx_lock(&nblock);
2071 needsbuffer |= flags;
2072 mtx_unlock(&nblock);
2073 mtx_unlock(&bqlock);
2074
2075 bd_speedup(); /* heeeelp */
2076 if (gbflags & GB_NOWAIT_BD)
2077 return (NULL);
2078
2079 mtx_lock(&nblock);
2080 while (needsbuffer & flags) {
2081 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) {
2082 mtx_unlock(&nblock);
2083 /*
2084 * getblk() is called with a vnode
2085 * locked, and some majority of the
2086 * dirty buffers may as well belong to
2087 * the vnode. Flushing the buffers
2088 * there would make a progress that
2089 * cannot be achieved by the
2090 * buf_daemon, that cannot lock the
2091 * vnode.
2092 */
2093 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
2094 (td->td_pflags & TDP_NORUNNINGBUF);
2095 /* play bufdaemon */
2096 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
2097 fl = buf_do_flush(vp);
2098 td->td_pflags &= norunbuf;
2099 mtx_lock(&nblock);
2100 if (fl != 0)
2101 continue;
2102 if ((needsbuffer & flags) == 0)
2103 break;
2104 }
2105 if (msleep(&needsbuffer, &nblock,
2106 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
2107 mtx_unlock(&nblock);
2108 return (NULL);
2109 }
2110 }
2111 mtx_unlock(&nblock);
2112 } else {
2113 /*
2114 * We finally have a valid bp. We aren't quite out of the
2115 * woods, we still have to reserve kva space. In order
2116 * to keep fragmentation sane we only allocate kva in
2117 * BKVASIZE chunks.
2118 */
2119 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2120
2121 if (maxsize != bp->b_kvasize) {
2122 vm_offset_t addr = 0;
2123
2124 bfreekva(bp);
2125
2126 vm_map_lock(buffer_map);
2127 if (vm_map_findspace(buffer_map,
2128 vm_map_min(buffer_map), maxsize, &addr)) {
2129 /*
2130 * Uh oh. Buffer map is to fragmented. We
2131 * must defragment the map.
2132 */
2133 atomic_add_int(&bufdefragcnt, 1);
2134 vm_map_unlock(buffer_map);
2135 defrag = 1;
2136 bp->b_flags |= B_INVAL;
2137 brelse(bp);
2138 goto restart;
2139 }
2140 if (addr) {
2141 vm_map_insert(buffer_map, NULL, 0,
2142 addr, addr + maxsize,
2143 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
2144
2145 bp->b_kvabase = (caddr_t) addr;
2146 bp->b_kvasize = maxsize;
2147 atomic_add_long(&bufspace, bp->b_kvasize);
2148 atomic_add_int(&bufreusecnt, 1);
2149 }
2150 vm_map_unlock(buffer_map);
2151 }
2152 bp->b_saveaddr = bp->b_kvabase;
2153 bp->b_data = bp->b_saveaddr;
2154 }
2155 return(bp);
2156 }
2157
2158 /*
2159 * buf_daemon:
2160 *
2161 * buffer flushing daemon. Buffers are normally flushed by the
2162 * update daemon but if it cannot keep up this process starts to
2163 * take the load in an attempt to prevent getnewbuf() from blocking.
2164 */
2165
2166 static struct kproc_desc buf_kp = {
2167 "bufdaemon",
2168 buf_daemon,
2169 &bufdaemonproc
2170 };
2171 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2172
2173 static int
2174 buf_do_flush(struct vnode *vp)
2175 {
2176 int flushed;
2177
2178 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0);
2179 /* The list empty check here is slightly racy */
2180 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) {
2181 mtx_lock(&Giant);
2182 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0);
2183 mtx_unlock(&Giant);
2184 }
2185 if (flushed == 0) {
2186 /*
2187 * Could not find any buffers without rollback
2188 * dependencies, so just write the first one
2189 * in the hopes of eventually making progress.
2190 */
2191 flushbufqueues(vp, QUEUE_DIRTY, 1);
2192 if (!TAILQ_EMPTY(
2193 &bufqueues[QUEUE_DIRTY_GIANT])) {
2194 mtx_lock(&Giant);
2195 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1);
2196 mtx_unlock(&Giant);
2197 }
2198 }
2199 return (flushed);
2200 }
2201
2202 static void
2203 buf_daemon()
2204 {
2205 int lodirtysave;
2206
2207 /*
2208 * This process needs to be suspended prior to shutdown sync.
2209 */
2210 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2211 SHUTDOWN_PRI_LAST);
2212
2213 /*
2214 * This process is allowed to take the buffer cache to the limit
2215 */
2216 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
2217 mtx_lock(&bdlock);
2218 for (;;) {
2219 bd_request = 0;
2220 mtx_unlock(&bdlock);
2221
2222 kproc_suspend_check(bufdaemonproc);
2223 lodirtysave = lodirtybuffers;
2224 if (bd_speedupreq) {
2225 lodirtybuffers = numdirtybuffers / 2;
2226 bd_speedupreq = 0;
2227 }
2228 /*
2229 * Do the flush. Limit the amount of in-transit I/O we
2230 * allow to build up, otherwise we would completely saturate
2231 * the I/O system. Wakeup any waiting processes before we
2232 * normally would so they can run in parallel with our drain.
2233 */
2234 while (numdirtybuffers > lodirtybuffers) {
2235 if (buf_do_flush(NULL) == 0)
2236 break;
2237 kern_yield(PRI_UNCHANGED);
2238 }
2239 lodirtybuffers = lodirtysave;
2240
2241 /*
2242 * Only clear bd_request if we have reached our low water
2243 * mark. The buf_daemon normally waits 1 second and
2244 * then incrementally flushes any dirty buffers that have
2245 * built up, within reason.
2246 *
2247 * If we were unable to hit our low water mark and couldn't
2248 * find any flushable buffers, we sleep half a second.
2249 * Otherwise we loop immediately.
2250 */
2251 mtx_lock(&bdlock);
2252 if (numdirtybuffers <= lodirtybuffers) {
2253 /*
2254 * We reached our low water mark, reset the
2255 * request and sleep until we are needed again.
2256 * The sleep is just so the suspend code works.
2257 */
2258 bd_request = 0;
2259 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2260 } else {
2261 /*
2262 * We couldn't find any flushable dirty buffers but
2263 * still have too many dirty buffers, we
2264 * have to sleep and try again. (rare)
2265 */
2266 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2267 }
2268 }
2269 }
2270
2271 /*
2272 * flushbufqueues:
2273 *
2274 * Try to flush a buffer in the dirty queue. We must be careful to
2275 * free up B_INVAL buffers instead of write them, which NFS is
2276 * particularly sensitive to.
2277 */
2278 static int flushwithdeps = 0;
2279 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2280 0, "Number of buffers flushed with dependecies that require rollbacks");
2281
2282 static int
2283 flushbufqueues(struct vnode *lvp, int queue, int flushdeps)
2284 {
2285 struct buf *sentinel;
2286 struct vnode *vp;
2287 struct mount *mp;
2288 struct buf *bp;
2289 int hasdeps;
2290 int flushed;
2291 int target;
2292
2293 if (lvp == NULL) {
2294 target = numdirtybuffers - lodirtybuffers;
2295 if (flushdeps && target > 2)
2296 target /= 2;
2297 } else
2298 target = flushbufqtarget;
2299 flushed = 0;
2300 bp = NULL;
2301 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
2302 sentinel->b_qindex = QUEUE_SENTINEL;
2303 mtx_lock(&bqlock);
2304 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
2305 while (flushed != target) {
2306 bp = TAILQ_NEXT(sentinel, b_freelist);
2307 if (bp != NULL) {
2308 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2309 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
2310 b_freelist);
2311 } else
2312 break;
2313 /*
2314 * Skip sentinels inserted by other invocations of the
2315 * flushbufqueues(), taking care to not reorder them.
2316 */
2317 if (bp->b_qindex == QUEUE_SENTINEL)
2318 continue;
2319 /*
2320 * Only flush the buffers that belong to the
2321 * vnode locked by the curthread.
2322 */
2323 if (lvp != NULL && bp->b_vp != lvp)
2324 continue;
2325 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2326 continue;
2327 if (bp->b_pin_count > 0) {
2328 BUF_UNLOCK(bp);
2329 continue;
2330 }
2331 BO_LOCK(bp->b_bufobj);
2332 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2333 (bp->b_flags & B_DELWRI) == 0) {
2334 BO_UNLOCK(bp->b_bufobj);
2335 BUF_UNLOCK(bp);
2336 continue;
2337 }
2338 BO_UNLOCK(bp->b_bufobj);
2339 if (bp->b_flags & B_INVAL) {
2340 bremfreel(bp);
2341 mtx_unlock(&bqlock);
2342 brelse(bp);
2343 flushed++;
2344 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2345 mtx_lock(&bqlock);
2346 continue;
2347 }
2348
2349 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
2350 if (flushdeps == 0) {
2351 BUF_UNLOCK(bp);
2352 continue;
2353 }
2354 hasdeps = 1;
2355 } else
2356 hasdeps = 0;
2357 /*
2358 * We must hold the lock on a vnode before writing
2359 * one of its buffers. Otherwise we may confuse, or
2360 * in the case of a snapshot vnode, deadlock the
2361 * system.
2362 *
2363 * The lock order here is the reverse of the normal
2364 * of vnode followed by buf lock. This is ok because
2365 * the NOWAIT will prevent deadlock.
2366 */
2367 vp = bp->b_vp;
2368 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2369 BUF_UNLOCK(bp);
2370 continue;
2371 }
2372 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) {
2373 mtx_unlock(&bqlock);
2374 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2375 bp, bp->b_vp, bp->b_flags);
2376 if (curproc == bufdaemonproc)
2377 vfs_bio_awrite(bp);
2378 else {
2379 bremfree(bp);
2380 bwrite(bp);
2381 notbufdflashes++;
2382 }
2383 vn_finished_write(mp);
2384 VOP_UNLOCK(vp, 0);
2385 flushwithdeps += hasdeps;
2386 flushed++;
2387
2388 /*
2389 * Sleeping on runningbufspace while holding
2390 * vnode lock leads to deadlock.
2391 */
2392 if (curproc == bufdaemonproc)
2393 waitrunningbufspace();
2394 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2395 mtx_lock(&bqlock);
2396 continue;
2397 }
2398 vn_finished_write(mp);
2399 BUF_UNLOCK(bp);
2400 }
2401 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2402 mtx_unlock(&bqlock);
2403 free(sentinel, M_TEMP);
2404 return (flushed);
2405 }
2406
2407 /*
2408 * Check to see if a block is currently memory resident.
2409 */
2410 struct buf *
2411 incore(struct bufobj *bo, daddr_t blkno)
2412 {
2413 struct buf *bp;
2414
2415 BO_LOCK(bo);
2416 bp = gbincore(bo, blkno);
2417 BO_UNLOCK(bo);
2418 return (bp);
2419 }
2420
2421 /*
2422 * Returns true if no I/O is needed to access the
2423 * associated VM object. This is like incore except
2424 * it also hunts around in the VM system for the data.
2425 */
2426
2427 static int
2428 inmem(struct vnode * vp, daddr_t blkno)
2429 {
2430 vm_object_t obj;
2431 vm_offset_t toff, tinc, size;
2432 vm_page_t m;
2433 vm_ooffset_t off;
2434
2435 ASSERT_VOP_LOCKED(vp, "inmem");
2436
2437 if (incore(&vp->v_bufobj, blkno))
2438 return 1;
2439 if (vp->v_mount == NULL)
2440 return 0;
2441 obj = vp->v_object;
2442 if (obj == NULL)
2443 return (0);
2444
2445 size = PAGE_SIZE;
2446 if (size > vp->v_mount->mnt_stat.f_iosize)
2447 size = vp->v_mount->mnt_stat.f_iosize;
2448 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2449
2450 VM_OBJECT_LOCK(obj);
2451 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2452 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2453 if (!m)
2454 goto notinmem;
2455 tinc = size;
2456 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2457 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2458 if (vm_page_is_valid(m,
2459 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2460 goto notinmem;
2461 }
2462 VM_OBJECT_UNLOCK(obj);
2463 return 1;
2464
2465 notinmem:
2466 VM_OBJECT_UNLOCK(obj);
2467 return (0);
2468 }
2469
2470 /*
2471 * Set the dirty range for a buffer based on the status of the dirty
2472 * bits in the pages comprising the buffer. The range is limited
2473 * to the size of the buffer.
2474 *
2475 * Tell the VM system that the pages associated with this buffer
2476 * are clean. This is used for delayed writes where the data is
2477 * going to go to disk eventually without additional VM intevention.
2478 *
2479 * Note that while we only really need to clean through to b_bcount, we
2480 * just go ahead and clean through to b_bufsize.
2481 */
2482 static void
2483 vfs_clean_pages_dirty_buf(struct buf *bp)
2484 {
2485 vm_ooffset_t foff, noff, eoff;
2486 vm_page_t m;
2487 int i;
2488
2489 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
2490 return;
2491
2492 foff = bp->b_offset;
2493 KASSERT(bp->b_offset != NOOFFSET,
2494 ("vfs_clean_pages_dirty_buf: no buffer offset"));
2495
2496 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2497 vfs_drain_busy_pages(bp);
2498 vfs_setdirty_locked_object(bp);
2499 for (i = 0; i < bp->b_npages; i++) {
2500 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2501 eoff = noff;
2502 if (eoff > bp->b_offset + bp->b_bufsize)
2503 eoff = bp->b_offset + bp->b_bufsize;
2504 m = bp->b_pages[i];
2505 vfs_page_set_validclean(bp, foff, m);
2506 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
2507 foff = noff;
2508 }
2509 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2510 }
2511
2512 static void
2513 vfs_setdirty_locked_object(struct buf *bp)
2514 {
2515 vm_object_t object;
2516 int i;
2517
2518 object = bp->b_bufobj->bo_object;
2519 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
2520
2521 /*
2522 * We qualify the scan for modified pages on whether the
2523 * object has been flushed yet.
2524 */
2525 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
2526 vm_offset_t boffset;
2527 vm_offset_t eoffset;
2528
2529 /*
2530 * test the pages to see if they have been modified directly
2531 * by users through the VM system.
2532 */
2533 for (i = 0; i < bp->b_npages; i++)
2534 vm_page_test_dirty(bp->b_pages[i]);
2535
2536 /*
2537 * Calculate the encompassing dirty range, boffset and eoffset,
2538 * (eoffset - boffset) bytes.
2539 */
2540
2541 for (i = 0; i < bp->b_npages; i++) {
2542 if (bp->b_pages[i]->dirty)
2543 break;
2544 }
2545 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2546
2547 for (i = bp->b_npages - 1; i >= 0; --i) {
2548 if (bp->b_pages[i]->dirty) {
2549 break;
2550 }
2551 }
2552 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2553
2554 /*
2555 * Fit it to the buffer.
2556 */
2557
2558 if (eoffset > bp->b_bcount)
2559 eoffset = bp->b_bcount;
2560
2561 /*
2562 * If we have a good dirty range, merge with the existing
2563 * dirty range.
2564 */
2565
2566 if (boffset < eoffset) {
2567 if (bp->b_dirtyoff > boffset)
2568 bp->b_dirtyoff = boffset;
2569 if (bp->b_dirtyend < eoffset)
2570 bp->b_dirtyend = eoffset;
2571 }
2572 }
2573 }
2574
2575 /*
2576 * getblk:
2577 *
2578 * Get a block given a specified block and offset into a file/device.
2579 * The buffers B_DONE bit will be cleared on return, making it almost
2580 * ready for an I/O initiation. B_INVAL may or may not be set on
2581 * return. The caller should clear B_INVAL prior to initiating a
2582 * READ.
2583 *
2584 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2585 * an existing buffer.
2586 *
2587 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2588 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2589 * and then cleared based on the backing VM. If the previous buffer is
2590 * non-0-sized but invalid, B_CACHE will be cleared.
2591 *
2592 * If getblk() must create a new buffer, the new buffer is returned with
2593 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2594 * case it is returned with B_INVAL clear and B_CACHE set based on the
2595 * backing VM.
2596 *
2597 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2598 * B_CACHE bit is clear.
2599 *
2600 * What this means, basically, is that the caller should use B_CACHE to
2601 * determine whether the buffer is fully valid or not and should clear
2602 * B_INVAL prior to issuing a read. If the caller intends to validate
2603 * the buffer by loading its data area with something, the caller needs
2604 * to clear B_INVAL. If the caller does this without issuing an I/O,
2605 * the caller should set B_CACHE ( as an optimization ), else the caller
2606 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2607 * a write attempt or if it was a successfull read. If the caller
2608 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2609 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2610 */
2611 struct buf *
2612 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2613 int flags)
2614 {
2615 struct buf *bp;
2616 struct bufobj *bo;
2617 int error;
2618
2619 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
2620 ASSERT_VOP_LOCKED(vp, "getblk");
2621 if (size > MAXBSIZE)
2622 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2623
2624 bo = &vp->v_bufobj;
2625 loop:
2626 /*
2627 * Block if we are low on buffers. Certain processes are allowed
2628 * to completely exhaust the buffer cache.
2629 *
2630 * If this check ever becomes a bottleneck it may be better to
2631 * move it into the else, when gbincore() fails. At the moment
2632 * it isn't a problem.
2633 *
2634 * XXX remove if 0 sections (clean this up after its proven)
2635 */
2636 if (numfreebuffers == 0) {
2637 if (TD_IS_IDLETHREAD(curthread))
2638 return NULL;
2639 mtx_lock(&nblock);
2640 needsbuffer |= VFS_BIO_NEED_ANY;
2641 mtx_unlock(&nblock);
2642 }
2643
2644 BO_LOCK(bo);
2645 bp = gbincore(bo, blkno);
2646 if (bp != NULL) {
2647 int lockflags;
2648 /*
2649 * Buffer is in-core. If the buffer is not busy, it must
2650 * be on a queue.
2651 */
2652 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2653
2654 if (flags & GB_LOCK_NOWAIT)
2655 lockflags |= LK_NOWAIT;
2656
2657 error = BUF_TIMELOCK(bp, lockflags,
2658 BO_MTX(bo), "getblk", slpflag, slptimeo);
2659
2660 /*
2661 * If we slept and got the lock we have to restart in case
2662 * the buffer changed identities.
2663 */
2664 if (error == ENOLCK)
2665 goto loop;
2666 /* We timed out or were interrupted. */
2667 else if (error)
2668 return (NULL);
2669
2670 /*
2671 * The buffer is locked. B_CACHE is cleared if the buffer is
2672 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2673 * and for a VMIO buffer B_CACHE is adjusted according to the
2674 * backing VM cache.
2675 */
2676 if (bp->b_flags & B_INVAL)
2677 bp->b_flags &= ~B_CACHE;
2678 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2679 bp->b_flags |= B_CACHE;
2680 BO_LOCK(bo);
2681 bremfree(bp);
2682 BO_UNLOCK(bo);
2683
2684 /*
2685 * check for size inconsistancies for non-VMIO case.
2686 */
2687
2688 if (bp->b_bcount != size) {
2689 if ((bp->b_flags & B_VMIO) == 0 ||
2690 (size > bp->b_kvasize)) {
2691 if (bp->b_flags & B_DELWRI) {
2692 /*
2693 * If buffer is pinned and caller does
2694 * not want sleep waiting for it to be
2695 * unpinned, bail out
2696 * */
2697 if (bp->b_pin_count > 0) {
2698 if (flags & GB_LOCK_NOWAIT) {
2699 bqrelse(bp);
2700 return (NULL);
2701 } else {
2702 bunpin_wait(bp);
2703 }
2704 }
2705 bp->b_flags |= B_NOCACHE;
2706 bwrite(bp);
2707 } else {
2708 if (LIST_EMPTY(&bp->b_dep)) {
2709 bp->b_flags |= B_RELBUF;
2710 brelse(bp);
2711 } else {
2712 bp->b_flags |= B_NOCACHE;
2713 bwrite(bp);
2714 }
2715 }
2716 goto loop;
2717 }
2718 }
2719
2720 /*
2721 * If the size is inconsistant in the VMIO case, we can resize
2722 * the buffer. This might lead to B_CACHE getting set or
2723 * cleared. If the size has not changed, B_CACHE remains
2724 * unchanged from its previous state.
2725 */
2726
2727 if (bp->b_bcount != size)
2728 allocbuf(bp, size);
2729
2730 KASSERT(bp->b_offset != NOOFFSET,
2731 ("getblk: no buffer offset"));
2732
2733 /*
2734 * A buffer with B_DELWRI set and B_CACHE clear must
2735 * be committed before we can return the buffer in
2736 * order to prevent the caller from issuing a read
2737 * ( due to B_CACHE not being set ) and overwriting
2738 * it.
2739 *
2740 * Most callers, including NFS and FFS, need this to
2741 * operate properly either because they assume they
2742 * can issue a read if B_CACHE is not set, or because
2743 * ( for example ) an uncached B_DELWRI might loop due
2744 * to softupdates re-dirtying the buffer. In the latter
2745 * case, B_CACHE is set after the first write completes,
2746 * preventing further loops.
2747 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2748 * above while extending the buffer, we cannot allow the
2749 * buffer to remain with B_CACHE set after the write
2750 * completes or it will represent a corrupt state. To
2751 * deal with this we set B_NOCACHE to scrap the buffer
2752 * after the write.
2753 *
2754 * We might be able to do something fancy, like setting
2755 * B_CACHE in bwrite() except if B_DELWRI is already set,
2756 * so the below call doesn't set B_CACHE, but that gets real
2757 * confusing. This is much easier.
2758 */
2759
2760 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2761 bp->b_flags |= B_NOCACHE;
2762 bwrite(bp);
2763 goto loop;
2764 }
2765 bp->b_flags &= ~B_DONE;
2766 } else {
2767 int bsize, maxsize, vmio;
2768 off_t offset;
2769
2770 /*
2771 * Buffer is not in-core, create new buffer. The buffer
2772 * returned by getnewbuf() is locked. Note that the returned
2773 * buffer is also considered valid (not marked B_INVAL).
2774 */
2775 BO_UNLOCK(bo);
2776 /*
2777 * If the user does not want us to create the buffer, bail out
2778 * here.
2779 */
2780 if (flags & GB_NOCREAT)
2781 return NULL;
2782 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
2783 offset = blkno * bsize;
2784 vmio = vp->v_object != NULL;
2785 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2786 maxsize = imax(maxsize, bsize);
2787
2788 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags);
2789 if (bp == NULL) {
2790 if (slpflag || slptimeo)
2791 return NULL;
2792 goto loop;
2793 }
2794
2795 /*
2796 * This code is used to make sure that a buffer is not
2797 * created while the getnewbuf routine is blocked.
2798 * This can be a problem whether the vnode is locked or not.
2799 * If the buffer is created out from under us, we have to
2800 * throw away the one we just created.
2801 *
2802 * Note: this must occur before we associate the buffer
2803 * with the vp especially considering limitations in
2804 * the splay tree implementation when dealing with duplicate
2805 * lblkno's.
2806 */
2807 BO_LOCK(bo);
2808 if (gbincore(bo, blkno)) {
2809 BO_UNLOCK(bo);
2810 bp->b_flags |= B_INVAL;
2811 brelse(bp);
2812 goto loop;
2813 }
2814
2815 /*
2816 * Insert the buffer into the hash, so that it can
2817 * be found by incore.
2818 */
2819 bp->b_blkno = bp->b_lblkno = blkno;
2820 bp->b_offset = offset;
2821 bgetvp(vp, bp);
2822 BO_UNLOCK(bo);
2823
2824 /*
2825 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2826 * buffer size starts out as 0, B_CACHE will be set by
2827 * allocbuf() for the VMIO case prior to it testing the
2828 * backing store for validity.
2829 */
2830
2831 if (vmio) {
2832 bp->b_flags |= B_VMIO;
2833 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
2834 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
2835 bp, vp->v_object, bp->b_bufobj->bo_object));
2836 } else {
2837 bp->b_flags &= ~B_VMIO;
2838 KASSERT(bp->b_bufobj->bo_object == NULL,
2839 ("ARGH! has b_bufobj->bo_object %p %p\n",
2840 bp, bp->b_bufobj->bo_object));
2841 }
2842
2843 allocbuf(bp, size);
2844 bp->b_flags &= ~B_DONE;
2845 }
2846 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
2847 BUF_ASSERT_HELD(bp);
2848 KASSERT(bp->b_bufobj == bo,
2849 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
2850 return (bp);
2851 }
2852
2853 /*
2854 * Get an empty, disassociated buffer of given size. The buffer is initially
2855 * set to B_INVAL.
2856 */
2857 struct buf *
2858 geteblk(int size, int flags)
2859 {
2860 struct buf *bp;
2861 int maxsize;
2862
2863 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2864 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) {
2865 if ((flags & GB_NOWAIT_BD) &&
2866 (curthread->td_pflags & TDP_BUFNEED) != 0)
2867 return (NULL);
2868 }
2869 allocbuf(bp, size);
2870 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2871 BUF_ASSERT_HELD(bp);
2872 return (bp);
2873 }
2874
2875
2876 /*
2877 * This code constitutes the buffer memory from either anonymous system
2878 * memory (in the case of non-VMIO operations) or from an associated
2879 * VM object (in the case of VMIO operations). This code is able to
2880 * resize a buffer up or down.
2881 *
2882 * Note that this code is tricky, and has many complications to resolve
2883 * deadlock or inconsistant data situations. Tread lightly!!!
2884 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2885 * the caller. Calling this code willy nilly can result in the loss of data.
2886 *
2887 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2888 * B_CACHE for the non-VMIO case.
2889 */
2890
2891 int
2892 allocbuf(struct buf *bp, int size)
2893 {
2894 int newbsize, mbsize;
2895 int i;
2896
2897 BUF_ASSERT_HELD(bp);
2898
2899 if (bp->b_kvasize < size)
2900 panic("allocbuf: buffer too small");
2901
2902 if ((bp->b_flags & B_VMIO) == 0) {
2903 caddr_t origbuf;
2904 int origbufsize;
2905 /*
2906 * Just get anonymous memory from the kernel. Don't
2907 * mess with B_CACHE.
2908 */
2909 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2910 if (bp->b_flags & B_MALLOC)
2911 newbsize = mbsize;
2912 else
2913 newbsize = round_page(size);
2914
2915 if (newbsize < bp->b_bufsize) {
2916 /*
2917 * malloced buffers are not shrunk
2918 */
2919 if (bp->b_flags & B_MALLOC) {
2920 if (newbsize) {
2921 bp->b_bcount = size;
2922 } else {
2923 free(bp->b_data, M_BIOBUF);
2924 if (bp->b_bufsize) {
2925 atomic_subtract_long(
2926 &bufmallocspace,
2927 bp->b_bufsize);
2928 bufspacewakeup();
2929 bp->b_bufsize = 0;
2930 }
2931 bp->b_saveaddr = bp->b_kvabase;
2932 bp->b_data = bp->b_saveaddr;
2933 bp->b_bcount = 0;
2934 bp->b_flags &= ~B_MALLOC;
2935 }
2936 return 1;
2937 }
2938 vm_hold_free_pages(bp, newbsize);
2939 } else if (newbsize > bp->b_bufsize) {
2940 /*
2941 * We only use malloced memory on the first allocation.
2942 * and revert to page-allocated memory when the buffer
2943 * grows.
2944 */
2945 /*
2946 * There is a potential smp race here that could lead
2947 * to bufmallocspace slightly passing the max. It
2948 * is probably extremely rare and not worth worrying
2949 * over.
2950 */
2951 if ( (bufmallocspace < maxbufmallocspace) &&
2952 (bp->b_bufsize == 0) &&
2953 (mbsize <= PAGE_SIZE/2)) {
2954
2955 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2956 bp->b_bufsize = mbsize;
2957 bp->b_bcount = size;
2958 bp->b_flags |= B_MALLOC;
2959 atomic_add_long(&bufmallocspace, mbsize);
2960 return 1;
2961 }
2962 origbuf = NULL;
2963 origbufsize = 0;
2964 /*
2965 * If the buffer is growing on its other-than-first allocation,
2966 * then we revert to the page-allocation scheme.
2967 */
2968 if (bp->b_flags & B_MALLOC) {
2969 origbuf = bp->b_data;
2970 origbufsize = bp->b_bufsize;
2971 bp->b_data = bp->b_kvabase;
2972 if (bp->b_bufsize) {
2973 atomic_subtract_long(&bufmallocspace,
2974 bp->b_bufsize);
2975 bufspacewakeup();
2976 bp->b_bufsize = 0;
2977 }
2978 bp->b_flags &= ~B_MALLOC;
2979 newbsize = round_page(newbsize);
2980 }
2981 vm_hold_load_pages(
2982 bp,
2983 (vm_offset_t) bp->b_data + bp->b_bufsize,
2984 (vm_offset_t) bp->b_data + newbsize);
2985 if (origbuf) {
2986 bcopy(origbuf, bp->b_data, origbufsize);
2987 free(origbuf, M_BIOBUF);
2988 }
2989 }
2990 } else {
2991 int desiredpages;
2992
2993 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2994 desiredpages = (size == 0) ? 0 :
2995 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2996
2997 if (bp->b_flags & B_MALLOC)
2998 panic("allocbuf: VMIO buffer can't be malloced");
2999 /*
3000 * Set B_CACHE initially if buffer is 0 length or will become
3001 * 0-length.
3002 */
3003 if (size == 0 || bp->b_bufsize == 0)
3004 bp->b_flags |= B_CACHE;
3005
3006 if (newbsize < bp->b_bufsize) {
3007 /*
3008 * DEV_BSIZE aligned new buffer size is less then the
3009 * DEV_BSIZE aligned existing buffer size. Figure out
3010 * if we have to remove any pages.
3011 */
3012 if (desiredpages < bp->b_npages) {
3013 vm_page_t m;
3014
3015 pmap_qremove((vm_offset_t)trunc_page(
3016 (vm_offset_t)bp->b_data) +
3017 (desiredpages << PAGE_SHIFT),
3018 (bp->b_npages - desiredpages));
3019 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3020 for (i = desiredpages; i < bp->b_npages; i++) {
3021 /*
3022 * the page is not freed here -- it
3023 * is the responsibility of
3024 * vnode_pager_setsize
3025 */
3026 m = bp->b_pages[i];
3027 KASSERT(m != bogus_page,
3028 ("allocbuf: bogus page found"));
3029 while (vm_page_sleep_if_busy(m, TRUE,
3030 "biodep"))
3031 continue;
3032
3033 bp->b_pages[i] = NULL;
3034 vm_page_lock(m);
3035 vm_page_unwire(m, 0);
3036 vm_page_unlock(m);
3037 }
3038 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3039 bp->b_npages = desiredpages;
3040 }
3041 } else if (size > bp->b_bcount) {
3042 /*
3043 * We are growing the buffer, possibly in a
3044 * byte-granular fashion.
3045 */
3046 vm_object_t obj;
3047 vm_offset_t toff;
3048 vm_offset_t tinc;
3049
3050 /*
3051 * Step 1, bring in the VM pages from the object,
3052 * allocating them if necessary. We must clear
3053 * B_CACHE if these pages are not valid for the
3054 * range covered by the buffer.
3055 */
3056
3057 obj = bp->b_bufobj->bo_object;
3058
3059 VM_OBJECT_LOCK(obj);
3060 while (bp->b_npages < desiredpages) {
3061 vm_page_t m;
3062
3063 /*
3064 * We must allocate system pages since blocking
3065 * here could intefere with paging I/O, no
3066 * matter which process we are.
3067 *
3068 * We can only test VPO_BUSY here. Blocking on
3069 * m->busy might lead to a deadlock:
3070 * vm_fault->getpages->cluster_read->allocbuf
3071 * Thus, we specify VM_ALLOC_IGN_SBUSY.
3072 */
3073 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
3074 bp->b_npages, VM_ALLOC_NOBUSY |
3075 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
3076 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY |
3077 VM_ALLOC_COUNT(desiredpages - bp->b_npages));
3078 if (m->valid == 0)
3079 bp->b_flags &= ~B_CACHE;
3080 bp->b_pages[bp->b_npages] = m;
3081 ++bp->b_npages;
3082 }
3083
3084 /*
3085 * Step 2. We've loaded the pages into the buffer,
3086 * we have to figure out if we can still have B_CACHE
3087 * set. Note that B_CACHE is set according to the
3088 * byte-granular range ( bcount and size ), new the
3089 * aligned range ( newbsize ).
3090 *
3091 * The VM test is against m->valid, which is DEV_BSIZE
3092 * aligned. Needless to say, the validity of the data
3093 * needs to also be DEV_BSIZE aligned. Note that this
3094 * fails with NFS if the server or some other client
3095 * extends the file's EOF. If our buffer is resized,
3096 * B_CACHE may remain set! XXX
3097 */
3098
3099 toff = bp->b_bcount;
3100 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3101
3102 while ((bp->b_flags & B_CACHE) && toff < size) {
3103 vm_pindex_t pi;
3104
3105 if (tinc > (size - toff))
3106 tinc = size - toff;
3107
3108 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
3109 PAGE_SHIFT;
3110
3111 vfs_buf_test_cache(
3112 bp,
3113 bp->b_offset,
3114 toff,
3115 tinc,
3116 bp->b_pages[pi]
3117 );
3118 toff += tinc;
3119 tinc = PAGE_SIZE;
3120 }
3121 VM_OBJECT_UNLOCK(obj);
3122
3123 /*
3124 * Step 3, fixup the KVM pmap. Remember that
3125 * bp->b_data is relative to bp->b_offset, but
3126 * bp->b_offset may be offset into the first page.
3127 */
3128
3129 bp->b_data = (caddr_t)
3130 trunc_page((vm_offset_t)bp->b_data);
3131 pmap_qenter(
3132 (vm_offset_t)bp->b_data,
3133 bp->b_pages,
3134 bp->b_npages
3135 );
3136
3137 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
3138 (vm_offset_t)(bp->b_offset & PAGE_MASK));
3139 }
3140 }
3141 if (newbsize < bp->b_bufsize)
3142 bufspacewakeup();
3143 bp->b_bufsize = newbsize; /* actual buffer allocation */
3144 bp->b_bcount = size; /* requested buffer size */
3145 return 1;
3146 }
3147
3148 void
3149 biodone(struct bio *bp)
3150 {
3151 struct mtx *mtxp;
3152 void (*done)(struct bio *);
3153
3154 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3155 mtx_lock(mtxp);
3156 bp->bio_flags |= BIO_DONE;
3157 done = bp->bio_done;
3158 if (done == NULL)
3159 wakeup(bp);
3160 mtx_unlock(mtxp);
3161 if (done != NULL)
3162 done(bp);
3163 }
3164
3165 /*
3166 * Wait for a BIO to finish.
3167 *
3168 * XXX: resort to a timeout for now. The optimal locking (if any) for this
3169 * case is not yet clear.
3170 */
3171 int
3172 biowait(struct bio *bp, const char *wchan)
3173 {
3174 struct mtx *mtxp;
3175
3176 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3177 mtx_lock(mtxp);
3178 while ((bp->bio_flags & BIO_DONE) == 0)
3179 msleep(bp, mtxp, PRIBIO, wchan, hz / 10);
3180 mtx_unlock(mtxp);
3181 if (bp->bio_error != 0)
3182 return (bp->bio_error);
3183 if (!(bp->bio_flags & BIO_ERROR))
3184 return (0);
3185 return (EIO);
3186 }
3187
3188 void
3189 biofinish(struct bio *bp, struct devstat *stat, int error)
3190 {
3191
3192 if (error) {
3193 bp->bio_error = error;
3194 bp->bio_flags |= BIO_ERROR;
3195 }
3196 if (stat != NULL)
3197 devstat_end_transaction_bio(stat, bp);
3198 biodone(bp);
3199 }
3200
3201 /*
3202 * bufwait:
3203 *
3204 * Wait for buffer I/O completion, returning error status. The buffer
3205 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3206 * error and cleared.
3207 */
3208 int
3209 bufwait(struct buf *bp)
3210 {
3211 if (bp->b_iocmd == BIO_READ)
3212 bwait(bp, PRIBIO, "biord");
3213 else
3214 bwait(bp, PRIBIO, "biowr");
3215 if (bp->b_flags & B_EINTR) {
3216 bp->b_flags &= ~B_EINTR;
3217 return (EINTR);
3218 }
3219 if (bp->b_ioflags & BIO_ERROR) {
3220 return (bp->b_error ? bp->b_error : EIO);
3221 } else {
3222 return (0);
3223 }
3224 }
3225
3226 /*
3227 * Call back function from struct bio back up to struct buf.
3228 */
3229 static void
3230 bufdonebio(struct bio *bip)
3231 {
3232 struct buf *bp;
3233
3234 bp = bip->bio_caller2;
3235 bp->b_resid = bp->b_bcount - bip->bio_completed;
3236 bp->b_resid = bip->bio_resid; /* XXX: remove */
3237 bp->b_ioflags = bip->bio_flags;
3238 bp->b_error = bip->bio_error;
3239 if (bp->b_error)
3240 bp->b_ioflags |= BIO_ERROR;
3241 bufdone(bp);
3242 g_destroy_bio(bip);
3243 }
3244
3245 void
3246 dev_strategy(struct cdev *dev, struct buf *bp)
3247 {
3248 struct cdevsw *csw;
3249 struct bio *bip;
3250 int ref;
3251
3252 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
3253 panic("b_iocmd botch");
3254 for (;;) {
3255 bip = g_new_bio();
3256 if (bip != NULL)
3257 break;
3258 /* Try again later */
3259 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3260 }
3261 bip->bio_cmd = bp->b_iocmd;
3262 bip->bio_offset = bp->b_iooffset;
3263 bip->bio_length = bp->b_bcount;
3264 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3265 bip->bio_data = bp->b_data;
3266 bip->bio_done = bufdonebio;
3267 bip->bio_caller2 = bp;
3268 bip->bio_dev = dev;
3269 KASSERT(dev->si_refcount > 0,
3270 ("dev_strategy on un-referenced struct cdev *(%s)",
3271 devtoname(dev)));
3272 csw = dev_refthread(dev, &ref);
3273 if (csw == NULL) {
3274 g_destroy_bio(bip);
3275 bp->b_error = ENXIO;
3276 bp->b_ioflags = BIO_ERROR;
3277 bufdone(bp);
3278 return;
3279 }
3280 (*csw->d_strategy)(bip);
3281 dev_relthread(dev, ref);
3282 }
3283
3284 /*
3285 * bufdone:
3286 *
3287 * Finish I/O on a buffer, optionally calling a completion function.
3288 * This is usually called from an interrupt so process blocking is
3289 * not allowed.
3290 *
3291 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3292 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3293 * assuming B_INVAL is clear.
3294 *
3295 * For the VMIO case, we set B_CACHE if the op was a read and no
3296 * read error occured, or if the op was a write. B_CACHE is never
3297 * set if the buffer is invalid or otherwise uncacheable.
3298 *
3299 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3300 * initiator to leave B_INVAL set to brelse the buffer out of existance
3301 * in the biodone routine.
3302 */
3303 void
3304 bufdone(struct buf *bp)
3305 {
3306 struct bufobj *dropobj;
3307 void (*biodone)(struct buf *);
3308
3309 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3310 dropobj = NULL;
3311
3312 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3313 BUF_ASSERT_HELD(bp);
3314
3315 runningbufwakeup(bp);
3316 if (bp->b_iocmd == BIO_WRITE)
3317 dropobj = bp->b_bufobj;
3318 /* call optional completion function if requested */
3319 if (bp->b_iodone != NULL) {
3320 biodone = bp->b_iodone;
3321 bp->b_iodone = NULL;
3322 (*biodone) (bp);
3323 if (dropobj)
3324 bufobj_wdrop(dropobj);
3325 return;
3326 }
3327
3328 bufdone_finish(bp);
3329
3330 if (dropobj)
3331 bufobj_wdrop(dropobj);
3332 }
3333
3334 void
3335 bufdone_finish(struct buf *bp)
3336 {
3337 BUF_ASSERT_HELD(bp);
3338
3339 if (!LIST_EMPTY(&bp->b_dep))
3340 buf_complete(bp);
3341
3342 if (bp->b_flags & B_VMIO) {
3343 vm_ooffset_t foff;
3344 vm_page_t m;
3345 vm_object_t obj;
3346 struct vnode *vp;
3347 int bogus, i, iosize;
3348
3349 obj = bp->b_bufobj->bo_object;
3350 KASSERT(obj->paging_in_progress >= bp->b_npages,
3351 ("biodone_finish: paging in progress(%d) < b_npages(%d)",
3352 obj->paging_in_progress, bp->b_npages));
3353
3354 vp = bp->b_vp;
3355 KASSERT(vp->v_holdcnt > 0,
3356 ("biodone_finish: vnode %p has zero hold count", vp));
3357 KASSERT(vp->v_object != NULL,
3358 ("biodone_finish: vnode %p has no vm_object", vp));
3359
3360 foff = bp->b_offset;
3361 KASSERT(bp->b_offset != NOOFFSET,
3362 ("biodone_finish: bp %p has no buffer offset", bp));
3363
3364 /*
3365 * Set B_CACHE if the op was a normal read and no error
3366 * occured. B_CACHE is set for writes in the b*write()
3367 * routines.
3368 */
3369 iosize = bp->b_bcount - bp->b_resid;
3370 if (bp->b_iocmd == BIO_READ &&
3371 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3372 !(bp->b_ioflags & BIO_ERROR)) {
3373 bp->b_flags |= B_CACHE;
3374 }
3375 bogus = 0;
3376 VM_OBJECT_LOCK(obj);
3377 for (i = 0; i < bp->b_npages; i++) {
3378 int bogusflag = 0;
3379 int resid;
3380
3381 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3382 if (resid > iosize)
3383 resid = iosize;
3384
3385 /*
3386 * cleanup bogus pages, restoring the originals
3387 */
3388 m = bp->b_pages[i];
3389 if (m == bogus_page) {
3390 bogus = bogusflag = 1;
3391 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3392 if (m == NULL)
3393 panic("biodone: page disappeared!");
3394 bp->b_pages[i] = m;
3395 }
3396 KASSERT(OFF_TO_IDX(foff) == m->pindex,
3397 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch",
3398 (intmax_t)foff, (uintmax_t)m->pindex));
3399
3400 /*
3401 * In the write case, the valid and clean bits are
3402 * already changed correctly ( see bdwrite() ), so we
3403 * only need to do this here in the read case.
3404 */
3405 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3406 KASSERT((m->dirty & vm_page_bits(foff &
3407 PAGE_MASK, resid)) == 0, ("bufdone_finish:"
3408 " page %p has unexpected dirty bits", m));
3409 vfs_page_set_valid(bp, foff, m);
3410 }
3411
3412 vm_page_io_finish(m);
3413 vm_object_pip_subtract(obj, 1);
3414 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3415 iosize -= resid;
3416 }
3417 vm_object_pip_wakeupn(obj, 0);
3418 VM_OBJECT_UNLOCK(obj);
3419 if (bogus)
3420 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3421 bp->b_pages, bp->b_npages);
3422 }
3423
3424 /*
3425 * For asynchronous completions, release the buffer now. The brelse
3426 * will do a wakeup there if necessary - so no need to do a wakeup
3427 * here in the async case. The sync case always needs to do a wakeup.
3428 */
3429
3430 if (bp->b_flags & B_ASYNC) {
3431 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3432 brelse(bp);
3433 else
3434 bqrelse(bp);
3435 } else
3436 bdone(bp);
3437 }
3438
3439 /*
3440 * This routine is called in lieu of iodone in the case of
3441 * incomplete I/O. This keeps the busy status for pages
3442 * consistant.
3443 */
3444 void
3445 vfs_unbusy_pages(struct buf *bp)
3446 {
3447 int i;
3448 vm_object_t obj;
3449 vm_page_t m;
3450
3451 runningbufwakeup(bp);
3452 if (!(bp->b_flags & B_VMIO))
3453 return;
3454
3455 obj = bp->b_bufobj->bo_object;
3456 VM_OBJECT_LOCK(obj);
3457 for (i = 0; i < bp->b_npages; i++) {
3458 m = bp->b_pages[i];
3459 if (m == bogus_page) {
3460 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3461 if (!m)
3462 panic("vfs_unbusy_pages: page missing\n");
3463 bp->b_pages[i] = m;
3464 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3465 bp->b_pages, bp->b_npages);
3466 }
3467 vm_object_pip_subtract(obj, 1);
3468 vm_page_io_finish(m);
3469 }
3470 vm_object_pip_wakeupn(obj, 0);
3471 VM_OBJECT_UNLOCK(obj);
3472 }
3473
3474 /*
3475 * vfs_page_set_valid:
3476 *
3477 * Set the valid bits in a page based on the supplied offset. The
3478 * range is restricted to the buffer's size.
3479 *
3480 * This routine is typically called after a read completes.
3481 */
3482 static void
3483 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3484 {
3485 vm_ooffset_t eoff;
3486
3487 /*
3488 * Compute the end offset, eoff, such that [off, eoff) does not span a
3489 * page boundary and eoff is not greater than the end of the buffer.
3490 * The end of the buffer, in this case, is our file EOF, not the
3491 * allocation size of the buffer.
3492 */
3493 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
3494 if (eoff > bp->b_offset + bp->b_bcount)
3495 eoff = bp->b_offset + bp->b_bcount;
3496
3497 /*
3498 * Set valid range. This is typically the entire buffer and thus the
3499 * entire page.
3500 */
3501 if (eoff > off)
3502 vm_page_set_valid(m, off & PAGE_MASK, eoff - off);
3503 }
3504
3505 /*
3506 * vfs_page_set_validclean:
3507 *
3508 * Set the valid bits and clear the dirty bits in a page based on the
3509 * supplied offset. The range is restricted to the buffer's size.
3510 */
3511 static void
3512 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3513 {
3514 vm_ooffset_t soff, eoff;
3515
3516 /*
3517 * Start and end offsets in buffer. eoff - soff may not cross a
3518 * page boundry or cross the end of the buffer. The end of the
3519 * buffer, in this case, is our file EOF, not the allocation size
3520 * of the buffer.
3521 */
3522 soff = off;
3523 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3524 if (eoff > bp->b_offset + bp->b_bcount)
3525 eoff = bp->b_offset + bp->b_bcount;
3526
3527 /*
3528 * Set valid range. This is typically the entire buffer and thus the
3529 * entire page.
3530 */
3531 if (eoff > soff) {
3532 vm_page_set_validclean(
3533 m,
3534 (vm_offset_t) (soff & PAGE_MASK),
3535 (vm_offset_t) (eoff - soff)
3536 );
3537 }
3538 }
3539
3540 /*
3541 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If
3542 * any page is busy, drain the flag.
3543 */
3544 static void
3545 vfs_drain_busy_pages(struct buf *bp)
3546 {
3547 vm_page_t m;
3548 int i, last_busied;
3549
3550 VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED);
3551 last_busied = 0;
3552 for (i = 0; i < bp->b_npages; i++) {
3553 m = bp->b_pages[i];
3554 if ((m->oflags & VPO_BUSY) != 0) {
3555 for (; last_busied < i; last_busied++)
3556 vm_page_busy(bp->b_pages[last_busied]);
3557 while ((m->oflags & VPO_BUSY) != 0)
3558 vm_page_sleep(m, "vbpage");
3559 }
3560 }
3561 for (i = 0; i < last_busied; i++)
3562 vm_page_wakeup(bp->b_pages[i]);
3563 }
3564
3565 /*
3566 * This routine is called before a device strategy routine.
3567 * It is used to tell the VM system that paging I/O is in
3568 * progress, and treat the pages associated with the buffer
3569 * almost as being VPO_BUSY. Also the object paging_in_progress
3570 * flag is handled to make sure that the object doesn't become
3571 * inconsistant.
3572 *
3573 * Since I/O has not been initiated yet, certain buffer flags
3574 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3575 * and should be ignored.
3576 */
3577 void
3578 vfs_busy_pages(struct buf *bp, int clear_modify)
3579 {
3580 int i, bogus;
3581 vm_object_t obj;
3582 vm_ooffset_t foff;
3583 vm_page_t m;
3584
3585 if (!(bp->b_flags & B_VMIO))
3586 return;
3587
3588 obj = bp->b_bufobj->bo_object;
3589 foff = bp->b_offset;
3590 KASSERT(bp->b_offset != NOOFFSET,
3591 ("vfs_busy_pages: no buffer offset"));
3592 VM_OBJECT_LOCK(obj);
3593 vfs_drain_busy_pages(bp);
3594 if (bp->b_bufsize != 0)
3595 vfs_setdirty_locked_object(bp);
3596 bogus = 0;
3597 for (i = 0; i < bp->b_npages; i++) {
3598 m = bp->b_pages[i];
3599
3600 if ((bp->b_flags & B_CLUSTER) == 0) {
3601 vm_object_pip_add(obj, 1);
3602 vm_page_io_start(m);
3603 }
3604 /*
3605 * When readying a buffer for a read ( i.e
3606 * clear_modify == 0 ), it is important to do
3607 * bogus_page replacement for valid pages in
3608 * partially instantiated buffers. Partially
3609 * instantiated buffers can, in turn, occur when
3610 * reconstituting a buffer from its VM backing store
3611 * base. We only have to do this if B_CACHE is
3612 * clear ( which causes the I/O to occur in the
3613 * first place ). The replacement prevents the read
3614 * I/O from overwriting potentially dirty VM-backed
3615 * pages. XXX bogus page replacement is, uh, bogus.
3616 * It may not work properly with small-block devices.
3617 * We need to find a better way.
3618 */
3619 if (clear_modify) {
3620 pmap_remove_write(m);
3621 vfs_page_set_validclean(bp, foff, m);
3622 } else if (m->valid == VM_PAGE_BITS_ALL &&
3623 (bp->b_flags & B_CACHE) == 0) {
3624 bp->b_pages[i] = bogus_page;
3625 bogus++;
3626 }
3627 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3628 }
3629 VM_OBJECT_UNLOCK(obj);
3630 if (bogus)
3631 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3632 bp->b_pages, bp->b_npages);
3633 }
3634
3635 /*
3636 * vfs_bio_set_valid:
3637 *
3638 * Set the range within the buffer to valid. The range is
3639 * relative to the beginning of the buffer, b_offset. Note that
3640 * b_offset itself may be offset from the beginning of the first
3641 * page.
3642 */
3643 void
3644 vfs_bio_set_valid(struct buf *bp, int base, int size)
3645 {
3646 int i, n;
3647 vm_page_t m;
3648
3649 if (!(bp->b_flags & B_VMIO))
3650 return;
3651
3652 /*
3653 * Fixup base to be relative to beginning of first page.
3654 * Set initial n to be the maximum number of bytes in the
3655 * first page that can be validated.
3656 */
3657 base += (bp->b_offset & PAGE_MASK);
3658 n = PAGE_SIZE - (base & PAGE_MASK);
3659
3660 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3661 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3662 m = bp->b_pages[i];
3663 if (n > size)
3664 n = size;
3665 vm_page_set_valid(m, base & PAGE_MASK, n);
3666 base += n;
3667 size -= n;
3668 n = PAGE_SIZE;
3669 }
3670 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3671 }
3672
3673 /*
3674 * vfs_bio_clrbuf:
3675 *
3676 * If the specified buffer is a non-VMIO buffer, clear the entire
3677 * buffer. If the specified buffer is a VMIO buffer, clear and
3678 * validate only the previously invalid portions of the buffer.
3679 * This routine essentially fakes an I/O, so we need to clear
3680 * BIO_ERROR and B_INVAL.
3681 *
3682 * Note that while we only theoretically need to clear through b_bcount,
3683 * we go ahead and clear through b_bufsize.
3684 */
3685 void
3686 vfs_bio_clrbuf(struct buf *bp)
3687 {
3688 int i, j, mask;
3689 caddr_t sa, ea;
3690
3691 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
3692 clrbuf(bp);
3693 return;
3694 }
3695 bp->b_flags &= ~B_INVAL;
3696 bp->b_ioflags &= ~BIO_ERROR;
3697 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3698 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3699 (bp->b_offset & PAGE_MASK) == 0) {
3700 if (bp->b_pages[0] == bogus_page)
3701 goto unlock;
3702 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3703 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3704 if ((bp->b_pages[0]->valid & mask) == mask)
3705 goto unlock;
3706 if ((bp->b_pages[0]->valid & mask) == 0) {
3707 bzero(bp->b_data, bp->b_bufsize);
3708 bp->b_pages[0]->valid |= mask;
3709 goto unlock;
3710 }
3711 }
3712 ea = sa = bp->b_data;
3713 for(i = 0; i < bp->b_npages; i++, sa = ea) {
3714 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3715 ea = (caddr_t)(vm_offset_t)ulmin(
3716 (u_long)(vm_offset_t)ea,
3717 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3718 if (bp->b_pages[i] == bogus_page)
3719 continue;
3720 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3721 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3722 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3723 if ((bp->b_pages[i]->valid & mask) == mask)
3724 continue;
3725 if ((bp->b_pages[i]->valid & mask) == 0)
3726 bzero(sa, ea - sa);
3727 else {
3728 for (; sa < ea; sa += DEV_BSIZE, j++) {
3729 if ((bp->b_pages[i]->valid & (1 << j)) == 0)
3730 bzero(sa, DEV_BSIZE);
3731 }
3732 }
3733 bp->b_pages[i]->valid |= mask;
3734 }
3735 unlock:
3736 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3737 bp->b_resid = 0;
3738 }
3739
3740 /*
3741 * vm_hold_load_pages and vm_hold_free_pages get pages into
3742 * a buffers address space. The pages are anonymous and are
3743 * not associated with a file object.
3744 */
3745 static void
3746 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3747 {
3748 vm_offset_t pg;
3749 vm_page_t p;
3750 int index;
3751
3752 to = round_page(to);
3753 from = round_page(from);
3754 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3755
3756 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3757 tryagain:
3758 /*
3759 * note: must allocate system pages since blocking here
3760 * could interfere with paging I/O, no matter which
3761 * process we are.
3762 */
3763 p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ |
3764 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
3765 VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
3766 if (!p) {
3767 VM_WAIT;
3768 goto tryagain;
3769 }
3770 pmap_qenter(pg, &p, 1);
3771 bp->b_pages[index] = p;
3772 }
3773 bp->b_npages = index;
3774 }
3775
3776 /* Return pages associated with this buf to the vm system */
3777 static void
3778 vm_hold_free_pages(struct buf *bp, int newbsize)
3779 {
3780 vm_offset_t from;
3781 vm_page_t p;
3782 int index, newnpages;
3783
3784 from = round_page((vm_offset_t)bp->b_data + newbsize);
3785 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3786 if (bp->b_npages > newnpages)
3787 pmap_qremove(from, bp->b_npages - newnpages);
3788 for (index = newnpages; index < bp->b_npages; index++) {
3789 p = bp->b_pages[index];
3790 bp->b_pages[index] = NULL;
3791 if (p->busy != 0)
3792 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3793 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
3794 p->wire_count--;
3795 vm_page_free(p);
3796 atomic_subtract_int(&cnt.v_wire_count, 1);
3797 }
3798 bp->b_npages = newnpages;
3799 }
3800
3801 /*
3802 * Map an IO request into kernel virtual address space.
3803 *
3804 * All requests are (re)mapped into kernel VA space.
3805 * Notice that we use b_bufsize for the size of the buffer
3806 * to be mapped. b_bcount might be modified by the driver.
3807 *
3808 * Note that even if the caller determines that the address space should
3809 * be valid, a race or a smaller-file mapped into a larger space may
3810 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3811 * check the return value.
3812 */
3813 int
3814 vmapbuf(struct buf *bp)
3815 {
3816 caddr_t kva;
3817 vm_prot_t prot;
3818 int pidx;
3819
3820 if (bp->b_bufsize < 0)
3821 return (-1);
3822 prot = VM_PROT_READ;
3823 if (bp->b_iocmd == BIO_READ)
3824 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
3825 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
3826 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
3827 btoc(MAXPHYS))) < 0)
3828 return (-1);
3829 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3830
3831 kva = bp->b_saveaddr;
3832 bp->b_npages = pidx;
3833 bp->b_saveaddr = bp->b_data;
3834 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3835 return(0);
3836 }
3837
3838 /*
3839 * Free the io map PTEs associated with this IO operation.
3840 * We also invalidate the TLB entries and restore the original b_addr.
3841 */
3842 void
3843 vunmapbuf(struct buf *bp)
3844 {
3845 int npages;
3846
3847 npages = bp->b_npages;
3848 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
3849 vm_page_unhold_pages(bp->b_pages, npages);
3850
3851 bp->b_data = bp->b_saveaddr;
3852 }
3853
3854 void
3855 bdone(struct buf *bp)
3856 {
3857 struct mtx *mtxp;
3858
3859 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3860 mtx_lock(mtxp);
3861 bp->b_flags |= B_DONE;
3862 wakeup(bp);
3863 mtx_unlock(mtxp);
3864 }
3865
3866 void
3867 bwait(struct buf *bp, u_char pri, const char *wchan)
3868 {
3869 struct mtx *mtxp;
3870
3871 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3872 mtx_lock(mtxp);
3873 while ((bp->b_flags & B_DONE) == 0)
3874 msleep(bp, mtxp, pri, wchan, 0);
3875 mtx_unlock(mtxp);
3876 }
3877
3878 int
3879 bufsync(struct bufobj *bo, int waitfor)
3880 {
3881
3882 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
3883 }
3884
3885 void
3886 bufstrategy(struct bufobj *bo, struct buf *bp)
3887 {
3888 int i = 0;
3889 struct vnode *vp;
3890
3891 vp = bp->b_vp;
3892 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
3893 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
3894 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
3895 i = VOP_STRATEGY(vp, bp);
3896 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
3897 }
3898
3899 void
3900 bufobj_wrefl(struct bufobj *bo)
3901 {
3902
3903 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3904 ASSERT_BO_LOCKED(bo);
3905 bo->bo_numoutput++;
3906 }
3907
3908 void
3909 bufobj_wref(struct bufobj *bo)
3910 {
3911
3912 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3913 BO_LOCK(bo);
3914 bo->bo_numoutput++;
3915 BO_UNLOCK(bo);
3916 }
3917
3918 void
3919 bufobj_wdrop(struct bufobj *bo)
3920 {
3921
3922 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
3923 BO_LOCK(bo);
3924 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
3925 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
3926 bo->bo_flag &= ~BO_WWAIT;
3927 wakeup(&bo->bo_numoutput);
3928 }
3929 BO_UNLOCK(bo);
3930 }
3931
3932 int
3933 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
3934 {
3935 int error;
3936
3937 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
3938 ASSERT_BO_LOCKED(bo);
3939 error = 0;
3940 while (bo->bo_numoutput) {
3941 bo->bo_flag |= BO_WWAIT;
3942 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
3943 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
3944 if (error)
3945 break;
3946 }
3947 return (error);
3948 }
3949
3950 void
3951 bpin(struct buf *bp)
3952 {
3953 struct mtx *mtxp;
3954
3955 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3956 mtx_lock(mtxp);
3957 bp->b_pin_count++;
3958 mtx_unlock(mtxp);
3959 }
3960
3961 void
3962 bunpin(struct buf *bp)
3963 {
3964 struct mtx *mtxp;
3965
3966 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3967 mtx_lock(mtxp);
3968 if (--bp->b_pin_count == 0)
3969 wakeup(bp);
3970 mtx_unlock(mtxp);
3971 }
3972
3973 void
3974 bunpin_wait(struct buf *bp)
3975 {
3976 struct mtx *mtxp;
3977
3978 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3979 mtx_lock(mtxp);
3980 while (bp->b_pin_count > 0)
3981 msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
3982 mtx_unlock(mtxp);
3983 }
3984
3985 #include "opt_ddb.h"
3986 #ifdef DDB
3987 #include <ddb/ddb.h>
3988
3989 /* DDB command to show buffer data */
3990 DB_SHOW_COMMAND(buffer, db_show_buffer)
3991 {
3992 /* get args */
3993 struct buf *bp = (struct buf *)addr;
3994
3995 if (!have_addr) {
3996 db_printf("usage: show buffer <addr>\n");
3997 return;
3998 }
3999
4000 db_printf("buf at %p\n", bp);
4001 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
4002 db_printf(
4003 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
4004 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
4005 "b_dep = %p\n",
4006 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4007 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4008 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
4009 if (bp->b_npages) {
4010 int i;
4011 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4012 for (i = 0; i < bp->b_npages; i++) {
4013 vm_page_t m;
4014 m = bp->b_pages[i];
4015 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4016 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4017 if ((i + 1) < bp->b_npages)
4018 db_printf(",");
4019 }
4020 db_printf("\n");
4021 }
4022 db_printf(" ");
4023 BUF_LOCKPRINTINFO(bp);
4024 }
4025
4026 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4027 {
4028 struct buf *bp;
4029 int i;
4030
4031 for (i = 0; i < nbuf; i++) {
4032 bp = &buf[i];
4033 if (BUF_ISLOCKED(bp)) {
4034 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4035 db_printf("\n");
4036 }
4037 }
4038 }
4039
4040 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
4041 {
4042 struct vnode *vp;
4043 struct buf *bp;
4044
4045 if (!have_addr) {
4046 db_printf("usage: show vnodebufs <addr>\n");
4047 return;
4048 }
4049 vp = (struct vnode *)addr;
4050 db_printf("Clean buffers:\n");
4051 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
4052 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4053 db_printf("\n");
4054 }
4055 db_printf("Dirty buffers:\n");
4056 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
4057 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4058 db_printf("\n");
4059 }
4060 }
4061
4062 DB_COMMAND(countfreebufs, db_coundfreebufs)
4063 {
4064 struct buf *bp;
4065 int i, used = 0, nfree = 0;
4066
4067 if (have_addr) {
4068 db_printf("usage: countfreebufs\n");
4069 return;
4070 }
4071
4072 for (i = 0; i < nbuf; i++) {
4073 bp = &buf[i];
4074 if ((bp->b_vflags & BV_INFREECNT) != 0)
4075 nfree++;
4076 else
4077 used++;
4078 }
4079
4080 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
4081 nfree + used);
4082 db_printf("numfreebuffers is %d\n", numfreebuffers);
4083 }
4084 #endif /* DDB */
Cache object: cb1d5b2eee733893e2708cba1d4b3eb6
|