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/8.2/sys/kern/vfs_bio.c 213890 2010-10-15 05:42:35Z alc $");
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 * This lock synchronizes access to bd_request.
219 */
220 static struct mtx bdlock;
221
222 /*
223 * bogus page -- for I/O to/from partially complete buffers
224 * this is a temporary solution to the problem, but it is not
225 * really that bad. it would be better to split the buffer
226 * for input in the case of buffers partially already in memory,
227 * but the code is intricate enough already.
228 */
229 vm_page_t bogus_page;
230
231 /*
232 * Synchronization (sleep/wakeup) variable for active buffer space requests.
233 * Set when wait starts, cleared prior to wakeup().
234 * Used in runningbufwakeup() and waitrunningbufspace().
235 */
236 static int runningbufreq;
237
238 /*
239 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
240 * waitrunningbufspace().
241 */
242 static struct mtx rbreqlock;
243
244 /*
245 * Synchronization (sleep/wakeup) variable for buffer requests.
246 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
247 * by and/or.
248 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
249 * getnewbuf(), and getblk().
250 */
251 static int needsbuffer;
252
253 /*
254 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
255 */
256 static struct mtx nblock;
257
258 /*
259 * Definitions for the buffer free lists.
260 */
261 #define BUFFER_QUEUES 6 /* number of free buffer queues */
262
263 #define QUEUE_NONE 0 /* on no queue */
264 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
265 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
266 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */
267 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
268 #define QUEUE_EMPTY 5 /* empty buffer headers */
269 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
270
271 /* Queues for free buffers with various properties */
272 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
273
274 /* Lock for the bufqueues */
275 static struct mtx bqlock;
276
277 /*
278 * Single global constant for BUF_WMESG, to avoid getting multiple references.
279 * buf_wmesg is referred from macros.
280 */
281 const char *buf_wmesg = BUF_WMESG;
282
283 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
284 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
285 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
286 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
287
288 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
289 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
290 static int
291 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
292 {
293 long lvalue;
294 int ivalue;
295
296 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
297 return (sysctl_handle_long(oidp, arg1, arg2, req));
298 lvalue = *(long *)arg1;
299 if (lvalue > INT_MAX)
300 /* On overflow, still write out a long to trigger ENOMEM. */
301 return (sysctl_handle_long(oidp, &lvalue, 0, req));
302 ivalue = lvalue;
303 return (sysctl_handle_int(oidp, &ivalue, 0, req));
304 }
305 #endif
306
307 #ifdef DIRECTIO
308 extern void ffs_rawread_setup(void);
309 #endif /* DIRECTIO */
310 /*
311 * numdirtywakeup:
312 *
313 * If someone is blocked due to there being too many dirty buffers,
314 * and numdirtybuffers is now reasonable, wake them up.
315 */
316
317 static __inline void
318 numdirtywakeup(int level)
319 {
320
321 if (numdirtybuffers <= level) {
322 mtx_lock(&nblock);
323 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
324 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
325 wakeup(&needsbuffer);
326 }
327 mtx_unlock(&nblock);
328 }
329 }
330
331 /*
332 * bufspacewakeup:
333 *
334 * Called when buffer space is potentially available for recovery.
335 * getnewbuf() will block on this flag when it is unable to free
336 * sufficient buffer space. Buffer space becomes recoverable when
337 * bp's get placed back in the queues.
338 */
339
340 static __inline void
341 bufspacewakeup(void)
342 {
343
344 /*
345 * If someone is waiting for BUF space, wake them up. Even
346 * though we haven't freed the kva space yet, the waiting
347 * process will be able to now.
348 */
349 mtx_lock(&nblock);
350 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
351 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
352 wakeup(&needsbuffer);
353 }
354 mtx_unlock(&nblock);
355 }
356
357 /*
358 * runningbufwakeup() - in-progress I/O accounting.
359 *
360 */
361 void
362 runningbufwakeup(struct buf *bp)
363 {
364
365 if (bp->b_runningbufspace) {
366 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace);
367 bp->b_runningbufspace = 0;
368 mtx_lock(&rbreqlock);
369 if (runningbufreq && runningbufspace <= lorunningspace) {
370 runningbufreq = 0;
371 wakeup(&runningbufreq);
372 }
373 mtx_unlock(&rbreqlock);
374 }
375 }
376
377 /*
378 * bufcountwakeup:
379 *
380 * Called when a buffer has been added to one of the free queues to
381 * account for the buffer and to wakeup anyone waiting for free buffers.
382 * This typically occurs when large amounts of metadata are being handled
383 * by the buffer cache ( else buffer space runs out first, usually ).
384 */
385
386 static __inline void
387 bufcountwakeup(struct buf *bp)
388 {
389 int old;
390
391 KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
392 ("buf %p already counted as free", bp));
393 if (bp->b_bufobj != NULL)
394 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
395 bp->b_vflags |= BV_INFREECNT;
396 old = atomic_fetchadd_int(&numfreebuffers, 1);
397 KASSERT(old >= 0 && old < nbuf,
398 ("numfreebuffers climbed to %d", old + 1));
399 mtx_lock(&nblock);
400 if (needsbuffer) {
401 needsbuffer &= ~VFS_BIO_NEED_ANY;
402 if (numfreebuffers >= hifreebuffers)
403 needsbuffer &= ~VFS_BIO_NEED_FREE;
404 wakeup(&needsbuffer);
405 }
406 mtx_unlock(&nblock);
407 }
408
409 /*
410 * waitrunningbufspace()
411 *
412 * runningbufspace is a measure of the amount of I/O currently
413 * running. This routine is used in async-write situations to
414 * prevent creating huge backups of pending writes to a device.
415 * Only asynchronous writes are governed by this function.
416 *
417 * Reads will adjust runningbufspace, but will not block based on it.
418 * The read load has a side effect of reducing the allowed write load.
419 *
420 * This does NOT turn an async write into a sync write. It waits
421 * for earlier writes to complete and generally returns before the
422 * caller's write has reached the device.
423 */
424 void
425 waitrunningbufspace(void)
426 {
427
428 mtx_lock(&rbreqlock);
429 while (runningbufspace > hirunningspace) {
430 ++runningbufreq;
431 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
432 }
433 mtx_unlock(&rbreqlock);
434 }
435
436
437 /*
438 * vfs_buf_test_cache:
439 *
440 * Called when a buffer is extended. This function clears the B_CACHE
441 * bit if the newly extended portion of the buffer does not contain
442 * valid data.
443 */
444 static __inline
445 void
446 vfs_buf_test_cache(struct buf *bp,
447 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
448 vm_page_t m)
449 {
450
451 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
452 if (bp->b_flags & B_CACHE) {
453 int base = (foff + off) & PAGE_MASK;
454 if (vm_page_is_valid(m, base, size) == 0)
455 bp->b_flags &= ~B_CACHE;
456 }
457 }
458
459 /* Wake up the buffer daemon if necessary */
460 static __inline
461 void
462 bd_wakeup(int dirtybuflevel)
463 {
464
465 mtx_lock(&bdlock);
466 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
467 bd_request = 1;
468 wakeup(&bd_request);
469 }
470 mtx_unlock(&bdlock);
471 }
472
473 /*
474 * bd_speedup - speedup the buffer cache flushing code
475 */
476
477 static __inline
478 void
479 bd_speedup(void)
480 {
481
482 bd_wakeup(1);
483 }
484
485 /*
486 * Calculating buffer cache scaling values and reserve space for buffer
487 * headers. This is called during low level kernel initialization and
488 * may be called more then once. We CANNOT write to the memory area
489 * being reserved at this time.
490 */
491 caddr_t
492 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
493 {
494 int tuned_nbuf;
495 long maxbuf;
496
497 /*
498 * physmem_est is in pages. Convert it to kilobytes (assumes
499 * PAGE_SIZE is >= 1K)
500 */
501 physmem_est = physmem_est * (PAGE_SIZE / 1024);
502
503 /*
504 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
505 * For the first 64MB of ram nominally allocate sufficient buffers to
506 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
507 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
508 * the buffer cache we limit the eventual kva reservation to
509 * maxbcache bytes.
510 *
511 * factor represents the 1/4 x ram conversion.
512 */
513 if (nbuf == 0) {
514 int factor = 4 * BKVASIZE / 1024;
515
516 nbuf = 50;
517 if (physmem_est > 4096)
518 nbuf += min((physmem_est - 4096) / factor,
519 65536 / factor);
520 if (physmem_est > 65536)
521 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
522
523 if (maxbcache && nbuf > maxbcache / BKVASIZE)
524 nbuf = maxbcache / BKVASIZE;
525 tuned_nbuf = 1;
526 } else
527 tuned_nbuf = 0;
528
529 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
530 maxbuf = (LONG_MAX / 3) / BKVASIZE;
531 if (nbuf > maxbuf) {
532 if (!tuned_nbuf)
533 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
534 maxbuf);
535 nbuf = maxbuf;
536 }
537
538 /*
539 * swbufs are used as temporary holders for I/O, such as paging I/O.
540 * We have no less then 16 and no more then 256.
541 */
542 nswbuf = max(min(nbuf/4, 256), 16);
543 #ifdef NSWBUF_MIN
544 if (nswbuf < NSWBUF_MIN)
545 nswbuf = NSWBUF_MIN;
546 #endif
547 #ifdef DIRECTIO
548 ffs_rawread_setup();
549 #endif
550
551 /*
552 * Reserve space for the buffer cache buffers
553 */
554 swbuf = (void *)v;
555 v = (caddr_t)(swbuf + nswbuf);
556 buf = (void *)v;
557 v = (caddr_t)(buf + nbuf);
558
559 return(v);
560 }
561
562 /* Initialize the buffer subsystem. Called before use of any buffers. */
563 void
564 bufinit(void)
565 {
566 struct buf *bp;
567 int i;
568
569 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
570 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
571 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
572 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
573
574 /* next, make a null set of free lists */
575 for (i = 0; i < BUFFER_QUEUES; i++)
576 TAILQ_INIT(&bufqueues[i]);
577
578 /* finally, initialize each buffer header and stick on empty q */
579 for (i = 0; i < nbuf; i++) {
580 bp = &buf[i];
581 bzero(bp, sizeof *bp);
582 bp->b_flags = B_INVAL; /* we're just an empty header */
583 bp->b_rcred = NOCRED;
584 bp->b_wcred = NOCRED;
585 bp->b_qindex = QUEUE_EMPTY;
586 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */
587 bp->b_xflags = 0;
588 LIST_INIT(&bp->b_dep);
589 BUF_LOCKINIT(bp);
590 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
591 }
592
593 /*
594 * maxbufspace is the absolute maximum amount of buffer space we are
595 * allowed to reserve in KVM and in real terms. The absolute maximum
596 * is nominally used by buf_daemon. hibufspace is the nominal maximum
597 * used by most other processes. The differential is required to
598 * ensure that buf_daemon is able to run when other processes might
599 * be blocked waiting for buffer space.
600 *
601 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
602 * this may result in KVM fragmentation which is not handled optimally
603 * by the system.
604 */
605 maxbufspace = (long)nbuf * BKVASIZE;
606 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
607 lobufspace = hibufspace - MAXBSIZE;
608
609 lorunningspace = 512 * 1024;
610 hirunningspace = 1024 * 1024;
611
612 /*
613 * Limit the amount of malloc memory since it is wired permanently into
614 * the kernel space. Even though this is accounted for in the buffer
615 * allocation, we don't want the malloced region to grow uncontrolled.
616 * The malloc scheme improves memory utilization significantly on average
617 * (small) directories.
618 */
619 maxbufmallocspace = hibufspace / 20;
620
621 /*
622 * Reduce the chance of a deadlock occuring by limiting the number
623 * of delayed-write dirty buffers we allow to stack up.
624 */
625 hidirtybuffers = nbuf / 4 + 20;
626 dirtybufthresh = hidirtybuffers * 9 / 10;
627 numdirtybuffers = 0;
628 /*
629 * To support extreme low-memory systems, make sure hidirtybuffers cannot
630 * eat up all available buffer space. This occurs when our minimum cannot
631 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
632 * BKVASIZE'd (8K) buffers.
633 */
634 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
635 hidirtybuffers >>= 1;
636 }
637 lodirtybuffers = hidirtybuffers / 2;
638
639 /*
640 * Try to keep the number of free buffers in the specified range,
641 * and give special processes (e.g. like buf_daemon) access to an
642 * emergency reserve.
643 */
644 lofreebuffers = nbuf / 18 + 5;
645 hifreebuffers = 2 * lofreebuffers;
646 numfreebuffers = nbuf;
647
648 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
649 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
650 }
651
652 /*
653 * bfreekva() - free the kva allocation for a buffer.
654 *
655 * Since this call frees up buffer space, we call bufspacewakeup().
656 */
657 static void
658 bfreekva(struct buf *bp)
659 {
660
661 if (bp->b_kvasize) {
662 atomic_add_int(&buffreekvacnt, 1);
663 atomic_subtract_long(&bufspace, bp->b_kvasize);
664 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase,
665 (vm_offset_t) bp->b_kvabase + bp->b_kvasize);
666 bp->b_kvasize = 0;
667 bufspacewakeup();
668 }
669 }
670
671 /*
672 * bremfree:
673 *
674 * Mark the buffer for removal from the appropriate free list in brelse.
675 *
676 */
677 void
678 bremfree(struct buf *bp)
679 {
680 int old;
681
682 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
683 KASSERT((bp->b_flags & B_REMFREE) == 0,
684 ("bremfree: buffer %p already marked for delayed removal.", bp));
685 KASSERT(bp->b_qindex != QUEUE_NONE,
686 ("bremfree: buffer %p not on a queue.", bp));
687 BUF_ASSERT_HELD(bp);
688
689 bp->b_flags |= B_REMFREE;
690 /* Fixup numfreebuffers count. */
691 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
692 KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
693 ("buf %p not counted in numfreebuffers", bp));
694 if (bp->b_bufobj != NULL)
695 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
696 bp->b_vflags &= ~BV_INFREECNT;
697 old = atomic_fetchadd_int(&numfreebuffers, -1);
698 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
699 }
700 }
701
702 /*
703 * bremfreef:
704 *
705 * Force an immediate removal from a free list. Used only in nfs when
706 * it abuses the b_freelist pointer.
707 */
708 void
709 bremfreef(struct buf *bp)
710 {
711 mtx_lock(&bqlock);
712 bremfreel(bp);
713 mtx_unlock(&bqlock);
714 }
715
716 /*
717 * bremfreel:
718 *
719 * Removes a buffer from the free list, must be called with the
720 * bqlock held.
721 */
722 static void
723 bremfreel(struct buf *bp)
724 {
725 int old;
726
727 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
728 bp, bp->b_vp, bp->b_flags);
729 KASSERT(bp->b_qindex != QUEUE_NONE,
730 ("bremfreel: buffer %p not on a queue.", bp));
731 BUF_ASSERT_HELD(bp);
732 mtx_assert(&bqlock, MA_OWNED);
733
734 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
735 bp->b_qindex = QUEUE_NONE;
736 /*
737 * If this was a delayed bremfree() we only need to remove the buffer
738 * from the queue and return the stats are already done.
739 */
740 if (bp->b_flags & B_REMFREE) {
741 bp->b_flags &= ~B_REMFREE;
742 return;
743 }
744 /*
745 * Fixup numfreebuffers count. If the buffer is invalid or not
746 * delayed-write, the buffer was free and we must decrement
747 * numfreebuffers.
748 */
749 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
750 KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
751 ("buf %p not counted in numfreebuffers", bp));
752 if (bp->b_bufobj != NULL)
753 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
754 bp->b_vflags &= ~BV_INFREECNT;
755 old = atomic_fetchadd_int(&numfreebuffers, -1);
756 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
757 }
758 }
759
760
761 /*
762 * Get a buffer with the specified data. Look in the cache first. We
763 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
764 * is set, the buffer is valid and we do not have to do anything ( see
765 * getblk() ). This is really just a special case of breadn().
766 */
767 int
768 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
769 struct buf **bpp)
770 {
771
772 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
773 }
774
775 /*
776 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
777 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
778 * the buffer is valid and we do not have to do anything.
779 */
780 void
781 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
782 int cnt, struct ucred * cred)
783 {
784 struct buf *rabp;
785 int i;
786
787 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
788 if (inmem(vp, *rablkno))
789 continue;
790 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
791
792 if ((rabp->b_flags & B_CACHE) == 0) {
793 if (!TD_IS_IDLETHREAD(curthread))
794 curthread->td_ru.ru_inblock++;
795 rabp->b_flags |= B_ASYNC;
796 rabp->b_flags &= ~B_INVAL;
797 rabp->b_ioflags &= ~BIO_ERROR;
798 rabp->b_iocmd = BIO_READ;
799 if (rabp->b_rcred == NOCRED && cred != NOCRED)
800 rabp->b_rcred = crhold(cred);
801 vfs_busy_pages(rabp, 0);
802 BUF_KERNPROC(rabp);
803 rabp->b_iooffset = dbtob(rabp->b_blkno);
804 bstrategy(rabp);
805 } else {
806 brelse(rabp);
807 }
808 }
809 }
810
811 /*
812 * Operates like bread, but also starts asynchronous I/O on
813 * read-ahead blocks.
814 */
815 int
816 breadn(struct vnode * vp, daddr_t blkno, int size,
817 daddr_t * rablkno, int *rabsize,
818 int cnt, struct ucred * cred, struct buf **bpp)
819 {
820 struct buf *bp;
821 int rv = 0, readwait = 0;
822
823 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
824 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
825
826 /* if not found in cache, do some I/O */
827 if ((bp->b_flags & B_CACHE) == 0) {
828 if (!TD_IS_IDLETHREAD(curthread))
829 curthread->td_ru.ru_inblock++;
830 bp->b_iocmd = BIO_READ;
831 bp->b_flags &= ~B_INVAL;
832 bp->b_ioflags &= ~BIO_ERROR;
833 if (bp->b_rcred == NOCRED && cred != NOCRED)
834 bp->b_rcred = crhold(cred);
835 vfs_busy_pages(bp, 0);
836 bp->b_iooffset = dbtob(bp->b_blkno);
837 bstrategy(bp);
838 ++readwait;
839 }
840
841 breada(vp, rablkno, rabsize, cnt, cred);
842
843 if (readwait) {
844 rv = bufwait(bp);
845 }
846 return (rv);
847 }
848
849 /*
850 * Write, release buffer on completion. (Done by iodone
851 * if async). Do not bother writing anything if the buffer
852 * is invalid.
853 *
854 * Note that we set B_CACHE here, indicating that buffer is
855 * fully valid and thus cacheable. This is true even of NFS
856 * now so we set it generally. This could be set either here
857 * or in biodone() since the I/O is synchronous. We put it
858 * here.
859 */
860 int
861 bufwrite(struct buf *bp)
862 {
863 int oldflags;
864 struct vnode *vp;
865 int vp_md;
866
867 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
868 if (bp->b_flags & B_INVAL) {
869 brelse(bp);
870 return (0);
871 }
872
873 oldflags = bp->b_flags;
874
875 BUF_ASSERT_HELD(bp);
876
877 if (bp->b_pin_count > 0)
878 bunpin_wait(bp);
879
880 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
881 ("FFS background buffer should not get here %p", bp));
882
883 vp = bp->b_vp;
884 if (vp)
885 vp_md = vp->v_vflag & VV_MD;
886 else
887 vp_md = 0;
888
889 /* Mark the buffer clean */
890 bundirty(bp);
891
892 bp->b_flags &= ~B_DONE;
893 bp->b_ioflags &= ~BIO_ERROR;
894 bp->b_flags |= B_CACHE;
895 bp->b_iocmd = BIO_WRITE;
896
897 bufobj_wref(bp->b_bufobj);
898 vfs_busy_pages(bp, 1);
899
900 /*
901 * Normal bwrites pipeline writes
902 */
903 bp->b_runningbufspace = bp->b_bufsize;
904 atomic_add_long(&runningbufspace, bp->b_runningbufspace);
905
906 if (!TD_IS_IDLETHREAD(curthread))
907 curthread->td_ru.ru_oublock++;
908 if (oldflags & B_ASYNC)
909 BUF_KERNPROC(bp);
910 bp->b_iooffset = dbtob(bp->b_blkno);
911 bstrategy(bp);
912
913 if ((oldflags & B_ASYNC) == 0) {
914 int rtval = bufwait(bp);
915 brelse(bp);
916 return (rtval);
917 } else {
918 /*
919 * don't allow the async write to saturate the I/O
920 * system. We will not deadlock here because
921 * we are blocking waiting for I/O that is already in-progress
922 * to complete. We do not block here if it is the update
923 * or syncer daemon trying to clean up as that can lead
924 * to deadlock.
925 */
926 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
927 waitrunningbufspace();
928 }
929
930 return (0);
931 }
932
933 void
934 bufbdflush(struct bufobj *bo, struct buf *bp)
935 {
936 struct buf *nbp;
937
938 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
939 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
940 altbufferflushes++;
941 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
942 BO_LOCK(bo);
943 /*
944 * Try to find a buffer to flush.
945 */
946 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
947 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
948 BUF_LOCK(nbp,
949 LK_EXCLUSIVE | LK_NOWAIT, NULL))
950 continue;
951 if (bp == nbp)
952 panic("bdwrite: found ourselves");
953 BO_UNLOCK(bo);
954 /* Don't countdeps with the bo lock held. */
955 if (buf_countdeps(nbp, 0)) {
956 BO_LOCK(bo);
957 BUF_UNLOCK(nbp);
958 continue;
959 }
960 if (nbp->b_flags & B_CLUSTEROK) {
961 vfs_bio_awrite(nbp);
962 } else {
963 bremfree(nbp);
964 bawrite(nbp);
965 }
966 dirtybufferflushes++;
967 break;
968 }
969 if (nbp == NULL)
970 BO_UNLOCK(bo);
971 }
972 }
973
974 /*
975 * Delayed write. (Buffer is marked dirty). Do not bother writing
976 * anything if the buffer is marked invalid.
977 *
978 * Note that since the buffer must be completely valid, we can safely
979 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
980 * biodone() in order to prevent getblk from writing the buffer
981 * out synchronously.
982 */
983 void
984 bdwrite(struct buf *bp)
985 {
986 struct thread *td = curthread;
987 struct vnode *vp;
988 struct bufobj *bo;
989
990 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
991 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
992 BUF_ASSERT_HELD(bp);
993
994 if (bp->b_flags & B_INVAL) {
995 brelse(bp);
996 return;
997 }
998
999 /*
1000 * If we have too many dirty buffers, don't create any more.
1001 * If we are wildly over our limit, then force a complete
1002 * cleanup. Otherwise, just keep the situation from getting
1003 * out of control. Note that we have to avoid a recursive
1004 * disaster and not try to clean up after our own cleanup!
1005 */
1006 vp = bp->b_vp;
1007 bo = bp->b_bufobj;
1008 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
1009 td->td_pflags |= TDP_INBDFLUSH;
1010 BO_BDFLUSH(bo, bp);
1011 td->td_pflags &= ~TDP_INBDFLUSH;
1012 } else
1013 recursiveflushes++;
1014
1015 bdirty(bp);
1016 /*
1017 * Set B_CACHE, indicating that the buffer is fully valid. This is
1018 * true even of NFS now.
1019 */
1020 bp->b_flags |= B_CACHE;
1021
1022 /*
1023 * This bmap keeps the system from needing to do the bmap later,
1024 * perhaps when the system is attempting to do a sync. Since it
1025 * is likely that the indirect block -- or whatever other datastructure
1026 * that the filesystem needs is still in memory now, it is a good
1027 * thing to do this. Note also, that if the pageout daemon is
1028 * requesting a sync -- there might not be enough memory to do
1029 * the bmap then... So, this is important to do.
1030 */
1031 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1032 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1033 }
1034
1035 /*
1036 * Set the *dirty* buffer range based upon the VM system dirty
1037 * pages.
1038 *
1039 * Mark the buffer pages as clean. We need to do this here to
1040 * satisfy the vnode_pager and the pageout daemon, so that it
1041 * thinks that the pages have been "cleaned". Note that since
1042 * the pages are in a delayed write buffer -- the VFS layer
1043 * "will" see that the pages get written out on the next sync,
1044 * or perhaps the cluster will be completed.
1045 */
1046 vfs_clean_pages_dirty_buf(bp);
1047 bqrelse(bp);
1048
1049 /*
1050 * Wakeup the buffer flushing daemon if we have a lot of dirty
1051 * buffers (midpoint between our recovery point and our stall
1052 * point).
1053 */
1054 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1055
1056 /*
1057 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1058 * due to the softdep code.
1059 */
1060 }
1061
1062 /*
1063 * bdirty:
1064 *
1065 * Turn buffer into delayed write request. We must clear BIO_READ and
1066 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1067 * itself to properly update it in the dirty/clean lists. We mark it
1068 * B_DONE to ensure that any asynchronization of the buffer properly
1069 * clears B_DONE ( else a panic will occur later ).
1070 *
1071 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1072 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1073 * should only be called if the buffer is known-good.
1074 *
1075 * Since the buffer is not on a queue, we do not update the numfreebuffers
1076 * count.
1077 *
1078 * The buffer must be on QUEUE_NONE.
1079 */
1080 void
1081 bdirty(struct buf *bp)
1082 {
1083
1084 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1085 bp, bp->b_vp, bp->b_flags);
1086 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1087 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1088 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1089 BUF_ASSERT_HELD(bp);
1090 bp->b_flags &= ~(B_RELBUF);
1091 bp->b_iocmd = BIO_WRITE;
1092
1093 if ((bp->b_flags & B_DELWRI) == 0) {
1094 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1095 reassignbuf(bp);
1096 atomic_add_int(&numdirtybuffers, 1);
1097 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1098 }
1099 }
1100
1101 /*
1102 * bundirty:
1103 *
1104 * Clear B_DELWRI for buffer.
1105 *
1106 * Since the buffer is not on a queue, we do not update the numfreebuffers
1107 * count.
1108 *
1109 * The buffer must be on QUEUE_NONE.
1110 */
1111
1112 void
1113 bundirty(struct buf *bp)
1114 {
1115
1116 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1117 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1118 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1119 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1120 BUF_ASSERT_HELD(bp);
1121
1122 if (bp->b_flags & B_DELWRI) {
1123 bp->b_flags &= ~B_DELWRI;
1124 reassignbuf(bp);
1125 atomic_subtract_int(&numdirtybuffers, 1);
1126 numdirtywakeup(lodirtybuffers);
1127 }
1128 /*
1129 * Since it is now being written, we can clear its deferred write flag.
1130 */
1131 bp->b_flags &= ~B_DEFERRED;
1132 }
1133
1134 /*
1135 * bawrite:
1136 *
1137 * Asynchronous write. Start output on a buffer, but do not wait for
1138 * it to complete. The buffer is released when the output completes.
1139 *
1140 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1141 * B_INVAL buffers. Not us.
1142 */
1143 void
1144 bawrite(struct buf *bp)
1145 {
1146
1147 bp->b_flags |= B_ASYNC;
1148 (void) bwrite(bp);
1149 }
1150
1151 /*
1152 * bwillwrite:
1153 *
1154 * Called prior to the locking of any vnodes when we are expecting to
1155 * write. We do not want to starve the buffer cache with too many
1156 * dirty buffers so we block here. By blocking prior to the locking
1157 * of any vnodes we attempt to avoid the situation where a locked vnode
1158 * prevents the various system daemons from flushing related buffers.
1159 */
1160
1161 void
1162 bwillwrite(void)
1163 {
1164
1165 if (numdirtybuffers >= hidirtybuffers) {
1166 mtx_lock(&nblock);
1167 while (numdirtybuffers >= hidirtybuffers) {
1168 bd_wakeup(1);
1169 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1170 msleep(&needsbuffer, &nblock,
1171 (PRIBIO + 4), "flswai", 0);
1172 }
1173 mtx_unlock(&nblock);
1174 }
1175 }
1176
1177 /*
1178 * Return true if we have too many dirty buffers.
1179 */
1180 int
1181 buf_dirty_count_severe(void)
1182 {
1183
1184 return(numdirtybuffers >= hidirtybuffers);
1185 }
1186
1187 static __noinline int
1188 buf_vm_page_count_severe(void)
1189 {
1190
1191 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1);
1192
1193 return vm_page_count_severe();
1194 }
1195
1196 /*
1197 * brelse:
1198 *
1199 * Release a busy buffer and, if requested, free its resources. The
1200 * buffer will be stashed in the appropriate bufqueue[] allowing it
1201 * to be accessed later as a cache entity or reused for other purposes.
1202 */
1203 void
1204 brelse(struct buf *bp)
1205 {
1206 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1207 bp, bp->b_vp, bp->b_flags);
1208 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1209 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1210
1211 if (bp->b_flags & B_MANAGED) {
1212 bqrelse(bp);
1213 return;
1214 }
1215
1216 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
1217 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) {
1218 /*
1219 * Failed write, redirty. Must clear BIO_ERROR to prevent
1220 * pages from being scrapped. If the error is anything
1221 * other than an I/O error (EIO), assume that retrying
1222 * is futile.
1223 */
1224 bp->b_ioflags &= ~BIO_ERROR;
1225 bdirty(bp);
1226 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1227 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1228 /*
1229 * Either a failed I/O or we were asked to free or not
1230 * cache the buffer.
1231 */
1232 bp->b_flags |= B_INVAL;
1233 if (!LIST_EMPTY(&bp->b_dep))
1234 buf_deallocate(bp);
1235 if (bp->b_flags & B_DELWRI) {
1236 atomic_subtract_int(&numdirtybuffers, 1);
1237 numdirtywakeup(lodirtybuffers);
1238 }
1239 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1240 if ((bp->b_flags & B_VMIO) == 0) {
1241 if (bp->b_bufsize)
1242 allocbuf(bp, 0);
1243 if (bp->b_vp)
1244 brelvp(bp);
1245 }
1246 }
1247
1248 /*
1249 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1250 * is called with B_DELWRI set, the underlying pages may wind up
1251 * getting freed causing a previous write (bdwrite()) to get 'lost'
1252 * because pages associated with a B_DELWRI bp are marked clean.
1253 *
1254 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1255 * if B_DELWRI is set.
1256 *
1257 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1258 * on pages to return pages to the VM page queues.
1259 */
1260 if (bp->b_flags & B_DELWRI)
1261 bp->b_flags &= ~B_RELBUF;
1262 else if (buf_vm_page_count_severe()) {
1263 /*
1264 * The locking of the BO_LOCK is not necessary since
1265 * BKGRDINPROG cannot be set while we hold the buf
1266 * lock, it can only be cleared if it is already
1267 * pending.
1268 */
1269 if (bp->b_vp) {
1270 if (!(bp->b_vflags & BV_BKGRDINPROG))
1271 bp->b_flags |= B_RELBUF;
1272 } else
1273 bp->b_flags |= B_RELBUF;
1274 }
1275
1276 /*
1277 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1278 * constituted, not even NFS buffers now. Two flags effect this. If
1279 * B_INVAL, the struct buf is invalidated but the VM object is kept
1280 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1281 *
1282 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1283 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1284 * buffer is also B_INVAL because it hits the re-dirtying code above.
1285 *
1286 * Normally we can do this whether a buffer is B_DELWRI or not. If
1287 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1288 * the commit state and we cannot afford to lose the buffer. If the
1289 * buffer has a background write in progress, we need to keep it
1290 * around to prevent it from being reconstituted and starting a second
1291 * background write.
1292 */
1293 if ((bp->b_flags & B_VMIO)
1294 && !(bp->b_vp->v_mount != NULL &&
1295 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1296 !vn_isdisk(bp->b_vp, NULL) &&
1297 (bp->b_flags & B_DELWRI))
1298 ) {
1299
1300 int i, j, resid;
1301 vm_page_t m;
1302 off_t foff;
1303 vm_pindex_t poff;
1304 vm_object_t obj;
1305
1306 obj = bp->b_bufobj->bo_object;
1307
1308 /*
1309 * Get the base offset and length of the buffer. Note that
1310 * in the VMIO case if the buffer block size is not
1311 * page-aligned then b_data pointer may not be page-aligned.
1312 * But our b_pages[] array *IS* page aligned.
1313 *
1314 * block sizes less then DEV_BSIZE (usually 512) are not
1315 * supported due to the page granularity bits (m->valid,
1316 * m->dirty, etc...).
1317 *
1318 * See man buf(9) for more information
1319 */
1320 resid = bp->b_bufsize;
1321 foff = bp->b_offset;
1322 VM_OBJECT_LOCK(obj);
1323 for (i = 0; i < bp->b_npages; i++) {
1324 int had_bogus = 0;
1325
1326 m = bp->b_pages[i];
1327
1328 /*
1329 * If we hit a bogus page, fixup *all* the bogus pages
1330 * now.
1331 */
1332 if (m == bogus_page) {
1333 poff = OFF_TO_IDX(bp->b_offset);
1334 had_bogus = 1;
1335
1336 for (j = i; j < bp->b_npages; j++) {
1337 vm_page_t mtmp;
1338 mtmp = bp->b_pages[j];
1339 if (mtmp == bogus_page) {
1340 mtmp = vm_page_lookup(obj, poff + j);
1341 if (!mtmp) {
1342 panic("brelse: page missing\n");
1343 }
1344 bp->b_pages[j] = mtmp;
1345 }
1346 }
1347
1348 if ((bp->b_flags & B_INVAL) == 0) {
1349 pmap_qenter(
1350 trunc_page((vm_offset_t)bp->b_data),
1351 bp->b_pages, bp->b_npages);
1352 }
1353 m = bp->b_pages[i];
1354 }
1355 if ((bp->b_flags & B_NOCACHE) ||
1356 (bp->b_ioflags & BIO_ERROR &&
1357 bp->b_iocmd == BIO_READ)) {
1358 int poffset = foff & PAGE_MASK;
1359 int presid = resid > (PAGE_SIZE - poffset) ?
1360 (PAGE_SIZE - poffset) : resid;
1361
1362 KASSERT(presid >= 0, ("brelse: extra page"));
1363 vm_page_lock_queues();
1364 vm_page_set_invalid(m, poffset, presid);
1365 vm_page_unlock_queues();
1366 if (had_bogus)
1367 printf("avoided corruption bug in bogus_page/brelse code\n");
1368 }
1369 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1370 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1371 }
1372 VM_OBJECT_UNLOCK(obj);
1373 if (bp->b_flags & (B_INVAL | B_RELBUF))
1374 vfs_vmio_release(bp);
1375
1376 } else if (bp->b_flags & B_VMIO) {
1377
1378 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1379 vfs_vmio_release(bp);
1380 }
1381
1382 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1383 if (bp->b_bufsize != 0)
1384 allocbuf(bp, 0);
1385 if (bp->b_vp != NULL)
1386 brelvp(bp);
1387 }
1388
1389 if (BUF_LOCKRECURSED(bp)) {
1390 /* do not release to free list */
1391 BUF_UNLOCK(bp);
1392 return;
1393 }
1394
1395 /* enqueue */
1396 mtx_lock(&bqlock);
1397 /* Handle delayed bremfree() processing. */
1398 if (bp->b_flags & B_REMFREE) {
1399 struct bufobj *bo;
1400
1401 bo = bp->b_bufobj;
1402 if (bo != NULL)
1403 BO_LOCK(bo);
1404 bremfreel(bp);
1405 if (bo != NULL)
1406 BO_UNLOCK(bo);
1407 }
1408 if (bp->b_qindex != QUEUE_NONE)
1409 panic("brelse: free buffer onto another queue???");
1410
1411 /*
1412 * If the buffer has junk contents signal it and eventually
1413 * clean up B_DELWRI and diassociate the vnode so that gbincore()
1414 * doesn't find it.
1415 */
1416 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
1417 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
1418 bp->b_flags |= B_INVAL;
1419 if (bp->b_flags & B_INVAL) {
1420 if (bp->b_flags & B_DELWRI)
1421 bundirty(bp);
1422 if (bp->b_vp)
1423 brelvp(bp);
1424 }
1425
1426 /* buffers with no memory */
1427 if (bp->b_bufsize == 0) {
1428 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1429 if (bp->b_vflags & BV_BKGRDINPROG)
1430 panic("losing buffer 1");
1431 if (bp->b_kvasize) {
1432 bp->b_qindex = QUEUE_EMPTYKVA;
1433 } else {
1434 bp->b_qindex = QUEUE_EMPTY;
1435 }
1436 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1437 /* buffers with junk contents */
1438 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1439 (bp->b_ioflags & BIO_ERROR)) {
1440 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1441 if (bp->b_vflags & BV_BKGRDINPROG)
1442 panic("losing buffer 2");
1443 bp->b_qindex = QUEUE_CLEAN;
1444 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1445 /* remaining buffers */
1446 } else {
1447 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) ==
1448 (B_DELWRI|B_NEEDSGIANT))
1449 bp->b_qindex = QUEUE_DIRTY_GIANT;
1450 else if (bp->b_flags & B_DELWRI)
1451 bp->b_qindex = QUEUE_DIRTY;
1452 else
1453 bp->b_qindex = QUEUE_CLEAN;
1454 if (bp->b_flags & B_AGE)
1455 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1456 else
1457 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1458 }
1459 mtx_unlock(&bqlock);
1460
1461 /*
1462 * Fixup numfreebuffers count. The bp is on an appropriate queue
1463 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1464 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1465 * if B_INVAL is set ).
1466 */
1467
1468 if (!(bp->b_flags & B_DELWRI)) {
1469 struct bufobj *bo;
1470
1471 bo = bp->b_bufobj;
1472 if (bo != NULL)
1473 BO_LOCK(bo);
1474 bufcountwakeup(bp);
1475 if (bo != NULL)
1476 BO_UNLOCK(bo);
1477 }
1478
1479 /*
1480 * Something we can maybe free or reuse
1481 */
1482 if (bp->b_bufsize || bp->b_kvasize)
1483 bufspacewakeup();
1484
1485 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1486 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1487 panic("brelse: not dirty");
1488 /* unlock */
1489 BUF_UNLOCK(bp);
1490 }
1491
1492 /*
1493 * Release a buffer back to the appropriate queue but do not try to free
1494 * it. The buffer is expected to be used again soon.
1495 *
1496 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1497 * biodone() to requeue an async I/O on completion. It is also used when
1498 * known good buffers need to be requeued but we think we may need the data
1499 * again soon.
1500 *
1501 * XXX we should be able to leave the B_RELBUF hint set on completion.
1502 */
1503 void
1504 bqrelse(struct buf *bp)
1505 {
1506 struct bufobj *bo;
1507
1508 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1509 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1510 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1511
1512 if (BUF_LOCKRECURSED(bp)) {
1513 /* do not release to free list */
1514 BUF_UNLOCK(bp);
1515 return;
1516 }
1517
1518 bo = bp->b_bufobj;
1519 if (bp->b_flags & B_MANAGED) {
1520 if (bp->b_flags & B_REMFREE) {
1521 mtx_lock(&bqlock);
1522 if (bo != NULL)
1523 BO_LOCK(bo);
1524 bremfreel(bp);
1525 if (bo != NULL)
1526 BO_UNLOCK(bo);
1527 mtx_unlock(&bqlock);
1528 }
1529 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1530 BUF_UNLOCK(bp);
1531 return;
1532 }
1533
1534 mtx_lock(&bqlock);
1535 /* Handle delayed bremfree() processing. */
1536 if (bp->b_flags & B_REMFREE) {
1537 if (bo != NULL)
1538 BO_LOCK(bo);
1539 bremfreel(bp);
1540 if (bo != NULL)
1541 BO_UNLOCK(bo);
1542 }
1543 if (bp->b_qindex != QUEUE_NONE)
1544 panic("bqrelse: free buffer onto another queue???");
1545 /* buffers with stale but valid contents */
1546 if (bp->b_flags & B_DELWRI) {
1547 if (bp->b_flags & B_NEEDSGIANT)
1548 bp->b_qindex = QUEUE_DIRTY_GIANT;
1549 else
1550 bp->b_qindex = QUEUE_DIRTY;
1551 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1552 } else {
1553 /*
1554 * The locking of the BO_LOCK for checking of the
1555 * BV_BKGRDINPROG is not necessary since the
1556 * BV_BKGRDINPROG cannot be set while we hold the buf
1557 * lock, it can only be cleared if it is already
1558 * pending.
1559 */
1560 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) {
1561 bp->b_qindex = QUEUE_CLEAN;
1562 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1563 b_freelist);
1564 } else {
1565 /*
1566 * We are too low on memory, we have to try to free
1567 * the buffer (most importantly: the wired pages
1568 * making up its backing store) *now*.
1569 */
1570 mtx_unlock(&bqlock);
1571 brelse(bp);
1572 return;
1573 }
1574 }
1575 mtx_unlock(&bqlock);
1576
1577 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) {
1578 if (bo != NULL)
1579 BO_LOCK(bo);
1580 bufcountwakeup(bp);
1581 if (bo != NULL)
1582 BO_UNLOCK(bo);
1583 }
1584
1585 /*
1586 * Something we can maybe free or reuse.
1587 */
1588 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1589 bufspacewakeup();
1590
1591 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1592 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1593 panic("bqrelse: not dirty");
1594 /* unlock */
1595 BUF_UNLOCK(bp);
1596 }
1597
1598 /* Give pages used by the bp back to the VM system (where possible) */
1599 static void
1600 vfs_vmio_release(struct buf *bp)
1601 {
1602 int i;
1603 vm_page_t m;
1604
1605 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
1606 vm_page_lock_queues();
1607 for (i = 0; i < bp->b_npages; i++) {
1608 m = bp->b_pages[i];
1609 bp->b_pages[i] = NULL;
1610 /*
1611 * In order to keep page LRU ordering consistent, put
1612 * everything on the inactive queue.
1613 */
1614 vm_page_unwire(m, 0);
1615 /*
1616 * We don't mess with busy pages, it is
1617 * the responsibility of the process that
1618 * busied the pages to deal with them.
1619 */
1620 if ((m->oflags & VPO_BUSY) || (m->busy != 0))
1621 continue;
1622
1623 if (m->wire_count == 0) {
1624 /*
1625 * Might as well free the page if we can and it has
1626 * no valid data. We also free the page if the
1627 * buffer was used for direct I/O
1628 */
1629 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1630 m->hold_count == 0) {
1631 vm_page_free(m);
1632 } else if (bp->b_flags & B_DIRECT) {
1633 vm_page_try_to_free(m);
1634 } else if (buf_vm_page_count_severe()) {
1635 vm_page_try_to_cache(m);
1636 }
1637 }
1638 }
1639 vm_page_unlock_queues();
1640 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
1641 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
1642
1643 if (bp->b_bufsize) {
1644 bufspacewakeup();
1645 bp->b_bufsize = 0;
1646 }
1647 bp->b_npages = 0;
1648 bp->b_flags &= ~B_VMIO;
1649 if (bp->b_vp)
1650 brelvp(bp);
1651 }
1652
1653 /*
1654 * Check to see if a block at a particular lbn is available for a clustered
1655 * write.
1656 */
1657 static int
1658 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1659 {
1660 struct buf *bpa;
1661 int match;
1662
1663 match = 0;
1664
1665 /* If the buf isn't in core skip it */
1666 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1667 return (0);
1668
1669 /* If the buf is busy we don't want to wait for it */
1670 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1671 return (0);
1672
1673 /* Only cluster with valid clusterable delayed write buffers */
1674 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1675 (B_DELWRI | B_CLUSTEROK))
1676 goto done;
1677
1678 if (bpa->b_bufsize != size)
1679 goto done;
1680
1681 /*
1682 * Check to see if it is in the expected place on disk and that the
1683 * block has been mapped.
1684 */
1685 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1686 match = 1;
1687 done:
1688 BUF_UNLOCK(bpa);
1689 return (match);
1690 }
1691
1692 /*
1693 * vfs_bio_awrite:
1694 *
1695 * Implement clustered async writes for clearing out B_DELWRI buffers.
1696 * This is much better then the old way of writing only one buffer at
1697 * a time. Note that we may not be presented with the buffers in the
1698 * correct order, so we search for the cluster in both directions.
1699 */
1700 int
1701 vfs_bio_awrite(struct buf *bp)
1702 {
1703 struct bufobj *bo;
1704 int i;
1705 int j;
1706 daddr_t lblkno = bp->b_lblkno;
1707 struct vnode *vp = bp->b_vp;
1708 int ncl;
1709 int nwritten;
1710 int size;
1711 int maxcl;
1712
1713 bo = &vp->v_bufobj;
1714 /*
1715 * right now we support clustered writing only to regular files. If
1716 * we find a clusterable block we could be in the middle of a cluster
1717 * rather then at the beginning.
1718 */
1719 if ((vp->v_type == VREG) &&
1720 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1721 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1722
1723 size = vp->v_mount->mnt_stat.f_iosize;
1724 maxcl = MAXPHYS / size;
1725
1726 BO_LOCK(bo);
1727 for (i = 1; i < maxcl; i++)
1728 if (vfs_bio_clcheck(vp, size, lblkno + i,
1729 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1730 break;
1731
1732 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1733 if (vfs_bio_clcheck(vp, size, lblkno - j,
1734 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1735 break;
1736 BO_UNLOCK(bo);
1737 --j;
1738 ncl = i + j;
1739 /*
1740 * this is a possible cluster write
1741 */
1742 if (ncl != 1) {
1743 BUF_UNLOCK(bp);
1744 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1745 return nwritten;
1746 }
1747 }
1748 bremfree(bp);
1749 bp->b_flags |= B_ASYNC;
1750 /*
1751 * default (old) behavior, writing out only one block
1752 *
1753 * XXX returns b_bufsize instead of b_bcount for nwritten?
1754 */
1755 nwritten = bp->b_bufsize;
1756 (void) bwrite(bp);
1757
1758 return nwritten;
1759 }
1760
1761 /*
1762 * getnewbuf:
1763 *
1764 * Find and initialize a new buffer header, freeing up existing buffers
1765 * in the bufqueues as necessary. The new buffer is returned locked.
1766 *
1767 * Important: B_INVAL is not set. If the caller wishes to throw the
1768 * buffer away, the caller must set B_INVAL prior to calling brelse().
1769 *
1770 * We block if:
1771 * We have insufficient buffer headers
1772 * We have insufficient buffer space
1773 * buffer_map is too fragmented ( space reservation fails )
1774 * If we have to flush dirty buffers ( but we try to avoid this )
1775 *
1776 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1777 * Instead we ask the buf daemon to do it for us. We attempt to
1778 * avoid piecemeal wakeups of the pageout daemon.
1779 */
1780
1781 static struct buf *
1782 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
1783 int gbflags)
1784 {
1785 struct thread *td;
1786 struct buf *bp;
1787 struct buf *nbp;
1788 int defrag = 0;
1789 int nqindex;
1790 static int flushingbufs;
1791
1792 td = curthread;
1793 /*
1794 * We can't afford to block since we might be holding a vnode lock,
1795 * which may prevent system daemons from running. We deal with
1796 * low-memory situations by proactively returning memory and running
1797 * async I/O rather then sync I/O.
1798 */
1799 atomic_add_int(&getnewbufcalls, 1);
1800 atomic_subtract_int(&getnewbufrestarts, 1);
1801 restart:
1802 atomic_add_int(&getnewbufrestarts, 1);
1803
1804 /*
1805 * Setup for scan. If we do not have enough free buffers,
1806 * we setup a degenerate case that immediately fails. Note
1807 * that if we are specially marked process, we are allowed to
1808 * dip into our reserves.
1809 *
1810 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1811 *
1812 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1813 * However, there are a number of cases (defragging, reusing, ...)
1814 * where we cannot backup.
1815 */
1816 mtx_lock(&bqlock);
1817 nqindex = QUEUE_EMPTYKVA;
1818 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1819
1820 if (nbp == NULL) {
1821 /*
1822 * If no EMPTYKVA buffers and we are either
1823 * defragging or reusing, locate a CLEAN buffer
1824 * to free or reuse. If bufspace useage is low
1825 * skip this step so we can allocate a new buffer.
1826 */
1827 if (defrag || bufspace >= lobufspace) {
1828 nqindex = QUEUE_CLEAN;
1829 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1830 }
1831
1832 /*
1833 * If we could not find or were not allowed to reuse a
1834 * CLEAN buffer, check to see if it is ok to use an EMPTY
1835 * buffer. We can only use an EMPTY buffer if allocating
1836 * its KVA would not otherwise run us out of buffer space.
1837 */
1838 if (nbp == NULL && defrag == 0 &&
1839 bufspace + maxsize < hibufspace) {
1840 nqindex = QUEUE_EMPTY;
1841 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1842 }
1843 }
1844
1845 /*
1846 * Run scan, possibly freeing data and/or kva mappings on the fly
1847 * depending.
1848 */
1849
1850 while ((bp = nbp) != NULL) {
1851 int qindex = nqindex;
1852
1853 /*
1854 * Calculate next bp ( we can only use it if we do not block
1855 * or do other fancy things ).
1856 */
1857 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1858 switch(qindex) {
1859 case QUEUE_EMPTY:
1860 nqindex = QUEUE_EMPTYKVA;
1861 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1862 break;
1863 /* FALLTHROUGH */
1864 case QUEUE_EMPTYKVA:
1865 nqindex = QUEUE_CLEAN;
1866 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1867 break;
1868 /* FALLTHROUGH */
1869 case QUEUE_CLEAN:
1870 /*
1871 * nbp is NULL.
1872 */
1873 break;
1874 }
1875 }
1876 /*
1877 * If we are defragging then we need a buffer with
1878 * b_kvasize != 0. XXX this situation should no longer
1879 * occur, if defrag is non-zero the buffer's b_kvasize
1880 * should also be non-zero at this point. XXX
1881 */
1882 if (defrag && bp->b_kvasize == 0) {
1883 printf("Warning: defrag empty buffer %p\n", bp);
1884 continue;
1885 }
1886
1887 /*
1888 * Start freeing the bp. This is somewhat involved. nbp
1889 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1890 */
1891 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1892 continue;
1893 if (bp->b_vp) {
1894 BO_LOCK(bp->b_bufobj);
1895 if (bp->b_vflags & BV_BKGRDINPROG) {
1896 BO_UNLOCK(bp->b_bufobj);
1897 BUF_UNLOCK(bp);
1898 continue;
1899 }
1900 BO_UNLOCK(bp->b_bufobj);
1901 }
1902 CTR6(KTR_BUF,
1903 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
1904 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
1905 bp->b_kvasize, bp->b_bufsize, qindex);
1906
1907 /*
1908 * Sanity Checks
1909 */
1910 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1911
1912 /*
1913 * Note: we no longer distinguish between VMIO and non-VMIO
1914 * buffers.
1915 */
1916
1917 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1918
1919 if (bp->b_bufobj != NULL)
1920 BO_LOCK(bp->b_bufobj);
1921 bremfreel(bp);
1922 if (bp->b_bufobj != NULL)
1923 BO_UNLOCK(bp->b_bufobj);
1924 mtx_unlock(&bqlock);
1925
1926 if (qindex == QUEUE_CLEAN) {
1927 if (bp->b_flags & B_VMIO) {
1928 bp->b_flags &= ~B_ASYNC;
1929 vfs_vmio_release(bp);
1930 }
1931 if (bp->b_vp)
1932 brelvp(bp);
1933 }
1934
1935 /*
1936 * NOTE: nbp is now entirely invalid. We can only restart
1937 * the scan from this point on.
1938 *
1939 * Get the rest of the buffer freed up. b_kva* is still
1940 * valid after this operation.
1941 */
1942
1943 if (bp->b_rcred != NOCRED) {
1944 crfree(bp->b_rcred);
1945 bp->b_rcred = NOCRED;
1946 }
1947 if (bp->b_wcred != NOCRED) {
1948 crfree(bp->b_wcred);
1949 bp->b_wcred = NOCRED;
1950 }
1951 if (!LIST_EMPTY(&bp->b_dep))
1952 buf_deallocate(bp);
1953 if (bp->b_vflags & BV_BKGRDINPROG)
1954 panic("losing buffer 3");
1955 KASSERT(bp->b_vp == NULL,
1956 ("bp: %p still has vnode %p. qindex: %d",
1957 bp, bp->b_vp, qindex));
1958 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1959 ("bp: %p still on a buffer list. xflags %X",
1960 bp, bp->b_xflags));
1961
1962 if (bp->b_bufsize)
1963 allocbuf(bp, 0);
1964
1965 bp->b_flags = 0;
1966 bp->b_ioflags = 0;
1967 bp->b_xflags = 0;
1968 KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
1969 ("buf %p still counted as free?", bp));
1970 bp->b_vflags = 0;
1971 bp->b_vp = NULL;
1972 bp->b_blkno = bp->b_lblkno = 0;
1973 bp->b_offset = NOOFFSET;
1974 bp->b_iodone = 0;
1975 bp->b_error = 0;
1976 bp->b_resid = 0;
1977 bp->b_bcount = 0;
1978 bp->b_npages = 0;
1979 bp->b_dirtyoff = bp->b_dirtyend = 0;
1980 bp->b_bufobj = NULL;
1981 bp->b_pin_count = 0;
1982 bp->b_fsprivate1 = NULL;
1983 bp->b_fsprivate2 = NULL;
1984 bp->b_fsprivate3 = NULL;
1985
1986 LIST_INIT(&bp->b_dep);
1987
1988 /*
1989 * If we are defragging then free the buffer.
1990 */
1991 if (defrag) {
1992 bp->b_flags |= B_INVAL;
1993 bfreekva(bp);
1994 brelse(bp);
1995 defrag = 0;
1996 goto restart;
1997 }
1998
1999 /*
2000 * Notify any waiters for the buffer lock about
2001 * identity change by freeing the buffer.
2002 */
2003 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
2004 bp->b_flags |= B_INVAL;
2005 bfreekva(bp);
2006 brelse(bp);
2007 goto restart;
2008 }
2009
2010 /*
2011 * If we are overcomitted then recover the buffer and its
2012 * KVM space. This occurs in rare situations when multiple
2013 * processes are blocked in getnewbuf() or allocbuf().
2014 */
2015 if (bufspace >= hibufspace)
2016 flushingbufs = 1;
2017 if (flushingbufs && bp->b_kvasize != 0) {
2018 bp->b_flags |= B_INVAL;
2019 bfreekva(bp);
2020 brelse(bp);
2021 goto restart;
2022 }
2023 if (bufspace < lobufspace)
2024 flushingbufs = 0;
2025 break;
2026 }
2027
2028 /*
2029 * If we exhausted our list, sleep as appropriate. We may have to
2030 * wakeup various daemons and write out some dirty buffers.
2031 *
2032 * Generally we are sleeping due to insufficient buffer space.
2033 */
2034
2035 if (bp == NULL) {
2036 int flags, norunbuf;
2037 char *waitmsg;
2038 int fl;
2039
2040 if (defrag) {
2041 flags = VFS_BIO_NEED_BUFSPACE;
2042 waitmsg = "nbufkv";
2043 } else if (bufspace >= hibufspace) {
2044 waitmsg = "nbufbs";
2045 flags = VFS_BIO_NEED_BUFSPACE;
2046 } else {
2047 waitmsg = "newbuf";
2048 flags = VFS_BIO_NEED_ANY;
2049 }
2050 mtx_lock(&nblock);
2051 needsbuffer |= flags;
2052 mtx_unlock(&nblock);
2053 mtx_unlock(&bqlock);
2054
2055 bd_speedup(); /* heeeelp */
2056 if (gbflags & GB_NOWAIT_BD)
2057 return (NULL);
2058
2059 mtx_lock(&nblock);
2060 while (needsbuffer & flags) {
2061 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) {
2062 mtx_unlock(&nblock);
2063 /*
2064 * getblk() is called with a vnode
2065 * locked, and some majority of the
2066 * dirty buffers may as well belong to
2067 * the vnode. Flushing the buffers
2068 * there would make a progress that
2069 * cannot be achieved by the
2070 * buf_daemon, that cannot lock the
2071 * vnode.
2072 */
2073 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
2074 (td->td_pflags & TDP_NORUNNINGBUF);
2075 /* play bufdaemon */
2076 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
2077 fl = buf_do_flush(vp);
2078 td->td_pflags &= norunbuf;
2079 mtx_lock(&nblock);
2080 if (fl != 0)
2081 continue;
2082 if ((needsbuffer & flags) == 0)
2083 break;
2084 }
2085 if (msleep(&needsbuffer, &nblock,
2086 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
2087 mtx_unlock(&nblock);
2088 return (NULL);
2089 }
2090 }
2091 mtx_unlock(&nblock);
2092 } else {
2093 /*
2094 * We finally have a valid bp. We aren't quite out of the
2095 * woods, we still have to reserve kva space. In order
2096 * to keep fragmentation sane we only allocate kva in
2097 * BKVASIZE chunks.
2098 */
2099 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2100
2101 if (maxsize != bp->b_kvasize) {
2102 vm_offset_t addr = 0;
2103
2104 bfreekva(bp);
2105
2106 vm_map_lock(buffer_map);
2107 if (vm_map_findspace(buffer_map,
2108 vm_map_min(buffer_map), maxsize, &addr)) {
2109 /*
2110 * Uh oh. Buffer map is to fragmented. We
2111 * must defragment the map.
2112 */
2113 atomic_add_int(&bufdefragcnt, 1);
2114 vm_map_unlock(buffer_map);
2115 defrag = 1;
2116 bp->b_flags |= B_INVAL;
2117 brelse(bp);
2118 goto restart;
2119 }
2120 if (addr) {
2121 vm_map_insert(buffer_map, NULL, 0,
2122 addr, addr + maxsize,
2123 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
2124
2125 bp->b_kvabase = (caddr_t) addr;
2126 bp->b_kvasize = maxsize;
2127 atomic_add_long(&bufspace, bp->b_kvasize);
2128 atomic_add_int(&bufreusecnt, 1);
2129 }
2130 vm_map_unlock(buffer_map);
2131 }
2132 bp->b_saveaddr = bp->b_kvabase;
2133 bp->b_data = bp->b_saveaddr;
2134 }
2135 return(bp);
2136 }
2137
2138 /*
2139 * buf_daemon:
2140 *
2141 * buffer flushing daemon. Buffers are normally flushed by the
2142 * update daemon but if it cannot keep up this process starts to
2143 * take the load in an attempt to prevent getnewbuf() from blocking.
2144 */
2145
2146 static struct kproc_desc buf_kp = {
2147 "bufdaemon",
2148 buf_daemon,
2149 &bufdaemonproc
2150 };
2151 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2152
2153 static int
2154 buf_do_flush(struct vnode *vp)
2155 {
2156 int flushed;
2157
2158 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0);
2159 /* The list empty check here is slightly racy */
2160 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) {
2161 mtx_lock(&Giant);
2162 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0);
2163 mtx_unlock(&Giant);
2164 }
2165 if (flushed == 0) {
2166 /*
2167 * Could not find any buffers without rollback
2168 * dependencies, so just write the first one
2169 * in the hopes of eventually making progress.
2170 */
2171 flushbufqueues(vp, QUEUE_DIRTY, 1);
2172 if (!TAILQ_EMPTY(
2173 &bufqueues[QUEUE_DIRTY_GIANT])) {
2174 mtx_lock(&Giant);
2175 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1);
2176 mtx_unlock(&Giant);
2177 }
2178 }
2179 return (flushed);
2180 }
2181
2182 static void
2183 buf_daemon()
2184 {
2185
2186 /*
2187 * This process needs to be suspended prior to shutdown sync.
2188 */
2189 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2190 SHUTDOWN_PRI_LAST);
2191
2192 /*
2193 * This process is allowed to take the buffer cache to the limit
2194 */
2195 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
2196 mtx_lock(&bdlock);
2197 for (;;) {
2198 bd_request = 0;
2199 mtx_unlock(&bdlock);
2200
2201 kproc_suspend_check(bufdaemonproc);
2202
2203 /*
2204 * Do the flush. Limit the amount of in-transit I/O we
2205 * allow to build up, otherwise we would completely saturate
2206 * the I/O system. Wakeup any waiting processes before we
2207 * normally would so they can run in parallel with our drain.
2208 */
2209 while (numdirtybuffers > lodirtybuffers) {
2210 if (buf_do_flush(NULL) == 0)
2211 break;
2212 uio_yield();
2213 }
2214
2215 /*
2216 * Only clear bd_request if we have reached our low water
2217 * mark. The buf_daemon normally waits 1 second and
2218 * then incrementally flushes any dirty buffers that have
2219 * built up, within reason.
2220 *
2221 * If we were unable to hit our low water mark and couldn't
2222 * find any flushable buffers, we sleep half a second.
2223 * Otherwise we loop immediately.
2224 */
2225 mtx_lock(&bdlock);
2226 if (numdirtybuffers <= lodirtybuffers) {
2227 /*
2228 * We reached our low water mark, reset the
2229 * request and sleep until we are needed again.
2230 * The sleep is just so the suspend code works.
2231 */
2232 bd_request = 0;
2233 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2234 } else {
2235 /*
2236 * We couldn't find any flushable dirty buffers but
2237 * still have too many dirty buffers, we
2238 * have to sleep and try again. (rare)
2239 */
2240 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2241 }
2242 }
2243 }
2244
2245 /*
2246 * flushbufqueues:
2247 *
2248 * Try to flush a buffer in the dirty queue. We must be careful to
2249 * free up B_INVAL buffers instead of write them, which NFS is
2250 * particularly sensitive to.
2251 */
2252 static int flushwithdeps = 0;
2253 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2254 0, "Number of buffers flushed with dependecies that require rollbacks");
2255
2256 static int
2257 flushbufqueues(struct vnode *lvp, int queue, int flushdeps)
2258 {
2259 struct buf *sentinel;
2260 struct vnode *vp;
2261 struct mount *mp;
2262 struct buf *bp;
2263 int hasdeps;
2264 int flushed;
2265 int target;
2266
2267 if (lvp == NULL) {
2268 target = numdirtybuffers - lodirtybuffers;
2269 if (flushdeps && target > 2)
2270 target /= 2;
2271 } else
2272 target = flushbufqtarget;
2273 flushed = 0;
2274 bp = NULL;
2275 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
2276 sentinel->b_qindex = QUEUE_SENTINEL;
2277 mtx_lock(&bqlock);
2278 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
2279 while (flushed != target) {
2280 bp = TAILQ_NEXT(sentinel, b_freelist);
2281 if (bp != NULL) {
2282 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2283 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
2284 b_freelist);
2285 } else
2286 break;
2287 /*
2288 * Skip sentinels inserted by other invocations of the
2289 * flushbufqueues(), taking care to not reorder them.
2290 */
2291 if (bp->b_qindex == QUEUE_SENTINEL)
2292 continue;
2293 /*
2294 * Only flush the buffers that belong to the
2295 * vnode locked by the curthread.
2296 */
2297 if (lvp != NULL && bp->b_vp != lvp)
2298 continue;
2299 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2300 continue;
2301 if (bp->b_pin_count > 0) {
2302 BUF_UNLOCK(bp);
2303 continue;
2304 }
2305 BO_LOCK(bp->b_bufobj);
2306 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2307 (bp->b_flags & B_DELWRI) == 0) {
2308 BO_UNLOCK(bp->b_bufobj);
2309 BUF_UNLOCK(bp);
2310 continue;
2311 }
2312 BO_UNLOCK(bp->b_bufobj);
2313 if (bp->b_flags & B_INVAL) {
2314 bremfreel(bp);
2315 mtx_unlock(&bqlock);
2316 brelse(bp);
2317 flushed++;
2318 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2319 mtx_lock(&bqlock);
2320 continue;
2321 }
2322
2323 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
2324 if (flushdeps == 0) {
2325 BUF_UNLOCK(bp);
2326 continue;
2327 }
2328 hasdeps = 1;
2329 } else
2330 hasdeps = 0;
2331 /*
2332 * We must hold the lock on a vnode before writing
2333 * one of its buffers. Otherwise we may confuse, or
2334 * in the case of a snapshot vnode, deadlock the
2335 * system.
2336 *
2337 * The lock order here is the reverse of the normal
2338 * of vnode followed by buf lock. This is ok because
2339 * the NOWAIT will prevent deadlock.
2340 */
2341 vp = bp->b_vp;
2342 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2343 BUF_UNLOCK(bp);
2344 continue;
2345 }
2346 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) {
2347 mtx_unlock(&bqlock);
2348 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2349 bp, bp->b_vp, bp->b_flags);
2350 if (curproc == bufdaemonproc)
2351 vfs_bio_awrite(bp);
2352 else {
2353 bremfree(bp);
2354 bwrite(bp);
2355 notbufdflashes++;
2356 }
2357 vn_finished_write(mp);
2358 VOP_UNLOCK(vp, 0);
2359 flushwithdeps += hasdeps;
2360 flushed++;
2361
2362 /*
2363 * Sleeping on runningbufspace while holding
2364 * vnode lock leads to deadlock.
2365 */
2366 if (curproc == bufdaemonproc)
2367 waitrunningbufspace();
2368 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2369 mtx_lock(&bqlock);
2370 continue;
2371 }
2372 vn_finished_write(mp);
2373 BUF_UNLOCK(bp);
2374 }
2375 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2376 mtx_unlock(&bqlock);
2377 free(sentinel, M_TEMP);
2378 return (flushed);
2379 }
2380
2381 /*
2382 * Check to see if a block is currently memory resident.
2383 */
2384 struct buf *
2385 incore(struct bufobj *bo, daddr_t blkno)
2386 {
2387 struct buf *bp;
2388
2389 BO_LOCK(bo);
2390 bp = gbincore(bo, blkno);
2391 BO_UNLOCK(bo);
2392 return (bp);
2393 }
2394
2395 /*
2396 * Returns true if no I/O is needed to access the
2397 * associated VM object. This is like incore except
2398 * it also hunts around in the VM system for the data.
2399 */
2400
2401 static int
2402 inmem(struct vnode * vp, daddr_t blkno)
2403 {
2404 vm_object_t obj;
2405 vm_offset_t toff, tinc, size;
2406 vm_page_t m;
2407 vm_ooffset_t off;
2408
2409 ASSERT_VOP_LOCKED(vp, "inmem");
2410
2411 if (incore(&vp->v_bufobj, blkno))
2412 return 1;
2413 if (vp->v_mount == NULL)
2414 return 0;
2415 obj = vp->v_object;
2416 if (obj == NULL)
2417 return (0);
2418
2419 size = PAGE_SIZE;
2420 if (size > vp->v_mount->mnt_stat.f_iosize)
2421 size = vp->v_mount->mnt_stat.f_iosize;
2422 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2423
2424 VM_OBJECT_LOCK(obj);
2425 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2426 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2427 if (!m)
2428 goto notinmem;
2429 tinc = size;
2430 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2431 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2432 if (vm_page_is_valid(m,
2433 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2434 goto notinmem;
2435 }
2436 VM_OBJECT_UNLOCK(obj);
2437 return 1;
2438
2439 notinmem:
2440 VM_OBJECT_UNLOCK(obj);
2441 return (0);
2442 }
2443
2444 /*
2445 * Set the dirty range for a buffer based on the status of the dirty
2446 * bits in the pages comprising the buffer. The range is limited
2447 * to the size of the buffer.
2448 *
2449 * Tell the VM system that the pages associated with this buffer
2450 * are clean. This is used for delayed writes where the data is
2451 * going to go to disk eventually without additional VM intevention.
2452 *
2453 * Note that while we only really need to clean through to b_bcount, we
2454 * just go ahead and clean through to b_bufsize.
2455 */
2456 static void
2457 vfs_clean_pages_dirty_buf(struct buf *bp)
2458 {
2459 vm_ooffset_t foff, noff, eoff;
2460 vm_page_t m;
2461 int i;
2462
2463 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
2464 return;
2465
2466 foff = bp->b_offset;
2467 KASSERT(bp->b_offset != NOOFFSET,
2468 ("vfs_clean_pages_dirty_buf: no buffer offset"));
2469
2470 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2471 vfs_drain_busy_pages(bp);
2472 vfs_setdirty_locked_object(bp);
2473 vm_page_lock_queues();
2474 for (i = 0; i < bp->b_npages; i++) {
2475 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2476 eoff = noff;
2477 if (eoff > bp->b_offset + bp->b_bufsize)
2478 eoff = bp->b_offset + bp->b_bufsize;
2479 m = bp->b_pages[i];
2480 vfs_page_set_validclean(bp, foff, m);
2481 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
2482 foff = noff;
2483 }
2484 vm_page_unlock_queues();
2485 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2486 }
2487
2488 static void
2489 vfs_setdirty_locked_object(struct buf *bp)
2490 {
2491 vm_object_t object;
2492 int i;
2493
2494 object = bp->b_bufobj->bo_object;
2495 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
2496
2497 /*
2498 * We qualify the scan for modified pages on whether the
2499 * object has been flushed yet.
2500 */
2501 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2502 vm_offset_t boffset;
2503 vm_offset_t eoffset;
2504
2505 vm_page_lock_queues();
2506 /*
2507 * test the pages to see if they have been modified directly
2508 * by users through the VM system.
2509 */
2510 for (i = 0; i < bp->b_npages; i++)
2511 vm_page_test_dirty(bp->b_pages[i]);
2512
2513 /*
2514 * Calculate the encompassing dirty range, boffset and eoffset,
2515 * (eoffset - boffset) bytes.
2516 */
2517
2518 for (i = 0; i < bp->b_npages; i++) {
2519 if (bp->b_pages[i]->dirty)
2520 break;
2521 }
2522 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2523
2524 for (i = bp->b_npages - 1; i >= 0; --i) {
2525 if (bp->b_pages[i]->dirty) {
2526 break;
2527 }
2528 }
2529 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2530
2531 vm_page_unlock_queues();
2532 /*
2533 * Fit it to the buffer.
2534 */
2535
2536 if (eoffset > bp->b_bcount)
2537 eoffset = bp->b_bcount;
2538
2539 /*
2540 * If we have a good dirty range, merge with the existing
2541 * dirty range.
2542 */
2543
2544 if (boffset < eoffset) {
2545 if (bp->b_dirtyoff > boffset)
2546 bp->b_dirtyoff = boffset;
2547 if (bp->b_dirtyend < eoffset)
2548 bp->b_dirtyend = eoffset;
2549 }
2550 }
2551 }
2552
2553 /*
2554 * getblk:
2555 *
2556 * Get a block given a specified block and offset into a file/device.
2557 * The buffers B_DONE bit will be cleared on return, making it almost
2558 * ready for an I/O initiation. B_INVAL may or may not be set on
2559 * return. The caller should clear B_INVAL prior to initiating a
2560 * READ.
2561 *
2562 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2563 * an existing buffer.
2564 *
2565 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2566 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2567 * and then cleared based on the backing VM. If the previous buffer is
2568 * non-0-sized but invalid, B_CACHE will be cleared.
2569 *
2570 * If getblk() must create a new buffer, the new buffer is returned with
2571 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2572 * case it is returned with B_INVAL clear and B_CACHE set based on the
2573 * backing VM.
2574 *
2575 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2576 * B_CACHE bit is clear.
2577 *
2578 * What this means, basically, is that the caller should use B_CACHE to
2579 * determine whether the buffer is fully valid or not and should clear
2580 * B_INVAL prior to issuing a read. If the caller intends to validate
2581 * the buffer by loading its data area with something, the caller needs
2582 * to clear B_INVAL. If the caller does this without issuing an I/O,
2583 * the caller should set B_CACHE ( as an optimization ), else the caller
2584 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2585 * a write attempt or if it was a successfull read. If the caller
2586 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2587 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2588 */
2589 struct buf *
2590 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2591 int flags)
2592 {
2593 struct buf *bp;
2594 struct bufobj *bo;
2595 int error;
2596
2597 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
2598 ASSERT_VOP_LOCKED(vp, "getblk");
2599 if (size > MAXBSIZE)
2600 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2601
2602 bo = &vp->v_bufobj;
2603 loop:
2604 /*
2605 * Block if we are low on buffers. Certain processes are allowed
2606 * to completely exhaust the buffer cache.
2607 *
2608 * If this check ever becomes a bottleneck it may be better to
2609 * move it into the else, when gbincore() fails. At the moment
2610 * it isn't a problem.
2611 *
2612 * XXX remove if 0 sections (clean this up after its proven)
2613 */
2614 if (numfreebuffers == 0) {
2615 if (TD_IS_IDLETHREAD(curthread))
2616 return NULL;
2617 mtx_lock(&nblock);
2618 needsbuffer |= VFS_BIO_NEED_ANY;
2619 mtx_unlock(&nblock);
2620 }
2621
2622 BO_LOCK(bo);
2623 bp = gbincore(bo, blkno);
2624 if (bp != NULL) {
2625 int lockflags;
2626 /*
2627 * Buffer is in-core. If the buffer is not busy, it must
2628 * be on a queue.
2629 */
2630 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2631
2632 if (flags & GB_LOCK_NOWAIT)
2633 lockflags |= LK_NOWAIT;
2634
2635 error = BUF_TIMELOCK(bp, lockflags,
2636 BO_MTX(bo), "getblk", slpflag, slptimeo);
2637
2638 /*
2639 * If we slept and got the lock we have to restart in case
2640 * the buffer changed identities.
2641 */
2642 if (error == ENOLCK)
2643 goto loop;
2644 /* We timed out or were interrupted. */
2645 else if (error)
2646 return (NULL);
2647
2648 /*
2649 * The buffer is locked. B_CACHE is cleared if the buffer is
2650 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2651 * and for a VMIO buffer B_CACHE is adjusted according to the
2652 * backing VM cache.
2653 */
2654 if (bp->b_flags & B_INVAL)
2655 bp->b_flags &= ~B_CACHE;
2656 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2657 bp->b_flags |= B_CACHE;
2658 BO_LOCK(bo);
2659 bremfree(bp);
2660 BO_UNLOCK(bo);
2661
2662 /*
2663 * check for size inconsistancies for non-VMIO case.
2664 */
2665
2666 if (bp->b_bcount != size) {
2667 if ((bp->b_flags & B_VMIO) == 0 ||
2668 (size > bp->b_kvasize)) {
2669 if (bp->b_flags & B_DELWRI) {
2670 /*
2671 * If buffer is pinned and caller does
2672 * not want sleep waiting for it to be
2673 * unpinned, bail out
2674 * */
2675 if (bp->b_pin_count > 0) {
2676 if (flags & GB_LOCK_NOWAIT) {
2677 bqrelse(bp);
2678 return (NULL);
2679 } else {
2680 bunpin_wait(bp);
2681 }
2682 }
2683 bp->b_flags |= B_NOCACHE;
2684 bwrite(bp);
2685 } else {
2686 if (LIST_EMPTY(&bp->b_dep)) {
2687 bp->b_flags |= B_RELBUF;
2688 brelse(bp);
2689 } else {
2690 bp->b_flags |= B_NOCACHE;
2691 bwrite(bp);
2692 }
2693 }
2694 goto loop;
2695 }
2696 }
2697
2698 /*
2699 * If the size is inconsistant in the VMIO case, we can resize
2700 * the buffer. This might lead to B_CACHE getting set or
2701 * cleared. If the size has not changed, B_CACHE remains
2702 * unchanged from its previous state.
2703 */
2704
2705 if (bp->b_bcount != size)
2706 allocbuf(bp, size);
2707
2708 KASSERT(bp->b_offset != NOOFFSET,
2709 ("getblk: no buffer offset"));
2710
2711 /*
2712 * A buffer with B_DELWRI set and B_CACHE clear must
2713 * be committed before we can return the buffer in
2714 * order to prevent the caller from issuing a read
2715 * ( due to B_CACHE not being set ) and overwriting
2716 * it.
2717 *
2718 * Most callers, including NFS and FFS, need this to
2719 * operate properly either because they assume they
2720 * can issue a read if B_CACHE is not set, or because
2721 * ( for example ) an uncached B_DELWRI might loop due
2722 * to softupdates re-dirtying the buffer. In the latter
2723 * case, B_CACHE is set after the first write completes,
2724 * preventing further loops.
2725 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2726 * above while extending the buffer, we cannot allow the
2727 * buffer to remain with B_CACHE set after the write
2728 * completes or it will represent a corrupt state. To
2729 * deal with this we set B_NOCACHE to scrap the buffer
2730 * after the write.
2731 *
2732 * We might be able to do something fancy, like setting
2733 * B_CACHE in bwrite() except if B_DELWRI is already set,
2734 * so the below call doesn't set B_CACHE, but that gets real
2735 * confusing. This is much easier.
2736 */
2737
2738 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2739 bp->b_flags |= B_NOCACHE;
2740 bwrite(bp);
2741 goto loop;
2742 }
2743 bp->b_flags &= ~B_DONE;
2744 } else {
2745 int bsize, maxsize, vmio;
2746 off_t offset;
2747
2748 /*
2749 * Buffer is not in-core, create new buffer. The buffer
2750 * returned by getnewbuf() is locked. Note that the returned
2751 * buffer is also considered valid (not marked B_INVAL).
2752 */
2753 BO_UNLOCK(bo);
2754 /*
2755 * If the user does not want us to create the buffer, bail out
2756 * here.
2757 */
2758 if (flags & GB_NOCREAT)
2759 return NULL;
2760 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
2761 offset = blkno * bsize;
2762 vmio = vp->v_object != NULL;
2763 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2764 maxsize = imax(maxsize, bsize);
2765
2766 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags);
2767 if (bp == NULL) {
2768 if (slpflag || slptimeo)
2769 return NULL;
2770 goto loop;
2771 }
2772
2773 /*
2774 * This code is used to make sure that a buffer is not
2775 * created while the getnewbuf routine is blocked.
2776 * This can be a problem whether the vnode is locked or not.
2777 * If the buffer is created out from under us, we have to
2778 * throw away the one we just created.
2779 *
2780 * Note: this must occur before we associate the buffer
2781 * with the vp especially considering limitations in
2782 * the splay tree implementation when dealing with duplicate
2783 * lblkno's.
2784 */
2785 BO_LOCK(bo);
2786 if (gbincore(bo, blkno)) {
2787 BO_UNLOCK(bo);
2788 bp->b_flags |= B_INVAL;
2789 brelse(bp);
2790 goto loop;
2791 }
2792
2793 /*
2794 * Insert the buffer into the hash, so that it can
2795 * be found by incore.
2796 */
2797 bp->b_blkno = bp->b_lblkno = blkno;
2798 bp->b_offset = offset;
2799 bgetvp(vp, bp);
2800 BO_UNLOCK(bo);
2801
2802 /*
2803 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2804 * buffer size starts out as 0, B_CACHE will be set by
2805 * allocbuf() for the VMIO case prior to it testing the
2806 * backing store for validity.
2807 */
2808
2809 if (vmio) {
2810 bp->b_flags |= B_VMIO;
2811 #if defined(VFS_BIO_DEBUG)
2812 if (vn_canvmio(vp) != TRUE)
2813 printf("getblk: VMIO on vnode type %d\n",
2814 vp->v_type);
2815 #endif
2816 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
2817 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
2818 bp, vp->v_object, bp->b_bufobj->bo_object));
2819 } else {
2820 bp->b_flags &= ~B_VMIO;
2821 KASSERT(bp->b_bufobj->bo_object == NULL,
2822 ("ARGH! has b_bufobj->bo_object %p %p\n",
2823 bp, bp->b_bufobj->bo_object));
2824 }
2825
2826 allocbuf(bp, size);
2827 bp->b_flags &= ~B_DONE;
2828 }
2829 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
2830 BUF_ASSERT_HELD(bp);
2831 KASSERT(bp->b_bufobj == bo,
2832 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
2833 return (bp);
2834 }
2835
2836 /*
2837 * Get an empty, disassociated buffer of given size. The buffer is initially
2838 * set to B_INVAL.
2839 */
2840 struct buf *
2841 geteblk(int size, int flags)
2842 {
2843 struct buf *bp;
2844 int maxsize;
2845
2846 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2847 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) {
2848 if ((flags & GB_NOWAIT_BD) &&
2849 (curthread->td_pflags & TDP_BUFNEED) != 0)
2850 return (NULL);
2851 }
2852 allocbuf(bp, size);
2853 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2854 BUF_ASSERT_HELD(bp);
2855 return (bp);
2856 }
2857
2858
2859 /*
2860 * This code constitutes the buffer memory from either anonymous system
2861 * memory (in the case of non-VMIO operations) or from an associated
2862 * VM object (in the case of VMIO operations). This code is able to
2863 * resize a buffer up or down.
2864 *
2865 * Note that this code is tricky, and has many complications to resolve
2866 * deadlock or inconsistant data situations. Tread lightly!!!
2867 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2868 * the caller. Calling this code willy nilly can result in the loss of data.
2869 *
2870 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2871 * B_CACHE for the non-VMIO case.
2872 */
2873
2874 int
2875 allocbuf(struct buf *bp, int size)
2876 {
2877 int newbsize, mbsize;
2878 int i;
2879
2880 BUF_ASSERT_HELD(bp);
2881
2882 if (bp->b_kvasize < size)
2883 panic("allocbuf: buffer too small");
2884
2885 if ((bp->b_flags & B_VMIO) == 0) {
2886 caddr_t origbuf;
2887 int origbufsize;
2888 /*
2889 * Just get anonymous memory from the kernel. Don't
2890 * mess with B_CACHE.
2891 */
2892 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2893 if (bp->b_flags & B_MALLOC)
2894 newbsize = mbsize;
2895 else
2896 newbsize = round_page(size);
2897
2898 if (newbsize < bp->b_bufsize) {
2899 /*
2900 * malloced buffers are not shrunk
2901 */
2902 if (bp->b_flags & B_MALLOC) {
2903 if (newbsize) {
2904 bp->b_bcount = size;
2905 } else {
2906 free(bp->b_data, M_BIOBUF);
2907 if (bp->b_bufsize) {
2908 atomic_subtract_long(
2909 &bufmallocspace,
2910 bp->b_bufsize);
2911 bufspacewakeup();
2912 bp->b_bufsize = 0;
2913 }
2914 bp->b_saveaddr = bp->b_kvabase;
2915 bp->b_data = bp->b_saveaddr;
2916 bp->b_bcount = 0;
2917 bp->b_flags &= ~B_MALLOC;
2918 }
2919 return 1;
2920 }
2921 vm_hold_free_pages(bp, newbsize);
2922 } else if (newbsize > bp->b_bufsize) {
2923 /*
2924 * We only use malloced memory on the first allocation.
2925 * and revert to page-allocated memory when the buffer
2926 * grows.
2927 */
2928 /*
2929 * There is a potential smp race here that could lead
2930 * to bufmallocspace slightly passing the max. It
2931 * is probably extremely rare and not worth worrying
2932 * over.
2933 */
2934 if ( (bufmallocspace < maxbufmallocspace) &&
2935 (bp->b_bufsize == 0) &&
2936 (mbsize <= PAGE_SIZE/2)) {
2937
2938 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2939 bp->b_bufsize = mbsize;
2940 bp->b_bcount = size;
2941 bp->b_flags |= B_MALLOC;
2942 atomic_add_long(&bufmallocspace, mbsize);
2943 return 1;
2944 }
2945 origbuf = NULL;
2946 origbufsize = 0;
2947 /*
2948 * If the buffer is growing on its other-than-first allocation,
2949 * then we revert to the page-allocation scheme.
2950 */
2951 if (bp->b_flags & B_MALLOC) {
2952 origbuf = bp->b_data;
2953 origbufsize = bp->b_bufsize;
2954 bp->b_data = bp->b_kvabase;
2955 if (bp->b_bufsize) {
2956 atomic_subtract_long(&bufmallocspace,
2957 bp->b_bufsize);
2958 bufspacewakeup();
2959 bp->b_bufsize = 0;
2960 }
2961 bp->b_flags &= ~B_MALLOC;
2962 newbsize = round_page(newbsize);
2963 }
2964 vm_hold_load_pages(
2965 bp,
2966 (vm_offset_t) bp->b_data + bp->b_bufsize,
2967 (vm_offset_t) bp->b_data + newbsize);
2968 if (origbuf) {
2969 bcopy(origbuf, bp->b_data, origbufsize);
2970 free(origbuf, M_BIOBUF);
2971 }
2972 }
2973 } else {
2974 int desiredpages;
2975
2976 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2977 desiredpages = (size == 0) ? 0 :
2978 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2979
2980 if (bp->b_flags & B_MALLOC)
2981 panic("allocbuf: VMIO buffer can't be malloced");
2982 /*
2983 * Set B_CACHE initially if buffer is 0 length or will become
2984 * 0-length.
2985 */
2986 if (size == 0 || bp->b_bufsize == 0)
2987 bp->b_flags |= B_CACHE;
2988
2989 if (newbsize < bp->b_bufsize) {
2990 /*
2991 * DEV_BSIZE aligned new buffer size is less then the
2992 * DEV_BSIZE aligned existing buffer size. Figure out
2993 * if we have to remove any pages.
2994 */
2995 if (desiredpages < bp->b_npages) {
2996 vm_page_t m;
2997
2998 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2999 vm_page_lock_queues();
3000 for (i = desiredpages; i < bp->b_npages; i++) {
3001 /*
3002 * the page is not freed here -- it
3003 * is the responsibility of
3004 * vnode_pager_setsize
3005 */
3006 m = bp->b_pages[i];
3007 KASSERT(m != bogus_page,
3008 ("allocbuf: bogus page found"));
3009 while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
3010 vm_page_lock_queues();
3011
3012 bp->b_pages[i] = NULL;
3013 vm_page_unwire(m, 0);
3014 }
3015 vm_page_unlock_queues();
3016 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3017 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
3018 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
3019 bp->b_npages = desiredpages;
3020 }
3021 } else if (size > bp->b_bcount) {
3022 /*
3023 * We are growing the buffer, possibly in a
3024 * byte-granular fashion.
3025 */
3026 vm_object_t obj;
3027 vm_offset_t toff;
3028 vm_offset_t tinc;
3029
3030 /*
3031 * Step 1, bring in the VM pages from the object,
3032 * allocating them if necessary. We must clear
3033 * B_CACHE if these pages are not valid for the
3034 * range covered by the buffer.
3035 */
3036
3037 obj = bp->b_bufobj->bo_object;
3038
3039 VM_OBJECT_LOCK(obj);
3040 while (bp->b_npages < desiredpages) {
3041 vm_page_t m;
3042 vm_pindex_t pi;
3043
3044 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
3045 if ((m = vm_page_lookup(obj, pi)) == NULL) {
3046 /*
3047 * note: must allocate system pages
3048 * since blocking here could intefere
3049 * with paging I/O, no matter which
3050 * process we are.
3051 */
3052 m = vm_page_alloc(obj, pi,
3053 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
3054 VM_ALLOC_WIRED);
3055 if (m == NULL) {
3056 atomic_add_int(&vm_pageout_deficit,
3057 desiredpages - bp->b_npages);
3058 VM_OBJECT_UNLOCK(obj);
3059 VM_WAIT;
3060 VM_OBJECT_LOCK(obj);
3061 } else {
3062 if (m->valid == 0)
3063 bp->b_flags &= ~B_CACHE;
3064 bp->b_pages[bp->b_npages] = m;
3065 ++bp->b_npages;
3066 }
3067 continue;
3068 }
3069
3070 /*
3071 * We found a page. If we have to sleep on it,
3072 * retry because it might have gotten freed out
3073 * from under us.
3074 *
3075 * We can only test VPO_BUSY here. Blocking on
3076 * m->busy might lead to a deadlock:
3077 *
3078 * vm_fault->getpages->cluster_read->allocbuf
3079 *
3080 */
3081 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
3082 continue;
3083
3084 /*
3085 * We have a good page.
3086 */
3087 vm_page_lock_queues();
3088 vm_page_wire(m);
3089 vm_page_unlock_queues();
3090 bp->b_pages[bp->b_npages] = m;
3091 ++bp->b_npages;
3092 }
3093
3094 /*
3095 * Step 2. We've loaded the pages into the buffer,
3096 * we have to figure out if we can still have B_CACHE
3097 * set. Note that B_CACHE is set according to the
3098 * byte-granular range ( bcount and size ), new the
3099 * aligned range ( newbsize ).
3100 *
3101 * The VM test is against m->valid, which is DEV_BSIZE
3102 * aligned. Needless to say, the validity of the data
3103 * needs to also be DEV_BSIZE aligned. Note that this
3104 * fails with NFS if the server or some other client
3105 * extends the file's EOF. If our buffer is resized,
3106 * B_CACHE may remain set! XXX
3107 */
3108
3109 toff = bp->b_bcount;
3110 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3111
3112 while ((bp->b_flags & B_CACHE) && toff < size) {
3113 vm_pindex_t pi;
3114
3115 if (tinc > (size - toff))
3116 tinc = size - toff;
3117
3118 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
3119 PAGE_SHIFT;
3120
3121 vfs_buf_test_cache(
3122 bp,
3123 bp->b_offset,
3124 toff,
3125 tinc,
3126 bp->b_pages[pi]
3127 );
3128 toff += tinc;
3129 tinc = PAGE_SIZE;
3130 }
3131 VM_OBJECT_UNLOCK(obj);
3132
3133 /*
3134 * Step 3, fixup the KVM pmap. Remember that
3135 * bp->b_data is relative to bp->b_offset, but
3136 * bp->b_offset may be offset into the first page.
3137 */
3138
3139 bp->b_data = (caddr_t)
3140 trunc_page((vm_offset_t)bp->b_data);
3141 pmap_qenter(
3142 (vm_offset_t)bp->b_data,
3143 bp->b_pages,
3144 bp->b_npages
3145 );
3146
3147 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
3148 (vm_offset_t)(bp->b_offset & PAGE_MASK));
3149 }
3150 }
3151 if (newbsize < bp->b_bufsize)
3152 bufspacewakeup();
3153 bp->b_bufsize = newbsize; /* actual buffer allocation */
3154 bp->b_bcount = size; /* requested buffer size */
3155 return 1;
3156 }
3157
3158 void
3159 biodone(struct bio *bp)
3160 {
3161 struct mtx *mtxp;
3162 void (*done)(struct bio *);
3163
3164 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3165 mtx_lock(mtxp);
3166 bp->bio_flags |= BIO_DONE;
3167 done = bp->bio_done;
3168 if (done == NULL)
3169 wakeup(bp);
3170 mtx_unlock(mtxp);
3171 if (done != NULL)
3172 done(bp);
3173 }
3174
3175 /*
3176 * Wait for a BIO to finish.
3177 *
3178 * XXX: resort to a timeout for now. The optimal locking (if any) for this
3179 * case is not yet clear.
3180 */
3181 int
3182 biowait(struct bio *bp, const char *wchan)
3183 {
3184 struct mtx *mtxp;
3185
3186 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3187 mtx_lock(mtxp);
3188 while ((bp->bio_flags & BIO_DONE) == 0)
3189 msleep(bp, mtxp, PRIBIO, wchan, hz / 10);
3190 mtx_unlock(mtxp);
3191 if (bp->bio_error != 0)
3192 return (bp->bio_error);
3193 if (!(bp->bio_flags & BIO_ERROR))
3194 return (0);
3195 return (EIO);
3196 }
3197
3198 void
3199 biofinish(struct bio *bp, struct devstat *stat, int error)
3200 {
3201
3202 if (error) {
3203 bp->bio_error = error;
3204 bp->bio_flags |= BIO_ERROR;
3205 }
3206 if (stat != NULL)
3207 devstat_end_transaction_bio(stat, bp);
3208 biodone(bp);
3209 }
3210
3211 /*
3212 * bufwait:
3213 *
3214 * Wait for buffer I/O completion, returning error status. The buffer
3215 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3216 * error and cleared.
3217 */
3218 int
3219 bufwait(struct buf *bp)
3220 {
3221 if (bp->b_iocmd == BIO_READ)
3222 bwait(bp, PRIBIO, "biord");
3223 else
3224 bwait(bp, PRIBIO, "biowr");
3225 if (bp->b_flags & B_EINTR) {
3226 bp->b_flags &= ~B_EINTR;
3227 return (EINTR);
3228 }
3229 if (bp->b_ioflags & BIO_ERROR) {
3230 return (bp->b_error ? bp->b_error : EIO);
3231 } else {
3232 return (0);
3233 }
3234 }
3235
3236 /*
3237 * Call back function from struct bio back up to struct buf.
3238 */
3239 static void
3240 bufdonebio(struct bio *bip)
3241 {
3242 struct buf *bp;
3243
3244 bp = bip->bio_caller2;
3245 bp->b_resid = bp->b_bcount - bip->bio_completed;
3246 bp->b_resid = bip->bio_resid; /* XXX: remove */
3247 bp->b_ioflags = bip->bio_flags;
3248 bp->b_error = bip->bio_error;
3249 if (bp->b_error)
3250 bp->b_ioflags |= BIO_ERROR;
3251 bufdone(bp);
3252 g_destroy_bio(bip);
3253 }
3254
3255 void
3256 dev_strategy(struct cdev *dev, struct buf *bp)
3257 {
3258 struct cdevsw *csw;
3259 struct bio *bip;
3260 int ref;
3261
3262 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
3263 panic("b_iocmd botch");
3264 for (;;) {
3265 bip = g_new_bio();
3266 if (bip != NULL)
3267 break;
3268 /* Try again later */
3269 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3270 }
3271 bip->bio_cmd = bp->b_iocmd;
3272 bip->bio_offset = bp->b_iooffset;
3273 bip->bio_length = bp->b_bcount;
3274 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3275 bip->bio_data = bp->b_data;
3276 bip->bio_done = bufdonebio;
3277 bip->bio_caller2 = bp;
3278 bip->bio_dev = dev;
3279 KASSERT(dev->si_refcount > 0,
3280 ("dev_strategy on un-referenced struct cdev *(%s)",
3281 devtoname(dev)));
3282 csw = dev_refthread(dev, &ref);
3283 if (csw == NULL) {
3284 g_destroy_bio(bip);
3285 bp->b_error = ENXIO;
3286 bp->b_ioflags = BIO_ERROR;
3287 bufdone(bp);
3288 return;
3289 }
3290 (*csw->d_strategy)(bip);
3291 dev_relthread(dev, ref);
3292 }
3293
3294 /*
3295 * bufdone:
3296 *
3297 * Finish I/O on a buffer, optionally calling a completion function.
3298 * This is usually called from an interrupt so process blocking is
3299 * not allowed.
3300 *
3301 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3302 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3303 * assuming B_INVAL is clear.
3304 *
3305 * For the VMIO case, we set B_CACHE if the op was a read and no
3306 * read error occured, or if the op was a write. B_CACHE is never
3307 * set if the buffer is invalid or otherwise uncacheable.
3308 *
3309 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3310 * initiator to leave B_INVAL set to brelse the buffer out of existance
3311 * in the biodone routine.
3312 */
3313 void
3314 bufdone(struct buf *bp)
3315 {
3316 struct bufobj *dropobj;
3317 void (*biodone)(struct buf *);
3318
3319 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3320 dropobj = NULL;
3321
3322 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3323 BUF_ASSERT_HELD(bp);
3324
3325 runningbufwakeup(bp);
3326 if (bp->b_iocmd == BIO_WRITE)
3327 dropobj = bp->b_bufobj;
3328 /* call optional completion function if requested */
3329 if (bp->b_iodone != NULL) {
3330 biodone = bp->b_iodone;
3331 bp->b_iodone = NULL;
3332 (*biodone) (bp);
3333 if (dropobj)
3334 bufobj_wdrop(dropobj);
3335 return;
3336 }
3337
3338 bufdone_finish(bp);
3339
3340 if (dropobj)
3341 bufobj_wdrop(dropobj);
3342 }
3343
3344 void
3345 bufdone_finish(struct buf *bp)
3346 {
3347 BUF_ASSERT_HELD(bp);
3348
3349 if (!LIST_EMPTY(&bp->b_dep))
3350 buf_complete(bp);
3351
3352 if (bp->b_flags & B_VMIO) {
3353 int i;
3354 vm_ooffset_t foff;
3355 vm_page_t m;
3356 vm_object_t obj;
3357 int bogus, iosize;
3358 struct vnode *vp = bp->b_vp;
3359
3360 obj = bp->b_bufobj->bo_object;
3361
3362 #if defined(VFS_BIO_DEBUG)
3363 mp_fixme("usecount and vflag accessed without locks.");
3364 if (vp->v_usecount == 0) {
3365 panic("biodone: zero vnode ref count");
3366 }
3367
3368 KASSERT(vp->v_object != NULL,
3369 ("biodone: vnode %p has no vm_object", vp));
3370 #endif
3371
3372 foff = bp->b_offset;
3373 KASSERT(bp->b_offset != NOOFFSET,
3374 ("biodone: no buffer offset"));
3375
3376 VM_OBJECT_LOCK(obj);
3377 #if defined(VFS_BIO_DEBUG)
3378 if (obj->paging_in_progress < bp->b_npages) {
3379 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
3380 obj->paging_in_progress, bp->b_npages);
3381 }
3382 #endif
3383
3384 /*
3385 * Set B_CACHE if the op was a normal read and no error
3386 * occured. B_CACHE is set for writes in the b*write()
3387 * routines.
3388 */
3389 iosize = bp->b_bcount - bp->b_resid;
3390 if (bp->b_iocmd == BIO_READ &&
3391 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3392 !(bp->b_ioflags & BIO_ERROR)) {
3393 bp->b_flags |= B_CACHE;
3394 }
3395 bogus = 0;
3396 for (i = 0; i < bp->b_npages; i++) {
3397 int bogusflag = 0;
3398 int resid;
3399
3400 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3401 if (resid > iosize)
3402 resid = iosize;
3403
3404 /*
3405 * cleanup bogus pages, restoring the originals
3406 */
3407 m = bp->b_pages[i];
3408 if (m == bogus_page) {
3409 bogus = bogusflag = 1;
3410 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3411 if (m == NULL)
3412 panic("biodone: page disappeared!");
3413 bp->b_pages[i] = m;
3414 }
3415 #if defined(VFS_BIO_DEBUG)
3416 if (OFF_TO_IDX(foff) != m->pindex) {
3417 printf(
3418 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
3419 (intmax_t)foff, (uintmax_t)m->pindex);
3420 }
3421 #endif
3422
3423 /*
3424 * In the write case, the valid and clean bits are
3425 * already changed correctly ( see bdwrite() ), so we
3426 * only need to do this here in the read case.
3427 */
3428 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3429 KASSERT((m->dirty & vm_page_bits(foff &
3430 PAGE_MASK, resid)) == 0, ("bufdone_finish:"
3431 " page %p has unexpected dirty bits", m));
3432 vfs_page_set_valid(bp, foff, m);
3433 }
3434
3435 /*
3436 * when debugging new filesystems or buffer I/O methods, this
3437 * is the most common error that pops up. if you see this, you
3438 * have not set the page busy flag correctly!!!
3439 */
3440 if (m->busy == 0) {
3441 printf("biodone: page busy < 0, "
3442 "pindex: %d, foff: 0x(%x,%x), "
3443 "resid: %d, index: %d\n",
3444 (int) m->pindex, (int)(foff >> 32),
3445 (int) foff & 0xffffffff, resid, i);
3446 if (!vn_isdisk(vp, NULL))
3447 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
3448 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
3449 (intmax_t) bp->b_lblkno,
3450 bp->b_flags, bp->b_npages);
3451 else
3452 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
3453 (intmax_t) bp->b_lblkno,
3454 bp->b_flags, bp->b_npages);
3455 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
3456 (u_long)m->valid, (u_long)m->dirty,
3457 m->wire_count);
3458 panic("biodone: page busy < 0\n");
3459 }
3460 vm_page_io_finish(m);
3461 vm_object_pip_subtract(obj, 1);
3462 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3463 iosize -= resid;
3464 }
3465 vm_object_pip_wakeupn(obj, 0);
3466 VM_OBJECT_UNLOCK(obj);
3467 if (bogus)
3468 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3469 bp->b_pages, bp->b_npages);
3470 }
3471
3472 /*
3473 * For asynchronous completions, release the buffer now. The brelse
3474 * will do a wakeup there if necessary - so no need to do a wakeup
3475 * here in the async case. The sync case always needs to do a wakeup.
3476 */
3477
3478 if (bp->b_flags & B_ASYNC) {
3479 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3480 brelse(bp);
3481 else
3482 bqrelse(bp);
3483 } else
3484 bdone(bp);
3485 }
3486
3487 /*
3488 * This routine is called in lieu of iodone in the case of
3489 * incomplete I/O. This keeps the busy status for pages
3490 * consistant.
3491 */
3492 void
3493 vfs_unbusy_pages(struct buf *bp)
3494 {
3495 int i;
3496 vm_object_t obj;
3497 vm_page_t m;
3498
3499 runningbufwakeup(bp);
3500 if (!(bp->b_flags & B_VMIO))
3501 return;
3502
3503 obj = bp->b_bufobj->bo_object;
3504 VM_OBJECT_LOCK(obj);
3505 for (i = 0; i < bp->b_npages; i++) {
3506 m = bp->b_pages[i];
3507 if (m == bogus_page) {
3508 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3509 if (!m)
3510 panic("vfs_unbusy_pages: page missing\n");
3511 bp->b_pages[i] = m;
3512 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3513 bp->b_pages, bp->b_npages);
3514 }
3515 vm_object_pip_subtract(obj, 1);
3516 vm_page_io_finish(m);
3517 }
3518 vm_object_pip_wakeupn(obj, 0);
3519 VM_OBJECT_UNLOCK(obj);
3520 }
3521
3522 /*
3523 * vfs_page_set_valid:
3524 *
3525 * Set the valid bits in a page based on the supplied offset. The
3526 * range is restricted to the buffer's size.
3527 *
3528 * This routine is typically called after a read completes.
3529 */
3530 static void
3531 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3532 {
3533 vm_ooffset_t eoff;
3534
3535 /*
3536 * Compute the end offset, eoff, such that [off, eoff) does not span a
3537 * page boundary and eoff is not greater than the end of the buffer.
3538 * The end of the buffer, in this case, is our file EOF, not the
3539 * allocation size of the buffer.
3540 */
3541 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
3542 if (eoff > bp->b_offset + bp->b_bcount)
3543 eoff = bp->b_offset + bp->b_bcount;
3544
3545 /*
3546 * Set valid range. This is typically the entire buffer and thus the
3547 * entire page.
3548 */
3549 if (eoff > off)
3550 vm_page_set_valid(m, off & PAGE_MASK, eoff - off);
3551 }
3552
3553 /*
3554 * vfs_page_set_validclean:
3555 *
3556 * Set the valid bits and clear the dirty bits in a page based on the
3557 * supplied offset. The range is restricted to the buffer's size.
3558 */
3559 static void
3560 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3561 {
3562 vm_ooffset_t soff, eoff;
3563
3564 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
3565 /*
3566 * Start and end offsets in buffer. eoff - soff may not cross a
3567 * page boundry or cross the end of the buffer. The end of the
3568 * buffer, in this case, is our file EOF, not the allocation size
3569 * of the buffer.
3570 */
3571 soff = off;
3572 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3573 if (eoff > bp->b_offset + bp->b_bcount)
3574 eoff = bp->b_offset + bp->b_bcount;
3575
3576 /*
3577 * Set valid range. This is typically the entire buffer and thus the
3578 * entire page.
3579 */
3580 if (eoff > soff) {
3581 vm_page_set_validclean(
3582 m,
3583 (vm_offset_t) (soff & PAGE_MASK),
3584 (vm_offset_t) (eoff - soff)
3585 );
3586 }
3587 }
3588
3589 /*
3590 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If
3591 * any page is busy, drain the flag.
3592 */
3593 static void
3594 vfs_drain_busy_pages(struct buf *bp)
3595 {
3596 vm_page_t m;
3597 int i, last_busied;
3598
3599 VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED);
3600 last_busied = 0;
3601 for (i = 0; i < bp->b_npages; i++) {
3602 m = bp->b_pages[i];
3603 if ((m->oflags & VPO_BUSY) != 0) {
3604 for (; last_busied < i; last_busied++)
3605 vm_page_busy(bp->b_pages[last_busied]);
3606 while ((m->oflags & VPO_BUSY) != 0)
3607 vm_page_sleep(m, "vbpage");
3608 }
3609 }
3610 for (i = 0; i < last_busied; i++)
3611 vm_page_wakeup(bp->b_pages[i]);
3612 }
3613
3614 /*
3615 * This routine is called before a device strategy routine.
3616 * It is used to tell the VM system that paging I/O is in
3617 * progress, and treat the pages associated with the buffer
3618 * almost as being VPO_BUSY. Also the object paging_in_progress
3619 * flag is handled to make sure that the object doesn't become
3620 * inconsistant.
3621 *
3622 * Since I/O has not been initiated yet, certain buffer flags
3623 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3624 * and should be ignored.
3625 */
3626 void
3627 vfs_busy_pages(struct buf *bp, int clear_modify)
3628 {
3629 int i, bogus;
3630 vm_object_t obj;
3631 vm_ooffset_t foff;
3632 vm_page_t m;
3633
3634 if (!(bp->b_flags & B_VMIO))
3635 return;
3636
3637 obj = bp->b_bufobj->bo_object;
3638 foff = bp->b_offset;
3639 KASSERT(bp->b_offset != NOOFFSET,
3640 ("vfs_busy_pages: no buffer offset"));
3641 VM_OBJECT_LOCK(obj);
3642 vfs_drain_busy_pages(bp);
3643 if (bp->b_bufsize != 0)
3644 vfs_setdirty_locked_object(bp);
3645 bogus = 0;
3646 if (clear_modify)
3647 vm_page_lock_queues();
3648 for (i = 0; i < bp->b_npages; i++) {
3649 m = bp->b_pages[i];
3650
3651 if ((bp->b_flags & B_CLUSTER) == 0) {
3652 vm_object_pip_add(obj, 1);
3653 vm_page_io_start(m);
3654 }
3655 /*
3656 * When readying a buffer for a read ( i.e
3657 * clear_modify == 0 ), it is important to do
3658 * bogus_page replacement for valid pages in
3659 * partially instantiated buffers. Partially
3660 * instantiated buffers can, in turn, occur when
3661 * reconstituting a buffer from its VM backing store
3662 * base. We only have to do this if B_CACHE is
3663 * clear ( which causes the I/O to occur in the
3664 * first place ). The replacement prevents the read
3665 * I/O from overwriting potentially dirty VM-backed
3666 * pages. XXX bogus page replacement is, uh, bogus.
3667 * It may not work properly with small-block devices.
3668 * We need to find a better way.
3669 */
3670 if (clear_modify) {
3671 pmap_remove_write(m);
3672 vfs_page_set_validclean(bp, foff, m);
3673 } else if (m->valid == VM_PAGE_BITS_ALL &&
3674 (bp->b_flags & B_CACHE) == 0) {
3675 bp->b_pages[i] = bogus_page;
3676 bogus++;
3677 }
3678 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3679 }
3680 if (clear_modify)
3681 vm_page_unlock_queues();
3682 VM_OBJECT_UNLOCK(obj);
3683 if (bogus)
3684 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3685 bp->b_pages, bp->b_npages);
3686 }
3687
3688 /*
3689 * vfs_bio_set_valid:
3690 *
3691 * Set the range within the buffer to valid. The range is
3692 * relative to the beginning of the buffer, b_offset. Note that
3693 * b_offset itself may be offset from the beginning of the first
3694 * page.
3695 */
3696 void
3697 vfs_bio_set_valid(struct buf *bp, int base, int size)
3698 {
3699 int i, n;
3700 vm_page_t m;
3701
3702 if (!(bp->b_flags & B_VMIO))
3703 return;
3704
3705 /*
3706 * Fixup base to be relative to beginning of first page.
3707 * Set initial n to be the maximum number of bytes in the
3708 * first page that can be validated.
3709 */
3710 base += (bp->b_offset & PAGE_MASK);
3711 n = PAGE_SIZE - (base & PAGE_MASK);
3712
3713 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3714 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3715 m = bp->b_pages[i];
3716 if (n > size)
3717 n = size;
3718 vm_page_set_valid(m, base & PAGE_MASK, n);
3719 base += n;
3720 size -= n;
3721 n = PAGE_SIZE;
3722 }
3723 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3724 }
3725
3726 /*
3727 * vfs_bio_clrbuf:
3728 *
3729 * If the specified buffer is a non-VMIO buffer, clear the entire
3730 * buffer. If the specified buffer is a VMIO buffer, clear and
3731 * validate only the previously invalid portions of the buffer.
3732 * This routine essentially fakes an I/O, so we need to clear
3733 * BIO_ERROR and B_INVAL.
3734 *
3735 * Note that while we only theoretically need to clear through b_bcount,
3736 * we go ahead and clear through b_bufsize.
3737 */
3738 void
3739 vfs_bio_clrbuf(struct buf *bp)
3740 {
3741 int i, j, mask;
3742 caddr_t sa, ea;
3743
3744 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
3745 clrbuf(bp);
3746 return;
3747 }
3748 bp->b_flags &= ~B_INVAL;
3749 bp->b_ioflags &= ~BIO_ERROR;
3750 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3751 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3752 (bp->b_offset & PAGE_MASK) == 0) {
3753 if (bp->b_pages[0] == bogus_page)
3754 goto unlock;
3755 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3756 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3757 if ((bp->b_pages[0]->valid & mask) == mask)
3758 goto unlock;
3759 if ((bp->b_pages[0]->valid & mask) == 0) {
3760 bzero(bp->b_data, bp->b_bufsize);
3761 bp->b_pages[0]->valid |= mask;
3762 goto unlock;
3763 }
3764 }
3765 ea = sa = bp->b_data;
3766 for(i = 0; i < bp->b_npages; i++, sa = ea) {
3767 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3768 ea = (caddr_t)(vm_offset_t)ulmin(
3769 (u_long)(vm_offset_t)ea,
3770 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3771 if (bp->b_pages[i] == bogus_page)
3772 continue;
3773 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3774 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3775 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3776 if ((bp->b_pages[i]->valid & mask) == mask)
3777 continue;
3778 if ((bp->b_pages[i]->valid & mask) == 0)
3779 bzero(sa, ea - sa);
3780 else {
3781 for (; sa < ea; sa += DEV_BSIZE, j++) {
3782 if ((bp->b_pages[i]->valid & (1 << j)) == 0)
3783 bzero(sa, DEV_BSIZE);
3784 }
3785 }
3786 bp->b_pages[i]->valid |= mask;
3787 }
3788 unlock:
3789 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3790 bp->b_resid = 0;
3791 }
3792
3793 /*
3794 * vm_hold_load_pages and vm_hold_free_pages get pages into
3795 * a buffers address space. The pages are anonymous and are
3796 * not associated with a file object.
3797 */
3798 static void
3799 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3800 {
3801 vm_offset_t pg;
3802 vm_page_t p;
3803 int index;
3804
3805 to = round_page(to);
3806 from = round_page(from);
3807 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3808
3809 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3810 tryagain:
3811 /*
3812 * note: must allocate system pages since blocking here
3813 * could interfere with paging I/O, no matter which
3814 * process we are.
3815 */
3816 p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ |
3817 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
3818 if (!p) {
3819 atomic_add_int(&vm_pageout_deficit,
3820 (to - pg) >> PAGE_SHIFT);
3821 VM_WAIT;
3822 goto tryagain;
3823 }
3824 pmap_qenter(pg, &p, 1);
3825 bp->b_pages[index] = p;
3826 }
3827 bp->b_npages = index;
3828 }
3829
3830 /* Return pages associated with this buf to the vm system */
3831 static void
3832 vm_hold_free_pages(struct buf *bp, int newbsize)
3833 {
3834 vm_offset_t from;
3835 vm_page_t p;
3836 int index, newnpages;
3837
3838 from = round_page((vm_offset_t)bp->b_data + newbsize);
3839 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3840 if (bp->b_npages > newnpages)
3841 pmap_qremove(from, bp->b_npages - newnpages);
3842 for (index = newnpages; index < bp->b_npages; index++) {
3843 p = bp->b_pages[index];
3844 bp->b_pages[index] = NULL;
3845 if (p->busy != 0)
3846 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3847 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
3848 p->wire_count--;
3849 vm_page_free(p);
3850 atomic_subtract_int(&cnt.v_wire_count, 1);
3851 }
3852 bp->b_npages = newnpages;
3853 }
3854
3855 /*
3856 * Map an IO request into kernel virtual address space.
3857 *
3858 * All requests are (re)mapped into kernel VA space.
3859 * Notice that we use b_bufsize for the size of the buffer
3860 * to be mapped. b_bcount might be modified by the driver.
3861 *
3862 * Note that even if the caller determines that the address space should
3863 * be valid, a race or a smaller-file mapped into a larger space may
3864 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3865 * check the return value.
3866 */
3867 int
3868 vmapbuf(struct buf *bp)
3869 {
3870 caddr_t addr, kva;
3871 vm_prot_t prot;
3872 int pidx, i;
3873 struct vm_page *m;
3874 struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
3875
3876 if (bp->b_bufsize < 0)
3877 return (-1);
3878 prot = VM_PROT_READ;
3879 if (bp->b_iocmd == BIO_READ)
3880 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
3881 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
3882 addr < bp->b_data + bp->b_bufsize;
3883 addr += PAGE_SIZE, pidx++) {
3884 /*
3885 * Do the vm_fault if needed; do the copy-on-write thing
3886 * when reading stuff off device into memory.
3887 *
3888 * NOTE! Must use pmap_extract() because addr may be in
3889 * the userland address space, and kextract is only guarenteed
3890 * to work for the kernland address space (see: sparc64 port).
3891 */
3892 retry:
3893 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
3894 prot) < 0) {
3895 vm_page_lock_queues();
3896 for (i = 0; i < pidx; ++i) {
3897 vm_page_unhold(bp->b_pages[i]);
3898 bp->b_pages[i] = NULL;
3899 }
3900 vm_page_unlock_queues();
3901 return(-1);
3902 }
3903 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
3904 if (m == NULL)
3905 goto retry;
3906 bp->b_pages[pidx] = m;
3907 }
3908 if (pidx > btoc(MAXPHYS))
3909 panic("vmapbuf: mapped more than MAXPHYS");
3910 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3911
3912 kva = bp->b_saveaddr;
3913 bp->b_npages = pidx;
3914 bp->b_saveaddr = bp->b_data;
3915 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3916 return(0);
3917 }
3918
3919 /*
3920 * Free the io map PTEs associated with this IO operation.
3921 * We also invalidate the TLB entries and restore the original b_addr.
3922 */
3923 void
3924 vunmapbuf(struct buf *bp)
3925 {
3926 int pidx;
3927 int npages;
3928
3929 npages = bp->b_npages;
3930 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
3931 vm_page_lock_queues();
3932 for (pidx = 0; pidx < npages; pidx++)
3933 vm_page_unhold(bp->b_pages[pidx]);
3934 vm_page_unlock_queues();
3935
3936 bp->b_data = bp->b_saveaddr;
3937 }
3938
3939 void
3940 bdone(struct buf *bp)
3941 {
3942 struct mtx *mtxp;
3943
3944 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3945 mtx_lock(mtxp);
3946 bp->b_flags |= B_DONE;
3947 wakeup(bp);
3948 mtx_unlock(mtxp);
3949 }
3950
3951 void
3952 bwait(struct buf *bp, u_char pri, const char *wchan)
3953 {
3954 struct mtx *mtxp;
3955
3956 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3957 mtx_lock(mtxp);
3958 while ((bp->b_flags & B_DONE) == 0)
3959 msleep(bp, mtxp, pri, wchan, 0);
3960 mtx_unlock(mtxp);
3961 }
3962
3963 int
3964 bufsync(struct bufobj *bo, int waitfor)
3965 {
3966
3967 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
3968 }
3969
3970 void
3971 bufstrategy(struct bufobj *bo, struct buf *bp)
3972 {
3973 int i = 0;
3974 struct vnode *vp;
3975
3976 vp = bp->b_vp;
3977 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
3978 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
3979 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
3980 i = VOP_STRATEGY(vp, bp);
3981 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
3982 }
3983
3984 void
3985 bufobj_wrefl(struct bufobj *bo)
3986 {
3987
3988 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3989 ASSERT_BO_LOCKED(bo);
3990 bo->bo_numoutput++;
3991 }
3992
3993 void
3994 bufobj_wref(struct bufobj *bo)
3995 {
3996
3997 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3998 BO_LOCK(bo);
3999 bo->bo_numoutput++;
4000 BO_UNLOCK(bo);
4001 }
4002
4003 void
4004 bufobj_wdrop(struct bufobj *bo)
4005 {
4006
4007 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
4008 BO_LOCK(bo);
4009 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
4010 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
4011 bo->bo_flag &= ~BO_WWAIT;
4012 wakeup(&bo->bo_numoutput);
4013 }
4014 BO_UNLOCK(bo);
4015 }
4016
4017 int
4018 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
4019 {
4020 int error;
4021
4022 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
4023 ASSERT_BO_LOCKED(bo);
4024 error = 0;
4025 while (bo->bo_numoutput) {
4026 bo->bo_flag |= BO_WWAIT;
4027 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
4028 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
4029 if (error)
4030 break;
4031 }
4032 return (error);
4033 }
4034
4035 void
4036 bpin(struct buf *bp)
4037 {
4038 struct mtx *mtxp;
4039
4040 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4041 mtx_lock(mtxp);
4042 bp->b_pin_count++;
4043 mtx_unlock(mtxp);
4044 }
4045
4046 void
4047 bunpin(struct buf *bp)
4048 {
4049 struct mtx *mtxp;
4050
4051 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4052 mtx_lock(mtxp);
4053 if (--bp->b_pin_count == 0)
4054 wakeup(bp);
4055 mtx_unlock(mtxp);
4056 }
4057
4058 void
4059 bunpin_wait(struct buf *bp)
4060 {
4061 struct mtx *mtxp;
4062
4063 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4064 mtx_lock(mtxp);
4065 while (bp->b_pin_count > 0)
4066 msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
4067 mtx_unlock(mtxp);
4068 }
4069
4070 #include "opt_ddb.h"
4071 #ifdef DDB
4072 #include <ddb/ddb.h>
4073
4074 /* DDB command to show buffer data */
4075 DB_SHOW_COMMAND(buffer, db_show_buffer)
4076 {
4077 /* get args */
4078 struct buf *bp = (struct buf *)addr;
4079
4080 if (!have_addr) {
4081 db_printf("usage: show buffer <addr>\n");
4082 return;
4083 }
4084
4085 db_printf("buf at %p\n", bp);
4086 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
4087 db_printf(
4088 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
4089 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_dep = %p\n",
4090 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4091 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4092 bp->b_dep.lh_first);
4093 if (bp->b_npages) {
4094 int i;
4095 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4096 for (i = 0; i < bp->b_npages; i++) {
4097 vm_page_t m;
4098 m = bp->b_pages[i];
4099 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4100 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4101 if ((i + 1) < bp->b_npages)
4102 db_printf(",");
4103 }
4104 db_printf("\n");
4105 }
4106 db_printf(" ");
4107 lockmgr_printinfo(&bp->b_lock);
4108 }
4109
4110 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4111 {
4112 struct buf *bp;
4113 int i;
4114
4115 for (i = 0; i < nbuf; i++) {
4116 bp = &buf[i];
4117 if (BUF_ISLOCKED(bp)) {
4118 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4119 db_printf("\n");
4120 }
4121 }
4122 }
4123
4124 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
4125 {
4126 struct vnode *vp;
4127 struct buf *bp;
4128
4129 if (!have_addr) {
4130 db_printf("usage: show vnodebufs <addr>\n");
4131 return;
4132 }
4133 vp = (struct vnode *)addr;
4134 db_printf("Clean buffers:\n");
4135 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
4136 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4137 db_printf("\n");
4138 }
4139 db_printf("Dirty buffers:\n");
4140 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
4141 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4142 db_printf("\n");
4143 }
4144 }
4145
4146 DB_COMMAND(countfreebufs, db_coundfreebufs)
4147 {
4148 struct buf *bp;
4149 int i, used = 0, nfree = 0;
4150
4151 if (have_addr) {
4152 db_printf("usage: countfreebufs\n");
4153 return;
4154 }
4155
4156 for (i = 0; i < nbuf; i++) {
4157 bp = &buf[i];
4158 if ((bp->b_vflags & BV_INFREECNT) != 0)
4159 nfree++;
4160 else
4161 used++;
4162 }
4163
4164 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
4165 nfree + used);
4166 db_printf("numfreebuffers is %d\n", numfreebuffers);
4167 }
4168 #endif /* DDB */
Cache object: 4388b61e9b3777da1719095de96ae94f
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