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: head/sys/kern/vfs_bio.c 232351 2012-03-01 18:45:25Z mckusick $");
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/bio.h>
47 #include <sys/conf.h>
48 #include <sys/buf.h>
49 #include <sys/devicestat.h>
50 #include <sys/eventhandler.h>
51 #include <sys/fail.h>
52 #include <sys/limits.h>
53 #include <sys/lock.h>
54 #include <sys/malloc.h>
55 #include <sys/mount.h>
56 #include <sys/mutex.h>
57 #include <sys/kernel.h>
58 #include <sys/kthread.h>
59 #include <sys/proc.h>
60 #include <sys/resourcevar.h>
61 #include <sys/sysctl.h>
62 #include <sys/vmmeter.h>
63 #include <sys/vnode.h>
64 #include <geom/geom.h>
65 #include <vm/vm.h>
66 #include <vm/vm_param.h>
67 #include <vm/vm_kern.h>
68 #include <vm/vm_pageout.h>
69 #include <vm/vm_page.h>
70 #include <vm/vm_object.h>
71 #include <vm/vm_extern.h>
72 #include <vm/vm_map.h>
73 #include "opt_compat.h"
74 #include "opt_directio.h"
75 #include "opt_swap.h"
76
77 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
78
79 struct bio_ops bioops; /* I/O operation notification */
80
81 struct buf_ops buf_ops_bio = {
82 .bop_name = "buf_ops_bio",
83 .bop_write = bufwrite,
84 .bop_strategy = bufstrategy,
85 .bop_sync = bufsync,
86 .bop_bdflush = bufbdflush,
87 };
88
89 /*
90 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
91 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
92 */
93 struct buf *buf; /* buffer header pool */
94
95 static struct proc *bufdaemonproc;
96
97 static int inmem(struct vnode *vp, daddr_t blkno);
98 static void vm_hold_free_pages(struct buf *bp, int newbsize);
99 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
100 vm_offset_t to);
101 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
102 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
103 vm_page_t m);
104 static void vfs_drain_busy_pages(struct buf *bp);
105 static void vfs_clean_pages_dirty_buf(struct buf *bp);
106 static void vfs_setdirty_locked_object(struct buf *bp);
107 static void vfs_vmio_release(struct buf *bp);
108 static int vfs_bio_clcheck(struct vnode *vp, int size,
109 daddr_t lblkno, daddr_t blkno);
110 static int buf_do_flush(struct vnode *vp);
111 static int flushbufqueues(struct vnode *, int, int);
112 static void buf_daemon(void);
113 static void bremfreel(struct buf *bp);
114 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
115 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
116 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
117 #endif
118
119 int vmiodirenable = TRUE;
120 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
121 "Use the VM system for directory writes");
122 long runningbufspace;
123 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
124 "Amount of presently outstanding async buffer io");
125 static long bufspace;
126 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
127 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
128 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
129 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
130 #else
131 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
132 "Virtual memory used for buffers");
133 #endif
134 static long maxbufspace;
135 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
136 "Maximum allowed value of bufspace (including buf_daemon)");
137 static long bufmallocspace;
138 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
139 "Amount of malloced memory for buffers");
140 static long maxbufmallocspace;
141 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
142 "Maximum amount of malloced memory for buffers");
143 static long lobufspace;
144 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
145 "Minimum amount of buffers we want to have");
146 long hibufspace;
147 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
148 "Maximum allowed value of bufspace (excluding buf_daemon)");
149 static int bufreusecnt;
150 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
151 "Number of times we have reused a buffer");
152 static int buffreekvacnt;
153 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
154 "Number of times we have freed the KVA space from some buffer");
155 static int bufdefragcnt;
156 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
157 "Number of times we have had to repeat buffer allocation to defragment");
158 static long lorunningspace;
159 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
160 "Minimum preferred space used for in-progress I/O");
161 static long hirunningspace;
162 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
163 "Maximum amount of space to use for in-progress I/O");
164 int dirtybufferflushes;
165 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
166 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
167 int bdwriteskip;
168 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
169 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
170 int altbufferflushes;
171 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
172 0, "Number of fsync flushes to limit dirty buffers");
173 static int recursiveflushes;
174 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
175 0, "Number of flushes skipped due to being recursive");
176 static int numdirtybuffers;
177 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
178 "Number of buffers that are dirty (has unwritten changes) at the moment");
179 static int lodirtybuffers;
180 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
181 "How many buffers we want to have free before bufdaemon can sleep");
182 static int hidirtybuffers;
183 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
184 "When the number of dirty buffers is considered severe");
185 int dirtybufthresh;
186 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
187 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
188 static int numfreebuffers;
189 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
190 "Number of free buffers");
191 static int lofreebuffers;
192 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
193 "XXX Unused");
194 static int hifreebuffers;
195 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
196 "XXX Complicatedly unused");
197 static int getnewbufcalls;
198 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
199 "Number of calls to getnewbuf");
200 static int getnewbufrestarts;
201 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
202 "Number of times getnewbuf has had to restart a buffer aquisition");
203 static int flushbufqtarget = 100;
204 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
205 "Amount of work to do in flushbufqueues when helping bufdaemon");
206 static long notbufdflashes;
207 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0,
208 "Number of dirty buffer flushes done by the bufdaemon helpers");
209
210 /*
211 * Wakeup point for bufdaemon, as well as indicator of whether it is already
212 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
213 * is idling.
214 */
215 static int bd_request;
216
217 /*
218 * Request for the buf daemon to write more buffers than is indicated by
219 * lodirtybuf. This may be necessary to push out excess dependencies or
220 * defragment the address space where a simple count of the number of dirty
221 * buffers is insufficient to characterize the demand for flushing them.
222 */
223 static int bd_speedupreq;
224
225 /*
226 * This lock synchronizes access to bd_request.
227 */
228 static struct mtx bdlock;
229
230 /*
231 * bogus page -- for I/O to/from partially complete buffers
232 * this is a temporary solution to the problem, but it is not
233 * really that bad. it would be better to split the buffer
234 * for input in the case of buffers partially already in memory,
235 * but the code is intricate enough already.
236 */
237 vm_page_t bogus_page;
238
239 /*
240 * Synchronization (sleep/wakeup) variable for active buffer space requests.
241 * Set when wait starts, cleared prior to wakeup().
242 * Used in runningbufwakeup() and waitrunningbufspace().
243 */
244 static int runningbufreq;
245
246 /*
247 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
248 * waitrunningbufspace().
249 */
250 static struct mtx rbreqlock;
251
252 /*
253 * Synchronization (sleep/wakeup) variable for buffer requests.
254 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
255 * by and/or.
256 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
257 * getnewbuf(), and getblk().
258 */
259 static int needsbuffer;
260
261 /*
262 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
263 */
264 static struct mtx nblock;
265
266 /*
267 * Definitions for the buffer free lists.
268 */
269 #define BUFFER_QUEUES 6 /* number of free buffer queues */
270
271 #define QUEUE_NONE 0 /* on no queue */
272 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
273 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
274 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */
275 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
276 #define QUEUE_EMPTY 5 /* empty buffer headers */
277 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
278
279 /* Queues for free buffers with various properties */
280 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
281
282 /* Lock for the bufqueues */
283 static struct mtx bqlock;
284
285 /*
286 * Single global constant for BUF_WMESG, to avoid getting multiple references.
287 * buf_wmesg is referred from macros.
288 */
289 const char *buf_wmesg = BUF_WMESG;
290
291 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
292 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
293 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
294 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
295
296 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
297 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
298 static int
299 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
300 {
301 long lvalue;
302 int ivalue;
303
304 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
305 return (sysctl_handle_long(oidp, arg1, arg2, req));
306 lvalue = *(long *)arg1;
307 if (lvalue > INT_MAX)
308 /* On overflow, still write out a long to trigger ENOMEM. */
309 return (sysctl_handle_long(oidp, &lvalue, 0, req));
310 ivalue = lvalue;
311 return (sysctl_handle_int(oidp, &ivalue, 0, req));
312 }
313 #endif
314
315 #ifdef DIRECTIO
316 extern void ffs_rawread_setup(void);
317 #endif /* DIRECTIO */
318 /*
319 * numdirtywakeup:
320 *
321 * If someone is blocked due to there being too many dirty buffers,
322 * and numdirtybuffers is now reasonable, wake them up.
323 */
324
325 static __inline void
326 numdirtywakeup(int level)
327 {
328
329 if (numdirtybuffers <= level) {
330 mtx_lock(&nblock);
331 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
332 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
333 wakeup(&needsbuffer);
334 }
335 mtx_unlock(&nblock);
336 }
337 }
338
339 /*
340 * bufspacewakeup:
341 *
342 * Called when buffer space is potentially available for recovery.
343 * getnewbuf() will block on this flag when it is unable to free
344 * sufficient buffer space. Buffer space becomes recoverable when
345 * bp's get placed back in the queues.
346 */
347
348 static __inline void
349 bufspacewakeup(void)
350 {
351
352 /*
353 * If someone is waiting for BUF space, wake them up. Even
354 * though we haven't freed the kva space yet, the waiting
355 * process will be able to now.
356 */
357 mtx_lock(&nblock);
358 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
359 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
360 wakeup(&needsbuffer);
361 }
362 mtx_unlock(&nblock);
363 }
364
365 /*
366 * runningbufwakeup() - in-progress I/O accounting.
367 *
368 */
369 void
370 runningbufwakeup(struct buf *bp)
371 {
372
373 if (bp->b_runningbufspace) {
374 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace);
375 bp->b_runningbufspace = 0;
376 mtx_lock(&rbreqlock);
377 if (runningbufreq && runningbufspace <= lorunningspace) {
378 runningbufreq = 0;
379 wakeup(&runningbufreq);
380 }
381 mtx_unlock(&rbreqlock);
382 }
383 }
384
385 /*
386 * bufcountwakeup:
387 *
388 * Called when a buffer has been added to one of the free queues to
389 * account for the buffer and to wakeup anyone waiting for free buffers.
390 * This typically occurs when large amounts of metadata are being handled
391 * by the buffer cache ( else buffer space runs out first, usually ).
392 */
393
394 static __inline void
395 bufcountwakeup(struct buf *bp)
396 {
397 int old;
398
399 KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
400 ("buf %p already counted as free", bp));
401 if (bp->b_bufobj != NULL)
402 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
403 bp->b_vflags |= BV_INFREECNT;
404 old = atomic_fetchadd_int(&numfreebuffers, 1);
405 KASSERT(old >= 0 && old < nbuf,
406 ("numfreebuffers climbed to %d", old + 1));
407 mtx_lock(&nblock);
408 if (needsbuffer) {
409 needsbuffer &= ~VFS_BIO_NEED_ANY;
410 if (numfreebuffers >= hifreebuffers)
411 needsbuffer &= ~VFS_BIO_NEED_FREE;
412 wakeup(&needsbuffer);
413 }
414 mtx_unlock(&nblock);
415 }
416
417 /*
418 * waitrunningbufspace()
419 *
420 * runningbufspace is a measure of the amount of I/O currently
421 * running. This routine is used in async-write situations to
422 * prevent creating huge backups of pending writes to a device.
423 * Only asynchronous writes are governed by this function.
424 *
425 * Reads will adjust runningbufspace, but will not block based on it.
426 * The read load has a side effect of reducing the allowed write load.
427 *
428 * This does NOT turn an async write into a sync write. It waits
429 * for earlier writes to complete and generally returns before the
430 * caller's write has reached the device.
431 */
432 void
433 waitrunningbufspace(void)
434 {
435
436 mtx_lock(&rbreqlock);
437 while (runningbufspace > hirunningspace) {
438 ++runningbufreq;
439 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
440 }
441 mtx_unlock(&rbreqlock);
442 }
443
444
445 /*
446 * vfs_buf_test_cache:
447 *
448 * Called when a buffer is extended. This function clears the B_CACHE
449 * bit if the newly extended portion of the buffer does not contain
450 * valid data.
451 */
452 static __inline
453 void
454 vfs_buf_test_cache(struct buf *bp,
455 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
456 vm_page_t m)
457 {
458
459 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
460 if (bp->b_flags & B_CACHE) {
461 int base = (foff + off) & PAGE_MASK;
462 if (vm_page_is_valid(m, base, size) == 0)
463 bp->b_flags &= ~B_CACHE;
464 }
465 }
466
467 /* Wake up the buffer daemon if necessary */
468 static __inline
469 void
470 bd_wakeup(int dirtybuflevel)
471 {
472
473 mtx_lock(&bdlock);
474 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
475 bd_request = 1;
476 wakeup(&bd_request);
477 }
478 mtx_unlock(&bdlock);
479 }
480
481 /*
482 * bd_speedup - speedup the buffer cache flushing code
483 */
484
485 void
486 bd_speedup(void)
487 {
488 int needwake;
489
490 mtx_lock(&bdlock);
491 needwake = 0;
492 if (bd_speedupreq == 0 || bd_request == 0)
493 needwake = 1;
494 bd_speedupreq = 1;
495 bd_request = 1;
496 if (needwake)
497 wakeup(&bd_request);
498 mtx_unlock(&bdlock);
499 }
500
501 /*
502 * Calculating buffer cache scaling values and reserve space for buffer
503 * headers. This is called during low level kernel initialization and
504 * may be called more then once. We CANNOT write to the memory area
505 * being reserved at this time.
506 */
507 caddr_t
508 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
509 {
510 int tuned_nbuf;
511 long maxbuf;
512
513 /*
514 * physmem_est is in pages. Convert it to kilobytes (assumes
515 * PAGE_SIZE is >= 1K)
516 */
517 physmem_est = physmem_est * (PAGE_SIZE / 1024);
518
519 /*
520 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
521 * For the first 64MB of ram nominally allocate sufficient buffers to
522 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
523 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
524 * the buffer cache we limit the eventual kva reservation to
525 * maxbcache bytes.
526 *
527 * factor represents the 1/4 x ram conversion.
528 */
529 if (nbuf == 0) {
530 int factor = 4 * BKVASIZE / 1024;
531
532 nbuf = 50;
533 if (physmem_est > 4096)
534 nbuf += min((physmem_est - 4096) / factor,
535 65536 / factor);
536 if (physmem_est > 65536)
537 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
538
539 if (maxbcache && nbuf > maxbcache / BKVASIZE)
540 nbuf = maxbcache / BKVASIZE;
541 tuned_nbuf = 1;
542 } else
543 tuned_nbuf = 0;
544
545 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
546 maxbuf = (LONG_MAX / 3) / BKVASIZE;
547 if (nbuf > maxbuf) {
548 if (!tuned_nbuf)
549 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
550 maxbuf);
551 nbuf = maxbuf;
552 }
553
554 /*
555 * swbufs are used as temporary holders for I/O, such as paging I/O.
556 * We have no less then 16 and no more then 256.
557 */
558 nswbuf = max(min(nbuf/4, 256), 16);
559 #ifdef NSWBUF_MIN
560 if (nswbuf < NSWBUF_MIN)
561 nswbuf = NSWBUF_MIN;
562 #endif
563 #ifdef DIRECTIO
564 ffs_rawread_setup();
565 #endif
566
567 /*
568 * Reserve space for the buffer cache buffers
569 */
570 swbuf = (void *)v;
571 v = (caddr_t)(swbuf + nswbuf);
572 buf = (void *)v;
573 v = (caddr_t)(buf + nbuf);
574
575 return(v);
576 }
577
578 /* Initialize the buffer subsystem. Called before use of any buffers. */
579 void
580 bufinit(void)
581 {
582 struct buf *bp;
583 int i;
584
585 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
586 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
587 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
588 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
589
590 /* next, make a null set of free lists */
591 for (i = 0; i < BUFFER_QUEUES; i++)
592 TAILQ_INIT(&bufqueues[i]);
593
594 /* finally, initialize each buffer header and stick on empty q */
595 for (i = 0; i < nbuf; i++) {
596 bp = &buf[i];
597 bzero(bp, sizeof *bp);
598 bp->b_flags = B_INVAL; /* we're just an empty header */
599 bp->b_rcred = NOCRED;
600 bp->b_wcred = NOCRED;
601 bp->b_qindex = QUEUE_EMPTY;
602 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */
603 bp->b_xflags = 0;
604 LIST_INIT(&bp->b_dep);
605 BUF_LOCKINIT(bp);
606 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
607 }
608
609 /*
610 * maxbufspace is the absolute maximum amount of buffer space we are
611 * allowed to reserve in KVM and in real terms. The absolute maximum
612 * is nominally used by buf_daemon. hibufspace is the nominal maximum
613 * used by most other processes. The differential is required to
614 * ensure that buf_daemon is able to run when other processes might
615 * be blocked waiting for buffer space.
616 *
617 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
618 * this may result in KVM fragmentation which is not handled optimally
619 * by the system.
620 */
621 maxbufspace = (long)nbuf * BKVASIZE;
622 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
623 lobufspace = hibufspace - MAXBSIZE;
624
625 /*
626 * Note: The 16 MiB upper limit for hirunningspace was chosen
627 * arbitrarily and may need further tuning. It corresponds to
628 * 128 outstanding write IO requests (if IO size is 128 KiB),
629 * which fits with many RAID controllers' tagged queuing limits.
630 * The lower 1 MiB limit is the historical upper limit for
631 * hirunningspace.
632 */
633 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE),
634 16 * 1024 * 1024), 1024 * 1024);
635 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE);
636
637 /*
638 * Limit the amount of malloc memory since it is wired permanently into
639 * the kernel space. Even though this is accounted for in the buffer
640 * allocation, we don't want the malloced region to grow uncontrolled.
641 * The malloc scheme improves memory utilization significantly on average
642 * (small) directories.
643 */
644 maxbufmallocspace = hibufspace / 20;
645
646 /*
647 * Reduce the chance of a deadlock occuring by limiting the number
648 * of delayed-write dirty buffers we allow to stack up.
649 */
650 hidirtybuffers = nbuf / 4 + 20;
651 dirtybufthresh = hidirtybuffers * 9 / 10;
652 numdirtybuffers = 0;
653 /*
654 * To support extreme low-memory systems, make sure hidirtybuffers cannot
655 * eat up all available buffer space. This occurs when our minimum cannot
656 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
657 * BKVASIZE'd buffers.
658 */
659 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
660 hidirtybuffers >>= 1;
661 }
662 lodirtybuffers = hidirtybuffers / 2;
663
664 /*
665 * Try to keep the number of free buffers in the specified range,
666 * and give special processes (e.g. like buf_daemon) access to an
667 * emergency reserve.
668 */
669 lofreebuffers = nbuf / 18 + 5;
670 hifreebuffers = 2 * lofreebuffers;
671 numfreebuffers = nbuf;
672
673 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
674 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
675 }
676
677 /*
678 * bfreekva() - free the kva allocation for a buffer.
679 *
680 * Since this call frees up buffer space, we call bufspacewakeup().
681 */
682 static void
683 bfreekva(struct buf *bp)
684 {
685
686 if (bp->b_kvasize) {
687 atomic_add_int(&buffreekvacnt, 1);
688 atomic_subtract_long(&bufspace, bp->b_kvasize);
689 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase,
690 (vm_offset_t) bp->b_kvabase + bp->b_kvasize);
691 bp->b_kvasize = 0;
692 bufspacewakeup();
693 }
694 }
695
696 /*
697 * bremfree:
698 *
699 * Mark the buffer for removal from the appropriate free list in brelse.
700 *
701 */
702 void
703 bremfree(struct buf *bp)
704 {
705 int old;
706
707 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
708 KASSERT((bp->b_flags & B_REMFREE) == 0,
709 ("bremfree: buffer %p already marked for delayed removal.", bp));
710 KASSERT(bp->b_qindex != QUEUE_NONE,
711 ("bremfree: buffer %p not on a queue.", bp));
712 BUF_ASSERT_HELD(bp);
713
714 bp->b_flags |= B_REMFREE;
715 /* Fixup numfreebuffers count. */
716 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
717 KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
718 ("buf %p not counted in numfreebuffers", bp));
719 if (bp->b_bufobj != NULL)
720 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
721 bp->b_vflags &= ~BV_INFREECNT;
722 old = atomic_fetchadd_int(&numfreebuffers, -1);
723 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
724 }
725 }
726
727 /*
728 * bremfreef:
729 *
730 * Force an immediate removal from a free list. Used only in nfs when
731 * it abuses the b_freelist pointer.
732 */
733 void
734 bremfreef(struct buf *bp)
735 {
736 mtx_lock(&bqlock);
737 bremfreel(bp);
738 mtx_unlock(&bqlock);
739 }
740
741 /*
742 * bremfreel:
743 *
744 * Removes a buffer from the free list, must be called with the
745 * bqlock held.
746 */
747 static void
748 bremfreel(struct buf *bp)
749 {
750 int old;
751
752 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
753 bp, bp->b_vp, bp->b_flags);
754 KASSERT(bp->b_qindex != QUEUE_NONE,
755 ("bremfreel: buffer %p not on a queue.", bp));
756 BUF_ASSERT_HELD(bp);
757 mtx_assert(&bqlock, MA_OWNED);
758
759 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
760 bp->b_qindex = QUEUE_NONE;
761 /*
762 * If this was a delayed bremfree() we only need to remove the buffer
763 * from the queue and return the stats are already done.
764 */
765 if (bp->b_flags & B_REMFREE) {
766 bp->b_flags &= ~B_REMFREE;
767 return;
768 }
769 /*
770 * Fixup numfreebuffers count. If the buffer is invalid or not
771 * delayed-write, the buffer was free and we must decrement
772 * numfreebuffers.
773 */
774 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
775 KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
776 ("buf %p not counted in numfreebuffers", bp));
777 if (bp->b_bufobj != NULL)
778 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
779 bp->b_vflags &= ~BV_INFREECNT;
780 old = atomic_fetchadd_int(&numfreebuffers, -1);
781 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
782 }
783 }
784
785 /*
786 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
787 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
788 * the buffer is valid and we do not have to do anything.
789 */
790 void
791 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
792 int cnt, struct ucred * cred)
793 {
794 struct buf *rabp;
795 int i;
796
797 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
798 if (inmem(vp, *rablkno))
799 continue;
800 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
801
802 if ((rabp->b_flags & B_CACHE) == 0) {
803 if (!TD_IS_IDLETHREAD(curthread))
804 curthread->td_ru.ru_inblock++;
805 rabp->b_flags |= B_ASYNC;
806 rabp->b_flags &= ~B_INVAL;
807 rabp->b_ioflags &= ~BIO_ERROR;
808 rabp->b_iocmd = BIO_READ;
809 if (rabp->b_rcred == NOCRED && cred != NOCRED)
810 rabp->b_rcred = crhold(cred);
811 vfs_busy_pages(rabp, 0);
812 BUF_KERNPROC(rabp);
813 rabp->b_iooffset = dbtob(rabp->b_blkno);
814 bstrategy(rabp);
815 } else {
816 brelse(rabp);
817 }
818 }
819 }
820
821 /*
822 * Entry point for bread() and breadn() via #defines in sys/buf.h.
823 *
824 * Get a buffer with the specified data. Look in the cache first. We
825 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
826 * is set, the buffer is valid and we do not have to do anything, see
827 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
828 */
829 int
830 breadn_flags(struct vnode * vp, daddr_t blkno, int size,
831 daddr_t * rablkno, int *rabsize, int cnt,
832 struct ucred * cred, int flags, struct buf **bpp)
833 {
834 struct buf *bp;
835 int rv = 0, readwait = 0;
836
837 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
838 /*
839 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
840 */
841 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
842 if (bp == NULL)
843 return (EBUSY);
844
845 /* if not found in cache, do some I/O */
846 if ((bp->b_flags & B_CACHE) == 0) {
847 if (!TD_IS_IDLETHREAD(curthread))
848 curthread->td_ru.ru_inblock++;
849 bp->b_iocmd = BIO_READ;
850 bp->b_flags &= ~B_INVAL;
851 bp->b_ioflags &= ~BIO_ERROR;
852 if (bp->b_rcred == NOCRED && cred != NOCRED)
853 bp->b_rcred = crhold(cred);
854 vfs_busy_pages(bp, 0);
855 bp->b_iooffset = dbtob(bp->b_blkno);
856 bstrategy(bp);
857 ++readwait;
858 }
859
860 breada(vp, rablkno, rabsize, cnt, cred);
861
862 if (readwait) {
863 rv = bufwait(bp);
864 }
865 return (rv);
866 }
867
868 /*
869 * Write, release buffer on completion. (Done by iodone
870 * if async). Do not bother writing anything if the buffer
871 * is invalid.
872 *
873 * Note that we set B_CACHE here, indicating that buffer is
874 * fully valid and thus cacheable. This is true even of NFS
875 * now so we set it generally. This could be set either here
876 * or in biodone() since the I/O is synchronous. We put it
877 * here.
878 */
879 int
880 bufwrite(struct buf *bp)
881 {
882 int oldflags;
883 struct vnode *vp;
884 int vp_md;
885
886 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
887 if (bp->b_flags & B_INVAL) {
888 brelse(bp);
889 return (0);
890 }
891
892 oldflags = bp->b_flags;
893
894 BUF_ASSERT_HELD(bp);
895
896 if (bp->b_pin_count > 0)
897 bunpin_wait(bp);
898
899 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
900 ("FFS background buffer should not get here %p", bp));
901
902 vp = bp->b_vp;
903 if (vp)
904 vp_md = vp->v_vflag & VV_MD;
905 else
906 vp_md = 0;
907
908 /* Mark the buffer clean */
909 bundirty(bp);
910
911 bp->b_flags &= ~B_DONE;
912 bp->b_ioflags &= ~BIO_ERROR;
913 bp->b_flags |= B_CACHE;
914 bp->b_iocmd = BIO_WRITE;
915
916 bufobj_wref(bp->b_bufobj);
917 vfs_busy_pages(bp, 1);
918
919 /*
920 * Normal bwrites pipeline writes
921 */
922 bp->b_runningbufspace = bp->b_bufsize;
923 atomic_add_long(&runningbufspace, bp->b_runningbufspace);
924
925 if (!TD_IS_IDLETHREAD(curthread))
926 curthread->td_ru.ru_oublock++;
927 if (oldflags & B_ASYNC)
928 BUF_KERNPROC(bp);
929 bp->b_iooffset = dbtob(bp->b_blkno);
930 bstrategy(bp);
931
932 if ((oldflags & B_ASYNC) == 0) {
933 int rtval = bufwait(bp);
934 brelse(bp);
935 return (rtval);
936 } else {
937 /*
938 * don't allow the async write to saturate the I/O
939 * system. We will not deadlock here because
940 * we are blocking waiting for I/O that is already in-progress
941 * to complete. We do not block here if it is the update
942 * or syncer daemon trying to clean up as that can lead
943 * to deadlock.
944 */
945 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
946 waitrunningbufspace();
947 }
948
949 return (0);
950 }
951
952 void
953 bufbdflush(struct bufobj *bo, struct buf *bp)
954 {
955 struct buf *nbp;
956
957 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
958 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
959 altbufferflushes++;
960 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
961 BO_LOCK(bo);
962 /*
963 * Try to find a buffer to flush.
964 */
965 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
966 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
967 BUF_LOCK(nbp,
968 LK_EXCLUSIVE | LK_NOWAIT, NULL))
969 continue;
970 if (bp == nbp)
971 panic("bdwrite: found ourselves");
972 BO_UNLOCK(bo);
973 /* Don't countdeps with the bo lock held. */
974 if (buf_countdeps(nbp, 0)) {
975 BO_LOCK(bo);
976 BUF_UNLOCK(nbp);
977 continue;
978 }
979 if (nbp->b_flags & B_CLUSTEROK) {
980 vfs_bio_awrite(nbp);
981 } else {
982 bremfree(nbp);
983 bawrite(nbp);
984 }
985 dirtybufferflushes++;
986 break;
987 }
988 if (nbp == NULL)
989 BO_UNLOCK(bo);
990 }
991 }
992
993 /*
994 * Delayed write. (Buffer is marked dirty). Do not bother writing
995 * anything if the buffer is marked invalid.
996 *
997 * Note that since the buffer must be completely valid, we can safely
998 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
999 * biodone() in order to prevent getblk from writing the buffer
1000 * out synchronously.
1001 */
1002 void
1003 bdwrite(struct buf *bp)
1004 {
1005 struct thread *td = curthread;
1006 struct vnode *vp;
1007 struct bufobj *bo;
1008
1009 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1010 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1011 BUF_ASSERT_HELD(bp);
1012
1013 if (bp->b_flags & B_INVAL) {
1014 brelse(bp);
1015 return;
1016 }
1017
1018 /*
1019 * If we have too many dirty buffers, don't create any more.
1020 * If we are wildly over our limit, then force a complete
1021 * cleanup. Otherwise, just keep the situation from getting
1022 * out of control. Note that we have to avoid a recursive
1023 * disaster and not try to clean up after our own cleanup!
1024 */
1025 vp = bp->b_vp;
1026 bo = bp->b_bufobj;
1027 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
1028 td->td_pflags |= TDP_INBDFLUSH;
1029 BO_BDFLUSH(bo, bp);
1030 td->td_pflags &= ~TDP_INBDFLUSH;
1031 } else
1032 recursiveflushes++;
1033
1034 bdirty(bp);
1035 /*
1036 * Set B_CACHE, indicating that the buffer is fully valid. This is
1037 * true even of NFS now.
1038 */
1039 bp->b_flags |= B_CACHE;
1040
1041 /*
1042 * This bmap keeps the system from needing to do the bmap later,
1043 * perhaps when the system is attempting to do a sync. Since it
1044 * is likely that the indirect block -- or whatever other datastructure
1045 * that the filesystem needs is still in memory now, it is a good
1046 * thing to do this. Note also, that if the pageout daemon is
1047 * requesting a sync -- there might not be enough memory to do
1048 * the bmap then... So, this is important to do.
1049 */
1050 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1051 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1052 }
1053
1054 /*
1055 * Set the *dirty* buffer range based upon the VM system dirty
1056 * pages.
1057 *
1058 * Mark the buffer pages as clean. We need to do this here to
1059 * satisfy the vnode_pager and the pageout daemon, so that it
1060 * thinks that the pages have been "cleaned". Note that since
1061 * the pages are in a delayed write buffer -- the VFS layer
1062 * "will" see that the pages get written out on the next sync,
1063 * or perhaps the cluster will be completed.
1064 */
1065 vfs_clean_pages_dirty_buf(bp);
1066 bqrelse(bp);
1067
1068 /*
1069 * Wakeup the buffer flushing daemon if we have a lot of dirty
1070 * buffers (midpoint between our recovery point and our stall
1071 * point).
1072 */
1073 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1074
1075 /*
1076 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1077 * due to the softdep code.
1078 */
1079 }
1080
1081 /*
1082 * bdirty:
1083 *
1084 * Turn buffer into delayed write request. We must clear BIO_READ and
1085 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1086 * itself to properly update it in the dirty/clean lists. We mark it
1087 * B_DONE to ensure that any asynchronization of the buffer properly
1088 * clears B_DONE ( else a panic will occur later ).
1089 *
1090 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1091 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1092 * should only be called if the buffer is known-good.
1093 *
1094 * Since the buffer is not on a queue, we do not update the numfreebuffers
1095 * count.
1096 *
1097 * The buffer must be on QUEUE_NONE.
1098 */
1099 void
1100 bdirty(struct buf *bp)
1101 {
1102
1103 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1104 bp, bp->b_vp, bp->b_flags);
1105 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1106 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1107 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1108 BUF_ASSERT_HELD(bp);
1109 bp->b_flags &= ~(B_RELBUF);
1110 bp->b_iocmd = BIO_WRITE;
1111
1112 if ((bp->b_flags & B_DELWRI) == 0) {
1113 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1114 reassignbuf(bp);
1115 atomic_add_int(&numdirtybuffers, 1);
1116 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1117 }
1118 }
1119
1120 /*
1121 * bundirty:
1122 *
1123 * Clear B_DELWRI for buffer.
1124 *
1125 * Since the buffer is not on a queue, we do not update the numfreebuffers
1126 * count.
1127 *
1128 * The buffer must be on QUEUE_NONE.
1129 */
1130
1131 void
1132 bundirty(struct buf *bp)
1133 {
1134
1135 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1136 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1137 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1138 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1139 BUF_ASSERT_HELD(bp);
1140
1141 if (bp->b_flags & B_DELWRI) {
1142 bp->b_flags &= ~B_DELWRI;
1143 reassignbuf(bp);
1144 atomic_subtract_int(&numdirtybuffers, 1);
1145 numdirtywakeup(lodirtybuffers);
1146 }
1147 /*
1148 * Since it is now being written, we can clear its deferred write flag.
1149 */
1150 bp->b_flags &= ~B_DEFERRED;
1151 }
1152
1153 /*
1154 * bawrite:
1155 *
1156 * Asynchronous write. Start output on a buffer, but do not wait for
1157 * it to complete. The buffer is released when the output completes.
1158 *
1159 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1160 * B_INVAL buffers. Not us.
1161 */
1162 void
1163 bawrite(struct buf *bp)
1164 {
1165
1166 bp->b_flags |= B_ASYNC;
1167 (void) bwrite(bp);
1168 }
1169
1170 /*
1171 * bwillwrite:
1172 *
1173 * Called prior to the locking of any vnodes when we are expecting to
1174 * write. We do not want to starve the buffer cache with too many
1175 * dirty buffers so we block here. By blocking prior to the locking
1176 * of any vnodes we attempt to avoid the situation where a locked vnode
1177 * prevents the various system daemons from flushing related buffers.
1178 */
1179
1180 void
1181 bwillwrite(void)
1182 {
1183
1184 if (numdirtybuffers >= hidirtybuffers) {
1185 mtx_lock(&nblock);
1186 while (numdirtybuffers >= hidirtybuffers) {
1187 bd_wakeup(1);
1188 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1189 msleep(&needsbuffer, &nblock,
1190 (PRIBIO + 4), "flswai", 0);
1191 }
1192 mtx_unlock(&nblock);
1193 }
1194 }
1195
1196 /*
1197 * Return true if we have too many dirty buffers.
1198 */
1199 int
1200 buf_dirty_count_severe(void)
1201 {
1202
1203 return(numdirtybuffers >= hidirtybuffers);
1204 }
1205
1206 static __noinline int
1207 buf_vm_page_count_severe(void)
1208 {
1209
1210 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1);
1211
1212 return vm_page_count_severe();
1213 }
1214
1215 /*
1216 * brelse:
1217 *
1218 * Release a busy buffer and, if requested, free its resources. The
1219 * buffer will be stashed in the appropriate bufqueue[] allowing it
1220 * to be accessed later as a cache entity or reused for other purposes.
1221 */
1222 void
1223 brelse(struct buf *bp)
1224 {
1225 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1226 bp, bp->b_vp, bp->b_flags);
1227 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1228 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1229
1230 if (bp->b_flags & B_MANAGED) {
1231 bqrelse(bp);
1232 return;
1233 }
1234
1235 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
1236 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) {
1237 /*
1238 * Failed write, redirty. Must clear BIO_ERROR to prevent
1239 * pages from being scrapped. If the error is anything
1240 * other than an I/O error (EIO), assume that retrying
1241 * is futile.
1242 */
1243 bp->b_ioflags &= ~BIO_ERROR;
1244 bdirty(bp);
1245 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1246 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1247 /*
1248 * Either a failed I/O or we were asked to free or not
1249 * cache the buffer.
1250 */
1251 bp->b_flags |= B_INVAL;
1252 if (!LIST_EMPTY(&bp->b_dep))
1253 buf_deallocate(bp);
1254 if (bp->b_flags & B_DELWRI) {
1255 atomic_subtract_int(&numdirtybuffers, 1);
1256 numdirtywakeup(lodirtybuffers);
1257 }
1258 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1259 if ((bp->b_flags & B_VMIO) == 0) {
1260 if (bp->b_bufsize)
1261 allocbuf(bp, 0);
1262 if (bp->b_vp)
1263 brelvp(bp);
1264 }
1265 }
1266
1267 /*
1268 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1269 * is called with B_DELWRI set, the underlying pages may wind up
1270 * getting freed causing a previous write (bdwrite()) to get 'lost'
1271 * because pages associated with a B_DELWRI bp are marked clean.
1272 *
1273 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1274 * if B_DELWRI is set.
1275 *
1276 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1277 * on pages to return pages to the VM page queues.
1278 */
1279 if (bp->b_flags & B_DELWRI)
1280 bp->b_flags &= ~B_RELBUF;
1281 else if (buf_vm_page_count_severe()) {
1282 /*
1283 * The locking of the BO_LOCK is not necessary since
1284 * BKGRDINPROG cannot be set while we hold the buf
1285 * lock, it can only be cleared if it is already
1286 * pending.
1287 */
1288 if (bp->b_vp) {
1289 if (!(bp->b_vflags & BV_BKGRDINPROG))
1290 bp->b_flags |= B_RELBUF;
1291 } else
1292 bp->b_flags |= B_RELBUF;
1293 }
1294
1295 /*
1296 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1297 * constituted, not even NFS buffers now. Two flags effect this. If
1298 * B_INVAL, the struct buf is invalidated but the VM object is kept
1299 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1300 *
1301 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1302 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1303 * buffer is also B_INVAL because it hits the re-dirtying code above.
1304 *
1305 * Normally we can do this whether a buffer is B_DELWRI or not. If
1306 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1307 * the commit state and we cannot afford to lose the buffer. If the
1308 * buffer has a background write in progress, we need to keep it
1309 * around to prevent it from being reconstituted and starting a second
1310 * background write.
1311 */
1312 if ((bp->b_flags & B_VMIO)
1313 && !(bp->b_vp->v_mount != NULL &&
1314 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1315 !vn_isdisk(bp->b_vp, NULL) &&
1316 (bp->b_flags & B_DELWRI))
1317 ) {
1318
1319 int i, j, resid;
1320 vm_page_t m;
1321 off_t foff;
1322 vm_pindex_t poff;
1323 vm_object_t obj;
1324
1325 obj = bp->b_bufobj->bo_object;
1326
1327 /*
1328 * Get the base offset and length of the buffer. Note that
1329 * in the VMIO case if the buffer block size is not
1330 * page-aligned then b_data pointer may not be page-aligned.
1331 * But our b_pages[] array *IS* page aligned.
1332 *
1333 * block sizes less then DEV_BSIZE (usually 512) are not
1334 * supported due to the page granularity bits (m->valid,
1335 * m->dirty, etc...).
1336 *
1337 * See man buf(9) for more information
1338 */
1339 resid = bp->b_bufsize;
1340 foff = bp->b_offset;
1341 VM_OBJECT_LOCK(obj);
1342 for (i = 0; i < bp->b_npages; i++) {
1343 int had_bogus = 0;
1344
1345 m = bp->b_pages[i];
1346
1347 /*
1348 * If we hit a bogus page, fixup *all* the bogus pages
1349 * now.
1350 */
1351 if (m == bogus_page) {
1352 poff = OFF_TO_IDX(bp->b_offset);
1353 had_bogus = 1;
1354
1355 for (j = i; j < bp->b_npages; j++) {
1356 vm_page_t mtmp;
1357 mtmp = bp->b_pages[j];
1358 if (mtmp == bogus_page) {
1359 mtmp = vm_page_lookup(obj, poff + j);
1360 if (!mtmp) {
1361 panic("brelse: page missing\n");
1362 }
1363 bp->b_pages[j] = mtmp;
1364 }
1365 }
1366
1367 if ((bp->b_flags & B_INVAL) == 0) {
1368 pmap_qenter(
1369 trunc_page((vm_offset_t)bp->b_data),
1370 bp->b_pages, bp->b_npages);
1371 }
1372 m = bp->b_pages[i];
1373 }
1374 if ((bp->b_flags & B_NOCACHE) ||
1375 (bp->b_ioflags & BIO_ERROR &&
1376 bp->b_iocmd == BIO_READ)) {
1377 int poffset = foff & PAGE_MASK;
1378 int presid = resid > (PAGE_SIZE - poffset) ?
1379 (PAGE_SIZE - poffset) : resid;
1380
1381 KASSERT(presid >= 0, ("brelse: extra page"));
1382 vm_page_set_invalid(m, poffset, presid);
1383 if (had_bogus)
1384 printf("avoided corruption bug in bogus_page/brelse code\n");
1385 }
1386 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1387 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1388 }
1389 VM_OBJECT_UNLOCK(obj);
1390 if (bp->b_flags & (B_INVAL | B_RELBUF))
1391 vfs_vmio_release(bp);
1392
1393 } else if (bp->b_flags & B_VMIO) {
1394
1395 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1396 vfs_vmio_release(bp);
1397 }
1398
1399 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1400 if (bp->b_bufsize != 0)
1401 allocbuf(bp, 0);
1402 if (bp->b_vp != NULL)
1403 brelvp(bp);
1404 }
1405
1406 if (BUF_LOCKRECURSED(bp)) {
1407 /* do not release to free list */
1408 BUF_UNLOCK(bp);
1409 return;
1410 }
1411
1412 /* enqueue */
1413 mtx_lock(&bqlock);
1414 /* Handle delayed bremfree() processing. */
1415 if (bp->b_flags & B_REMFREE) {
1416 struct bufobj *bo;
1417
1418 bo = bp->b_bufobj;
1419 if (bo != NULL)
1420 BO_LOCK(bo);
1421 bremfreel(bp);
1422 if (bo != NULL)
1423 BO_UNLOCK(bo);
1424 }
1425 if (bp->b_qindex != QUEUE_NONE)
1426 panic("brelse: free buffer onto another queue???");
1427
1428 /*
1429 * If the buffer has junk contents signal it and eventually
1430 * clean up B_DELWRI and diassociate the vnode so that gbincore()
1431 * doesn't find it.
1432 */
1433 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
1434 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
1435 bp->b_flags |= B_INVAL;
1436 if (bp->b_flags & B_INVAL) {
1437 if (bp->b_flags & B_DELWRI)
1438 bundirty(bp);
1439 if (bp->b_vp)
1440 brelvp(bp);
1441 }
1442
1443 /* buffers with no memory */
1444 if (bp->b_bufsize == 0) {
1445 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1446 if (bp->b_vflags & BV_BKGRDINPROG)
1447 panic("losing buffer 1");
1448 if (bp->b_kvasize) {
1449 bp->b_qindex = QUEUE_EMPTYKVA;
1450 } else {
1451 bp->b_qindex = QUEUE_EMPTY;
1452 }
1453 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1454 /* buffers with junk contents */
1455 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1456 (bp->b_ioflags & BIO_ERROR)) {
1457 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1458 if (bp->b_vflags & BV_BKGRDINPROG)
1459 panic("losing buffer 2");
1460 bp->b_qindex = QUEUE_CLEAN;
1461 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1462 /* remaining buffers */
1463 } else {
1464 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) ==
1465 (B_DELWRI|B_NEEDSGIANT))
1466 bp->b_qindex = QUEUE_DIRTY_GIANT;
1467 else if (bp->b_flags & B_DELWRI)
1468 bp->b_qindex = QUEUE_DIRTY;
1469 else
1470 bp->b_qindex = QUEUE_CLEAN;
1471 if (bp->b_flags & B_AGE)
1472 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1473 else
1474 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1475 }
1476 mtx_unlock(&bqlock);
1477
1478 /*
1479 * Fixup numfreebuffers count. The bp is on an appropriate queue
1480 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1481 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1482 * if B_INVAL is set ).
1483 */
1484
1485 if (!(bp->b_flags & B_DELWRI)) {
1486 struct bufobj *bo;
1487
1488 bo = bp->b_bufobj;
1489 if (bo != NULL)
1490 BO_LOCK(bo);
1491 bufcountwakeup(bp);
1492 if (bo != NULL)
1493 BO_UNLOCK(bo);
1494 }
1495
1496 /*
1497 * Something we can maybe free or reuse
1498 */
1499 if (bp->b_bufsize || bp->b_kvasize)
1500 bufspacewakeup();
1501
1502 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1503 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1504 panic("brelse: not dirty");
1505 /* unlock */
1506 BUF_UNLOCK(bp);
1507 }
1508
1509 /*
1510 * Release a buffer back to the appropriate queue but do not try to free
1511 * it. The buffer is expected to be used again soon.
1512 *
1513 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1514 * biodone() to requeue an async I/O on completion. It is also used when
1515 * known good buffers need to be requeued but we think we may need the data
1516 * again soon.
1517 *
1518 * XXX we should be able to leave the B_RELBUF hint set on completion.
1519 */
1520 void
1521 bqrelse(struct buf *bp)
1522 {
1523 struct bufobj *bo;
1524
1525 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1526 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1527 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1528
1529 if (BUF_LOCKRECURSED(bp)) {
1530 /* do not release to free list */
1531 BUF_UNLOCK(bp);
1532 return;
1533 }
1534
1535 bo = bp->b_bufobj;
1536 if (bp->b_flags & B_MANAGED) {
1537 if (bp->b_flags & B_REMFREE) {
1538 mtx_lock(&bqlock);
1539 if (bo != NULL)
1540 BO_LOCK(bo);
1541 bremfreel(bp);
1542 if (bo != NULL)
1543 BO_UNLOCK(bo);
1544 mtx_unlock(&bqlock);
1545 }
1546 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1547 BUF_UNLOCK(bp);
1548 return;
1549 }
1550
1551 mtx_lock(&bqlock);
1552 /* Handle delayed bremfree() processing. */
1553 if (bp->b_flags & B_REMFREE) {
1554 if (bo != NULL)
1555 BO_LOCK(bo);
1556 bremfreel(bp);
1557 if (bo != NULL)
1558 BO_UNLOCK(bo);
1559 }
1560 if (bp->b_qindex != QUEUE_NONE)
1561 panic("bqrelse: free buffer onto another queue???");
1562 /* buffers with stale but valid contents */
1563 if (bp->b_flags & B_DELWRI) {
1564 if (bp->b_flags & B_NEEDSGIANT)
1565 bp->b_qindex = QUEUE_DIRTY_GIANT;
1566 else
1567 bp->b_qindex = QUEUE_DIRTY;
1568 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1569 } else {
1570 /*
1571 * The locking of the BO_LOCK for checking of the
1572 * BV_BKGRDINPROG is not necessary since the
1573 * BV_BKGRDINPROG cannot be set while we hold the buf
1574 * lock, it can only be cleared if it is already
1575 * pending.
1576 */
1577 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) {
1578 bp->b_qindex = QUEUE_CLEAN;
1579 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1580 b_freelist);
1581 } else {
1582 /*
1583 * We are too low on memory, we have to try to free
1584 * the buffer (most importantly: the wired pages
1585 * making up its backing store) *now*.
1586 */
1587 mtx_unlock(&bqlock);
1588 brelse(bp);
1589 return;
1590 }
1591 }
1592 mtx_unlock(&bqlock);
1593
1594 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) {
1595 if (bo != NULL)
1596 BO_LOCK(bo);
1597 bufcountwakeup(bp);
1598 if (bo != NULL)
1599 BO_UNLOCK(bo);
1600 }
1601
1602 /*
1603 * Something we can maybe free or reuse.
1604 */
1605 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1606 bufspacewakeup();
1607
1608 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1609 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1610 panic("bqrelse: not dirty");
1611 /* unlock */
1612 BUF_UNLOCK(bp);
1613 }
1614
1615 /* Give pages used by the bp back to the VM system (where possible) */
1616 static void
1617 vfs_vmio_release(struct buf *bp)
1618 {
1619 int i;
1620 vm_page_t m;
1621
1622 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
1623 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
1624 for (i = 0; i < bp->b_npages; i++) {
1625 m = bp->b_pages[i];
1626 bp->b_pages[i] = NULL;
1627 /*
1628 * In order to keep page LRU ordering consistent, put
1629 * everything on the inactive queue.
1630 */
1631 vm_page_lock(m);
1632 vm_page_unwire(m, 0);
1633 /*
1634 * We don't mess with busy pages, it is
1635 * the responsibility of the process that
1636 * busied the pages to deal with them.
1637 */
1638 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 &&
1639 m->wire_count == 0) {
1640 /*
1641 * Might as well free the page if we can and it has
1642 * no valid data. We also free the page if the
1643 * buffer was used for direct I/O
1644 */
1645 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) {
1646 vm_page_free(m);
1647 } else if (bp->b_flags & B_DIRECT) {
1648 vm_page_try_to_free(m);
1649 } else if (buf_vm_page_count_severe()) {
1650 vm_page_try_to_cache(m);
1651 }
1652 }
1653 vm_page_unlock(m);
1654 }
1655 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
1656
1657 if (bp->b_bufsize) {
1658 bufspacewakeup();
1659 bp->b_bufsize = 0;
1660 }
1661 bp->b_npages = 0;
1662 bp->b_flags &= ~B_VMIO;
1663 if (bp->b_vp)
1664 brelvp(bp);
1665 }
1666
1667 /*
1668 * Check to see if a block at a particular lbn is available for a clustered
1669 * write.
1670 */
1671 static int
1672 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1673 {
1674 struct buf *bpa;
1675 int match;
1676
1677 match = 0;
1678
1679 /* If the buf isn't in core skip it */
1680 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1681 return (0);
1682
1683 /* If the buf is busy we don't want to wait for it */
1684 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1685 return (0);
1686
1687 /* Only cluster with valid clusterable delayed write buffers */
1688 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1689 (B_DELWRI | B_CLUSTEROK))
1690 goto done;
1691
1692 if (bpa->b_bufsize != size)
1693 goto done;
1694
1695 /*
1696 * Check to see if it is in the expected place on disk and that the
1697 * block has been mapped.
1698 */
1699 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1700 match = 1;
1701 done:
1702 BUF_UNLOCK(bpa);
1703 return (match);
1704 }
1705
1706 /*
1707 * vfs_bio_awrite:
1708 *
1709 * Implement clustered async writes for clearing out B_DELWRI buffers.
1710 * This is much better then the old way of writing only one buffer at
1711 * a time. Note that we may not be presented with the buffers in the
1712 * correct order, so we search for the cluster in both directions.
1713 */
1714 int
1715 vfs_bio_awrite(struct buf *bp)
1716 {
1717 struct bufobj *bo;
1718 int i;
1719 int j;
1720 daddr_t lblkno = bp->b_lblkno;
1721 struct vnode *vp = bp->b_vp;
1722 int ncl;
1723 int nwritten;
1724 int size;
1725 int maxcl;
1726
1727 bo = &vp->v_bufobj;
1728 /*
1729 * right now we support clustered writing only to regular files. If
1730 * we find a clusterable block we could be in the middle of a cluster
1731 * rather then at the beginning.
1732 */
1733 if ((vp->v_type == VREG) &&
1734 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1735 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1736
1737 size = vp->v_mount->mnt_stat.f_iosize;
1738 maxcl = MAXPHYS / size;
1739
1740 BO_LOCK(bo);
1741 for (i = 1; i < maxcl; i++)
1742 if (vfs_bio_clcheck(vp, size, lblkno + i,
1743 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1744 break;
1745
1746 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1747 if (vfs_bio_clcheck(vp, size, lblkno - j,
1748 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1749 break;
1750 BO_UNLOCK(bo);
1751 --j;
1752 ncl = i + j;
1753 /*
1754 * this is a possible cluster write
1755 */
1756 if (ncl != 1) {
1757 BUF_UNLOCK(bp);
1758 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1759 return nwritten;
1760 }
1761 }
1762 bremfree(bp);
1763 bp->b_flags |= B_ASYNC;
1764 /*
1765 * default (old) behavior, writing out only one block
1766 *
1767 * XXX returns b_bufsize instead of b_bcount for nwritten?
1768 */
1769 nwritten = bp->b_bufsize;
1770 (void) bwrite(bp);
1771
1772 return nwritten;
1773 }
1774
1775 /*
1776 * getnewbuf:
1777 *
1778 * Find and initialize a new buffer header, freeing up existing buffers
1779 * in the bufqueues as necessary. The new buffer is returned locked.
1780 *
1781 * Important: B_INVAL is not set. If the caller wishes to throw the
1782 * buffer away, the caller must set B_INVAL prior to calling brelse().
1783 *
1784 * We block if:
1785 * We have insufficient buffer headers
1786 * We have insufficient buffer space
1787 * buffer_map is too fragmented ( space reservation fails )
1788 * If we have to flush dirty buffers ( but we try to avoid this )
1789 *
1790 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1791 * Instead we ask the buf daemon to do it for us. We attempt to
1792 * avoid piecemeal wakeups of the pageout daemon.
1793 */
1794
1795 static struct buf *
1796 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
1797 int gbflags)
1798 {
1799 struct thread *td;
1800 struct buf *bp;
1801 struct buf *nbp;
1802 int defrag = 0;
1803 int nqindex;
1804 static int flushingbufs;
1805
1806 td = curthread;
1807 /*
1808 * We can't afford to block since we might be holding a vnode lock,
1809 * which may prevent system daemons from running. We deal with
1810 * low-memory situations by proactively returning memory and running
1811 * async I/O rather then sync I/O.
1812 */
1813 atomic_add_int(&getnewbufcalls, 1);
1814 atomic_subtract_int(&getnewbufrestarts, 1);
1815 restart:
1816 atomic_add_int(&getnewbufrestarts, 1);
1817
1818 /*
1819 * Setup for scan. If we do not have enough free buffers,
1820 * we setup a degenerate case that immediately fails. Note
1821 * that if we are specially marked process, we are allowed to
1822 * dip into our reserves.
1823 *
1824 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1825 *
1826 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1827 * However, there are a number of cases (defragging, reusing, ...)
1828 * where we cannot backup.
1829 */
1830 mtx_lock(&bqlock);
1831 nqindex = QUEUE_EMPTYKVA;
1832 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1833
1834 if (nbp == NULL) {
1835 /*
1836 * If no EMPTYKVA buffers and we are either
1837 * defragging or reusing, locate a CLEAN buffer
1838 * to free or reuse. If bufspace useage is low
1839 * skip this step so we can allocate a new buffer.
1840 */
1841 if (defrag || bufspace >= lobufspace) {
1842 nqindex = QUEUE_CLEAN;
1843 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1844 }
1845
1846 /*
1847 * If we could not find or were not allowed to reuse a
1848 * CLEAN buffer, check to see if it is ok to use an EMPTY
1849 * buffer. We can only use an EMPTY buffer if allocating
1850 * its KVA would not otherwise run us out of buffer space.
1851 */
1852 if (nbp == NULL && defrag == 0 &&
1853 bufspace + maxsize < hibufspace) {
1854 nqindex = QUEUE_EMPTY;
1855 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1856 }
1857 }
1858
1859 /*
1860 * Run scan, possibly freeing data and/or kva mappings on the fly
1861 * depending.
1862 */
1863
1864 while ((bp = nbp) != NULL) {
1865 int qindex = nqindex;
1866
1867 /*
1868 * Calculate next bp ( we can only use it if we do not block
1869 * or do other fancy things ).
1870 */
1871 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1872 switch(qindex) {
1873 case QUEUE_EMPTY:
1874 nqindex = QUEUE_EMPTYKVA;
1875 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1876 break;
1877 /* FALLTHROUGH */
1878 case QUEUE_EMPTYKVA:
1879 nqindex = QUEUE_CLEAN;
1880 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1881 break;
1882 /* FALLTHROUGH */
1883 case QUEUE_CLEAN:
1884 /*
1885 * nbp is NULL.
1886 */
1887 break;
1888 }
1889 }
1890 /*
1891 * If we are defragging then we need a buffer with
1892 * b_kvasize != 0. XXX this situation should no longer
1893 * occur, if defrag is non-zero the buffer's b_kvasize
1894 * should also be non-zero at this point. XXX
1895 */
1896 if (defrag && bp->b_kvasize == 0) {
1897 printf("Warning: defrag empty buffer %p\n", bp);
1898 continue;
1899 }
1900
1901 /*
1902 * Start freeing the bp. This is somewhat involved. nbp
1903 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1904 */
1905 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1906 continue;
1907 if (bp->b_vp) {
1908 BO_LOCK(bp->b_bufobj);
1909 if (bp->b_vflags & BV_BKGRDINPROG) {
1910 BO_UNLOCK(bp->b_bufobj);
1911 BUF_UNLOCK(bp);
1912 continue;
1913 }
1914 BO_UNLOCK(bp->b_bufobj);
1915 }
1916 CTR6(KTR_BUF,
1917 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
1918 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
1919 bp->b_kvasize, bp->b_bufsize, qindex);
1920
1921 /*
1922 * Sanity Checks
1923 */
1924 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1925
1926 /*
1927 * Note: we no longer distinguish between VMIO and non-VMIO
1928 * buffers.
1929 */
1930
1931 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1932
1933 if (bp->b_bufobj != NULL)
1934 BO_LOCK(bp->b_bufobj);
1935 bremfreel(bp);
1936 if (bp->b_bufobj != NULL)
1937 BO_UNLOCK(bp->b_bufobj);
1938 mtx_unlock(&bqlock);
1939
1940 if (qindex == QUEUE_CLEAN) {
1941 if (bp->b_flags & B_VMIO) {
1942 bp->b_flags &= ~B_ASYNC;
1943 vfs_vmio_release(bp);
1944 }
1945 if (bp->b_vp)
1946 brelvp(bp);
1947 }
1948
1949 /*
1950 * NOTE: nbp is now entirely invalid. We can only restart
1951 * the scan from this point on.
1952 *
1953 * Get the rest of the buffer freed up. b_kva* is still
1954 * valid after this operation.
1955 */
1956
1957 if (bp->b_rcred != NOCRED) {
1958 crfree(bp->b_rcred);
1959 bp->b_rcred = NOCRED;
1960 }
1961 if (bp->b_wcred != NOCRED) {
1962 crfree(bp->b_wcred);
1963 bp->b_wcred = NOCRED;
1964 }
1965 if (!LIST_EMPTY(&bp->b_dep))
1966 buf_deallocate(bp);
1967 if (bp->b_vflags & BV_BKGRDINPROG)
1968 panic("losing buffer 3");
1969 KASSERT(bp->b_vp == NULL,
1970 ("bp: %p still has vnode %p. qindex: %d",
1971 bp, bp->b_vp, qindex));
1972 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1973 ("bp: %p still on a buffer list. xflags %X",
1974 bp, bp->b_xflags));
1975
1976 if (bp->b_bufsize)
1977 allocbuf(bp, 0);
1978
1979 bp->b_flags = 0;
1980 bp->b_ioflags = 0;
1981 bp->b_xflags = 0;
1982 KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
1983 ("buf %p still counted as free?", bp));
1984 bp->b_vflags = 0;
1985 bp->b_vp = NULL;
1986 bp->b_blkno = bp->b_lblkno = 0;
1987 bp->b_offset = NOOFFSET;
1988 bp->b_iodone = 0;
1989 bp->b_error = 0;
1990 bp->b_resid = 0;
1991 bp->b_bcount = 0;
1992 bp->b_npages = 0;
1993 bp->b_dirtyoff = bp->b_dirtyend = 0;
1994 bp->b_bufobj = NULL;
1995 bp->b_pin_count = 0;
1996 bp->b_fsprivate1 = NULL;
1997 bp->b_fsprivate2 = NULL;
1998 bp->b_fsprivate3 = NULL;
1999
2000 LIST_INIT(&bp->b_dep);
2001
2002 /*
2003 * If we are defragging then free the buffer.
2004 */
2005 if (defrag) {
2006 bp->b_flags |= B_INVAL;
2007 bfreekva(bp);
2008 brelse(bp);
2009 defrag = 0;
2010 goto restart;
2011 }
2012
2013 /*
2014 * Notify any waiters for the buffer lock about
2015 * identity change by freeing the buffer.
2016 */
2017 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
2018 bp->b_flags |= B_INVAL;
2019 bfreekva(bp);
2020 brelse(bp);
2021 goto restart;
2022 }
2023
2024 /*
2025 * If we are overcomitted then recover the buffer and its
2026 * KVM space. This occurs in rare situations when multiple
2027 * processes are blocked in getnewbuf() or allocbuf().
2028 */
2029 if (bufspace >= hibufspace)
2030 flushingbufs = 1;
2031 if (flushingbufs && bp->b_kvasize != 0) {
2032 bp->b_flags |= B_INVAL;
2033 bfreekva(bp);
2034 brelse(bp);
2035 goto restart;
2036 }
2037 if (bufspace < lobufspace)
2038 flushingbufs = 0;
2039 break;
2040 }
2041
2042 /*
2043 * If we exhausted our list, sleep as appropriate. We may have to
2044 * wakeup various daemons and write out some dirty buffers.
2045 *
2046 * Generally we are sleeping due to insufficient buffer space.
2047 */
2048
2049 if (bp == NULL) {
2050 int flags, norunbuf;
2051 char *waitmsg;
2052 int fl;
2053
2054 if (defrag) {
2055 flags = VFS_BIO_NEED_BUFSPACE;
2056 waitmsg = "nbufkv";
2057 } else if (bufspace >= hibufspace) {
2058 waitmsg = "nbufbs";
2059 flags = VFS_BIO_NEED_BUFSPACE;
2060 } else {
2061 waitmsg = "newbuf";
2062 flags = VFS_BIO_NEED_ANY;
2063 }
2064 mtx_lock(&nblock);
2065 needsbuffer |= flags;
2066 mtx_unlock(&nblock);
2067 mtx_unlock(&bqlock);
2068
2069 bd_speedup(); /* heeeelp */
2070 if (gbflags & GB_NOWAIT_BD)
2071 return (NULL);
2072
2073 mtx_lock(&nblock);
2074 while (needsbuffer & flags) {
2075 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) {
2076 mtx_unlock(&nblock);
2077 /*
2078 * getblk() is called with a vnode
2079 * locked, and some majority of the
2080 * dirty buffers may as well belong to
2081 * the vnode. Flushing the buffers
2082 * there would make a progress that
2083 * cannot be achieved by the
2084 * buf_daemon, that cannot lock the
2085 * vnode.
2086 */
2087 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
2088 (td->td_pflags & TDP_NORUNNINGBUF);
2089 /* play bufdaemon */
2090 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
2091 fl = buf_do_flush(vp);
2092 td->td_pflags &= norunbuf;
2093 mtx_lock(&nblock);
2094 if (fl != 0)
2095 continue;
2096 if ((needsbuffer & flags) == 0)
2097 break;
2098 }
2099 if (msleep(&needsbuffer, &nblock,
2100 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
2101 mtx_unlock(&nblock);
2102 return (NULL);
2103 }
2104 }
2105 mtx_unlock(&nblock);
2106 } else {
2107 /*
2108 * We finally have a valid bp. We aren't quite out of the
2109 * woods, we still have to reserve kva space. In order
2110 * to keep fragmentation sane we only allocate kva in
2111 * BKVASIZE chunks.
2112 */
2113 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2114
2115 if (maxsize != bp->b_kvasize) {
2116 vm_offset_t addr = 0;
2117
2118 bfreekva(bp);
2119
2120 vm_map_lock(buffer_map);
2121 if (vm_map_findspace(buffer_map,
2122 vm_map_min(buffer_map), maxsize, &addr)) {
2123 /*
2124 * Uh oh. Buffer map is to fragmented. We
2125 * must defragment the map.
2126 */
2127 atomic_add_int(&bufdefragcnt, 1);
2128 vm_map_unlock(buffer_map);
2129 defrag = 1;
2130 bp->b_flags |= B_INVAL;
2131 brelse(bp);
2132 goto restart;
2133 }
2134 if (addr) {
2135 vm_map_insert(buffer_map, NULL, 0,
2136 addr, addr + maxsize,
2137 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
2138
2139 bp->b_kvabase = (caddr_t) addr;
2140 bp->b_kvasize = maxsize;
2141 atomic_add_long(&bufspace, bp->b_kvasize);
2142 atomic_add_int(&bufreusecnt, 1);
2143 }
2144 vm_map_unlock(buffer_map);
2145 }
2146 bp->b_saveaddr = bp->b_kvabase;
2147 bp->b_data = bp->b_saveaddr;
2148 }
2149 return(bp);
2150 }
2151
2152 /*
2153 * buf_daemon:
2154 *
2155 * buffer flushing daemon. Buffers are normally flushed by the
2156 * update daemon but if it cannot keep up this process starts to
2157 * take the load in an attempt to prevent getnewbuf() from blocking.
2158 */
2159
2160 static struct kproc_desc buf_kp = {
2161 "bufdaemon",
2162 buf_daemon,
2163 &bufdaemonproc
2164 };
2165 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2166
2167 static int
2168 buf_do_flush(struct vnode *vp)
2169 {
2170 int flushed;
2171
2172 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0);
2173 /* The list empty check here is slightly racy */
2174 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) {
2175 mtx_lock(&Giant);
2176 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0);
2177 mtx_unlock(&Giant);
2178 }
2179 if (flushed == 0) {
2180 /*
2181 * Could not find any buffers without rollback
2182 * dependencies, so just write the first one
2183 * in the hopes of eventually making progress.
2184 */
2185 flushbufqueues(vp, QUEUE_DIRTY, 1);
2186 if (!TAILQ_EMPTY(
2187 &bufqueues[QUEUE_DIRTY_GIANT])) {
2188 mtx_lock(&Giant);
2189 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1);
2190 mtx_unlock(&Giant);
2191 }
2192 }
2193 return (flushed);
2194 }
2195
2196 static void
2197 buf_daemon()
2198 {
2199 int lodirtysave;
2200
2201 /*
2202 * This process needs to be suspended prior to shutdown sync.
2203 */
2204 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2205 SHUTDOWN_PRI_LAST);
2206
2207 /*
2208 * This process is allowed to take the buffer cache to the limit
2209 */
2210 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
2211 mtx_lock(&bdlock);
2212 for (;;) {
2213 bd_request = 0;
2214 mtx_unlock(&bdlock);
2215
2216 kproc_suspend_check(bufdaemonproc);
2217 lodirtysave = lodirtybuffers;
2218 if (bd_speedupreq) {
2219 lodirtybuffers = numdirtybuffers / 2;
2220 bd_speedupreq = 0;
2221 }
2222 /*
2223 * Do the flush. Limit the amount of in-transit I/O we
2224 * allow to build up, otherwise we would completely saturate
2225 * the I/O system. Wakeup any waiting processes before we
2226 * normally would so they can run in parallel with our drain.
2227 */
2228 while (numdirtybuffers > lodirtybuffers) {
2229 if (buf_do_flush(NULL) == 0)
2230 break;
2231 kern_yield(PRI_UNCHANGED);
2232 }
2233 lodirtybuffers = lodirtysave;
2234
2235 /*
2236 * Only clear bd_request if we have reached our low water
2237 * mark. The buf_daemon normally waits 1 second and
2238 * then incrementally flushes any dirty buffers that have
2239 * built up, within reason.
2240 *
2241 * If we were unable to hit our low water mark and couldn't
2242 * find any flushable buffers, we sleep half a second.
2243 * Otherwise we loop immediately.
2244 */
2245 mtx_lock(&bdlock);
2246 if (numdirtybuffers <= lodirtybuffers) {
2247 /*
2248 * We reached our low water mark, reset the
2249 * request and sleep until we are needed again.
2250 * The sleep is just so the suspend code works.
2251 */
2252 bd_request = 0;
2253 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2254 } else {
2255 /*
2256 * We couldn't find any flushable dirty buffers but
2257 * still have too many dirty buffers, we
2258 * have to sleep and try again. (rare)
2259 */
2260 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2261 }
2262 }
2263 }
2264
2265 /*
2266 * flushbufqueues:
2267 *
2268 * Try to flush a buffer in the dirty queue. We must be careful to
2269 * free up B_INVAL buffers instead of write them, which NFS is
2270 * particularly sensitive to.
2271 */
2272 static int flushwithdeps = 0;
2273 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2274 0, "Number of buffers flushed with dependecies that require rollbacks");
2275
2276 static int
2277 flushbufqueues(struct vnode *lvp, int queue, int flushdeps)
2278 {
2279 struct buf *sentinel;
2280 struct vnode *vp;
2281 struct mount *mp;
2282 struct buf *bp;
2283 int hasdeps;
2284 int flushed;
2285 int target;
2286
2287 if (lvp == NULL) {
2288 target = numdirtybuffers - lodirtybuffers;
2289 if (flushdeps && target > 2)
2290 target /= 2;
2291 } else
2292 target = flushbufqtarget;
2293 flushed = 0;
2294 bp = NULL;
2295 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
2296 sentinel->b_qindex = QUEUE_SENTINEL;
2297 mtx_lock(&bqlock);
2298 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
2299 while (flushed != target) {
2300 bp = TAILQ_NEXT(sentinel, b_freelist);
2301 if (bp != NULL) {
2302 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2303 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
2304 b_freelist);
2305 } else
2306 break;
2307 /*
2308 * Skip sentinels inserted by other invocations of the
2309 * flushbufqueues(), taking care to not reorder them.
2310 */
2311 if (bp->b_qindex == QUEUE_SENTINEL)
2312 continue;
2313 /*
2314 * Only flush the buffers that belong to the
2315 * vnode locked by the curthread.
2316 */
2317 if (lvp != NULL && bp->b_vp != lvp)
2318 continue;
2319 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2320 continue;
2321 if (bp->b_pin_count > 0) {
2322 BUF_UNLOCK(bp);
2323 continue;
2324 }
2325 BO_LOCK(bp->b_bufobj);
2326 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2327 (bp->b_flags & B_DELWRI) == 0) {
2328 BO_UNLOCK(bp->b_bufobj);
2329 BUF_UNLOCK(bp);
2330 continue;
2331 }
2332 BO_UNLOCK(bp->b_bufobj);
2333 if (bp->b_flags & B_INVAL) {
2334 bremfreel(bp);
2335 mtx_unlock(&bqlock);
2336 brelse(bp);
2337 flushed++;
2338 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2339 mtx_lock(&bqlock);
2340 continue;
2341 }
2342
2343 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
2344 if (flushdeps == 0) {
2345 BUF_UNLOCK(bp);
2346 continue;
2347 }
2348 hasdeps = 1;
2349 } else
2350 hasdeps = 0;
2351 /*
2352 * We must hold the lock on a vnode before writing
2353 * one of its buffers. Otherwise we may confuse, or
2354 * in the case of a snapshot vnode, deadlock the
2355 * system.
2356 *
2357 * The lock order here is the reverse of the normal
2358 * of vnode followed by buf lock. This is ok because
2359 * the NOWAIT will prevent deadlock.
2360 */
2361 vp = bp->b_vp;
2362 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2363 BUF_UNLOCK(bp);
2364 continue;
2365 }
2366 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) {
2367 mtx_unlock(&bqlock);
2368 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2369 bp, bp->b_vp, bp->b_flags);
2370 if (curproc == bufdaemonproc)
2371 vfs_bio_awrite(bp);
2372 else {
2373 bremfree(bp);
2374 bwrite(bp);
2375 notbufdflashes++;
2376 }
2377 vn_finished_write(mp);
2378 VOP_UNLOCK(vp, 0);
2379 flushwithdeps += hasdeps;
2380 flushed++;
2381
2382 /*
2383 * Sleeping on runningbufspace while holding
2384 * vnode lock leads to deadlock.
2385 */
2386 if (curproc == bufdaemonproc)
2387 waitrunningbufspace();
2388 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2389 mtx_lock(&bqlock);
2390 continue;
2391 }
2392 vn_finished_write(mp);
2393 BUF_UNLOCK(bp);
2394 }
2395 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2396 mtx_unlock(&bqlock);
2397 free(sentinel, M_TEMP);
2398 return (flushed);
2399 }
2400
2401 /*
2402 * Check to see if a block is currently memory resident.
2403 */
2404 struct buf *
2405 incore(struct bufobj *bo, daddr_t blkno)
2406 {
2407 struct buf *bp;
2408
2409 BO_LOCK(bo);
2410 bp = gbincore(bo, blkno);
2411 BO_UNLOCK(bo);
2412 return (bp);
2413 }
2414
2415 /*
2416 * Returns true if no I/O is needed to access the
2417 * associated VM object. This is like incore except
2418 * it also hunts around in the VM system for the data.
2419 */
2420
2421 static int
2422 inmem(struct vnode * vp, daddr_t blkno)
2423 {
2424 vm_object_t obj;
2425 vm_offset_t toff, tinc, size;
2426 vm_page_t m;
2427 vm_ooffset_t off;
2428
2429 ASSERT_VOP_LOCKED(vp, "inmem");
2430
2431 if (incore(&vp->v_bufobj, blkno))
2432 return 1;
2433 if (vp->v_mount == NULL)
2434 return 0;
2435 obj = vp->v_object;
2436 if (obj == NULL)
2437 return (0);
2438
2439 size = PAGE_SIZE;
2440 if (size > vp->v_mount->mnt_stat.f_iosize)
2441 size = vp->v_mount->mnt_stat.f_iosize;
2442 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2443
2444 VM_OBJECT_LOCK(obj);
2445 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2446 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2447 if (!m)
2448 goto notinmem;
2449 tinc = size;
2450 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2451 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2452 if (vm_page_is_valid(m,
2453 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2454 goto notinmem;
2455 }
2456 VM_OBJECT_UNLOCK(obj);
2457 return 1;
2458
2459 notinmem:
2460 VM_OBJECT_UNLOCK(obj);
2461 return (0);
2462 }
2463
2464 /*
2465 * Set the dirty range for a buffer based on the status of the dirty
2466 * bits in the pages comprising the buffer. The range is limited
2467 * to the size of the buffer.
2468 *
2469 * Tell the VM system that the pages associated with this buffer
2470 * are clean. This is used for delayed writes where the data is
2471 * going to go to disk eventually without additional VM intevention.
2472 *
2473 * Note that while we only really need to clean through to b_bcount, we
2474 * just go ahead and clean through to b_bufsize.
2475 */
2476 static void
2477 vfs_clean_pages_dirty_buf(struct buf *bp)
2478 {
2479 vm_ooffset_t foff, noff, eoff;
2480 vm_page_t m;
2481 int i;
2482
2483 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
2484 return;
2485
2486 foff = bp->b_offset;
2487 KASSERT(bp->b_offset != NOOFFSET,
2488 ("vfs_clean_pages_dirty_buf: no buffer offset"));
2489
2490 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2491 vfs_drain_busy_pages(bp);
2492 vfs_setdirty_locked_object(bp);
2493 for (i = 0; i < bp->b_npages; i++) {
2494 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2495 eoff = noff;
2496 if (eoff > bp->b_offset + bp->b_bufsize)
2497 eoff = bp->b_offset + bp->b_bufsize;
2498 m = bp->b_pages[i];
2499 vfs_page_set_validclean(bp, foff, m);
2500 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
2501 foff = noff;
2502 }
2503 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2504 }
2505
2506 static void
2507 vfs_setdirty_locked_object(struct buf *bp)
2508 {
2509 vm_object_t object;
2510 int i;
2511
2512 object = bp->b_bufobj->bo_object;
2513 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
2514
2515 /*
2516 * We qualify the scan for modified pages on whether the
2517 * object has been flushed yet.
2518 */
2519 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
2520 vm_offset_t boffset;
2521 vm_offset_t eoffset;
2522
2523 /*
2524 * test the pages to see if they have been modified directly
2525 * by users through the VM system.
2526 */
2527 for (i = 0; i < bp->b_npages; i++)
2528 vm_page_test_dirty(bp->b_pages[i]);
2529
2530 /*
2531 * Calculate the encompassing dirty range, boffset and eoffset,
2532 * (eoffset - boffset) bytes.
2533 */
2534
2535 for (i = 0; i < bp->b_npages; i++) {
2536 if (bp->b_pages[i]->dirty)
2537 break;
2538 }
2539 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2540
2541 for (i = bp->b_npages - 1; i >= 0; --i) {
2542 if (bp->b_pages[i]->dirty) {
2543 break;
2544 }
2545 }
2546 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2547
2548 /*
2549 * Fit it to the buffer.
2550 */
2551
2552 if (eoffset > bp->b_bcount)
2553 eoffset = bp->b_bcount;
2554
2555 /*
2556 * If we have a good dirty range, merge with the existing
2557 * dirty range.
2558 */
2559
2560 if (boffset < eoffset) {
2561 if (bp->b_dirtyoff > boffset)
2562 bp->b_dirtyoff = boffset;
2563 if (bp->b_dirtyend < eoffset)
2564 bp->b_dirtyend = eoffset;
2565 }
2566 }
2567 }
2568
2569 /*
2570 * getblk:
2571 *
2572 * Get a block given a specified block and offset into a file/device.
2573 * The buffers B_DONE bit will be cleared on return, making it almost
2574 * ready for an I/O initiation. B_INVAL may or may not be set on
2575 * return. The caller should clear B_INVAL prior to initiating a
2576 * READ.
2577 *
2578 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2579 * an existing buffer.
2580 *
2581 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2582 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2583 * and then cleared based on the backing VM. If the previous buffer is
2584 * non-0-sized but invalid, B_CACHE will be cleared.
2585 *
2586 * If getblk() must create a new buffer, the new buffer is returned with
2587 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2588 * case it is returned with B_INVAL clear and B_CACHE set based on the
2589 * backing VM.
2590 *
2591 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2592 * B_CACHE bit is clear.
2593 *
2594 * What this means, basically, is that the caller should use B_CACHE to
2595 * determine whether the buffer is fully valid or not and should clear
2596 * B_INVAL prior to issuing a read. If the caller intends to validate
2597 * the buffer by loading its data area with something, the caller needs
2598 * to clear B_INVAL. If the caller does this without issuing an I/O,
2599 * the caller should set B_CACHE ( as an optimization ), else the caller
2600 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2601 * a write attempt or if it was a successfull read. If the caller
2602 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2603 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2604 */
2605 struct buf *
2606 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2607 int flags)
2608 {
2609 struct buf *bp;
2610 struct bufobj *bo;
2611 int error;
2612
2613 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
2614 ASSERT_VOP_LOCKED(vp, "getblk");
2615 if (size > MAXBSIZE)
2616 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2617
2618 bo = &vp->v_bufobj;
2619 loop:
2620 /*
2621 * Block if we are low on buffers. Certain processes are allowed
2622 * to completely exhaust the buffer cache.
2623 *
2624 * If this check ever becomes a bottleneck it may be better to
2625 * move it into the else, when gbincore() fails. At the moment
2626 * it isn't a problem.
2627 *
2628 * XXX remove if 0 sections (clean this up after its proven)
2629 */
2630 if (numfreebuffers == 0) {
2631 if (TD_IS_IDLETHREAD(curthread))
2632 return NULL;
2633 mtx_lock(&nblock);
2634 needsbuffer |= VFS_BIO_NEED_ANY;
2635 mtx_unlock(&nblock);
2636 }
2637
2638 BO_LOCK(bo);
2639 bp = gbincore(bo, blkno);
2640 if (bp != NULL) {
2641 int lockflags;
2642 /*
2643 * Buffer is in-core. If the buffer is not busy, it must
2644 * be on a queue.
2645 */
2646 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2647
2648 if (flags & GB_LOCK_NOWAIT)
2649 lockflags |= LK_NOWAIT;
2650
2651 error = BUF_TIMELOCK(bp, lockflags,
2652 BO_MTX(bo), "getblk", slpflag, slptimeo);
2653
2654 /*
2655 * If we slept and got the lock we have to restart in case
2656 * the buffer changed identities.
2657 */
2658 if (error == ENOLCK)
2659 goto loop;
2660 /* We timed out or were interrupted. */
2661 else if (error)
2662 return (NULL);
2663
2664 /*
2665 * The buffer is locked. B_CACHE is cleared if the buffer is
2666 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2667 * and for a VMIO buffer B_CACHE is adjusted according to the
2668 * backing VM cache.
2669 */
2670 if (bp->b_flags & B_INVAL)
2671 bp->b_flags &= ~B_CACHE;
2672 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2673 bp->b_flags |= B_CACHE;
2674 BO_LOCK(bo);
2675 bremfree(bp);
2676 BO_UNLOCK(bo);
2677
2678 /*
2679 * check for size inconsistancies for non-VMIO case.
2680 */
2681
2682 if (bp->b_bcount != size) {
2683 if ((bp->b_flags & B_VMIO) == 0 ||
2684 (size > bp->b_kvasize)) {
2685 if (bp->b_flags & B_DELWRI) {
2686 /*
2687 * If buffer is pinned and caller does
2688 * not want sleep waiting for it to be
2689 * unpinned, bail out
2690 * */
2691 if (bp->b_pin_count > 0) {
2692 if (flags & GB_LOCK_NOWAIT) {
2693 bqrelse(bp);
2694 return (NULL);
2695 } else {
2696 bunpin_wait(bp);
2697 }
2698 }
2699 bp->b_flags |= B_NOCACHE;
2700 bwrite(bp);
2701 } else {
2702 if (LIST_EMPTY(&bp->b_dep)) {
2703 bp->b_flags |= B_RELBUF;
2704 brelse(bp);
2705 } else {
2706 bp->b_flags |= B_NOCACHE;
2707 bwrite(bp);
2708 }
2709 }
2710 goto loop;
2711 }
2712 }
2713
2714 /*
2715 * If the size is inconsistant in the VMIO case, we can resize
2716 * the buffer. This might lead to B_CACHE getting set or
2717 * cleared. If the size has not changed, B_CACHE remains
2718 * unchanged from its previous state.
2719 */
2720
2721 if (bp->b_bcount != size)
2722 allocbuf(bp, size);
2723
2724 KASSERT(bp->b_offset != NOOFFSET,
2725 ("getblk: no buffer offset"));
2726
2727 /*
2728 * A buffer with B_DELWRI set and B_CACHE clear must
2729 * be committed before we can return the buffer in
2730 * order to prevent the caller from issuing a read
2731 * ( due to B_CACHE not being set ) and overwriting
2732 * it.
2733 *
2734 * Most callers, including NFS and FFS, need this to
2735 * operate properly either because they assume they
2736 * can issue a read if B_CACHE is not set, or because
2737 * ( for example ) an uncached B_DELWRI might loop due
2738 * to softupdates re-dirtying the buffer. In the latter
2739 * case, B_CACHE is set after the first write completes,
2740 * preventing further loops.
2741 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2742 * above while extending the buffer, we cannot allow the
2743 * buffer to remain with B_CACHE set after the write
2744 * completes or it will represent a corrupt state. To
2745 * deal with this we set B_NOCACHE to scrap the buffer
2746 * after the write.
2747 *
2748 * We might be able to do something fancy, like setting
2749 * B_CACHE in bwrite() except if B_DELWRI is already set,
2750 * so the below call doesn't set B_CACHE, but that gets real
2751 * confusing. This is much easier.
2752 */
2753
2754 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2755 bp->b_flags |= B_NOCACHE;
2756 bwrite(bp);
2757 goto loop;
2758 }
2759 bp->b_flags &= ~B_DONE;
2760 } else {
2761 int bsize, maxsize, vmio;
2762 off_t offset;
2763
2764 /*
2765 * Buffer is not in-core, create new buffer. The buffer
2766 * returned by getnewbuf() is locked. Note that the returned
2767 * buffer is also considered valid (not marked B_INVAL).
2768 */
2769 BO_UNLOCK(bo);
2770 /*
2771 * If the user does not want us to create the buffer, bail out
2772 * here.
2773 */
2774 if (flags & GB_NOCREAT)
2775 return NULL;
2776 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
2777 offset = blkno * bsize;
2778 vmio = vp->v_object != NULL;
2779 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2780 maxsize = imax(maxsize, bsize);
2781
2782 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags);
2783 if (bp == NULL) {
2784 if (slpflag || slptimeo)
2785 return NULL;
2786 goto loop;
2787 }
2788
2789 /*
2790 * This code is used to make sure that a buffer is not
2791 * created while the getnewbuf routine is blocked.
2792 * This can be a problem whether the vnode is locked or not.
2793 * If the buffer is created out from under us, we have to
2794 * throw away the one we just created.
2795 *
2796 * Note: this must occur before we associate the buffer
2797 * with the vp especially considering limitations in
2798 * the splay tree implementation when dealing with duplicate
2799 * lblkno's.
2800 */
2801 BO_LOCK(bo);
2802 if (gbincore(bo, blkno)) {
2803 BO_UNLOCK(bo);
2804 bp->b_flags |= B_INVAL;
2805 brelse(bp);
2806 goto loop;
2807 }
2808
2809 /*
2810 * Insert the buffer into the hash, so that it can
2811 * be found by incore.
2812 */
2813 bp->b_blkno = bp->b_lblkno = blkno;
2814 bp->b_offset = offset;
2815 bgetvp(vp, bp);
2816 BO_UNLOCK(bo);
2817
2818 /*
2819 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2820 * buffer size starts out as 0, B_CACHE will be set by
2821 * allocbuf() for the VMIO case prior to it testing the
2822 * backing store for validity.
2823 */
2824
2825 if (vmio) {
2826 bp->b_flags |= B_VMIO;
2827 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
2828 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
2829 bp, vp->v_object, bp->b_bufobj->bo_object));
2830 } else {
2831 bp->b_flags &= ~B_VMIO;
2832 KASSERT(bp->b_bufobj->bo_object == NULL,
2833 ("ARGH! has b_bufobj->bo_object %p %p\n",
2834 bp, bp->b_bufobj->bo_object));
2835 }
2836
2837 allocbuf(bp, size);
2838 bp->b_flags &= ~B_DONE;
2839 }
2840 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
2841 BUF_ASSERT_HELD(bp);
2842 KASSERT(bp->b_bufobj == bo,
2843 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
2844 return (bp);
2845 }
2846
2847 /*
2848 * Get an empty, disassociated buffer of given size. The buffer is initially
2849 * set to B_INVAL.
2850 */
2851 struct buf *
2852 geteblk(int size, int flags)
2853 {
2854 struct buf *bp;
2855 int maxsize;
2856
2857 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2858 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) {
2859 if ((flags & GB_NOWAIT_BD) &&
2860 (curthread->td_pflags & TDP_BUFNEED) != 0)
2861 return (NULL);
2862 }
2863 allocbuf(bp, size);
2864 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2865 BUF_ASSERT_HELD(bp);
2866 return (bp);
2867 }
2868
2869
2870 /*
2871 * This code constitutes the buffer memory from either anonymous system
2872 * memory (in the case of non-VMIO operations) or from an associated
2873 * VM object (in the case of VMIO operations). This code is able to
2874 * resize a buffer up or down.
2875 *
2876 * Note that this code is tricky, and has many complications to resolve
2877 * deadlock or inconsistant data situations. Tread lightly!!!
2878 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2879 * the caller. Calling this code willy nilly can result in the loss of data.
2880 *
2881 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2882 * B_CACHE for the non-VMIO case.
2883 */
2884
2885 int
2886 allocbuf(struct buf *bp, int size)
2887 {
2888 int newbsize, mbsize;
2889 int i;
2890
2891 BUF_ASSERT_HELD(bp);
2892
2893 if (bp->b_kvasize < size)
2894 panic("allocbuf: buffer too small");
2895
2896 if ((bp->b_flags & B_VMIO) == 0) {
2897 caddr_t origbuf;
2898 int origbufsize;
2899 /*
2900 * Just get anonymous memory from the kernel. Don't
2901 * mess with B_CACHE.
2902 */
2903 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2904 if (bp->b_flags & B_MALLOC)
2905 newbsize = mbsize;
2906 else
2907 newbsize = round_page(size);
2908
2909 if (newbsize < bp->b_bufsize) {
2910 /*
2911 * malloced buffers are not shrunk
2912 */
2913 if (bp->b_flags & B_MALLOC) {
2914 if (newbsize) {
2915 bp->b_bcount = size;
2916 } else {
2917 free(bp->b_data, M_BIOBUF);
2918 if (bp->b_bufsize) {
2919 atomic_subtract_long(
2920 &bufmallocspace,
2921 bp->b_bufsize);
2922 bufspacewakeup();
2923 bp->b_bufsize = 0;
2924 }
2925 bp->b_saveaddr = bp->b_kvabase;
2926 bp->b_data = bp->b_saveaddr;
2927 bp->b_bcount = 0;
2928 bp->b_flags &= ~B_MALLOC;
2929 }
2930 return 1;
2931 }
2932 vm_hold_free_pages(bp, newbsize);
2933 } else if (newbsize > bp->b_bufsize) {
2934 /*
2935 * We only use malloced memory on the first allocation.
2936 * and revert to page-allocated memory when the buffer
2937 * grows.
2938 */
2939 /*
2940 * There is a potential smp race here that could lead
2941 * to bufmallocspace slightly passing the max. It
2942 * is probably extremely rare and not worth worrying
2943 * over.
2944 */
2945 if ( (bufmallocspace < maxbufmallocspace) &&
2946 (bp->b_bufsize == 0) &&
2947 (mbsize <= PAGE_SIZE/2)) {
2948
2949 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2950 bp->b_bufsize = mbsize;
2951 bp->b_bcount = size;
2952 bp->b_flags |= B_MALLOC;
2953 atomic_add_long(&bufmallocspace, mbsize);
2954 return 1;
2955 }
2956 origbuf = NULL;
2957 origbufsize = 0;
2958 /*
2959 * If the buffer is growing on its other-than-first allocation,
2960 * then we revert to the page-allocation scheme.
2961 */
2962 if (bp->b_flags & B_MALLOC) {
2963 origbuf = bp->b_data;
2964 origbufsize = bp->b_bufsize;
2965 bp->b_data = bp->b_kvabase;
2966 if (bp->b_bufsize) {
2967 atomic_subtract_long(&bufmallocspace,
2968 bp->b_bufsize);
2969 bufspacewakeup();
2970 bp->b_bufsize = 0;
2971 }
2972 bp->b_flags &= ~B_MALLOC;
2973 newbsize = round_page(newbsize);
2974 }
2975 vm_hold_load_pages(
2976 bp,
2977 (vm_offset_t) bp->b_data + bp->b_bufsize,
2978 (vm_offset_t) bp->b_data + newbsize);
2979 if (origbuf) {
2980 bcopy(origbuf, bp->b_data, origbufsize);
2981 free(origbuf, M_BIOBUF);
2982 }
2983 }
2984 } else {
2985 int desiredpages;
2986
2987 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2988 desiredpages = (size == 0) ? 0 :
2989 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2990
2991 if (bp->b_flags & B_MALLOC)
2992 panic("allocbuf: VMIO buffer can't be malloced");
2993 /*
2994 * Set B_CACHE initially if buffer is 0 length or will become
2995 * 0-length.
2996 */
2997 if (size == 0 || bp->b_bufsize == 0)
2998 bp->b_flags |= B_CACHE;
2999
3000 if (newbsize < bp->b_bufsize) {
3001 /*
3002 * DEV_BSIZE aligned new buffer size is less then the
3003 * DEV_BSIZE aligned existing buffer size. Figure out
3004 * if we have to remove any pages.
3005 */
3006 if (desiredpages < bp->b_npages) {
3007 vm_page_t m;
3008
3009 pmap_qremove((vm_offset_t)trunc_page(
3010 (vm_offset_t)bp->b_data) +
3011 (desiredpages << PAGE_SHIFT),
3012 (bp->b_npages - desiredpages));
3013 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3014 for (i = desiredpages; i < bp->b_npages; i++) {
3015 /*
3016 * the page is not freed here -- it
3017 * is the responsibility of
3018 * vnode_pager_setsize
3019 */
3020 m = bp->b_pages[i];
3021 KASSERT(m != bogus_page,
3022 ("allocbuf: bogus page found"));
3023 while (vm_page_sleep_if_busy(m, TRUE,
3024 "biodep"))
3025 continue;
3026
3027 bp->b_pages[i] = NULL;
3028 vm_page_lock(m);
3029 vm_page_unwire(m, 0);
3030 vm_page_unlock(m);
3031 }
3032 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3033 bp->b_npages = desiredpages;
3034 }
3035 } else if (size > bp->b_bcount) {
3036 /*
3037 * We are growing the buffer, possibly in a
3038 * byte-granular fashion.
3039 */
3040 vm_object_t obj;
3041 vm_offset_t toff;
3042 vm_offset_t tinc;
3043
3044 /*
3045 * Step 1, bring in the VM pages from the object,
3046 * allocating them if necessary. We must clear
3047 * B_CACHE if these pages are not valid for the
3048 * range covered by the buffer.
3049 */
3050
3051 obj = bp->b_bufobj->bo_object;
3052
3053 VM_OBJECT_LOCK(obj);
3054 while (bp->b_npages < desiredpages) {
3055 vm_page_t m;
3056
3057 /*
3058 * We must allocate system pages since blocking
3059 * here could interfere with paging I/O, no
3060 * matter which process we are.
3061 *
3062 * We can only test VPO_BUSY here. Blocking on
3063 * m->busy might lead to a deadlock:
3064 * vm_fault->getpages->cluster_read->allocbuf
3065 * Thus, we specify VM_ALLOC_IGN_SBUSY.
3066 */
3067 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
3068 bp->b_npages, VM_ALLOC_NOBUSY |
3069 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
3070 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY |
3071 VM_ALLOC_COUNT(desiredpages - bp->b_npages));
3072 if (m->valid == 0)
3073 bp->b_flags &= ~B_CACHE;
3074 bp->b_pages[bp->b_npages] = m;
3075 ++bp->b_npages;
3076 }
3077
3078 /*
3079 * Step 2. We've loaded the pages into the buffer,
3080 * we have to figure out if we can still have B_CACHE
3081 * set. Note that B_CACHE is set according to the
3082 * byte-granular range ( bcount and size ), new the
3083 * aligned range ( newbsize ).
3084 *
3085 * The VM test is against m->valid, which is DEV_BSIZE
3086 * aligned. Needless to say, the validity of the data
3087 * needs to also be DEV_BSIZE aligned. Note that this
3088 * fails with NFS if the server or some other client
3089 * extends the file's EOF. If our buffer is resized,
3090 * B_CACHE may remain set! XXX
3091 */
3092
3093 toff = bp->b_bcount;
3094 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3095
3096 while ((bp->b_flags & B_CACHE) && toff < size) {
3097 vm_pindex_t pi;
3098
3099 if (tinc > (size - toff))
3100 tinc = size - toff;
3101
3102 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
3103 PAGE_SHIFT;
3104
3105 vfs_buf_test_cache(
3106 bp,
3107 bp->b_offset,
3108 toff,
3109 tinc,
3110 bp->b_pages[pi]
3111 );
3112 toff += tinc;
3113 tinc = PAGE_SIZE;
3114 }
3115 VM_OBJECT_UNLOCK(obj);
3116
3117 /*
3118 * Step 3, fixup the KVM pmap. Remember that
3119 * bp->b_data is relative to bp->b_offset, but
3120 * bp->b_offset may be offset into the first page.
3121 */
3122
3123 bp->b_data = (caddr_t)
3124 trunc_page((vm_offset_t)bp->b_data);
3125 pmap_qenter(
3126 (vm_offset_t)bp->b_data,
3127 bp->b_pages,
3128 bp->b_npages
3129 );
3130
3131 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
3132 (vm_offset_t)(bp->b_offset & PAGE_MASK));
3133 }
3134 }
3135 if (newbsize < bp->b_bufsize)
3136 bufspacewakeup();
3137 bp->b_bufsize = newbsize; /* actual buffer allocation */
3138 bp->b_bcount = size; /* requested buffer size */
3139 return 1;
3140 }
3141
3142 void
3143 biodone(struct bio *bp)
3144 {
3145 struct mtx *mtxp;
3146 void (*done)(struct bio *);
3147
3148 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3149 mtx_lock(mtxp);
3150 bp->bio_flags |= BIO_DONE;
3151 done = bp->bio_done;
3152 if (done == NULL)
3153 wakeup(bp);
3154 mtx_unlock(mtxp);
3155 if (done != NULL)
3156 done(bp);
3157 }
3158
3159 /*
3160 * Wait for a BIO to finish.
3161 *
3162 * XXX: resort to a timeout for now. The optimal locking (if any) for this
3163 * case is not yet clear.
3164 */
3165 int
3166 biowait(struct bio *bp, const char *wchan)
3167 {
3168 struct mtx *mtxp;
3169
3170 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3171 mtx_lock(mtxp);
3172 while ((bp->bio_flags & BIO_DONE) == 0)
3173 msleep(bp, mtxp, PRIBIO, wchan, hz / 10);
3174 mtx_unlock(mtxp);
3175 if (bp->bio_error != 0)
3176 return (bp->bio_error);
3177 if (!(bp->bio_flags & BIO_ERROR))
3178 return (0);
3179 return (EIO);
3180 }
3181
3182 void
3183 biofinish(struct bio *bp, struct devstat *stat, int error)
3184 {
3185
3186 if (error) {
3187 bp->bio_error = error;
3188 bp->bio_flags |= BIO_ERROR;
3189 }
3190 if (stat != NULL)
3191 devstat_end_transaction_bio(stat, bp);
3192 biodone(bp);
3193 }
3194
3195 /*
3196 * bufwait:
3197 *
3198 * Wait for buffer I/O completion, returning error status. The buffer
3199 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3200 * error and cleared.
3201 */
3202 int
3203 bufwait(struct buf *bp)
3204 {
3205 if (bp->b_iocmd == BIO_READ)
3206 bwait(bp, PRIBIO, "biord");
3207 else
3208 bwait(bp, PRIBIO, "biowr");
3209 if (bp->b_flags & B_EINTR) {
3210 bp->b_flags &= ~B_EINTR;
3211 return (EINTR);
3212 }
3213 if (bp->b_ioflags & BIO_ERROR) {
3214 return (bp->b_error ? bp->b_error : EIO);
3215 } else {
3216 return (0);
3217 }
3218 }
3219
3220 /*
3221 * Call back function from struct bio back up to struct buf.
3222 */
3223 static void
3224 bufdonebio(struct bio *bip)
3225 {
3226 struct buf *bp;
3227
3228 bp = bip->bio_caller2;
3229 bp->b_resid = bp->b_bcount - bip->bio_completed;
3230 bp->b_resid = bip->bio_resid; /* XXX: remove */
3231 bp->b_ioflags = bip->bio_flags;
3232 bp->b_error = bip->bio_error;
3233 if (bp->b_error)
3234 bp->b_ioflags |= BIO_ERROR;
3235 bufdone(bp);
3236 g_destroy_bio(bip);
3237 }
3238
3239 void
3240 dev_strategy(struct cdev *dev, struct buf *bp)
3241 {
3242 struct cdevsw *csw;
3243 struct bio *bip;
3244 int ref;
3245
3246 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
3247 panic("b_iocmd botch");
3248 for (;;) {
3249 bip = g_new_bio();
3250 if (bip != NULL)
3251 break;
3252 /* Try again later */
3253 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3254 }
3255 bip->bio_cmd = bp->b_iocmd;
3256 bip->bio_offset = bp->b_iooffset;
3257 bip->bio_length = bp->b_bcount;
3258 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3259 bip->bio_data = bp->b_data;
3260 bip->bio_done = bufdonebio;
3261 bip->bio_caller2 = bp;
3262 bip->bio_dev = dev;
3263 KASSERT(dev->si_refcount > 0,
3264 ("dev_strategy on un-referenced struct cdev *(%s)",
3265 devtoname(dev)));
3266 csw = dev_refthread(dev, &ref);
3267 if (csw == NULL) {
3268 g_destroy_bio(bip);
3269 bp->b_error = ENXIO;
3270 bp->b_ioflags = BIO_ERROR;
3271 bufdone(bp);
3272 return;
3273 }
3274 (*csw->d_strategy)(bip);
3275 dev_relthread(dev, ref);
3276 }
3277
3278 /*
3279 * bufdone:
3280 *
3281 * Finish I/O on a buffer, optionally calling a completion function.
3282 * This is usually called from an interrupt so process blocking is
3283 * not allowed.
3284 *
3285 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3286 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3287 * assuming B_INVAL is clear.
3288 *
3289 * For the VMIO case, we set B_CACHE if the op was a read and no
3290 * read error occured, or if the op was a write. B_CACHE is never
3291 * set if the buffer is invalid or otherwise uncacheable.
3292 *
3293 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3294 * initiator to leave B_INVAL set to brelse the buffer out of existance
3295 * in the biodone routine.
3296 */
3297 void
3298 bufdone(struct buf *bp)
3299 {
3300 struct bufobj *dropobj;
3301 void (*biodone)(struct buf *);
3302
3303 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3304 dropobj = NULL;
3305
3306 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3307 BUF_ASSERT_HELD(bp);
3308
3309 runningbufwakeup(bp);
3310 if (bp->b_iocmd == BIO_WRITE)
3311 dropobj = bp->b_bufobj;
3312 /* call optional completion function if requested */
3313 if (bp->b_iodone != NULL) {
3314 biodone = bp->b_iodone;
3315 bp->b_iodone = NULL;
3316 (*biodone) (bp);
3317 if (dropobj)
3318 bufobj_wdrop(dropobj);
3319 return;
3320 }
3321
3322 bufdone_finish(bp);
3323
3324 if (dropobj)
3325 bufobj_wdrop(dropobj);
3326 }
3327
3328 void
3329 bufdone_finish(struct buf *bp)
3330 {
3331 BUF_ASSERT_HELD(bp);
3332
3333 if (!LIST_EMPTY(&bp->b_dep))
3334 buf_complete(bp);
3335
3336 if (bp->b_flags & B_VMIO) {
3337 vm_ooffset_t foff;
3338 vm_page_t m;
3339 vm_object_t obj;
3340 struct vnode *vp;
3341 int bogus, i, iosize;
3342
3343 obj = bp->b_bufobj->bo_object;
3344 KASSERT(obj->paging_in_progress >= bp->b_npages,
3345 ("biodone_finish: paging in progress(%d) < b_npages(%d)",
3346 obj->paging_in_progress, bp->b_npages));
3347
3348 vp = bp->b_vp;
3349 KASSERT(vp->v_holdcnt > 0,
3350 ("biodone_finish: vnode %p has zero hold count", vp));
3351 KASSERT(vp->v_object != NULL,
3352 ("biodone_finish: vnode %p has no vm_object", vp));
3353
3354 foff = bp->b_offset;
3355 KASSERT(bp->b_offset != NOOFFSET,
3356 ("biodone_finish: bp %p has no buffer offset", bp));
3357
3358 /*
3359 * Set B_CACHE if the op was a normal read and no error
3360 * occured. B_CACHE is set for writes in the b*write()
3361 * routines.
3362 */
3363 iosize = bp->b_bcount - bp->b_resid;
3364 if (bp->b_iocmd == BIO_READ &&
3365 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3366 !(bp->b_ioflags & BIO_ERROR)) {
3367 bp->b_flags |= B_CACHE;
3368 }
3369 bogus = 0;
3370 VM_OBJECT_LOCK(obj);
3371 for (i = 0; i < bp->b_npages; i++) {
3372 int bogusflag = 0;
3373 int resid;
3374
3375 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3376 if (resid > iosize)
3377 resid = iosize;
3378
3379 /*
3380 * cleanup bogus pages, restoring the originals
3381 */
3382 m = bp->b_pages[i];
3383 if (m == bogus_page) {
3384 bogus = bogusflag = 1;
3385 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3386 if (m == NULL)
3387 panic("biodone: page disappeared!");
3388 bp->b_pages[i] = m;
3389 }
3390 KASSERT(OFF_TO_IDX(foff) == m->pindex,
3391 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch",
3392 (intmax_t)foff, (uintmax_t)m->pindex));
3393
3394 /*
3395 * In the write case, the valid and clean bits are
3396 * already changed correctly ( see bdwrite() ), so we
3397 * only need to do this here in the read case.
3398 */
3399 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3400 KASSERT((m->dirty & vm_page_bits(foff &
3401 PAGE_MASK, resid)) == 0, ("bufdone_finish:"
3402 " page %p has unexpected dirty bits", m));
3403 vfs_page_set_valid(bp, foff, m);
3404 }
3405
3406 vm_page_io_finish(m);
3407 vm_object_pip_subtract(obj, 1);
3408 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3409 iosize -= resid;
3410 }
3411 vm_object_pip_wakeupn(obj, 0);
3412 VM_OBJECT_UNLOCK(obj);
3413 if (bogus)
3414 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3415 bp->b_pages, bp->b_npages);
3416 }
3417
3418 /*
3419 * For asynchronous completions, release the buffer now. The brelse
3420 * will do a wakeup there if necessary - so no need to do a wakeup
3421 * here in the async case. The sync case always needs to do a wakeup.
3422 */
3423
3424 if (bp->b_flags & B_ASYNC) {
3425 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3426 brelse(bp);
3427 else
3428 bqrelse(bp);
3429 } else
3430 bdone(bp);
3431 }
3432
3433 /*
3434 * This routine is called in lieu of iodone in the case of
3435 * incomplete I/O. This keeps the busy status for pages
3436 * consistant.
3437 */
3438 void
3439 vfs_unbusy_pages(struct buf *bp)
3440 {
3441 int i;
3442 vm_object_t obj;
3443 vm_page_t m;
3444
3445 runningbufwakeup(bp);
3446 if (!(bp->b_flags & B_VMIO))
3447 return;
3448
3449 obj = bp->b_bufobj->bo_object;
3450 VM_OBJECT_LOCK(obj);
3451 for (i = 0; i < bp->b_npages; i++) {
3452 m = bp->b_pages[i];
3453 if (m == bogus_page) {
3454 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3455 if (!m)
3456 panic("vfs_unbusy_pages: page missing\n");
3457 bp->b_pages[i] = m;
3458 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3459 bp->b_pages, bp->b_npages);
3460 }
3461 vm_object_pip_subtract(obj, 1);
3462 vm_page_io_finish(m);
3463 }
3464 vm_object_pip_wakeupn(obj, 0);
3465 VM_OBJECT_UNLOCK(obj);
3466 }
3467
3468 /*
3469 * vfs_page_set_valid:
3470 *
3471 * Set the valid bits in a page based on the supplied offset. The
3472 * range is restricted to the buffer's size.
3473 *
3474 * This routine is typically called after a read completes.
3475 */
3476 static void
3477 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3478 {
3479 vm_ooffset_t eoff;
3480
3481 /*
3482 * Compute the end offset, eoff, such that [off, eoff) does not span a
3483 * page boundary and eoff is not greater than the end of the buffer.
3484 * The end of the buffer, in this case, is our file EOF, not the
3485 * allocation size of the buffer.
3486 */
3487 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
3488 if (eoff > bp->b_offset + bp->b_bcount)
3489 eoff = bp->b_offset + bp->b_bcount;
3490
3491 /*
3492 * Set valid range. This is typically the entire buffer and thus the
3493 * entire page.
3494 */
3495 if (eoff > off)
3496 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
3497 }
3498
3499 /*
3500 * vfs_page_set_validclean:
3501 *
3502 * Set the valid bits and clear the dirty bits in a page based on the
3503 * supplied offset. The range is restricted to the buffer's size.
3504 */
3505 static void
3506 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3507 {
3508 vm_ooffset_t soff, eoff;
3509
3510 /*
3511 * Start and end offsets in buffer. eoff - soff may not cross a
3512 * page boundry or cross the end of the buffer. The end of the
3513 * buffer, in this case, is our file EOF, not the allocation size
3514 * of the buffer.
3515 */
3516 soff = off;
3517 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3518 if (eoff > bp->b_offset + bp->b_bcount)
3519 eoff = bp->b_offset + bp->b_bcount;
3520
3521 /*
3522 * Set valid range. This is typically the entire buffer and thus the
3523 * entire page.
3524 */
3525 if (eoff > soff) {
3526 vm_page_set_validclean(
3527 m,
3528 (vm_offset_t) (soff & PAGE_MASK),
3529 (vm_offset_t) (eoff - soff)
3530 );
3531 }
3532 }
3533
3534 /*
3535 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If
3536 * any page is busy, drain the flag.
3537 */
3538 static void
3539 vfs_drain_busy_pages(struct buf *bp)
3540 {
3541 vm_page_t m;
3542 int i, last_busied;
3543
3544 VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED);
3545 last_busied = 0;
3546 for (i = 0; i < bp->b_npages; i++) {
3547 m = bp->b_pages[i];
3548 if ((m->oflags & VPO_BUSY) != 0) {
3549 for (; last_busied < i; last_busied++)
3550 vm_page_busy(bp->b_pages[last_busied]);
3551 while ((m->oflags & VPO_BUSY) != 0)
3552 vm_page_sleep(m, "vbpage");
3553 }
3554 }
3555 for (i = 0; i < last_busied; i++)
3556 vm_page_wakeup(bp->b_pages[i]);
3557 }
3558
3559 /*
3560 * This routine is called before a device strategy routine.
3561 * It is used to tell the VM system that paging I/O is in
3562 * progress, and treat the pages associated with the buffer
3563 * almost as being VPO_BUSY. Also the object paging_in_progress
3564 * flag is handled to make sure that the object doesn't become
3565 * inconsistant.
3566 *
3567 * Since I/O has not been initiated yet, certain buffer flags
3568 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3569 * and should be ignored.
3570 */
3571 void
3572 vfs_busy_pages(struct buf *bp, int clear_modify)
3573 {
3574 int i, bogus;
3575 vm_object_t obj;
3576 vm_ooffset_t foff;
3577 vm_page_t m;
3578
3579 if (!(bp->b_flags & B_VMIO))
3580 return;
3581
3582 obj = bp->b_bufobj->bo_object;
3583 foff = bp->b_offset;
3584 KASSERT(bp->b_offset != NOOFFSET,
3585 ("vfs_busy_pages: no buffer offset"));
3586 VM_OBJECT_LOCK(obj);
3587 vfs_drain_busy_pages(bp);
3588 if (bp->b_bufsize != 0)
3589 vfs_setdirty_locked_object(bp);
3590 bogus = 0;
3591 for (i = 0; i < bp->b_npages; i++) {
3592 m = bp->b_pages[i];
3593
3594 if ((bp->b_flags & B_CLUSTER) == 0) {
3595 vm_object_pip_add(obj, 1);
3596 vm_page_io_start(m);
3597 }
3598 /*
3599 * When readying a buffer for a read ( i.e
3600 * clear_modify == 0 ), it is important to do
3601 * bogus_page replacement for valid pages in
3602 * partially instantiated buffers. Partially
3603 * instantiated buffers can, in turn, occur when
3604 * reconstituting a buffer from its VM backing store
3605 * base. We only have to do this if B_CACHE is
3606 * clear ( which causes the I/O to occur in the
3607 * first place ). The replacement prevents the read
3608 * I/O from overwriting potentially dirty VM-backed
3609 * pages. XXX bogus page replacement is, uh, bogus.
3610 * It may not work properly with small-block devices.
3611 * We need to find a better way.
3612 */
3613 if (clear_modify) {
3614 pmap_remove_write(m);
3615 vfs_page_set_validclean(bp, foff, m);
3616 } else if (m->valid == VM_PAGE_BITS_ALL &&
3617 (bp->b_flags & B_CACHE) == 0) {
3618 bp->b_pages[i] = bogus_page;
3619 bogus++;
3620 }
3621 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3622 }
3623 VM_OBJECT_UNLOCK(obj);
3624 if (bogus)
3625 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3626 bp->b_pages, bp->b_npages);
3627 }
3628
3629 /*
3630 * vfs_bio_set_valid:
3631 *
3632 * Set the range within the buffer to valid. The range is
3633 * relative to the beginning of the buffer, b_offset. Note that
3634 * b_offset itself may be offset from the beginning of the first
3635 * page.
3636 */
3637 void
3638 vfs_bio_set_valid(struct buf *bp, int base, int size)
3639 {
3640 int i, n;
3641 vm_page_t m;
3642
3643 if (!(bp->b_flags & B_VMIO))
3644 return;
3645
3646 /*
3647 * Fixup base to be relative to beginning of first page.
3648 * Set initial n to be the maximum number of bytes in the
3649 * first page that can be validated.
3650 */
3651 base += (bp->b_offset & PAGE_MASK);
3652 n = PAGE_SIZE - (base & PAGE_MASK);
3653
3654 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3655 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3656 m = bp->b_pages[i];
3657 if (n > size)
3658 n = size;
3659 vm_page_set_valid_range(m, base & PAGE_MASK, n);
3660 base += n;
3661 size -= n;
3662 n = PAGE_SIZE;
3663 }
3664 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3665 }
3666
3667 /*
3668 * vfs_bio_clrbuf:
3669 *
3670 * If the specified buffer is a non-VMIO buffer, clear the entire
3671 * buffer. If the specified buffer is a VMIO buffer, clear and
3672 * validate only the previously invalid portions of the buffer.
3673 * This routine essentially fakes an I/O, so we need to clear
3674 * BIO_ERROR and B_INVAL.
3675 *
3676 * Note that while we only theoretically need to clear through b_bcount,
3677 * we go ahead and clear through b_bufsize.
3678 */
3679 void
3680 vfs_bio_clrbuf(struct buf *bp)
3681 {
3682 int i, j, mask;
3683 caddr_t sa, ea;
3684
3685 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
3686 clrbuf(bp);
3687 return;
3688 }
3689 bp->b_flags &= ~B_INVAL;
3690 bp->b_ioflags &= ~BIO_ERROR;
3691 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3692 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3693 (bp->b_offset & PAGE_MASK) == 0) {
3694 if (bp->b_pages[0] == bogus_page)
3695 goto unlock;
3696 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3697 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3698 if ((bp->b_pages[0]->valid & mask) == mask)
3699 goto unlock;
3700 if ((bp->b_pages[0]->valid & mask) == 0) {
3701 bzero(bp->b_data, bp->b_bufsize);
3702 bp->b_pages[0]->valid |= mask;
3703 goto unlock;
3704 }
3705 }
3706 ea = sa = bp->b_data;
3707 for(i = 0; i < bp->b_npages; i++, sa = ea) {
3708 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3709 ea = (caddr_t)(vm_offset_t)ulmin(
3710 (u_long)(vm_offset_t)ea,
3711 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3712 if (bp->b_pages[i] == bogus_page)
3713 continue;
3714 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3715 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3716 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3717 if ((bp->b_pages[i]->valid & mask) == mask)
3718 continue;
3719 if ((bp->b_pages[i]->valid & mask) == 0)
3720 bzero(sa, ea - sa);
3721 else {
3722 for (; sa < ea; sa += DEV_BSIZE, j++) {
3723 if ((bp->b_pages[i]->valid & (1 << j)) == 0)
3724 bzero(sa, DEV_BSIZE);
3725 }
3726 }
3727 bp->b_pages[i]->valid |= mask;
3728 }
3729 unlock:
3730 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3731 bp->b_resid = 0;
3732 }
3733
3734 /*
3735 * vm_hold_load_pages and vm_hold_free_pages get pages into
3736 * a buffers address space. The pages are anonymous and are
3737 * not associated with a file object.
3738 */
3739 static void
3740 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3741 {
3742 vm_offset_t pg;
3743 vm_page_t p;
3744 int index;
3745
3746 to = round_page(to);
3747 from = round_page(from);
3748 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3749
3750 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3751 tryagain:
3752 /*
3753 * note: must allocate system pages since blocking here
3754 * could interfere with paging I/O, no matter which
3755 * process we are.
3756 */
3757 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
3758 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
3759 if (p == NULL) {
3760 VM_WAIT;
3761 goto tryagain;
3762 }
3763 pmap_qenter(pg, &p, 1);
3764 bp->b_pages[index] = p;
3765 }
3766 bp->b_npages = index;
3767 }
3768
3769 /* Return pages associated with this buf to the vm system */
3770 static void
3771 vm_hold_free_pages(struct buf *bp, int newbsize)
3772 {
3773 vm_offset_t from;
3774 vm_page_t p;
3775 int index, newnpages;
3776
3777 from = round_page((vm_offset_t)bp->b_data + newbsize);
3778 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3779 if (bp->b_npages > newnpages)
3780 pmap_qremove(from, bp->b_npages - newnpages);
3781 for (index = newnpages; index < bp->b_npages; index++) {
3782 p = bp->b_pages[index];
3783 bp->b_pages[index] = NULL;
3784 if (p->busy != 0)
3785 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3786 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
3787 p->wire_count--;
3788 vm_page_free(p);
3789 atomic_subtract_int(&cnt.v_wire_count, 1);
3790 }
3791 bp->b_npages = newnpages;
3792 }
3793
3794 /*
3795 * Map an IO request into kernel virtual address space.
3796 *
3797 * All requests are (re)mapped into kernel VA space.
3798 * Notice that we use b_bufsize for the size of the buffer
3799 * to be mapped. b_bcount might be modified by the driver.
3800 *
3801 * Note that even if the caller determines that the address space should
3802 * be valid, a race or a smaller-file mapped into a larger space may
3803 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3804 * check the return value.
3805 */
3806 int
3807 vmapbuf(struct buf *bp)
3808 {
3809 caddr_t kva;
3810 vm_prot_t prot;
3811 int pidx;
3812
3813 if (bp->b_bufsize < 0)
3814 return (-1);
3815 prot = VM_PROT_READ;
3816 if (bp->b_iocmd == BIO_READ)
3817 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
3818 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
3819 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
3820 btoc(MAXPHYS))) < 0)
3821 return (-1);
3822 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3823
3824 kva = bp->b_saveaddr;
3825 bp->b_npages = pidx;
3826 bp->b_saveaddr = bp->b_data;
3827 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3828 return(0);
3829 }
3830
3831 /*
3832 * Free the io map PTEs associated with this IO operation.
3833 * We also invalidate the TLB entries and restore the original b_addr.
3834 */
3835 void
3836 vunmapbuf(struct buf *bp)
3837 {
3838 int npages;
3839
3840 npages = bp->b_npages;
3841 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
3842 vm_page_unhold_pages(bp->b_pages, npages);
3843
3844 bp->b_data = bp->b_saveaddr;
3845 }
3846
3847 void
3848 bdone(struct buf *bp)
3849 {
3850 struct mtx *mtxp;
3851
3852 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3853 mtx_lock(mtxp);
3854 bp->b_flags |= B_DONE;
3855 wakeup(bp);
3856 mtx_unlock(mtxp);
3857 }
3858
3859 void
3860 bwait(struct buf *bp, u_char pri, const char *wchan)
3861 {
3862 struct mtx *mtxp;
3863
3864 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3865 mtx_lock(mtxp);
3866 while ((bp->b_flags & B_DONE) == 0)
3867 msleep(bp, mtxp, pri, wchan, 0);
3868 mtx_unlock(mtxp);
3869 }
3870
3871 int
3872 bufsync(struct bufobj *bo, int waitfor)
3873 {
3874
3875 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
3876 }
3877
3878 void
3879 bufstrategy(struct bufobj *bo, struct buf *bp)
3880 {
3881 int i = 0;
3882 struct vnode *vp;
3883
3884 vp = bp->b_vp;
3885 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
3886 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
3887 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
3888 i = VOP_STRATEGY(vp, bp);
3889 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
3890 }
3891
3892 void
3893 bufobj_wrefl(struct bufobj *bo)
3894 {
3895
3896 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3897 ASSERT_BO_LOCKED(bo);
3898 bo->bo_numoutput++;
3899 }
3900
3901 void
3902 bufobj_wref(struct bufobj *bo)
3903 {
3904
3905 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3906 BO_LOCK(bo);
3907 bo->bo_numoutput++;
3908 BO_UNLOCK(bo);
3909 }
3910
3911 void
3912 bufobj_wdrop(struct bufobj *bo)
3913 {
3914
3915 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
3916 BO_LOCK(bo);
3917 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
3918 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
3919 bo->bo_flag &= ~BO_WWAIT;
3920 wakeup(&bo->bo_numoutput);
3921 }
3922 BO_UNLOCK(bo);
3923 }
3924
3925 int
3926 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
3927 {
3928 int error;
3929
3930 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
3931 ASSERT_BO_LOCKED(bo);
3932 error = 0;
3933 while (bo->bo_numoutput) {
3934 bo->bo_flag |= BO_WWAIT;
3935 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
3936 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
3937 if (error)
3938 break;
3939 }
3940 return (error);
3941 }
3942
3943 void
3944 bpin(struct buf *bp)
3945 {
3946 struct mtx *mtxp;
3947
3948 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3949 mtx_lock(mtxp);
3950 bp->b_pin_count++;
3951 mtx_unlock(mtxp);
3952 }
3953
3954 void
3955 bunpin(struct buf *bp)
3956 {
3957 struct mtx *mtxp;
3958
3959 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3960 mtx_lock(mtxp);
3961 if (--bp->b_pin_count == 0)
3962 wakeup(bp);
3963 mtx_unlock(mtxp);
3964 }
3965
3966 void
3967 bunpin_wait(struct buf *bp)
3968 {
3969 struct mtx *mtxp;
3970
3971 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3972 mtx_lock(mtxp);
3973 while (bp->b_pin_count > 0)
3974 msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
3975 mtx_unlock(mtxp);
3976 }
3977
3978 #include "opt_ddb.h"
3979 #ifdef DDB
3980 #include <ddb/ddb.h>
3981
3982 /* DDB command to show buffer data */
3983 DB_SHOW_COMMAND(buffer, db_show_buffer)
3984 {
3985 /* get args */
3986 struct buf *bp = (struct buf *)addr;
3987
3988 if (!have_addr) {
3989 db_printf("usage: show buffer <addr>\n");
3990 return;
3991 }
3992
3993 db_printf("buf at %p\n", bp);
3994 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3995 db_printf(
3996 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
3997 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
3998 "b_dep = %p\n",
3999 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4000 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4001 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
4002 if (bp->b_npages) {
4003 int i;
4004 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4005 for (i = 0; i < bp->b_npages; i++) {
4006 vm_page_t m;
4007 m = bp->b_pages[i];
4008 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4009 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4010 if ((i + 1) < bp->b_npages)
4011 db_printf(",");
4012 }
4013 db_printf("\n");
4014 }
4015 db_printf(" ");
4016 BUF_LOCKPRINTINFO(bp);
4017 }
4018
4019 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4020 {
4021 struct buf *bp;
4022 int i;
4023
4024 for (i = 0; i < nbuf; i++) {
4025 bp = &buf[i];
4026 if (BUF_ISLOCKED(bp)) {
4027 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4028 db_printf("\n");
4029 }
4030 }
4031 }
4032
4033 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
4034 {
4035 struct vnode *vp;
4036 struct buf *bp;
4037
4038 if (!have_addr) {
4039 db_printf("usage: show vnodebufs <addr>\n");
4040 return;
4041 }
4042 vp = (struct vnode *)addr;
4043 db_printf("Clean buffers:\n");
4044 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
4045 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4046 db_printf("\n");
4047 }
4048 db_printf("Dirty buffers:\n");
4049 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
4050 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4051 db_printf("\n");
4052 }
4053 }
4054
4055 DB_COMMAND(countfreebufs, db_coundfreebufs)
4056 {
4057 struct buf *bp;
4058 int i, used = 0, nfree = 0;
4059
4060 if (have_addr) {
4061 db_printf("usage: countfreebufs\n");
4062 return;
4063 }
4064
4065 for (i = 0; i < nbuf; i++) {
4066 bp = &buf[i];
4067 if ((bp->b_vflags & BV_INFREECNT) != 0)
4068 nfree++;
4069 else
4070 used++;
4071 }
4072
4073 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
4074 nfree + used);
4075 db_printf("numfreebuffers is %d\n", numfreebuffers);
4076 }
4077 #endif /* DDB */
Cache object: 5916c49dfec5b838a83031b547dd01f8
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