FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_bio.c
1 /*-
2 * Copyright (c) 2004 Poul-Henning Kamp
3 * Copyright (c) 1994,1997 John S. Dyson
4 * Copyright (c) 2013 The FreeBSD Foundation
5 * All rights reserved.
6 *
7 * Portions of this software were developed by Konstantin Belousov
8 * under sponsorship from the FreeBSD Foundation.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 /*
33 * this file contains a new buffer I/O scheme implementing a coherent
34 * VM object and buffer cache scheme. Pains have been taken to make
35 * sure that the performance degradation associated with schemes such
36 * as this is not realized.
37 *
38 * Author: John S. Dyson
39 * Significant help during the development and debugging phases
40 * had been provided by David Greenman, also of the FreeBSD core team.
41 *
42 * see man buf(9) for more info.
43 */
44
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD: releng/9.2/sys/kern/vfs_bio.c 253259 2013-07-12 10:07:48Z kib $");
47
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/bio.h>
51 #include <sys/conf.h>
52 #include <sys/buf.h>
53 #include <sys/devicestat.h>
54 #include <sys/eventhandler.h>
55 #include <sys/fail.h>
56 #include <sys/limits.h>
57 #include <sys/lock.h>
58 #include <sys/malloc.h>
59 #include <sys/mount.h>
60 #include <sys/mutex.h>
61 #include <sys/kernel.h>
62 #include <sys/kthread.h>
63 #include <sys/proc.h>
64 #include <sys/resourcevar.h>
65 #include <sys/sysctl.h>
66 #include <sys/vmmeter.h>
67 #include <sys/vnode.h>
68 #include <geom/geom.h>
69 #include <vm/vm.h>
70 #include <vm/vm_param.h>
71 #include <vm/vm_kern.h>
72 #include <vm/vm_pageout.h>
73 #include <vm/vm_page.h>
74 #include <vm/vm_object.h>
75 #include <vm/vm_extern.h>
76 #include <vm/vm_map.h>
77 #include "opt_compat.h"
78 #include "opt_directio.h"
79 #include "opt_swap.h"
80
81 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
82
83 struct bio_ops bioops; /* I/O operation notification */
84
85 struct buf_ops buf_ops_bio = {
86 .bop_name = "buf_ops_bio",
87 .bop_write = bufwrite,
88 .bop_strategy = bufstrategy,
89 .bop_sync = bufsync,
90 .bop_bdflush = bufbdflush,
91 };
92
93 /*
94 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
95 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
96 */
97 struct buf *buf; /* buffer header pool */
98 caddr_t unmapped_buf;
99
100 static struct proc *bufdaemonproc;
101
102 static int inmem(struct vnode *vp, daddr_t blkno);
103 static void vm_hold_free_pages(struct buf *bp, int newbsize);
104 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
105 vm_offset_t to);
106 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
107 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
108 vm_page_t m);
109 static void vfs_drain_busy_pages(struct buf *bp);
110 static void vfs_clean_pages_dirty_buf(struct buf *bp);
111 static void vfs_setdirty_locked_object(struct buf *bp);
112 static void vfs_vmio_release(struct buf *bp);
113 static int vfs_bio_clcheck(struct vnode *vp, int size,
114 daddr_t lblkno, daddr_t blkno);
115 static int buf_do_flush(struct vnode *vp);
116 static int flushbufqueues(struct vnode *, int, int);
117 static void buf_daemon(void);
118 static void bremfreel(struct buf *bp);
119 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
120 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
121 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
122 #endif
123
124 int vmiodirenable = TRUE;
125 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
126 "Use the VM system for directory writes");
127 long runningbufspace;
128 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
129 "Amount of presently outstanding async buffer io");
130 static long bufspace;
131 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
132 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
133 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
134 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
135 #else
136 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
137 "Virtual memory used for buffers");
138 #endif
139 static long unmapped_bufspace;
140 SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD,
141 &unmapped_bufspace, 0,
142 "Amount of unmapped buffers, inclusive in the bufspace");
143 static long maxbufspace;
144 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
145 "Maximum allowed value of bufspace (including buf_daemon)");
146 static long bufmallocspace;
147 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
148 "Amount of malloced memory for buffers");
149 static long maxbufmallocspace;
150 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
151 "Maximum amount of malloced memory for buffers");
152 static long lobufspace;
153 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
154 "Minimum amount of buffers we want to have");
155 long hibufspace;
156 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
157 "Maximum allowed value of bufspace (excluding buf_daemon)");
158 static int bufreusecnt;
159 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
160 "Number of times we have reused a buffer");
161 static int buffreekvacnt;
162 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
163 "Number of times we have freed the KVA space from some buffer");
164 static int bufdefragcnt;
165 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
166 "Number of times we have had to repeat buffer allocation to defragment");
167 static long lorunningspace;
168 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
169 "Minimum preferred space used for in-progress I/O");
170 static long hirunningspace;
171 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
172 "Maximum amount of space to use for in-progress I/O");
173 int dirtybufferflushes;
174 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
175 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
176 int bdwriteskip;
177 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
178 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
179 int altbufferflushes;
180 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
181 0, "Number of fsync flushes to limit dirty buffers");
182 static int recursiveflushes;
183 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
184 0, "Number of flushes skipped due to being recursive");
185 static int numdirtybuffers;
186 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
187 "Number of buffers that are dirty (has unwritten changes) at the moment");
188 static int lodirtybuffers;
189 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
190 "How many buffers we want to have free before bufdaemon can sleep");
191 static int hidirtybuffers;
192 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
193 "When the number of dirty buffers is considered severe");
194 int dirtybufthresh;
195 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
196 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
197 static int numfreebuffers;
198 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
199 "Number of free buffers");
200 static int lofreebuffers;
201 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
202 "XXX Unused");
203 static int hifreebuffers;
204 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
205 "XXX Complicatedly unused");
206 static int getnewbufcalls;
207 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
208 "Number of calls to getnewbuf");
209 static int getnewbufrestarts;
210 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
211 "Number of times getnewbuf has had to restart a buffer aquisition");
212 static int mappingrestarts;
213 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0,
214 "Number of times getblk has had to restart a buffer mapping for "
215 "unmapped buffer");
216 static int flushbufqtarget = 100;
217 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
218 "Amount of work to do in flushbufqueues when helping bufdaemon");
219 static long notbufdflashes;
220 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0,
221 "Number of dirty buffer flushes done by the bufdaemon helpers");
222 static long barrierwrites;
223 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
224 "Number of barrier writes");
225 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
226 &unmapped_buf_allowed, 0,
227 "Permit the use of the unmapped i/o");
228
229 /*
230 * Wakeup point for bufdaemon, as well as indicator of whether it is already
231 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
232 * is idling.
233 */
234 static int bd_request;
235
236 /*
237 * Request for the buf daemon to write more buffers than is indicated by
238 * lodirtybuf. This may be necessary to push out excess dependencies or
239 * defragment the address space where a simple count of the number of dirty
240 * buffers is insufficient to characterize the demand for flushing them.
241 */
242 static int bd_speedupreq;
243
244 /*
245 * This lock synchronizes access to bd_request.
246 */
247 static struct mtx bdlock;
248
249 /*
250 * bogus page -- for I/O to/from partially complete buffers
251 * this is a temporary solution to the problem, but it is not
252 * really that bad. it would be better to split the buffer
253 * for input in the case of buffers partially already in memory,
254 * but the code is intricate enough already.
255 */
256 vm_page_t bogus_page;
257
258 /*
259 * Synchronization (sleep/wakeup) variable for active buffer space requests.
260 * Set when wait starts, cleared prior to wakeup().
261 * Used in runningbufwakeup() and waitrunningbufspace().
262 */
263 static int runningbufreq;
264
265 /*
266 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
267 * waitrunningbufspace().
268 */
269 static struct mtx rbreqlock;
270
271 /*
272 * Synchronization (sleep/wakeup) variable for buffer requests.
273 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
274 * by and/or.
275 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
276 * getnewbuf(), and getblk().
277 */
278 static int needsbuffer;
279
280 /*
281 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
282 */
283 static struct mtx nblock;
284
285 /*
286 * Definitions for the buffer free lists.
287 */
288 #define BUFFER_QUEUES 6 /* number of free buffer queues */
289
290 #define QUEUE_NONE 0 /* on no queue */
291 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
292 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
293 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */
294 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
295 #define QUEUE_EMPTY 5 /* empty buffer headers */
296 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
297
298 /* Queues for free buffers with various properties */
299 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
300 #ifdef INVARIANTS
301 static int bq_len[BUFFER_QUEUES];
302 #endif
303
304 /* Lock for the bufqueues */
305 static struct mtx bqlock;
306
307 /*
308 * Single global constant for BUF_WMESG, to avoid getting multiple references.
309 * buf_wmesg is referred from macros.
310 */
311 const char *buf_wmesg = BUF_WMESG;
312
313 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
314 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
315 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
316 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
317
318 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
319 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
320 static int
321 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
322 {
323 long lvalue;
324 int ivalue;
325
326 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
327 return (sysctl_handle_long(oidp, arg1, arg2, req));
328 lvalue = *(long *)arg1;
329 if (lvalue > INT_MAX)
330 /* On overflow, still write out a long to trigger ENOMEM. */
331 return (sysctl_handle_long(oidp, &lvalue, 0, req));
332 ivalue = lvalue;
333 return (sysctl_handle_int(oidp, &ivalue, 0, req));
334 }
335 #endif
336
337 #ifdef DIRECTIO
338 extern void ffs_rawread_setup(void);
339 #endif /* DIRECTIO */
340 /*
341 * numdirtywakeup:
342 *
343 * If someone is blocked due to there being too many dirty buffers,
344 * and numdirtybuffers is now reasonable, wake them up.
345 */
346
347 static __inline void
348 numdirtywakeup(int level)
349 {
350
351 if (numdirtybuffers <= level) {
352 mtx_lock(&nblock);
353 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
354 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
355 wakeup(&needsbuffer);
356 }
357 mtx_unlock(&nblock);
358 }
359 }
360
361 /*
362 * bufspacewakeup:
363 *
364 * Called when buffer space is potentially available for recovery.
365 * getnewbuf() will block on this flag when it is unable to free
366 * sufficient buffer space. Buffer space becomes recoverable when
367 * bp's get placed back in the queues.
368 */
369
370 static __inline void
371 bufspacewakeup(void)
372 {
373
374 /*
375 * If someone is waiting for BUF space, wake them up. Even
376 * though we haven't freed the kva space yet, the waiting
377 * process will be able to now.
378 */
379 mtx_lock(&nblock);
380 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
381 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
382 wakeup(&needsbuffer);
383 }
384 mtx_unlock(&nblock);
385 }
386
387 /*
388 * runningbufwakeup() - in-progress I/O accounting.
389 *
390 */
391 void
392 runningbufwakeup(struct buf *bp)
393 {
394
395 if (bp->b_runningbufspace) {
396 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace);
397 bp->b_runningbufspace = 0;
398 mtx_lock(&rbreqlock);
399 if (runningbufreq && runningbufspace <= lorunningspace) {
400 runningbufreq = 0;
401 wakeup(&runningbufreq);
402 }
403 mtx_unlock(&rbreqlock);
404 }
405 }
406
407 /*
408 * bufcountwakeup:
409 *
410 * Called when a buffer has been added to one of the free queues to
411 * account for the buffer and to wakeup anyone waiting for free buffers.
412 * This typically occurs when large amounts of metadata are being handled
413 * by the buffer cache ( else buffer space runs out first, usually ).
414 */
415
416 static __inline void
417 bufcountwakeup(struct buf *bp)
418 {
419 int old;
420
421 KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
422 ("buf %p already counted as free", bp));
423 if (bp->b_bufobj != NULL)
424 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
425 bp->b_vflags |= BV_INFREECNT;
426 old = atomic_fetchadd_int(&numfreebuffers, 1);
427 KASSERT(old >= 0 && old < nbuf,
428 ("numfreebuffers climbed to %d", old + 1));
429 mtx_lock(&nblock);
430 if (needsbuffer) {
431 needsbuffer &= ~VFS_BIO_NEED_ANY;
432 if (numfreebuffers >= hifreebuffers)
433 needsbuffer &= ~VFS_BIO_NEED_FREE;
434 wakeup(&needsbuffer);
435 }
436 mtx_unlock(&nblock);
437 }
438
439 /*
440 * waitrunningbufspace()
441 *
442 * runningbufspace is a measure of the amount of I/O currently
443 * running. This routine is used in async-write situations to
444 * prevent creating huge backups of pending writes to a device.
445 * Only asynchronous writes are governed by this function.
446 *
447 * Reads will adjust runningbufspace, but will not block based on it.
448 * The read load has a side effect of reducing the allowed write load.
449 *
450 * This does NOT turn an async write into a sync write. It waits
451 * for earlier writes to complete and generally returns before the
452 * caller's write has reached the device.
453 */
454 void
455 waitrunningbufspace(void)
456 {
457
458 mtx_lock(&rbreqlock);
459 while (runningbufspace > hirunningspace) {
460 ++runningbufreq;
461 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
462 }
463 mtx_unlock(&rbreqlock);
464 }
465
466
467 /*
468 * vfs_buf_test_cache:
469 *
470 * Called when a buffer is extended. This function clears the B_CACHE
471 * bit if the newly extended portion of the buffer does not contain
472 * valid data.
473 */
474 static __inline
475 void
476 vfs_buf_test_cache(struct buf *bp,
477 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
478 vm_page_t m)
479 {
480
481 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
482 if (bp->b_flags & B_CACHE) {
483 int base = (foff + off) & PAGE_MASK;
484 if (vm_page_is_valid(m, base, size) == 0)
485 bp->b_flags &= ~B_CACHE;
486 }
487 }
488
489 /* Wake up the buffer daemon if necessary */
490 static __inline
491 void
492 bd_wakeup(int dirtybuflevel)
493 {
494
495 mtx_lock(&bdlock);
496 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
497 bd_request = 1;
498 wakeup(&bd_request);
499 }
500 mtx_unlock(&bdlock);
501 }
502
503 /*
504 * bd_speedup - speedup the buffer cache flushing code
505 */
506
507 void
508 bd_speedup(void)
509 {
510 int needwake;
511
512 mtx_lock(&bdlock);
513 needwake = 0;
514 if (bd_speedupreq == 0 || bd_request == 0)
515 needwake = 1;
516 bd_speedupreq = 1;
517 bd_request = 1;
518 if (needwake)
519 wakeup(&bd_request);
520 mtx_unlock(&bdlock);
521 }
522
523 #ifdef __i386__
524 #define TRANSIENT_DENOM 5
525 #else
526 #define TRANSIENT_DENOM 10
527 #endif
528
529 /*
530 * Calculating buffer cache scaling values and reserve space for buffer
531 * headers. This is called during low level kernel initialization and
532 * may be called more then once. We CANNOT write to the memory area
533 * being reserved at this time.
534 */
535 caddr_t
536 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
537 {
538 int tuned_nbuf;
539 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
540
541 /*
542 * physmem_est is in pages. Convert it to kilobytes (assumes
543 * PAGE_SIZE is >= 1K)
544 */
545 physmem_est = physmem_est * (PAGE_SIZE / 1024);
546
547 /*
548 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
549 * For the first 64MB of ram nominally allocate sufficient buffers to
550 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
551 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
552 * the buffer cache we limit the eventual kva reservation to
553 * maxbcache bytes.
554 *
555 * factor represents the 1/4 x ram conversion.
556 */
557 if (nbuf == 0) {
558 int factor = 4 * BKVASIZE / 1024;
559
560 nbuf = 50;
561 if (physmem_est > 4096)
562 nbuf += min((physmem_est - 4096) / factor,
563 65536 / factor);
564 if (physmem_est > 65536)
565 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
566 32 * 1024 * 1024 / (factor * 5));
567
568 if (maxbcache && nbuf > maxbcache / BKVASIZE)
569 nbuf = maxbcache / BKVASIZE;
570 tuned_nbuf = 1;
571 } else
572 tuned_nbuf = 0;
573
574 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
575 maxbuf = (LONG_MAX / 3) / BKVASIZE;
576 if (nbuf > maxbuf) {
577 if (!tuned_nbuf)
578 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
579 maxbuf);
580 nbuf = maxbuf;
581 }
582
583 /*
584 * Ideal allocation size for the transient bio submap if 10%
585 * of the maximal space buffer map. This roughly corresponds
586 * to the amount of the buffer mapped for typical UFS load.
587 *
588 * Clip the buffer map to reserve space for the transient
589 * BIOs, if its extent is bigger than 90% (80% on i386) of the
590 * maximum buffer map extent on the platform.
591 *
592 * The fall-back to the maxbuf in case of maxbcache unset,
593 * allows to not trim the buffer KVA for the architectures
594 * with ample KVA space.
595 */
596 if (bio_transient_maxcnt == 0) {
597 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
598 buf_sz = (long)nbuf * BKVASIZE;
599 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
600 (TRANSIENT_DENOM - 1)) {
601 /*
602 * There is more KVA than memory. Do not
603 * adjust buffer map size, and assign the rest
604 * of maxbuf to transient map.
605 */
606 biotmap_sz = maxbuf_sz - buf_sz;
607 } else {
608 /*
609 * Buffer map spans all KVA we could afford on
610 * this platform. Give 10% (20% on i386) of
611 * the buffer map to the transient bio map.
612 */
613 biotmap_sz = buf_sz / TRANSIENT_DENOM;
614 buf_sz -= biotmap_sz;
615 }
616 if (biotmap_sz / INT_MAX > MAXPHYS)
617 bio_transient_maxcnt = INT_MAX;
618 else
619 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
620 /*
621 * Artifically limit to 1024 simultaneous in-flight I/Os
622 * using the transient mapping.
623 */
624 if (bio_transient_maxcnt > 1024)
625 bio_transient_maxcnt = 1024;
626 if (tuned_nbuf)
627 nbuf = buf_sz / BKVASIZE;
628 }
629
630 /*
631 * swbufs are used as temporary holders for I/O, such as paging I/O.
632 * We have no less then 16 and no more then 256.
633 */
634 nswbuf = max(min(nbuf/4, 256), 16);
635 #ifdef NSWBUF_MIN
636 if (nswbuf < NSWBUF_MIN)
637 nswbuf = NSWBUF_MIN;
638 #endif
639 #ifdef DIRECTIO
640 ffs_rawread_setup();
641 #endif
642
643 /*
644 * Reserve space for the buffer cache buffers
645 */
646 swbuf = (void *)v;
647 v = (caddr_t)(swbuf + nswbuf);
648 buf = (void *)v;
649 v = (caddr_t)(buf + nbuf);
650
651 return(v);
652 }
653
654 /* Initialize the buffer subsystem. Called before use of any buffers. */
655 void
656 bufinit(void)
657 {
658 struct buf *bp;
659 int i;
660
661 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
662 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
663 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
664 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
665
666 /* next, make a null set of free lists */
667 for (i = 0; i < BUFFER_QUEUES; i++)
668 TAILQ_INIT(&bufqueues[i]);
669
670 /* finally, initialize each buffer header and stick on empty q */
671 for (i = 0; i < nbuf; i++) {
672 bp = &buf[i];
673 bzero(bp, sizeof *bp);
674 bp->b_flags = B_INVAL; /* we're just an empty header */
675 bp->b_rcred = NOCRED;
676 bp->b_wcred = NOCRED;
677 bp->b_qindex = QUEUE_EMPTY;
678 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */
679 bp->b_xflags = 0;
680 LIST_INIT(&bp->b_dep);
681 BUF_LOCKINIT(bp);
682 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
683 #ifdef INVARIANTS
684 bq_len[QUEUE_EMPTY]++;
685 #endif
686 }
687
688 /*
689 * maxbufspace is the absolute maximum amount of buffer space we are
690 * allowed to reserve in KVM and in real terms. The absolute maximum
691 * is nominally used by buf_daemon. hibufspace is the nominal maximum
692 * used by most other processes. The differential is required to
693 * ensure that buf_daemon is able to run when other processes might
694 * be blocked waiting for buffer space.
695 *
696 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
697 * this may result in KVM fragmentation which is not handled optimally
698 * by the system.
699 */
700 maxbufspace = (long)nbuf * BKVASIZE;
701 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
702 lobufspace = hibufspace - MAXBSIZE;
703
704 /*
705 * Note: The 16 MiB upper limit for hirunningspace was chosen
706 * arbitrarily and may need further tuning. It corresponds to
707 * 128 outstanding write IO requests (if IO size is 128 KiB),
708 * which fits with many RAID controllers' tagged queuing limits.
709 * The lower 1 MiB limit is the historical upper limit for
710 * hirunningspace.
711 */
712 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE),
713 16 * 1024 * 1024), 1024 * 1024);
714 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE);
715
716 /*
717 * Limit the amount of malloc memory since it is wired permanently into
718 * the kernel space. Even though this is accounted for in the buffer
719 * allocation, we don't want the malloced region to grow uncontrolled.
720 * The malloc scheme improves memory utilization significantly on average
721 * (small) directories.
722 */
723 maxbufmallocspace = hibufspace / 20;
724
725 /*
726 * Reduce the chance of a deadlock occuring by limiting the number
727 * of delayed-write dirty buffers we allow to stack up.
728 */
729 hidirtybuffers = nbuf / 4 + 20;
730 dirtybufthresh = hidirtybuffers * 9 / 10;
731 numdirtybuffers = 0;
732 /*
733 * To support extreme low-memory systems, make sure hidirtybuffers cannot
734 * eat up all available buffer space. This occurs when our minimum cannot
735 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
736 * BKVASIZE'd buffers.
737 */
738 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
739 hidirtybuffers >>= 1;
740 }
741 lodirtybuffers = hidirtybuffers / 2;
742
743 /*
744 * Try to keep the number of free buffers in the specified range,
745 * and give special processes (e.g. like buf_daemon) access to an
746 * emergency reserve.
747 */
748 lofreebuffers = nbuf / 18 + 5;
749 hifreebuffers = 2 * lofreebuffers;
750 numfreebuffers = nbuf;
751
752 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
753 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
754 unmapped_buf = (caddr_t)kmem_alloc_nofault(kernel_map, MAXPHYS);
755 }
756
757 #ifdef INVARIANTS
758 static inline void
759 vfs_buf_check_mapped(struct buf *bp)
760 {
761
762 KASSERT((bp->b_flags & B_UNMAPPED) == 0,
763 ("mapped buf %p %x", bp, bp->b_flags));
764 KASSERT(bp->b_kvabase != unmapped_buf,
765 ("mapped buf: b_kvabase was not updated %p", bp));
766 KASSERT(bp->b_data != unmapped_buf,
767 ("mapped buf: b_data was not updated %p", bp));
768 }
769
770 static inline void
771 vfs_buf_check_unmapped(struct buf *bp)
772 {
773
774 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED,
775 ("unmapped buf %p %x", bp, bp->b_flags));
776 KASSERT(bp->b_kvabase == unmapped_buf,
777 ("unmapped buf: corrupted b_kvabase %p", bp));
778 KASSERT(bp->b_data == unmapped_buf,
779 ("unmapped buf: corrupted b_data %p", bp));
780 }
781
782 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
783 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
784 #else
785 #define BUF_CHECK_MAPPED(bp) do {} while (0)
786 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
787 #endif
788
789 static void
790 bpmap_qenter(struct buf *bp)
791 {
792
793 BUF_CHECK_MAPPED(bp);
794
795 /*
796 * bp->b_data is relative to bp->b_offset, but
797 * bp->b_offset may be offset into the first page.
798 */
799 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
800 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
801 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
802 (vm_offset_t)(bp->b_offset & PAGE_MASK));
803 }
804
805 /*
806 * bfreekva() - free the kva allocation for a buffer.
807 *
808 * Since this call frees up buffer space, we call bufspacewakeup().
809 */
810 static void
811 bfreekva(struct buf *bp)
812 {
813
814 if (bp->b_kvasize == 0)
815 return;
816
817 atomic_add_int(&buffreekvacnt, 1);
818 atomic_subtract_long(&bufspace, bp->b_kvasize);
819 if ((bp->b_flags & B_UNMAPPED) == 0) {
820 BUF_CHECK_MAPPED(bp);
821 vm_map_remove(buffer_map, (vm_offset_t)bp->b_kvabase,
822 (vm_offset_t)bp->b_kvabase + bp->b_kvasize);
823 } else {
824 BUF_CHECK_UNMAPPED(bp);
825 if ((bp->b_flags & B_KVAALLOC) != 0) {
826 vm_map_remove(buffer_map, (vm_offset_t)bp->b_kvaalloc,
827 (vm_offset_t)bp->b_kvaalloc + bp->b_kvasize);
828 }
829 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
830 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
831 }
832 bp->b_kvasize = 0;
833 bufspacewakeup();
834 }
835
836 /*
837 * bremfree:
838 *
839 * Mark the buffer for removal from the appropriate free list in brelse.
840 *
841 */
842 void
843 bremfree(struct buf *bp)
844 {
845 int old;
846
847 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
848 KASSERT((bp->b_flags & B_REMFREE) == 0,
849 ("bremfree: buffer %p already marked for delayed removal.", bp));
850 KASSERT(bp->b_qindex != QUEUE_NONE,
851 ("bremfree: buffer %p not on a queue.", bp));
852 BUF_ASSERT_HELD(bp);
853
854 bp->b_flags |= B_REMFREE;
855 /* Fixup numfreebuffers count. */
856 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
857 KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
858 ("buf %p not counted in numfreebuffers", bp));
859 if (bp->b_bufobj != NULL)
860 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
861 bp->b_vflags &= ~BV_INFREECNT;
862 old = atomic_fetchadd_int(&numfreebuffers, -1);
863 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
864 }
865 }
866
867 /*
868 * bremfreef:
869 *
870 * Force an immediate removal from a free list. Used only in nfs when
871 * it abuses the b_freelist pointer.
872 */
873 void
874 bremfreef(struct buf *bp)
875 {
876 mtx_lock(&bqlock);
877 bremfreel(bp);
878 mtx_unlock(&bqlock);
879 }
880
881 /*
882 * bremfreel:
883 *
884 * Removes a buffer from the free list, must be called with the
885 * bqlock held.
886 */
887 static void
888 bremfreel(struct buf *bp)
889 {
890 int old;
891
892 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
893 bp, bp->b_vp, bp->b_flags);
894 KASSERT(bp->b_qindex != QUEUE_NONE,
895 ("bremfreel: buffer %p not on a queue.", bp));
896 BUF_ASSERT_HELD(bp);
897 mtx_assert(&bqlock, MA_OWNED);
898
899 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
900 #ifdef INVARIANTS
901 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow",
902 bp->b_qindex));
903 bq_len[bp->b_qindex]--;
904 #endif
905 bp->b_qindex = QUEUE_NONE;
906 /*
907 * If this was a delayed bremfree() we only need to remove the buffer
908 * from the queue and return the stats are already done.
909 */
910 if (bp->b_flags & B_REMFREE) {
911 bp->b_flags &= ~B_REMFREE;
912 return;
913 }
914 /*
915 * Fixup numfreebuffers count. If the buffer is invalid or not
916 * delayed-write, the buffer was free and we must decrement
917 * numfreebuffers.
918 */
919 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
920 KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
921 ("buf %p not counted in numfreebuffers", bp));
922 if (bp->b_bufobj != NULL)
923 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
924 bp->b_vflags &= ~BV_INFREECNT;
925 old = atomic_fetchadd_int(&numfreebuffers, -1);
926 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
927 }
928 }
929
930 /*
931 * Get a buffer with the specified data.
932 */
933 int
934 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
935 struct buf **bpp)
936 {
937
938 return (breadn_flags(vp, blkno, size, 0, 0, 0, cred, 0, bpp));
939 }
940
941 /*
942 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
943 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
944 * the buffer is valid and we do not have to do anything.
945 */
946 void
947 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
948 int cnt, struct ucred * cred)
949 {
950 struct buf *rabp;
951 int i;
952
953 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
954 if (inmem(vp, *rablkno))
955 continue;
956 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
957
958 if ((rabp->b_flags & B_CACHE) == 0) {
959 if (!TD_IS_IDLETHREAD(curthread))
960 curthread->td_ru.ru_inblock++;
961 rabp->b_flags |= B_ASYNC;
962 rabp->b_flags &= ~B_INVAL;
963 rabp->b_ioflags &= ~BIO_ERROR;
964 rabp->b_iocmd = BIO_READ;
965 if (rabp->b_rcred == NOCRED && cred != NOCRED)
966 rabp->b_rcred = crhold(cred);
967 vfs_busy_pages(rabp, 0);
968 BUF_KERNPROC(rabp);
969 rabp->b_iooffset = dbtob(rabp->b_blkno);
970 bstrategy(rabp);
971 } else {
972 brelse(rabp);
973 }
974 }
975 }
976
977 /*
978 * Operates like bread, but with getblk flags.
979 */
980 int
981 bread_gb(struct vnode * vp, daddr_t blkno, int cnt, struct ucred * cred,
982 int gbflags, struct buf **bpp)
983 {
984
985 return (breadn_flags(vp, blkno, cnt, NULL, NULL, 0,
986 cred, gbflags, bpp));
987 }
988
989 /*
990 * Operates like bread, but also starts asynchronous I/O on
991 * read-ahead blocks.
992 */
993 int
994 breadn(struct vnode * vp, daddr_t blkno, int size,
995 daddr_t * rablkno, int *rabsize,
996 int cnt, struct ucred * cred, struct buf **bpp)
997 {
998
999 return (breadn_flags(vp, blkno, size, rablkno, rabsize, cnt,
1000 cred, 0, bpp));
1001 }
1002
1003 /*
1004 * Entry point for bread() and breadn().
1005 *
1006 * Get a buffer with the specified data. Look in the cache first. We
1007 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
1008 * is set, the buffer is valid and we do not have to do anything, see
1009 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
1010 */
1011 int
1012 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
1013 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp)
1014 {
1015 struct buf *bp;
1016 int rv = 0, readwait = 0;
1017
1018 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
1019 /*
1020 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
1021 */
1022 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
1023 if (bp == NULL)
1024 return (EBUSY);
1025
1026 /* if not found in cache, do some I/O */
1027 if ((bp->b_flags & B_CACHE) == 0) {
1028 if (!TD_IS_IDLETHREAD(curthread))
1029 curthread->td_ru.ru_inblock++;
1030 bp->b_iocmd = BIO_READ;
1031 bp->b_flags &= ~B_INVAL;
1032 bp->b_ioflags &= ~BIO_ERROR;
1033 if (bp->b_rcred == NOCRED && cred != NOCRED)
1034 bp->b_rcred = crhold(cred);
1035 vfs_busy_pages(bp, 0);
1036 bp->b_iooffset = dbtob(bp->b_blkno);
1037 bstrategy(bp);
1038 ++readwait;
1039 }
1040
1041 breada(vp, rablkno, rabsize, cnt, cred);
1042
1043 if (readwait) {
1044 rv = bufwait(bp);
1045 }
1046 return (rv);
1047 }
1048
1049 /*
1050 * Write, release buffer on completion. (Done by iodone
1051 * if async). Do not bother writing anything if the buffer
1052 * is invalid.
1053 *
1054 * Note that we set B_CACHE here, indicating that buffer is
1055 * fully valid and thus cacheable. This is true even of NFS
1056 * now so we set it generally. This could be set either here
1057 * or in biodone() since the I/O is synchronous. We put it
1058 * here.
1059 */
1060 int
1061 bufwrite(struct buf *bp)
1062 {
1063 int oldflags;
1064 struct vnode *vp;
1065 int vp_md;
1066
1067 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1068 if (bp->b_flags & B_INVAL) {
1069 brelse(bp);
1070 return (0);
1071 }
1072
1073 if (bp->b_flags & B_BARRIER)
1074 barrierwrites++;
1075
1076 oldflags = bp->b_flags;
1077
1078 BUF_ASSERT_HELD(bp);
1079
1080 if (bp->b_pin_count > 0)
1081 bunpin_wait(bp);
1082
1083 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
1084 ("FFS background buffer should not get here %p", bp));
1085
1086 vp = bp->b_vp;
1087 if (vp)
1088 vp_md = vp->v_vflag & VV_MD;
1089 else
1090 vp_md = 0;
1091
1092 /*
1093 * Mark the buffer clean. Increment the bufobj write count
1094 * before bundirty() call, to prevent other thread from seeing
1095 * empty dirty list and zero counter for writes in progress,
1096 * falsely indicating that the bufobj is clean.
1097 */
1098 bufobj_wref(bp->b_bufobj);
1099 bundirty(bp);
1100
1101 bp->b_flags &= ~B_DONE;
1102 bp->b_ioflags &= ~BIO_ERROR;
1103 bp->b_flags |= B_CACHE;
1104 bp->b_iocmd = BIO_WRITE;
1105
1106 vfs_busy_pages(bp, 1);
1107
1108 /*
1109 * Normal bwrites pipeline writes
1110 */
1111 bp->b_runningbufspace = bp->b_bufsize;
1112 atomic_add_long(&runningbufspace, bp->b_runningbufspace);
1113
1114 if (!TD_IS_IDLETHREAD(curthread))
1115 curthread->td_ru.ru_oublock++;
1116 if (oldflags & B_ASYNC)
1117 BUF_KERNPROC(bp);
1118 bp->b_iooffset = dbtob(bp->b_blkno);
1119 bstrategy(bp);
1120
1121 if ((oldflags & B_ASYNC) == 0) {
1122 int rtval = bufwait(bp);
1123 brelse(bp);
1124 return (rtval);
1125 } else {
1126 /*
1127 * don't allow the async write to saturate the I/O
1128 * system. We will not deadlock here because
1129 * we are blocking waiting for I/O that is already in-progress
1130 * to complete. We do not block here if it is the update
1131 * or syncer daemon trying to clean up as that can lead
1132 * to deadlock.
1133 */
1134 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
1135 waitrunningbufspace();
1136 }
1137
1138 return (0);
1139 }
1140
1141 void
1142 bufbdflush(struct bufobj *bo, struct buf *bp)
1143 {
1144 struct buf *nbp;
1145
1146 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
1147 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
1148 altbufferflushes++;
1149 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
1150 BO_LOCK(bo);
1151 /*
1152 * Try to find a buffer to flush.
1153 */
1154 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
1155 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
1156 BUF_LOCK(nbp,
1157 LK_EXCLUSIVE | LK_NOWAIT, NULL))
1158 continue;
1159 if (bp == nbp)
1160 panic("bdwrite: found ourselves");
1161 BO_UNLOCK(bo);
1162 /* Don't countdeps with the bo lock held. */
1163 if (buf_countdeps(nbp, 0)) {
1164 BO_LOCK(bo);
1165 BUF_UNLOCK(nbp);
1166 continue;
1167 }
1168 if (nbp->b_flags & B_CLUSTEROK) {
1169 vfs_bio_awrite(nbp);
1170 } else {
1171 bremfree(nbp);
1172 bawrite(nbp);
1173 }
1174 dirtybufferflushes++;
1175 break;
1176 }
1177 if (nbp == NULL)
1178 BO_UNLOCK(bo);
1179 }
1180 }
1181
1182 /*
1183 * Delayed write. (Buffer is marked dirty). Do not bother writing
1184 * anything if the buffer is marked invalid.
1185 *
1186 * Note that since the buffer must be completely valid, we can safely
1187 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
1188 * biodone() in order to prevent getblk from writing the buffer
1189 * out synchronously.
1190 */
1191 void
1192 bdwrite(struct buf *bp)
1193 {
1194 struct thread *td = curthread;
1195 struct vnode *vp;
1196 struct bufobj *bo;
1197
1198 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1199 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1200 KASSERT((bp->b_flags & B_BARRIER) == 0,
1201 ("Barrier request in delayed write %p", bp));
1202 BUF_ASSERT_HELD(bp);
1203
1204 if (bp->b_flags & B_INVAL) {
1205 brelse(bp);
1206 return;
1207 }
1208
1209 /*
1210 * If we have too many dirty buffers, don't create any more.
1211 * If we are wildly over our limit, then force a complete
1212 * cleanup. Otherwise, just keep the situation from getting
1213 * out of control. Note that we have to avoid a recursive
1214 * disaster and not try to clean up after our own cleanup!
1215 */
1216 vp = bp->b_vp;
1217 bo = bp->b_bufobj;
1218 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
1219 td->td_pflags |= TDP_INBDFLUSH;
1220 BO_BDFLUSH(bo, bp);
1221 td->td_pflags &= ~TDP_INBDFLUSH;
1222 } else
1223 recursiveflushes++;
1224
1225 bdirty(bp);
1226 /*
1227 * Set B_CACHE, indicating that the buffer is fully valid. This is
1228 * true even of NFS now.
1229 */
1230 bp->b_flags |= B_CACHE;
1231
1232 /*
1233 * This bmap keeps the system from needing to do the bmap later,
1234 * perhaps when the system is attempting to do a sync. Since it
1235 * is likely that the indirect block -- or whatever other datastructure
1236 * that the filesystem needs is still in memory now, it is a good
1237 * thing to do this. Note also, that if the pageout daemon is
1238 * requesting a sync -- there might not be enough memory to do
1239 * the bmap then... So, this is important to do.
1240 */
1241 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1242 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1243 }
1244
1245 /*
1246 * Set the *dirty* buffer range based upon the VM system dirty
1247 * pages.
1248 *
1249 * Mark the buffer pages as clean. We need to do this here to
1250 * satisfy the vnode_pager and the pageout daemon, so that it
1251 * thinks that the pages have been "cleaned". Note that since
1252 * the pages are in a delayed write buffer -- the VFS layer
1253 * "will" see that the pages get written out on the next sync,
1254 * or perhaps the cluster will be completed.
1255 */
1256 vfs_clean_pages_dirty_buf(bp);
1257 bqrelse(bp);
1258
1259 /*
1260 * Wakeup the buffer flushing daemon if we have a lot of dirty
1261 * buffers (midpoint between our recovery point and our stall
1262 * point).
1263 */
1264 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1265
1266 /*
1267 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1268 * due to the softdep code.
1269 */
1270 }
1271
1272 /*
1273 * bdirty:
1274 *
1275 * Turn buffer into delayed write request. We must clear BIO_READ and
1276 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1277 * itself to properly update it in the dirty/clean lists. We mark it
1278 * B_DONE to ensure that any asynchronization of the buffer properly
1279 * clears B_DONE ( else a panic will occur later ).
1280 *
1281 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1282 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1283 * should only be called if the buffer is known-good.
1284 *
1285 * Since the buffer is not on a queue, we do not update the numfreebuffers
1286 * count.
1287 *
1288 * The buffer must be on QUEUE_NONE.
1289 */
1290 void
1291 bdirty(struct buf *bp)
1292 {
1293
1294 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1295 bp, bp->b_vp, bp->b_flags);
1296 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1297 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1298 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1299 BUF_ASSERT_HELD(bp);
1300 bp->b_flags &= ~(B_RELBUF);
1301 bp->b_iocmd = BIO_WRITE;
1302
1303 if ((bp->b_flags & B_DELWRI) == 0) {
1304 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1305 reassignbuf(bp);
1306 atomic_add_int(&numdirtybuffers, 1);
1307 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1308 }
1309 }
1310
1311 /*
1312 * bundirty:
1313 *
1314 * Clear B_DELWRI for buffer.
1315 *
1316 * Since the buffer is not on a queue, we do not update the numfreebuffers
1317 * count.
1318 *
1319 * The buffer must be on QUEUE_NONE.
1320 */
1321
1322 void
1323 bundirty(struct buf *bp)
1324 {
1325
1326 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1327 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1328 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1329 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1330 BUF_ASSERT_HELD(bp);
1331
1332 if (bp->b_flags & B_DELWRI) {
1333 bp->b_flags &= ~B_DELWRI;
1334 reassignbuf(bp);
1335 atomic_subtract_int(&numdirtybuffers, 1);
1336 numdirtywakeup(lodirtybuffers);
1337 }
1338 /*
1339 * Since it is now being written, we can clear its deferred write flag.
1340 */
1341 bp->b_flags &= ~B_DEFERRED;
1342 }
1343
1344 /*
1345 * bawrite:
1346 *
1347 * Asynchronous write. Start output on a buffer, but do not wait for
1348 * it to complete. The buffer is released when the output completes.
1349 *
1350 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1351 * B_INVAL buffers. Not us.
1352 */
1353 void
1354 bawrite(struct buf *bp)
1355 {
1356
1357 bp->b_flags |= B_ASYNC;
1358 (void) bwrite(bp);
1359 }
1360
1361 /*
1362 * babarrierwrite:
1363 *
1364 * Asynchronous barrier write. Start output on a buffer, but do not
1365 * wait for it to complete. Place a write barrier after this write so
1366 * that this buffer and all buffers written before it are committed to
1367 * the disk before any buffers written after this write are committed
1368 * to the disk. The buffer is released when the output completes.
1369 */
1370 void
1371 babarrierwrite(struct buf *bp)
1372 {
1373
1374 bp->b_flags |= B_ASYNC | B_BARRIER;
1375 (void) bwrite(bp);
1376 }
1377
1378 /*
1379 * bbarrierwrite:
1380 *
1381 * Synchronous barrier write. Start output on a buffer and wait for
1382 * it to complete. Place a write barrier after this write so that
1383 * this buffer and all buffers written before it are committed to
1384 * the disk before any buffers written after this write are committed
1385 * to the disk. The buffer is released when the output completes.
1386 */
1387 int
1388 bbarrierwrite(struct buf *bp)
1389 {
1390
1391 bp->b_flags |= B_BARRIER;
1392 return (bwrite(bp));
1393 }
1394
1395 /*
1396 * bwillwrite:
1397 *
1398 * Called prior to the locking of any vnodes when we are expecting to
1399 * write. We do not want to starve the buffer cache with too many
1400 * dirty buffers so we block here. By blocking prior to the locking
1401 * of any vnodes we attempt to avoid the situation where a locked vnode
1402 * prevents the various system daemons from flushing related buffers.
1403 */
1404
1405 void
1406 bwillwrite(void)
1407 {
1408
1409 if (numdirtybuffers >= hidirtybuffers) {
1410 mtx_lock(&nblock);
1411 while (numdirtybuffers >= hidirtybuffers) {
1412 bd_wakeup(1);
1413 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1414 msleep(&needsbuffer, &nblock,
1415 (PRIBIO + 4), "flswai", 0);
1416 }
1417 mtx_unlock(&nblock);
1418 }
1419 }
1420
1421 /*
1422 * Return true if we have too many dirty buffers.
1423 */
1424 int
1425 buf_dirty_count_severe(void)
1426 {
1427
1428 return(numdirtybuffers >= hidirtybuffers);
1429 }
1430
1431 static __noinline int
1432 buf_vm_page_count_severe(void)
1433 {
1434
1435 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1);
1436
1437 return vm_page_count_severe();
1438 }
1439
1440 /*
1441 * brelse:
1442 *
1443 * Release a busy buffer and, if requested, free its resources. The
1444 * buffer will be stashed in the appropriate bufqueue[] allowing it
1445 * to be accessed later as a cache entity or reused for other purposes.
1446 */
1447 void
1448 brelse(struct buf *bp)
1449 {
1450 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1451 bp, bp->b_vp, bp->b_flags);
1452 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1453 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1454
1455 if (BUF_LOCKRECURSED(bp)) {
1456 /*
1457 * Do not process, in particular, do not handle the
1458 * B_INVAL/B_RELBUF and do not release to free list.
1459 */
1460 BUF_UNLOCK(bp);
1461 return;
1462 }
1463
1464 if (bp->b_flags & B_MANAGED) {
1465 bqrelse(bp);
1466 return;
1467 }
1468
1469 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
1470 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) {
1471 /*
1472 * Failed write, redirty. Must clear BIO_ERROR to prevent
1473 * pages from being scrapped. If the error is anything
1474 * other than an I/O error (EIO), assume that retrying
1475 * is futile.
1476 */
1477 bp->b_ioflags &= ~BIO_ERROR;
1478 bdirty(bp);
1479 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1480 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1481 /*
1482 * Either a failed I/O or we were asked to free or not
1483 * cache the buffer.
1484 */
1485 bp->b_flags |= B_INVAL;
1486 if (!LIST_EMPTY(&bp->b_dep))
1487 buf_deallocate(bp);
1488 if (bp->b_flags & B_DELWRI) {
1489 atomic_subtract_int(&numdirtybuffers, 1);
1490 numdirtywakeup(lodirtybuffers);
1491 }
1492 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1493 if ((bp->b_flags & B_VMIO) == 0) {
1494 if (bp->b_bufsize)
1495 allocbuf(bp, 0);
1496 if (bp->b_vp)
1497 brelvp(bp);
1498 }
1499 }
1500
1501 /*
1502 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1503 * is called with B_DELWRI set, the underlying pages may wind up
1504 * getting freed causing a previous write (bdwrite()) to get 'lost'
1505 * because pages associated with a B_DELWRI bp are marked clean.
1506 *
1507 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1508 * if B_DELWRI is set.
1509 *
1510 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1511 * on pages to return pages to the VM page queues.
1512 */
1513 if (bp->b_flags & B_DELWRI)
1514 bp->b_flags &= ~B_RELBUF;
1515 else if (buf_vm_page_count_severe()) {
1516 /*
1517 * The locking of the BO_LOCK is not necessary since
1518 * BKGRDINPROG cannot be set while we hold the buf
1519 * lock, it can only be cleared if it is already
1520 * pending.
1521 */
1522 if (bp->b_vp) {
1523 if (!(bp->b_vflags & BV_BKGRDINPROG))
1524 bp->b_flags |= B_RELBUF;
1525 } else
1526 bp->b_flags |= B_RELBUF;
1527 }
1528
1529 /*
1530 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1531 * constituted, not even NFS buffers now. Two flags effect this. If
1532 * B_INVAL, the struct buf is invalidated but the VM object is kept
1533 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1534 *
1535 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1536 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1537 * buffer is also B_INVAL because it hits the re-dirtying code above.
1538 *
1539 * Normally we can do this whether a buffer is B_DELWRI or not. If
1540 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1541 * the commit state and we cannot afford to lose the buffer. If the
1542 * buffer has a background write in progress, we need to keep it
1543 * around to prevent it from being reconstituted and starting a second
1544 * background write.
1545 */
1546 if ((bp->b_flags & B_VMIO)
1547 && !(bp->b_vp->v_mount != NULL &&
1548 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1549 !vn_isdisk(bp->b_vp, NULL) &&
1550 (bp->b_flags & B_DELWRI))
1551 ) {
1552
1553 int i, j, resid;
1554 vm_page_t m;
1555 off_t foff;
1556 vm_pindex_t poff;
1557 vm_object_t obj;
1558
1559 obj = bp->b_bufobj->bo_object;
1560
1561 /*
1562 * Get the base offset and length of the buffer. Note that
1563 * in the VMIO case if the buffer block size is not
1564 * page-aligned then b_data pointer may not be page-aligned.
1565 * But our b_pages[] array *IS* page aligned.
1566 *
1567 * block sizes less then DEV_BSIZE (usually 512) are not
1568 * supported due to the page granularity bits (m->valid,
1569 * m->dirty, etc...).
1570 *
1571 * See man buf(9) for more information
1572 */
1573 resid = bp->b_bufsize;
1574 foff = bp->b_offset;
1575 VM_OBJECT_LOCK(obj);
1576 for (i = 0; i < bp->b_npages; i++) {
1577 int had_bogus = 0;
1578
1579 m = bp->b_pages[i];
1580
1581 /*
1582 * If we hit a bogus page, fixup *all* the bogus pages
1583 * now.
1584 */
1585 if (m == bogus_page) {
1586 poff = OFF_TO_IDX(bp->b_offset);
1587 had_bogus = 1;
1588
1589 for (j = i; j < bp->b_npages; j++) {
1590 vm_page_t mtmp;
1591 mtmp = bp->b_pages[j];
1592 if (mtmp == bogus_page) {
1593 mtmp = vm_page_lookup(obj, poff + j);
1594 if (!mtmp) {
1595 panic("brelse: page missing\n");
1596 }
1597 bp->b_pages[j] = mtmp;
1598 }
1599 }
1600
1601 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) {
1602 BUF_CHECK_MAPPED(bp);
1603 pmap_qenter(
1604 trunc_page((vm_offset_t)bp->b_data),
1605 bp->b_pages, bp->b_npages);
1606 }
1607 m = bp->b_pages[i];
1608 }
1609 if ((bp->b_flags & B_NOCACHE) ||
1610 (bp->b_ioflags & BIO_ERROR &&
1611 bp->b_iocmd == BIO_READ)) {
1612 int poffset = foff & PAGE_MASK;
1613 int presid = resid > (PAGE_SIZE - poffset) ?
1614 (PAGE_SIZE - poffset) : resid;
1615
1616 KASSERT(presid >= 0, ("brelse: extra page"));
1617 vm_page_set_invalid(m, poffset, presid);
1618 if (had_bogus)
1619 printf("avoided corruption bug in bogus_page/brelse code\n");
1620 }
1621 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1622 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1623 }
1624 VM_OBJECT_UNLOCK(obj);
1625 if (bp->b_flags & (B_INVAL | B_RELBUF))
1626 vfs_vmio_release(bp);
1627
1628 } else if (bp->b_flags & B_VMIO) {
1629
1630 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1631 vfs_vmio_release(bp);
1632 }
1633
1634 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1635 if (bp->b_bufsize != 0)
1636 allocbuf(bp, 0);
1637 if (bp->b_vp != NULL)
1638 brelvp(bp);
1639 }
1640
1641 /* enqueue */
1642 mtx_lock(&bqlock);
1643 /* Handle delayed bremfree() processing. */
1644 if (bp->b_flags & B_REMFREE) {
1645 struct bufobj *bo;
1646
1647 bo = bp->b_bufobj;
1648 if (bo != NULL)
1649 BO_LOCK(bo);
1650 bremfreel(bp);
1651 if (bo != NULL)
1652 BO_UNLOCK(bo);
1653 }
1654 if (bp->b_qindex != QUEUE_NONE)
1655 panic("brelse: free buffer onto another queue???");
1656
1657 /*
1658 * If the buffer has junk contents signal it and eventually
1659 * clean up B_DELWRI and diassociate the vnode so that gbincore()
1660 * doesn't find it.
1661 */
1662 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
1663 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
1664 bp->b_flags |= B_INVAL;
1665 if (bp->b_flags & B_INVAL) {
1666 if (bp->b_flags & B_DELWRI)
1667 bundirty(bp);
1668 if (bp->b_vp)
1669 brelvp(bp);
1670 }
1671
1672 /* buffers with no memory */
1673 if (bp->b_bufsize == 0) {
1674 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1675 if (bp->b_vflags & BV_BKGRDINPROG)
1676 panic("losing buffer 1");
1677 if (bp->b_kvasize) {
1678 bp->b_qindex = QUEUE_EMPTYKVA;
1679 } else {
1680 bp->b_qindex = QUEUE_EMPTY;
1681 }
1682 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1683 /* buffers with junk contents */
1684 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1685 (bp->b_ioflags & BIO_ERROR)) {
1686 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1687 if (bp->b_vflags & BV_BKGRDINPROG)
1688 panic("losing buffer 2");
1689 bp->b_qindex = QUEUE_CLEAN;
1690 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1691 /* remaining buffers */
1692 } else {
1693 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) ==
1694 (B_DELWRI|B_NEEDSGIANT))
1695 bp->b_qindex = QUEUE_DIRTY_GIANT;
1696 else if (bp->b_flags & B_DELWRI)
1697 bp->b_qindex = QUEUE_DIRTY;
1698 else
1699 bp->b_qindex = QUEUE_CLEAN;
1700 if (bp->b_flags & B_AGE) {
1701 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp,
1702 b_freelist);
1703 } else {
1704 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp,
1705 b_freelist);
1706 }
1707 }
1708 #ifdef INVARIANTS
1709 bq_len[bp->b_qindex]++;
1710 #endif
1711 mtx_unlock(&bqlock);
1712
1713 /*
1714 * Fixup numfreebuffers count. The bp is on an appropriate queue
1715 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1716 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1717 * if B_INVAL is set ).
1718 */
1719
1720 if (!(bp->b_flags & B_DELWRI)) {
1721 struct bufobj *bo;
1722
1723 bo = bp->b_bufobj;
1724 if (bo != NULL)
1725 BO_LOCK(bo);
1726 bufcountwakeup(bp);
1727 if (bo != NULL)
1728 BO_UNLOCK(bo);
1729 }
1730
1731 /*
1732 * Something we can maybe free or reuse
1733 */
1734 if (bp->b_bufsize || bp->b_kvasize)
1735 bufspacewakeup();
1736
1737 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1738 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1739 panic("brelse: not dirty");
1740 /* unlock */
1741 BUF_UNLOCK(bp);
1742 }
1743
1744 /*
1745 * Release a buffer back to the appropriate queue but do not try to free
1746 * it. The buffer is expected to be used again soon.
1747 *
1748 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1749 * biodone() to requeue an async I/O on completion. It is also used when
1750 * known good buffers need to be requeued but we think we may need the data
1751 * again soon.
1752 *
1753 * XXX we should be able to leave the B_RELBUF hint set on completion.
1754 */
1755 void
1756 bqrelse(struct buf *bp)
1757 {
1758 struct bufobj *bo;
1759
1760 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1761 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1762 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1763
1764 if (BUF_LOCKRECURSED(bp)) {
1765 /* do not release to free list */
1766 BUF_UNLOCK(bp);
1767 return;
1768 }
1769
1770 bo = bp->b_bufobj;
1771 if (bp->b_flags & B_MANAGED) {
1772 if (bp->b_flags & B_REMFREE) {
1773 mtx_lock(&bqlock);
1774 if (bo != NULL)
1775 BO_LOCK(bo);
1776 bremfreel(bp);
1777 if (bo != NULL)
1778 BO_UNLOCK(bo);
1779 mtx_unlock(&bqlock);
1780 }
1781 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1782 BUF_UNLOCK(bp);
1783 return;
1784 }
1785
1786 mtx_lock(&bqlock);
1787 /* Handle delayed bremfree() processing. */
1788 if (bp->b_flags & B_REMFREE) {
1789 if (bo != NULL)
1790 BO_LOCK(bo);
1791 bremfreel(bp);
1792 if (bo != NULL)
1793 BO_UNLOCK(bo);
1794 }
1795 if (bp->b_qindex != QUEUE_NONE)
1796 panic("bqrelse: free buffer onto another queue???");
1797 /* buffers with stale but valid contents */
1798 if (bp->b_flags & B_DELWRI) {
1799 if (bp->b_flags & B_NEEDSGIANT)
1800 bp->b_qindex = QUEUE_DIRTY_GIANT;
1801 else
1802 bp->b_qindex = QUEUE_DIRTY;
1803 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1804 #ifdef INVARIANTS
1805 bq_len[bp->b_qindex]++;
1806 #endif
1807 } else {
1808 /*
1809 * The locking of the BO_LOCK for checking of the
1810 * BV_BKGRDINPROG is not necessary since the
1811 * BV_BKGRDINPROG cannot be set while we hold the buf
1812 * lock, it can only be cleared if it is already
1813 * pending.
1814 */
1815 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) {
1816 bp->b_qindex = QUEUE_CLEAN;
1817 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1818 b_freelist);
1819 #ifdef INVARIANTS
1820 bq_len[QUEUE_CLEAN]++;
1821 #endif
1822 } else {
1823 /*
1824 * We are too low on memory, we have to try to free
1825 * the buffer (most importantly: the wired pages
1826 * making up its backing store) *now*.
1827 */
1828 mtx_unlock(&bqlock);
1829 brelse(bp);
1830 return;
1831 }
1832 }
1833 mtx_unlock(&bqlock);
1834
1835 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) {
1836 if (bo != NULL)
1837 BO_LOCK(bo);
1838 bufcountwakeup(bp);
1839 if (bo != NULL)
1840 BO_UNLOCK(bo);
1841 }
1842
1843 /*
1844 * Something we can maybe free or reuse.
1845 */
1846 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1847 bufspacewakeup();
1848
1849 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1850 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1851 panic("bqrelse: not dirty");
1852 /* unlock */
1853 BUF_UNLOCK(bp);
1854 }
1855
1856 /* Give pages used by the bp back to the VM system (where possible) */
1857 static void
1858 vfs_vmio_release(struct buf *bp)
1859 {
1860 int i;
1861 vm_page_t m;
1862
1863 if ((bp->b_flags & B_UNMAPPED) == 0) {
1864 BUF_CHECK_MAPPED(bp);
1865 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
1866 } else
1867 BUF_CHECK_UNMAPPED(bp);
1868 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
1869 for (i = 0; i < bp->b_npages; i++) {
1870 m = bp->b_pages[i];
1871 bp->b_pages[i] = NULL;
1872 /*
1873 * In order to keep page LRU ordering consistent, put
1874 * everything on the inactive queue.
1875 */
1876 vm_page_lock(m);
1877 vm_page_unwire(m, 0);
1878 /*
1879 * We don't mess with busy pages, it is
1880 * the responsibility of the process that
1881 * busied the pages to deal with them.
1882 */
1883 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 &&
1884 m->wire_count == 0) {
1885 /*
1886 * Might as well free the page if we can and it has
1887 * no valid data. We also free the page if the
1888 * buffer was used for direct I/O
1889 */
1890 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) {
1891 vm_page_free(m);
1892 } else if (bp->b_flags & B_DIRECT) {
1893 vm_page_try_to_free(m);
1894 } else if (buf_vm_page_count_severe()) {
1895 vm_page_try_to_cache(m);
1896 }
1897 }
1898 vm_page_unlock(m);
1899 }
1900 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
1901
1902 if (bp->b_bufsize) {
1903 bufspacewakeup();
1904 bp->b_bufsize = 0;
1905 }
1906 bp->b_npages = 0;
1907 bp->b_flags &= ~B_VMIO;
1908 if (bp->b_vp)
1909 brelvp(bp);
1910 }
1911
1912 /*
1913 * Check to see if a block at a particular lbn is available for a clustered
1914 * write.
1915 */
1916 static int
1917 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1918 {
1919 struct buf *bpa;
1920 int match;
1921
1922 match = 0;
1923
1924 /* If the buf isn't in core skip it */
1925 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1926 return (0);
1927
1928 /* If the buf is busy we don't want to wait for it */
1929 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1930 return (0);
1931
1932 /* Only cluster with valid clusterable delayed write buffers */
1933 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1934 (B_DELWRI | B_CLUSTEROK))
1935 goto done;
1936
1937 if (bpa->b_bufsize != size)
1938 goto done;
1939
1940 /*
1941 * Check to see if it is in the expected place on disk and that the
1942 * block has been mapped.
1943 */
1944 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1945 match = 1;
1946 done:
1947 BUF_UNLOCK(bpa);
1948 return (match);
1949 }
1950
1951 /*
1952 * vfs_bio_awrite:
1953 *
1954 * Implement clustered async writes for clearing out B_DELWRI buffers.
1955 * This is much better then the old way of writing only one buffer at
1956 * a time. Note that we may not be presented with the buffers in the
1957 * correct order, so we search for the cluster in both directions.
1958 */
1959 int
1960 vfs_bio_awrite(struct buf *bp)
1961 {
1962 struct bufobj *bo;
1963 int i;
1964 int j;
1965 daddr_t lblkno = bp->b_lblkno;
1966 struct vnode *vp = bp->b_vp;
1967 int ncl;
1968 int nwritten;
1969 int size;
1970 int maxcl;
1971 int gbflags;
1972
1973 bo = &vp->v_bufobj;
1974 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0;
1975 /*
1976 * right now we support clustered writing only to regular files. If
1977 * we find a clusterable block we could be in the middle of a cluster
1978 * rather then at the beginning.
1979 */
1980 if ((vp->v_type == VREG) &&
1981 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1982 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1983
1984 size = vp->v_mount->mnt_stat.f_iosize;
1985 maxcl = MAXPHYS / size;
1986
1987 BO_LOCK(bo);
1988 for (i = 1; i < maxcl; i++)
1989 if (vfs_bio_clcheck(vp, size, lblkno + i,
1990 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1991 break;
1992
1993 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1994 if (vfs_bio_clcheck(vp, size, lblkno - j,
1995 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1996 break;
1997 BO_UNLOCK(bo);
1998 --j;
1999 ncl = i + j;
2000 /*
2001 * this is a possible cluster write
2002 */
2003 if (ncl != 1) {
2004 BUF_UNLOCK(bp);
2005 nwritten = cluster_wbuild_gb(vp, size, lblkno - j,
2006 ncl, gbflags);
2007 return (nwritten);
2008 }
2009 }
2010 bremfree(bp);
2011 bp->b_flags |= B_ASYNC;
2012 /*
2013 * default (old) behavior, writing out only one block
2014 *
2015 * XXX returns b_bufsize instead of b_bcount for nwritten?
2016 */
2017 nwritten = bp->b_bufsize;
2018 (void) bwrite(bp);
2019
2020 return (nwritten);
2021 }
2022
2023 static void
2024 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags)
2025 {
2026
2027 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 &&
2028 bp->b_kvasize == 0, ("call bfreekva(%p)", bp));
2029 if ((gbflags & GB_UNMAPPED) == 0) {
2030 bp->b_kvabase = (caddr_t)addr;
2031 } else if ((gbflags & GB_KVAALLOC) != 0) {
2032 KASSERT((gbflags & GB_UNMAPPED) != 0,
2033 ("GB_KVAALLOC without GB_UNMAPPED"));
2034 bp->b_kvaalloc = (caddr_t)addr;
2035 bp->b_flags |= B_UNMAPPED | B_KVAALLOC;
2036 atomic_add_long(&unmapped_bufspace, bp->b_kvasize);
2037 }
2038 bp->b_kvasize = maxsize;
2039 }
2040
2041 /*
2042 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if
2043 * needed.
2044 */
2045 static int
2046 allocbufkva(struct buf *bp, int maxsize, int gbflags)
2047 {
2048 vm_offset_t addr;
2049 int rv;
2050
2051 bfreekva(bp);
2052 addr = 0;
2053
2054 vm_map_lock(buffer_map);
2055 if (vm_map_findspace(buffer_map, vm_map_min(buffer_map), maxsize,
2056 &addr)) {
2057 vm_map_unlock(buffer_map);
2058 /*
2059 * Buffer map is too fragmented. Request the caller
2060 * to defragment the map.
2061 */
2062 atomic_add_int(&bufdefragcnt, 1);
2063 return (1);
2064 }
2065 rv = vm_map_insert(buffer_map, NULL, 0, addr, addr + maxsize,
2066 VM_PROT_RW, VM_PROT_RW, MAP_NOFAULT);
2067 KASSERT(rv == KERN_SUCCESS, ("vm_map_insert(buffer_map) rv %d", rv));
2068 vm_map_unlock(buffer_map);
2069 setbufkva(bp, addr, maxsize, gbflags);
2070 atomic_add_long(&bufspace, bp->b_kvasize);
2071 return (0);
2072 }
2073
2074 /*
2075 * Ask the bufdaemon for help, or act as bufdaemon itself, when a
2076 * locked vnode is supplied.
2077 */
2078 static void
2079 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo,
2080 int defrag)
2081 {
2082 struct thread *td;
2083 char *waitmsg;
2084 int fl, flags, norunbuf;
2085
2086 mtx_assert(&bqlock, MA_OWNED);
2087
2088 if (defrag) {
2089 flags = VFS_BIO_NEED_BUFSPACE;
2090 waitmsg = "nbufkv";
2091 } else if (bufspace >= hibufspace) {
2092 waitmsg = "nbufbs";
2093 flags = VFS_BIO_NEED_BUFSPACE;
2094 } else {
2095 waitmsg = "newbuf";
2096 flags = VFS_BIO_NEED_ANY;
2097 }
2098 mtx_lock(&nblock);
2099 needsbuffer |= flags;
2100 mtx_unlock(&nblock);
2101 mtx_unlock(&bqlock);
2102
2103 bd_speedup(); /* heeeelp */
2104 if ((gbflags & GB_NOWAIT_BD) != 0)
2105 return;
2106
2107 td = curthread;
2108 mtx_lock(&nblock);
2109 while (needsbuffer & flags) {
2110 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) {
2111 mtx_unlock(&nblock);
2112 /*
2113 * getblk() is called with a vnode locked, and
2114 * some majority of the dirty buffers may as
2115 * well belong to the vnode. Flushing the
2116 * buffers there would make a progress that
2117 * cannot be achieved by the buf_daemon, that
2118 * cannot lock the vnode.
2119 */
2120 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
2121 (td->td_pflags & TDP_NORUNNINGBUF);
2122 /* play bufdaemon */
2123 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
2124 fl = buf_do_flush(vp);
2125 td->td_pflags &= norunbuf;
2126 mtx_lock(&nblock);
2127 if (fl != 0)
2128 continue;
2129 if ((needsbuffer & flags) == 0)
2130 break;
2131 }
2132 if (msleep(&needsbuffer, &nblock, (PRIBIO + 4) | slpflag,
2133 waitmsg, slptimeo))
2134 break;
2135 }
2136 mtx_unlock(&nblock);
2137 }
2138
2139 static void
2140 getnewbuf_reuse_bp(struct buf *bp, int qindex)
2141 {
2142
2143 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
2144 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
2145 bp->b_kvasize, bp->b_bufsize, qindex);
2146 mtx_assert(&bqlock, MA_NOTOWNED);
2147
2148 /*
2149 * Note: we no longer distinguish between VMIO and non-VMIO
2150 * buffers.
2151 */
2152 KASSERT((bp->b_flags & B_DELWRI) == 0,
2153 ("delwri buffer %p found in queue %d", bp, qindex));
2154
2155 if (qindex == QUEUE_CLEAN) {
2156 if (bp->b_flags & B_VMIO) {
2157 bp->b_flags &= ~B_ASYNC;
2158 vfs_vmio_release(bp);
2159 }
2160 if (bp->b_vp != NULL)
2161 brelvp(bp);
2162 }
2163
2164 /*
2165 * Get the rest of the buffer freed up. b_kva* is still valid
2166 * after this operation.
2167 */
2168
2169 if (bp->b_rcred != NOCRED) {
2170 crfree(bp->b_rcred);
2171 bp->b_rcred = NOCRED;
2172 }
2173 if (bp->b_wcred != NOCRED) {
2174 crfree(bp->b_wcred);
2175 bp->b_wcred = NOCRED;
2176 }
2177 if (!LIST_EMPTY(&bp->b_dep))
2178 buf_deallocate(bp);
2179 if (bp->b_vflags & BV_BKGRDINPROG)
2180 panic("losing buffer 3");
2181 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d",
2182 bp, bp->b_vp, qindex));
2183 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
2184 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
2185
2186 if (bp->b_bufsize)
2187 allocbuf(bp, 0);
2188
2189 bp->b_flags &= B_UNMAPPED | B_KVAALLOC;
2190 bp->b_ioflags = 0;
2191 bp->b_xflags = 0;
2192 KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
2193 ("buf %p still counted as free?", bp));
2194 bp->b_vflags = 0;
2195 bp->b_vp = NULL;
2196 bp->b_blkno = bp->b_lblkno = 0;
2197 bp->b_offset = NOOFFSET;
2198 bp->b_iodone = 0;
2199 bp->b_error = 0;
2200 bp->b_resid = 0;
2201 bp->b_bcount = 0;
2202 bp->b_npages = 0;
2203 bp->b_dirtyoff = bp->b_dirtyend = 0;
2204 bp->b_bufobj = NULL;
2205 bp->b_pin_count = 0;
2206 bp->b_fsprivate1 = NULL;
2207 bp->b_fsprivate2 = NULL;
2208 bp->b_fsprivate3 = NULL;
2209
2210 LIST_INIT(&bp->b_dep);
2211 }
2212
2213 static int flushingbufs;
2214
2215 static struct buf *
2216 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata)
2217 {
2218 struct buf *bp, *nbp;
2219 int nqindex, qindex, pass;
2220
2221 KASSERT(!unmapped || !defrag, ("both unmapped and defrag"));
2222
2223 pass = 1;
2224 restart:
2225 atomic_add_int(&getnewbufrestarts, 1);
2226
2227 /*
2228 * Setup for scan. If we do not have enough free buffers,
2229 * we setup a degenerate case that immediately fails. Note
2230 * that if we are specially marked process, we are allowed to
2231 * dip into our reserves.
2232 *
2233 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
2234 * for the allocation of the mapped buffer. For unmapped, the
2235 * easiest is to start with EMPTY outright.
2236 *
2237 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
2238 * However, there are a number of cases (defragging, reusing, ...)
2239 * where we cannot backup.
2240 */
2241 nbp = NULL;
2242 mtx_lock(&bqlock);
2243 if (!defrag && unmapped) {
2244 nqindex = QUEUE_EMPTY;
2245 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
2246 }
2247 if (nbp == NULL) {
2248 nqindex = QUEUE_EMPTYKVA;
2249 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
2250 }
2251
2252 /*
2253 * If no EMPTYKVA buffers and we are either defragging or
2254 * reusing, locate a CLEAN buffer to free or reuse. If
2255 * bufspace useage is low skip this step so we can allocate a
2256 * new buffer.
2257 */
2258 if (nbp == NULL && (defrag || bufspace >= lobufspace)) {
2259 nqindex = QUEUE_CLEAN;
2260 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2261 }
2262
2263 /*
2264 * If we could not find or were not allowed to reuse a CLEAN
2265 * buffer, check to see if it is ok to use an EMPTY buffer.
2266 * We can only use an EMPTY buffer if allocating its KVA would
2267 * not otherwise run us out of buffer space. No KVA is needed
2268 * for the unmapped allocation.
2269 */
2270 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace ||
2271 metadata)) {
2272 nqindex = QUEUE_EMPTY;
2273 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
2274 }
2275
2276 /*
2277 * All available buffers might be clean, retry ignoring the
2278 * lobufspace as the last resort.
2279 */
2280 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) {
2281 nqindex = QUEUE_CLEAN;
2282 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2283 }
2284
2285 /*
2286 * Run scan, possibly freeing data and/or kva mappings on the fly
2287 * depending.
2288 */
2289 while ((bp = nbp) != NULL) {
2290 qindex = nqindex;
2291
2292 /*
2293 * Calculate next bp (we can only use it if we do not
2294 * block or do other fancy things).
2295 */
2296 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
2297 switch (qindex) {
2298 case QUEUE_EMPTY:
2299 nqindex = QUEUE_EMPTYKVA;
2300 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
2301 if (nbp != NULL)
2302 break;
2303 /* FALLTHROUGH */
2304 case QUEUE_EMPTYKVA:
2305 nqindex = QUEUE_CLEAN;
2306 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2307 if (nbp != NULL)
2308 break;
2309 /* FALLTHROUGH */
2310 case QUEUE_CLEAN:
2311 if (metadata && pass == 1) {
2312 pass = 2;
2313 nqindex = QUEUE_EMPTY;
2314 nbp = TAILQ_FIRST(
2315 &bufqueues[QUEUE_EMPTY]);
2316 }
2317 /*
2318 * nbp is NULL.
2319 */
2320 break;
2321 }
2322 }
2323 /*
2324 * If we are defragging then we need a buffer with
2325 * b_kvasize != 0. XXX this situation should no longer
2326 * occur, if defrag is non-zero the buffer's b_kvasize
2327 * should also be non-zero at this point. XXX
2328 */
2329 if (defrag && bp->b_kvasize == 0) {
2330 printf("Warning: defrag empty buffer %p\n", bp);
2331 continue;
2332 }
2333
2334 /*
2335 * Start freeing the bp. This is somewhat involved. nbp
2336 * remains valid only for QUEUE_EMPTY[KVA] bp's.
2337 */
2338 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2339 continue;
2340 if (bp->b_vp) {
2341 BO_LOCK(bp->b_bufobj);
2342 if (bp->b_vflags & BV_BKGRDINPROG) {
2343 BO_UNLOCK(bp->b_bufobj);
2344 BUF_UNLOCK(bp);
2345 continue;
2346 }
2347 BO_UNLOCK(bp->b_bufobj);
2348 }
2349
2350 KASSERT(bp->b_qindex == qindex,
2351 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
2352
2353 if (bp->b_bufobj != NULL)
2354 BO_LOCK(bp->b_bufobj);
2355 bremfreel(bp);
2356 if (bp->b_bufobj != NULL)
2357 BO_UNLOCK(bp->b_bufobj);
2358 mtx_unlock(&bqlock);
2359 /*
2360 * NOTE: nbp is now entirely invalid. We can only restart
2361 * the scan from this point on.
2362 */
2363
2364 getnewbuf_reuse_bp(bp, qindex);
2365 mtx_assert(&bqlock, MA_NOTOWNED);
2366
2367 /*
2368 * If we are defragging then free the buffer.
2369 */
2370 if (defrag) {
2371 bp->b_flags |= B_INVAL;
2372 bfreekva(bp);
2373 brelse(bp);
2374 defrag = 0;
2375 goto restart;
2376 }
2377
2378 /*
2379 * Notify any waiters for the buffer lock about
2380 * identity change by freeing the buffer.
2381 */
2382 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
2383 bp->b_flags |= B_INVAL;
2384 bfreekva(bp);
2385 brelse(bp);
2386 goto restart;
2387 }
2388
2389 if (metadata)
2390 break;
2391
2392 /*
2393 * If we are overcomitted then recover the buffer and its
2394 * KVM space. This occurs in rare situations when multiple
2395 * processes are blocked in getnewbuf() or allocbuf().
2396 */
2397 if (bufspace >= hibufspace)
2398 flushingbufs = 1;
2399 if (flushingbufs && bp->b_kvasize != 0) {
2400 bp->b_flags |= B_INVAL;
2401 bfreekva(bp);
2402 brelse(bp);
2403 goto restart;
2404 }
2405 if (bufspace < lobufspace)
2406 flushingbufs = 0;
2407 break;
2408 }
2409 return (bp);
2410 }
2411
2412 /*
2413 * getnewbuf:
2414 *
2415 * Find and initialize a new buffer header, freeing up existing buffers
2416 * in the bufqueues as necessary. The new buffer is returned locked.
2417 *
2418 * Important: B_INVAL is not set. If the caller wishes to throw the
2419 * buffer away, the caller must set B_INVAL prior to calling brelse().
2420 *
2421 * We block if:
2422 * We have insufficient buffer headers
2423 * We have insufficient buffer space
2424 * buffer_map is too fragmented ( space reservation fails )
2425 * If we have to flush dirty buffers ( but we try to avoid this )
2426 *
2427 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
2428 * Instead we ask the buf daemon to do it for us. We attempt to
2429 * avoid piecemeal wakeups of the pageout daemon.
2430 */
2431 static struct buf *
2432 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
2433 int gbflags)
2434 {
2435 struct buf *bp;
2436 int defrag, metadata;
2437
2438 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
2439 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
2440 if (!unmapped_buf_allowed)
2441 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
2442
2443 defrag = 0;
2444 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
2445 vp->v_type == VCHR)
2446 metadata = 1;
2447 else
2448 metadata = 0;
2449 /*
2450 * We can't afford to block since we might be holding a vnode lock,
2451 * which may prevent system daemons from running. We deal with
2452 * low-memory situations by proactively returning memory and running
2453 * async I/O rather then sync I/O.
2454 */
2455 atomic_add_int(&getnewbufcalls, 1);
2456 atomic_subtract_int(&getnewbufrestarts, 1);
2457 restart:
2458 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED |
2459 GB_KVAALLOC)) == GB_UNMAPPED, metadata);
2460 if (bp != NULL)
2461 defrag = 0;
2462
2463 /*
2464 * If we exhausted our list, sleep as appropriate. We may have to
2465 * wakeup various daemons and write out some dirty buffers.
2466 *
2467 * Generally we are sleeping due to insufficient buffer space.
2468 */
2469 if (bp == NULL) {
2470 mtx_assert(&bqlock, MA_OWNED);
2471 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag);
2472 mtx_assert(&bqlock, MA_NOTOWNED);
2473 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) {
2474 mtx_assert(&bqlock, MA_NOTOWNED);
2475
2476 bfreekva(bp);
2477 bp->b_flags |= B_UNMAPPED;
2478 bp->b_kvabase = bp->b_data = unmapped_buf;
2479 bp->b_kvasize = maxsize;
2480 atomic_add_long(&bufspace, bp->b_kvasize);
2481 atomic_add_long(&unmapped_bufspace, bp->b_kvasize);
2482 atomic_add_int(&bufreusecnt, 1);
2483 } else {
2484 mtx_assert(&bqlock, MA_NOTOWNED);
2485
2486 /*
2487 * We finally have a valid bp. We aren't quite out of the
2488 * woods, we still have to reserve kva space. In order
2489 * to keep fragmentation sane we only allocate kva in
2490 * BKVASIZE chunks.
2491 */
2492 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2493
2494 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED |
2495 B_KVAALLOC)) == B_UNMAPPED) {
2496 if (allocbufkva(bp, maxsize, gbflags)) {
2497 defrag = 1;
2498 bp->b_flags |= B_INVAL;
2499 brelse(bp);
2500 goto restart;
2501 }
2502 atomic_add_int(&bufreusecnt, 1);
2503 } else if ((bp->b_flags & B_KVAALLOC) != 0 &&
2504 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) {
2505 /*
2506 * If the reused buffer has KVA allocated,
2507 * reassign b_kvaalloc to b_kvabase.
2508 */
2509 bp->b_kvabase = bp->b_kvaalloc;
2510 bp->b_flags &= ~B_KVAALLOC;
2511 atomic_subtract_long(&unmapped_bufspace,
2512 bp->b_kvasize);
2513 atomic_add_int(&bufreusecnt, 1);
2514 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 &&
2515 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED |
2516 GB_KVAALLOC)) {
2517 /*
2518 * The case of reused buffer already have KVA
2519 * mapped, but the request is for unmapped
2520 * buffer with KVA allocated.
2521 */
2522 bp->b_kvaalloc = bp->b_kvabase;
2523 bp->b_data = bp->b_kvabase = unmapped_buf;
2524 bp->b_flags |= B_UNMAPPED | B_KVAALLOC;
2525 atomic_add_long(&unmapped_bufspace,
2526 bp->b_kvasize);
2527 atomic_add_int(&bufreusecnt, 1);
2528 }
2529 if ((gbflags & GB_UNMAPPED) == 0) {
2530 bp->b_saveaddr = bp->b_kvabase;
2531 bp->b_data = bp->b_saveaddr;
2532 bp->b_flags &= ~B_UNMAPPED;
2533 BUF_CHECK_MAPPED(bp);
2534 }
2535 }
2536 return (bp);
2537 }
2538
2539 /*
2540 * buf_daemon:
2541 *
2542 * buffer flushing daemon. Buffers are normally flushed by the
2543 * update daemon but if it cannot keep up this process starts to
2544 * take the load in an attempt to prevent getnewbuf() from blocking.
2545 */
2546
2547 static struct kproc_desc buf_kp = {
2548 "bufdaemon",
2549 buf_daemon,
2550 &bufdaemonproc
2551 };
2552 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2553
2554 static int
2555 buf_do_flush(struct vnode *vp)
2556 {
2557 int flushed;
2558
2559 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0);
2560 /* The list empty check here is slightly racy */
2561 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) {
2562 mtx_lock(&Giant);
2563 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0);
2564 mtx_unlock(&Giant);
2565 }
2566 if (flushed == 0) {
2567 /*
2568 * Could not find any buffers without rollback
2569 * dependencies, so just write the first one
2570 * in the hopes of eventually making progress.
2571 */
2572 flushbufqueues(vp, QUEUE_DIRTY, 1);
2573 if (!TAILQ_EMPTY(
2574 &bufqueues[QUEUE_DIRTY_GIANT])) {
2575 mtx_lock(&Giant);
2576 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1);
2577 mtx_unlock(&Giant);
2578 }
2579 }
2580 return (flushed);
2581 }
2582
2583 static void
2584 buf_daemon()
2585 {
2586 int lodirtysave;
2587
2588 /*
2589 * This process needs to be suspended prior to shutdown sync.
2590 */
2591 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2592 SHUTDOWN_PRI_LAST);
2593
2594 /*
2595 * This process is allowed to take the buffer cache to the limit
2596 */
2597 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
2598 mtx_lock(&bdlock);
2599 for (;;) {
2600 bd_request = 0;
2601 mtx_unlock(&bdlock);
2602
2603 kproc_suspend_check(bufdaemonproc);
2604 lodirtysave = lodirtybuffers;
2605 if (bd_speedupreq) {
2606 lodirtybuffers = numdirtybuffers / 2;
2607 bd_speedupreq = 0;
2608 }
2609 /*
2610 * Do the flush. Limit the amount of in-transit I/O we
2611 * allow to build up, otherwise we would completely saturate
2612 * the I/O system. Wakeup any waiting processes before we
2613 * normally would so they can run in parallel with our drain.
2614 */
2615 while (numdirtybuffers > lodirtybuffers) {
2616 if (buf_do_flush(NULL) == 0)
2617 break;
2618 kern_yield(PRI_UNCHANGED);
2619 }
2620 lodirtybuffers = lodirtysave;
2621
2622 /*
2623 * Only clear bd_request if we have reached our low water
2624 * mark. The buf_daemon normally waits 1 second and
2625 * then incrementally flushes any dirty buffers that have
2626 * built up, within reason.
2627 *
2628 * If we were unable to hit our low water mark and couldn't
2629 * find any flushable buffers, we sleep half a second.
2630 * Otherwise we loop immediately.
2631 */
2632 mtx_lock(&bdlock);
2633 if (numdirtybuffers <= lodirtybuffers) {
2634 /*
2635 * We reached our low water mark, reset the
2636 * request and sleep until we are needed again.
2637 * The sleep is just so the suspend code works.
2638 */
2639 bd_request = 0;
2640 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2641 } else {
2642 /*
2643 * We couldn't find any flushable dirty buffers but
2644 * still have too many dirty buffers, we
2645 * have to sleep and try again. (rare)
2646 */
2647 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2648 }
2649 }
2650 }
2651
2652 /*
2653 * flushbufqueues:
2654 *
2655 * Try to flush a buffer in the dirty queue. We must be careful to
2656 * free up B_INVAL buffers instead of write them, which NFS is
2657 * particularly sensitive to.
2658 */
2659 static int flushwithdeps = 0;
2660 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2661 0, "Number of buffers flushed with dependecies that require rollbacks");
2662
2663 static int
2664 flushbufqueues(struct vnode *lvp, int queue, int flushdeps)
2665 {
2666 struct buf *sentinel;
2667 struct vnode *vp;
2668 struct mount *mp;
2669 struct buf *bp;
2670 int hasdeps;
2671 int flushed;
2672 int target;
2673
2674 if (lvp == NULL) {
2675 target = numdirtybuffers - lodirtybuffers;
2676 if (flushdeps && target > 2)
2677 target /= 2;
2678 } else
2679 target = flushbufqtarget;
2680 flushed = 0;
2681 bp = NULL;
2682 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
2683 sentinel->b_qindex = QUEUE_SENTINEL;
2684 mtx_lock(&bqlock);
2685 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
2686 while (flushed != target) {
2687 bp = TAILQ_NEXT(sentinel, b_freelist);
2688 if (bp != NULL) {
2689 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2690 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
2691 b_freelist);
2692 } else
2693 break;
2694 /*
2695 * Skip sentinels inserted by other invocations of the
2696 * flushbufqueues(), taking care to not reorder them.
2697 */
2698 if (bp->b_qindex == QUEUE_SENTINEL)
2699 continue;
2700 /*
2701 * Only flush the buffers that belong to the
2702 * vnode locked by the curthread.
2703 */
2704 if (lvp != NULL && bp->b_vp != lvp)
2705 continue;
2706 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2707 continue;
2708 if (bp->b_pin_count > 0) {
2709 BUF_UNLOCK(bp);
2710 continue;
2711 }
2712 BO_LOCK(bp->b_bufobj);
2713 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2714 (bp->b_flags & B_DELWRI) == 0) {
2715 BO_UNLOCK(bp->b_bufobj);
2716 BUF_UNLOCK(bp);
2717 continue;
2718 }
2719 BO_UNLOCK(bp->b_bufobj);
2720 if (bp->b_flags & B_INVAL) {
2721 bremfreel(bp);
2722 mtx_unlock(&bqlock);
2723 brelse(bp);
2724 flushed++;
2725 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2726 mtx_lock(&bqlock);
2727 continue;
2728 }
2729
2730 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
2731 if (flushdeps == 0) {
2732 BUF_UNLOCK(bp);
2733 continue;
2734 }
2735 hasdeps = 1;
2736 } else
2737 hasdeps = 0;
2738 /*
2739 * We must hold the lock on a vnode before writing
2740 * one of its buffers. Otherwise we may confuse, or
2741 * in the case of a snapshot vnode, deadlock the
2742 * system.
2743 *
2744 * The lock order here is the reverse of the normal
2745 * of vnode followed by buf lock. This is ok because
2746 * the NOWAIT will prevent deadlock.
2747 */
2748 vp = bp->b_vp;
2749 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2750 BUF_UNLOCK(bp);
2751 continue;
2752 }
2753 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) {
2754 mtx_unlock(&bqlock);
2755 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2756 bp, bp->b_vp, bp->b_flags);
2757 if (curproc == bufdaemonproc)
2758 vfs_bio_awrite(bp);
2759 else {
2760 bremfree(bp);
2761 bwrite(bp);
2762 notbufdflashes++;
2763 }
2764 vn_finished_write(mp);
2765 VOP_UNLOCK(vp, 0);
2766 flushwithdeps += hasdeps;
2767 flushed++;
2768
2769 /*
2770 * Sleeping on runningbufspace while holding
2771 * vnode lock leads to deadlock.
2772 */
2773 if (curproc == bufdaemonproc)
2774 waitrunningbufspace();
2775 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2776 mtx_lock(&bqlock);
2777 continue;
2778 }
2779 vn_finished_write(mp);
2780 BUF_UNLOCK(bp);
2781 }
2782 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2783 mtx_unlock(&bqlock);
2784 free(sentinel, M_TEMP);
2785 return (flushed);
2786 }
2787
2788 /*
2789 * Check to see if a block is currently memory resident.
2790 */
2791 struct buf *
2792 incore(struct bufobj *bo, daddr_t blkno)
2793 {
2794 struct buf *bp;
2795
2796 BO_LOCK(bo);
2797 bp = gbincore(bo, blkno);
2798 BO_UNLOCK(bo);
2799 return (bp);
2800 }
2801
2802 /*
2803 * Returns true if no I/O is needed to access the
2804 * associated VM object. This is like incore except
2805 * it also hunts around in the VM system for the data.
2806 */
2807
2808 static int
2809 inmem(struct vnode * vp, daddr_t blkno)
2810 {
2811 vm_object_t obj;
2812 vm_offset_t toff, tinc, size;
2813 vm_page_t m;
2814 vm_ooffset_t off;
2815
2816 ASSERT_VOP_LOCKED(vp, "inmem");
2817
2818 if (incore(&vp->v_bufobj, blkno))
2819 return 1;
2820 if (vp->v_mount == NULL)
2821 return 0;
2822 obj = vp->v_object;
2823 if (obj == NULL)
2824 return (0);
2825
2826 size = PAGE_SIZE;
2827 if (size > vp->v_mount->mnt_stat.f_iosize)
2828 size = vp->v_mount->mnt_stat.f_iosize;
2829 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2830
2831 VM_OBJECT_LOCK(obj);
2832 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2833 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2834 if (!m)
2835 goto notinmem;
2836 tinc = size;
2837 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2838 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2839 if (vm_page_is_valid(m,
2840 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2841 goto notinmem;
2842 }
2843 VM_OBJECT_UNLOCK(obj);
2844 return 1;
2845
2846 notinmem:
2847 VM_OBJECT_UNLOCK(obj);
2848 return (0);
2849 }
2850
2851 /*
2852 * Set the dirty range for a buffer based on the status of the dirty
2853 * bits in the pages comprising the buffer. The range is limited
2854 * to the size of the buffer.
2855 *
2856 * Tell the VM system that the pages associated with this buffer
2857 * are clean. This is used for delayed writes where the data is
2858 * going to go to disk eventually without additional VM intevention.
2859 *
2860 * Note that while we only really need to clean through to b_bcount, we
2861 * just go ahead and clean through to b_bufsize.
2862 */
2863 static void
2864 vfs_clean_pages_dirty_buf(struct buf *bp)
2865 {
2866 vm_ooffset_t foff, noff, eoff;
2867 vm_page_t m;
2868 int i;
2869
2870 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
2871 return;
2872
2873 foff = bp->b_offset;
2874 KASSERT(bp->b_offset != NOOFFSET,
2875 ("vfs_clean_pages_dirty_buf: no buffer offset"));
2876
2877 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2878 vfs_drain_busy_pages(bp);
2879 vfs_setdirty_locked_object(bp);
2880 for (i = 0; i < bp->b_npages; i++) {
2881 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2882 eoff = noff;
2883 if (eoff > bp->b_offset + bp->b_bufsize)
2884 eoff = bp->b_offset + bp->b_bufsize;
2885 m = bp->b_pages[i];
2886 vfs_page_set_validclean(bp, foff, m);
2887 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
2888 foff = noff;
2889 }
2890 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2891 }
2892
2893 static void
2894 vfs_setdirty_locked_object(struct buf *bp)
2895 {
2896 vm_object_t object;
2897 int i;
2898
2899 object = bp->b_bufobj->bo_object;
2900 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
2901
2902 /*
2903 * We qualify the scan for modified pages on whether the
2904 * object has been flushed yet.
2905 */
2906 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
2907 vm_offset_t boffset;
2908 vm_offset_t eoffset;
2909
2910 /*
2911 * test the pages to see if they have been modified directly
2912 * by users through the VM system.
2913 */
2914 for (i = 0; i < bp->b_npages; i++)
2915 vm_page_test_dirty(bp->b_pages[i]);
2916
2917 /*
2918 * Calculate the encompassing dirty range, boffset and eoffset,
2919 * (eoffset - boffset) bytes.
2920 */
2921
2922 for (i = 0; i < bp->b_npages; i++) {
2923 if (bp->b_pages[i]->dirty)
2924 break;
2925 }
2926 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2927
2928 for (i = bp->b_npages - 1; i >= 0; --i) {
2929 if (bp->b_pages[i]->dirty) {
2930 break;
2931 }
2932 }
2933 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2934
2935 /*
2936 * Fit it to the buffer.
2937 */
2938
2939 if (eoffset > bp->b_bcount)
2940 eoffset = bp->b_bcount;
2941
2942 /*
2943 * If we have a good dirty range, merge with the existing
2944 * dirty range.
2945 */
2946
2947 if (boffset < eoffset) {
2948 if (bp->b_dirtyoff > boffset)
2949 bp->b_dirtyoff = boffset;
2950 if (bp->b_dirtyend < eoffset)
2951 bp->b_dirtyend = eoffset;
2952 }
2953 }
2954 }
2955
2956 /*
2957 * Allocate the KVA mapping for an existing buffer. It handles the
2958 * cases of both B_UNMAPPED buffer, and buffer with the preallocated
2959 * KVA which is not mapped (B_KVAALLOC).
2960 */
2961 static void
2962 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
2963 {
2964 struct buf *scratch_bp;
2965 int bsize, maxsize, need_mapping, need_kva;
2966 off_t offset;
2967
2968 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 &&
2969 (gbflags & GB_UNMAPPED) == 0;
2970 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED &&
2971 (gbflags & GB_KVAALLOC) != 0;
2972 if (!need_mapping && !need_kva)
2973 return;
2974
2975 BUF_CHECK_UNMAPPED(bp);
2976
2977 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) {
2978 /*
2979 * Buffer is not mapped, but the KVA was already
2980 * reserved at the time of the instantiation. Use the
2981 * allocated space.
2982 */
2983 bp->b_flags &= ~B_KVAALLOC;
2984 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0"));
2985 bp->b_kvabase = bp->b_kvaalloc;
2986 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
2987 goto has_addr;
2988 }
2989
2990 /*
2991 * Calculate the amount of the address space we would reserve
2992 * if the buffer was mapped.
2993 */
2994 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
2995 offset = blkno * bsize;
2996 maxsize = size + (offset & PAGE_MASK);
2997 maxsize = imax(maxsize, bsize);
2998
2999 mapping_loop:
3000 if (allocbufkva(bp, maxsize, gbflags)) {
3001 /*
3002 * Request defragmentation. getnewbuf() returns us the
3003 * allocated space by the scratch buffer KVA.
3004 */
3005 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags |
3006 (GB_UNMAPPED | GB_KVAALLOC));
3007 if (scratch_bp == NULL) {
3008 if ((gbflags & GB_NOWAIT_BD) != 0) {
3009 /*
3010 * XXXKIB: defragmentation cannot
3011 * succeed, not sure what else to do.
3012 */
3013 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp);
3014 }
3015 atomic_add_int(&mappingrestarts, 1);
3016 goto mapping_loop;
3017 }
3018 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0,
3019 ("scratch bp !B_KVAALLOC %p", scratch_bp));
3020 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc,
3021 scratch_bp->b_kvasize, gbflags);
3022
3023 /* Get rid of the scratch buffer. */
3024 scratch_bp->b_kvasize = 0;
3025 scratch_bp->b_flags |= B_INVAL;
3026 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
3027 brelse(scratch_bp);
3028 }
3029 if (!need_mapping)
3030 return;
3031
3032 has_addr:
3033 bp->b_saveaddr = bp->b_kvabase;
3034 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */
3035 bp->b_flags &= ~B_UNMAPPED;
3036 BUF_CHECK_MAPPED(bp);
3037 bpmap_qenter(bp);
3038 }
3039
3040 /*
3041 * getblk:
3042 *
3043 * Get a block given a specified block and offset into a file/device.
3044 * The buffers B_DONE bit will be cleared on return, making it almost
3045 * ready for an I/O initiation. B_INVAL may or may not be set on
3046 * return. The caller should clear B_INVAL prior to initiating a
3047 * READ.
3048 *
3049 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3050 * an existing buffer.
3051 *
3052 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3053 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3054 * and then cleared based on the backing VM. If the previous buffer is
3055 * non-0-sized but invalid, B_CACHE will be cleared.
3056 *
3057 * If getblk() must create a new buffer, the new buffer is returned with
3058 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3059 * case it is returned with B_INVAL clear and B_CACHE set based on the
3060 * backing VM.
3061 *
3062 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3063 * B_CACHE bit is clear.
3064 *
3065 * What this means, basically, is that the caller should use B_CACHE to
3066 * determine whether the buffer is fully valid or not and should clear
3067 * B_INVAL prior to issuing a read. If the caller intends to validate
3068 * the buffer by loading its data area with something, the caller needs
3069 * to clear B_INVAL. If the caller does this without issuing an I/O,
3070 * the caller should set B_CACHE ( as an optimization ), else the caller
3071 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3072 * a write attempt or if it was a successfull read. If the caller
3073 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3074 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3075 */
3076 struct buf *
3077 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3078 int flags)
3079 {
3080 struct buf *bp;
3081 struct bufobj *bo;
3082 int bsize, error, maxsize, vmio;
3083 off_t offset;
3084
3085 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3086 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3087 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3088 ASSERT_VOP_LOCKED(vp, "getblk");
3089 if (size > MAXBSIZE)
3090 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
3091 if (!unmapped_buf_allowed)
3092 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3093
3094 bo = &vp->v_bufobj;
3095 loop:
3096 /*
3097 * Block if we are low on buffers. Certain processes are allowed
3098 * to completely exhaust the buffer cache.
3099 *
3100 * If this check ever becomes a bottleneck it may be better to
3101 * move it into the else, when gbincore() fails. At the moment
3102 * it isn't a problem.
3103 */
3104 if (numfreebuffers == 0) {
3105 if (TD_IS_IDLETHREAD(curthread))
3106 return NULL;
3107 mtx_lock(&nblock);
3108 needsbuffer |= VFS_BIO_NEED_ANY;
3109 mtx_unlock(&nblock);
3110 }
3111
3112 BO_LOCK(bo);
3113 bp = gbincore(bo, blkno);
3114 if (bp != NULL) {
3115 int lockflags;
3116 /*
3117 * Buffer is in-core. If the buffer is not busy, it must
3118 * be on a queue.
3119 */
3120 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3121
3122 if (flags & GB_LOCK_NOWAIT)
3123 lockflags |= LK_NOWAIT;
3124
3125 error = BUF_TIMELOCK(bp, lockflags,
3126 BO_MTX(bo), "getblk", slpflag, slptimeo);
3127
3128 /*
3129 * If we slept and got the lock we have to restart in case
3130 * the buffer changed identities.
3131 */
3132 if (error == ENOLCK)
3133 goto loop;
3134 /* We timed out or were interrupted. */
3135 else if (error)
3136 return (NULL);
3137 /* If recursed, assume caller knows the rules. */
3138 else if (BUF_LOCKRECURSED(bp))
3139 goto end;
3140
3141 /*
3142 * The buffer is locked. B_CACHE is cleared if the buffer is
3143 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3144 * and for a VMIO buffer B_CACHE is adjusted according to the
3145 * backing VM cache.
3146 */
3147 if (bp->b_flags & B_INVAL)
3148 bp->b_flags &= ~B_CACHE;
3149 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3150 bp->b_flags |= B_CACHE;
3151 BO_LOCK(bo);
3152 bremfree(bp);
3153 BO_UNLOCK(bo);
3154
3155 /*
3156 * check for size inconsistencies for non-VMIO case.
3157 */
3158 if (bp->b_bcount != size) {
3159 if ((bp->b_flags & B_VMIO) == 0 ||
3160 (size > bp->b_kvasize)) {
3161 if (bp->b_flags & B_DELWRI) {
3162 /*
3163 * If buffer is pinned and caller does
3164 * not want sleep waiting for it to be
3165 * unpinned, bail out
3166 * */
3167 if (bp->b_pin_count > 0) {
3168 if (flags & GB_LOCK_NOWAIT) {
3169 bqrelse(bp);
3170 return (NULL);
3171 } else {
3172 bunpin_wait(bp);
3173 }
3174 }
3175 bp->b_flags |= B_NOCACHE;
3176 bwrite(bp);
3177 } else {
3178 if (LIST_EMPTY(&bp->b_dep)) {
3179 bp->b_flags |= B_RELBUF;
3180 brelse(bp);
3181 } else {
3182 bp->b_flags |= B_NOCACHE;
3183 bwrite(bp);
3184 }
3185 }
3186 goto loop;
3187 }
3188 }
3189
3190 /*
3191 * Handle the case of unmapped buffer which should
3192 * become mapped, or the buffer for which KVA
3193 * reservation is requested.
3194 */
3195 bp_unmapped_get_kva(bp, blkno, size, flags);
3196
3197 /*
3198 * If the size is inconsistant in the VMIO case, we can resize
3199 * the buffer. This might lead to B_CACHE getting set or
3200 * cleared. If the size has not changed, B_CACHE remains
3201 * unchanged from its previous state.
3202 */
3203 if (bp->b_bcount != size)
3204 allocbuf(bp, size);
3205
3206 KASSERT(bp->b_offset != NOOFFSET,
3207 ("getblk: no buffer offset"));
3208
3209 /*
3210 * A buffer with B_DELWRI set and B_CACHE clear must
3211 * be committed before we can return the buffer in
3212 * order to prevent the caller from issuing a read
3213 * ( due to B_CACHE not being set ) and overwriting
3214 * it.
3215 *
3216 * Most callers, including NFS and FFS, need this to
3217 * operate properly either because they assume they
3218 * can issue a read if B_CACHE is not set, or because
3219 * ( for example ) an uncached B_DELWRI might loop due
3220 * to softupdates re-dirtying the buffer. In the latter
3221 * case, B_CACHE is set after the first write completes,
3222 * preventing further loops.
3223 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3224 * above while extending the buffer, we cannot allow the
3225 * buffer to remain with B_CACHE set after the write
3226 * completes or it will represent a corrupt state. To
3227 * deal with this we set B_NOCACHE to scrap the buffer
3228 * after the write.
3229 *
3230 * We might be able to do something fancy, like setting
3231 * B_CACHE in bwrite() except if B_DELWRI is already set,
3232 * so the below call doesn't set B_CACHE, but that gets real
3233 * confusing. This is much easier.
3234 */
3235
3236 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3237 bp->b_flags |= B_NOCACHE;
3238 bwrite(bp);
3239 goto loop;
3240 }
3241 bp->b_flags &= ~B_DONE;
3242 } else {
3243 /*
3244 * Buffer is not in-core, create new buffer. The buffer
3245 * returned by getnewbuf() is locked. Note that the returned
3246 * buffer is also considered valid (not marked B_INVAL).
3247 */
3248 BO_UNLOCK(bo);
3249 /*
3250 * If the user does not want us to create the buffer, bail out
3251 * here.
3252 */
3253 if (flags & GB_NOCREAT)
3254 return NULL;
3255 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
3256 offset = blkno * bsize;
3257 vmio = vp->v_object != NULL;
3258 if (vmio) {
3259 maxsize = size + (offset & PAGE_MASK);
3260 } else {
3261 maxsize = size;
3262 /* Do not allow non-VMIO notmapped buffers. */
3263 flags &= ~GB_UNMAPPED;
3264 }
3265 maxsize = imax(maxsize, bsize);
3266
3267 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags);
3268 if (bp == NULL) {
3269 if (slpflag || slptimeo)
3270 return NULL;
3271 goto loop;
3272 }
3273
3274 /*
3275 * This code is used to make sure that a buffer is not
3276 * created while the getnewbuf routine is blocked.
3277 * This can be a problem whether the vnode is locked or not.
3278 * If the buffer is created out from under us, we have to
3279 * throw away the one we just created.
3280 *
3281 * Note: this must occur before we associate the buffer
3282 * with the vp especially considering limitations in
3283 * the splay tree implementation when dealing with duplicate
3284 * lblkno's.
3285 */
3286 BO_LOCK(bo);
3287 if (gbincore(bo, blkno)) {
3288 BO_UNLOCK(bo);
3289 bp->b_flags |= B_INVAL;
3290 brelse(bp);
3291 goto loop;
3292 }
3293
3294 /*
3295 * Insert the buffer into the hash, so that it can
3296 * be found by incore.
3297 */
3298 bp->b_blkno = bp->b_lblkno = blkno;
3299 bp->b_offset = offset;
3300 bgetvp(vp, bp);
3301 BO_UNLOCK(bo);
3302
3303 /*
3304 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
3305 * buffer size starts out as 0, B_CACHE will be set by
3306 * allocbuf() for the VMIO case prior to it testing the
3307 * backing store for validity.
3308 */
3309
3310 if (vmio) {
3311 bp->b_flags |= B_VMIO;
3312 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
3313 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
3314 bp, vp->v_object, bp->b_bufobj->bo_object));
3315 } else {
3316 bp->b_flags &= ~B_VMIO;
3317 KASSERT(bp->b_bufobj->bo_object == NULL,
3318 ("ARGH! has b_bufobj->bo_object %p %p\n",
3319 bp, bp->b_bufobj->bo_object));
3320 BUF_CHECK_MAPPED(bp);
3321 }
3322
3323 allocbuf(bp, size);
3324 bp->b_flags &= ~B_DONE;
3325 }
3326 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
3327 BUF_ASSERT_HELD(bp);
3328 end:
3329 KASSERT(bp->b_bufobj == bo,
3330 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
3331 return (bp);
3332 }
3333
3334 /*
3335 * Get an empty, disassociated buffer of given size. The buffer is initially
3336 * set to B_INVAL.
3337 */
3338 struct buf *
3339 geteblk(int size, int flags)
3340 {
3341 struct buf *bp;
3342 int maxsize;
3343
3344 maxsize = (size + BKVAMASK) & ~BKVAMASK;
3345 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) {
3346 if ((flags & GB_NOWAIT_BD) &&
3347 (curthread->td_pflags & TDP_BUFNEED) != 0)
3348 return (NULL);
3349 }
3350 allocbuf(bp, size);
3351 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
3352 BUF_ASSERT_HELD(bp);
3353 return (bp);
3354 }
3355
3356
3357 /*
3358 * This code constitutes the buffer memory from either anonymous system
3359 * memory (in the case of non-VMIO operations) or from an associated
3360 * VM object (in the case of VMIO operations). This code is able to
3361 * resize a buffer up or down.
3362 *
3363 * Note that this code is tricky, and has many complications to resolve
3364 * deadlock or inconsistant data situations. Tread lightly!!!
3365 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3366 * the caller. Calling this code willy nilly can result in the loss of data.
3367 *
3368 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3369 * B_CACHE for the non-VMIO case.
3370 */
3371
3372 int
3373 allocbuf(struct buf *bp, int size)
3374 {
3375 int newbsize, mbsize;
3376 int i;
3377
3378 BUF_ASSERT_HELD(bp);
3379
3380 if (bp->b_kvasize < size)
3381 panic("allocbuf: buffer too small");
3382
3383 if ((bp->b_flags & B_VMIO) == 0) {
3384 caddr_t origbuf;
3385 int origbufsize;
3386 /*
3387 * Just get anonymous memory from the kernel. Don't
3388 * mess with B_CACHE.
3389 */
3390 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3391 if (bp->b_flags & B_MALLOC)
3392 newbsize = mbsize;
3393 else
3394 newbsize = round_page(size);
3395
3396 if (newbsize < bp->b_bufsize) {
3397 /*
3398 * malloced buffers are not shrunk
3399 */
3400 if (bp->b_flags & B_MALLOC) {
3401 if (newbsize) {
3402 bp->b_bcount = size;
3403 } else {
3404 free(bp->b_data, M_BIOBUF);
3405 if (bp->b_bufsize) {
3406 atomic_subtract_long(
3407 &bufmallocspace,
3408 bp->b_bufsize);
3409 bufspacewakeup();
3410 bp->b_bufsize = 0;
3411 }
3412 bp->b_saveaddr = bp->b_kvabase;
3413 bp->b_data = bp->b_saveaddr;
3414 bp->b_bcount = 0;
3415 bp->b_flags &= ~B_MALLOC;
3416 }
3417 return 1;
3418 }
3419 vm_hold_free_pages(bp, newbsize);
3420 } else if (newbsize > bp->b_bufsize) {
3421 /*
3422 * We only use malloced memory on the first allocation.
3423 * and revert to page-allocated memory when the buffer
3424 * grows.
3425 */
3426 /*
3427 * There is a potential smp race here that could lead
3428 * to bufmallocspace slightly passing the max. It
3429 * is probably extremely rare and not worth worrying
3430 * over.
3431 */
3432 if ( (bufmallocspace < maxbufmallocspace) &&
3433 (bp->b_bufsize == 0) &&
3434 (mbsize <= PAGE_SIZE/2)) {
3435
3436 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
3437 bp->b_bufsize = mbsize;
3438 bp->b_bcount = size;
3439 bp->b_flags |= B_MALLOC;
3440 atomic_add_long(&bufmallocspace, mbsize);
3441 return 1;
3442 }
3443 origbuf = NULL;
3444 origbufsize = 0;
3445 /*
3446 * If the buffer is growing on its other-than-first allocation,
3447 * then we revert to the page-allocation scheme.
3448 */
3449 if (bp->b_flags & B_MALLOC) {
3450 origbuf = bp->b_data;
3451 origbufsize = bp->b_bufsize;
3452 bp->b_data = bp->b_kvabase;
3453 if (bp->b_bufsize) {
3454 atomic_subtract_long(&bufmallocspace,
3455 bp->b_bufsize);
3456 bufspacewakeup();
3457 bp->b_bufsize = 0;
3458 }
3459 bp->b_flags &= ~B_MALLOC;
3460 newbsize = round_page(newbsize);
3461 }
3462 vm_hold_load_pages(
3463 bp,
3464 (vm_offset_t) bp->b_data + bp->b_bufsize,
3465 (vm_offset_t) bp->b_data + newbsize);
3466 if (origbuf) {
3467 bcopy(origbuf, bp->b_data, origbufsize);
3468 free(origbuf, M_BIOBUF);
3469 }
3470 }
3471 } else {
3472 int desiredpages;
3473
3474 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3475 desiredpages = (size == 0) ? 0 :
3476 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
3477
3478 if (bp->b_flags & B_MALLOC)
3479 panic("allocbuf: VMIO buffer can't be malloced");
3480 /*
3481 * Set B_CACHE initially if buffer is 0 length or will become
3482 * 0-length.
3483 */
3484 if (size == 0 || bp->b_bufsize == 0)
3485 bp->b_flags |= B_CACHE;
3486
3487 if (newbsize < bp->b_bufsize) {
3488 /*
3489 * DEV_BSIZE aligned new buffer size is less then the
3490 * DEV_BSIZE aligned existing buffer size. Figure out
3491 * if we have to remove any pages.
3492 */
3493 if (desiredpages < bp->b_npages) {
3494 vm_page_t m;
3495
3496 if ((bp->b_flags & B_UNMAPPED) == 0) {
3497 BUF_CHECK_MAPPED(bp);
3498 pmap_qremove((vm_offset_t)trunc_page(
3499 (vm_offset_t)bp->b_data) +
3500 (desiredpages << PAGE_SHIFT),
3501 (bp->b_npages - desiredpages));
3502 } else
3503 BUF_CHECK_UNMAPPED(bp);
3504 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3505 for (i = desiredpages; i < bp->b_npages; i++) {
3506 /*
3507 * the page is not freed here -- it
3508 * is the responsibility of
3509 * vnode_pager_setsize
3510 */
3511 m = bp->b_pages[i];
3512 KASSERT(m != bogus_page,
3513 ("allocbuf: bogus page found"));
3514 while (vm_page_sleep_if_busy(m, TRUE,
3515 "biodep"))
3516 continue;
3517
3518 bp->b_pages[i] = NULL;
3519 vm_page_lock(m);
3520 vm_page_unwire(m, 0);
3521 vm_page_unlock(m);
3522 }
3523 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3524 bp->b_npages = desiredpages;
3525 }
3526 } else if (size > bp->b_bcount) {
3527 /*
3528 * We are growing the buffer, possibly in a
3529 * byte-granular fashion.
3530 */
3531 vm_object_t obj;
3532 vm_offset_t toff;
3533 vm_offset_t tinc;
3534
3535 /*
3536 * Step 1, bring in the VM pages from the object,
3537 * allocating them if necessary. We must clear
3538 * B_CACHE if these pages are not valid for the
3539 * range covered by the buffer.
3540 */
3541
3542 obj = bp->b_bufobj->bo_object;
3543
3544 VM_OBJECT_LOCK(obj);
3545 while (bp->b_npages < desiredpages) {
3546 vm_page_t m;
3547
3548 /*
3549 * We must allocate system pages since blocking
3550 * here could interfere with paging I/O, no
3551 * matter which process we are.
3552 *
3553 * We can only test VPO_BUSY here. Blocking on
3554 * m->busy might lead to a deadlock:
3555 * vm_fault->getpages->cluster_read->allocbuf
3556 * Thus, we specify VM_ALLOC_IGN_SBUSY.
3557 */
3558 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
3559 bp->b_npages, VM_ALLOC_NOBUSY |
3560 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
3561 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY |
3562 VM_ALLOC_COUNT(desiredpages - bp->b_npages));
3563 if (m->valid == 0)
3564 bp->b_flags &= ~B_CACHE;
3565 bp->b_pages[bp->b_npages] = m;
3566 ++bp->b_npages;
3567 }
3568
3569 /*
3570 * Step 2. We've loaded the pages into the buffer,
3571 * we have to figure out if we can still have B_CACHE
3572 * set. Note that B_CACHE is set according to the
3573 * byte-granular range ( bcount and size ), new the
3574 * aligned range ( newbsize ).
3575 *
3576 * The VM test is against m->valid, which is DEV_BSIZE
3577 * aligned. Needless to say, the validity of the data
3578 * needs to also be DEV_BSIZE aligned. Note that this
3579 * fails with NFS if the server or some other client
3580 * extends the file's EOF. If our buffer is resized,
3581 * B_CACHE may remain set! XXX
3582 */
3583
3584 toff = bp->b_bcount;
3585 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3586
3587 while ((bp->b_flags & B_CACHE) && toff < size) {
3588 vm_pindex_t pi;
3589
3590 if (tinc > (size - toff))
3591 tinc = size - toff;
3592
3593 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
3594 PAGE_SHIFT;
3595
3596 vfs_buf_test_cache(
3597 bp,
3598 bp->b_offset,
3599 toff,
3600 tinc,
3601 bp->b_pages[pi]
3602 );
3603 toff += tinc;
3604 tinc = PAGE_SIZE;
3605 }
3606 VM_OBJECT_UNLOCK(obj);
3607
3608 /*
3609 * Step 3, fixup the KVM pmap.
3610 */
3611 if ((bp->b_flags & B_UNMAPPED) == 0)
3612 bpmap_qenter(bp);
3613 else
3614 BUF_CHECK_UNMAPPED(bp);
3615 }
3616 }
3617 if (newbsize < bp->b_bufsize)
3618 bufspacewakeup();
3619 bp->b_bufsize = newbsize; /* actual buffer allocation */
3620 bp->b_bcount = size; /* requested buffer size */
3621 return 1;
3622 }
3623
3624 extern int inflight_transient_maps;
3625
3626 void
3627 biodone(struct bio *bp)
3628 {
3629 struct mtx *mtxp;
3630 void (*done)(struct bio *);
3631 vm_offset_t start, end;
3632 int transient;
3633
3634 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3635 mtx_lock(mtxp);
3636 bp->bio_flags |= BIO_DONE;
3637 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
3638 start = trunc_page((vm_offset_t)bp->bio_data);
3639 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
3640 transient = 1;
3641 } else {
3642 transient = 0;
3643 start = end = 0;
3644 }
3645 done = bp->bio_done;
3646 if (done == NULL)
3647 wakeup(bp);
3648 mtx_unlock(mtxp);
3649 if (done != NULL)
3650 done(bp);
3651 if (transient) {
3652 pmap_qremove(start, OFF_TO_IDX(end - start));
3653 vm_map_remove(bio_transient_map, start, end);
3654 atomic_add_int(&inflight_transient_maps, -1);
3655 }
3656 }
3657
3658 /*
3659 * Wait for a BIO to finish.
3660 *
3661 * XXX: resort to a timeout for now. The optimal locking (if any) for this
3662 * case is not yet clear.
3663 */
3664 int
3665 biowait(struct bio *bp, const char *wchan)
3666 {
3667 struct mtx *mtxp;
3668
3669 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3670 mtx_lock(mtxp);
3671 while ((bp->bio_flags & BIO_DONE) == 0)
3672 msleep(bp, mtxp, PRIBIO, wchan, hz / 10);
3673 mtx_unlock(mtxp);
3674 if (bp->bio_error != 0)
3675 return (bp->bio_error);
3676 if (!(bp->bio_flags & BIO_ERROR))
3677 return (0);
3678 return (EIO);
3679 }
3680
3681 void
3682 biofinish(struct bio *bp, struct devstat *stat, int error)
3683 {
3684
3685 if (error) {
3686 bp->bio_error = error;
3687 bp->bio_flags |= BIO_ERROR;
3688 }
3689 if (stat != NULL)
3690 devstat_end_transaction_bio(stat, bp);
3691 biodone(bp);
3692 }
3693
3694 /*
3695 * bufwait:
3696 *
3697 * Wait for buffer I/O completion, returning error status. The buffer
3698 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3699 * error and cleared.
3700 */
3701 int
3702 bufwait(struct buf *bp)
3703 {
3704 if (bp->b_iocmd == BIO_READ)
3705 bwait(bp, PRIBIO, "biord");
3706 else
3707 bwait(bp, PRIBIO, "biowr");
3708 if (bp->b_flags & B_EINTR) {
3709 bp->b_flags &= ~B_EINTR;
3710 return (EINTR);
3711 }
3712 if (bp->b_ioflags & BIO_ERROR) {
3713 return (bp->b_error ? bp->b_error : EIO);
3714 } else {
3715 return (0);
3716 }
3717 }
3718
3719 /*
3720 * Call back function from struct bio back up to struct buf.
3721 */
3722 static void
3723 bufdonebio(struct bio *bip)
3724 {
3725 struct buf *bp;
3726
3727 bp = bip->bio_caller2;
3728 bp->b_resid = bp->b_bcount - bip->bio_completed;
3729 bp->b_resid = bip->bio_resid; /* XXX: remove */
3730 bp->b_ioflags = bip->bio_flags;
3731 bp->b_error = bip->bio_error;
3732 if (bp->b_error)
3733 bp->b_ioflags |= BIO_ERROR;
3734 bufdone(bp);
3735 g_destroy_bio(bip);
3736 }
3737
3738 void
3739 dev_strategy(struct cdev *dev, struct buf *bp)
3740 {
3741 struct cdevsw *csw;
3742 int ref;
3743
3744 KASSERT(dev->si_refcount > 0,
3745 ("dev_strategy on un-referenced struct cdev *(%s) %p",
3746 devtoname(dev), dev));
3747
3748 csw = dev_refthread(dev, &ref);
3749 dev_strategy_csw(dev, csw, bp);
3750 dev_relthread(dev, ref);
3751 }
3752
3753 void
3754 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp)
3755 {
3756 struct bio *bip;
3757
3758 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE,
3759 ("b_iocmd botch"));
3760 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) ||
3761 dev->si_threadcount > 0,
3762 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev),
3763 dev));
3764 if (csw == NULL) {
3765 bp->b_error = ENXIO;
3766 bp->b_ioflags = BIO_ERROR;
3767 bufdone(bp);
3768 return;
3769 }
3770 for (;;) {
3771 bip = g_new_bio();
3772 if (bip != NULL)
3773 break;
3774 /* Try again later */
3775 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3776 }
3777 bip->bio_cmd = bp->b_iocmd;
3778 bip->bio_offset = bp->b_iooffset;
3779 bip->bio_length = bp->b_bcount;
3780 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3781 bdata2bio(bp, bip);
3782 bip->bio_done = bufdonebio;
3783 bip->bio_caller2 = bp;
3784 bip->bio_dev = dev;
3785 (*csw->d_strategy)(bip);
3786 }
3787
3788 /*
3789 * bufdone:
3790 *
3791 * Finish I/O on a buffer, optionally calling a completion function.
3792 * This is usually called from an interrupt so process blocking is
3793 * not allowed.
3794 *
3795 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3796 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3797 * assuming B_INVAL is clear.
3798 *
3799 * For the VMIO case, we set B_CACHE if the op was a read and no
3800 * read error occured, or if the op was a write. B_CACHE is never
3801 * set if the buffer is invalid or otherwise uncacheable.
3802 *
3803 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3804 * initiator to leave B_INVAL set to brelse the buffer out of existance
3805 * in the biodone routine.
3806 */
3807 void
3808 bufdone(struct buf *bp)
3809 {
3810 struct bufobj *dropobj;
3811 void (*biodone)(struct buf *);
3812
3813 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3814 dropobj = NULL;
3815
3816 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3817 BUF_ASSERT_HELD(bp);
3818
3819 runningbufwakeup(bp);
3820 if (bp->b_iocmd == BIO_WRITE)
3821 dropobj = bp->b_bufobj;
3822 /* call optional completion function if requested */
3823 if (bp->b_iodone != NULL) {
3824 biodone = bp->b_iodone;
3825 bp->b_iodone = NULL;
3826 (*biodone) (bp);
3827 if (dropobj)
3828 bufobj_wdrop(dropobj);
3829 return;
3830 }
3831
3832 bufdone_finish(bp);
3833
3834 if (dropobj)
3835 bufobj_wdrop(dropobj);
3836 }
3837
3838 void
3839 bufdone_finish(struct buf *bp)
3840 {
3841 BUF_ASSERT_HELD(bp);
3842
3843 if (!LIST_EMPTY(&bp->b_dep))
3844 buf_complete(bp);
3845
3846 if (bp->b_flags & B_VMIO) {
3847 vm_ooffset_t foff;
3848 vm_page_t m;
3849 vm_object_t obj;
3850 struct vnode *vp;
3851 int bogus, i, iosize;
3852
3853 obj = bp->b_bufobj->bo_object;
3854 KASSERT(obj->paging_in_progress >= bp->b_npages,
3855 ("biodone_finish: paging in progress(%d) < b_npages(%d)",
3856 obj->paging_in_progress, bp->b_npages));
3857
3858 vp = bp->b_vp;
3859 KASSERT(vp->v_holdcnt > 0,
3860 ("biodone_finish: vnode %p has zero hold count", vp));
3861 KASSERT(vp->v_object != NULL,
3862 ("biodone_finish: vnode %p has no vm_object", vp));
3863
3864 foff = bp->b_offset;
3865 KASSERT(bp->b_offset != NOOFFSET,
3866 ("biodone_finish: bp %p has no buffer offset", bp));
3867
3868 /*
3869 * Set B_CACHE if the op was a normal read and no error
3870 * occured. B_CACHE is set for writes in the b*write()
3871 * routines.
3872 */
3873 iosize = bp->b_bcount - bp->b_resid;
3874 if (bp->b_iocmd == BIO_READ &&
3875 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3876 !(bp->b_ioflags & BIO_ERROR)) {
3877 bp->b_flags |= B_CACHE;
3878 }
3879 bogus = 0;
3880 VM_OBJECT_LOCK(obj);
3881 for (i = 0; i < bp->b_npages; i++) {
3882 int bogusflag = 0;
3883 int resid;
3884
3885 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3886 if (resid > iosize)
3887 resid = iosize;
3888
3889 /*
3890 * cleanup bogus pages, restoring the originals
3891 */
3892 m = bp->b_pages[i];
3893 if (m == bogus_page) {
3894 bogus = bogusflag = 1;
3895 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3896 if (m == NULL)
3897 panic("biodone: page disappeared!");
3898 bp->b_pages[i] = m;
3899 }
3900 KASSERT(OFF_TO_IDX(foff) == m->pindex,
3901 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch",
3902 (intmax_t)foff, (uintmax_t)m->pindex));
3903
3904 /*
3905 * In the write case, the valid and clean bits are
3906 * already changed correctly ( see bdwrite() ), so we
3907 * only need to do this here in the read case.
3908 */
3909 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3910 KASSERT((m->dirty & vm_page_bits(foff &
3911 PAGE_MASK, resid)) == 0, ("bufdone_finish:"
3912 " page %p has unexpected dirty bits", m));
3913 vfs_page_set_valid(bp, foff, m);
3914 }
3915
3916 vm_page_io_finish(m);
3917 vm_object_pip_subtract(obj, 1);
3918 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3919 iosize -= resid;
3920 }
3921 vm_object_pip_wakeupn(obj, 0);
3922 VM_OBJECT_UNLOCK(obj);
3923 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) {
3924 BUF_CHECK_MAPPED(bp);
3925 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3926 bp->b_pages, bp->b_npages);
3927 }
3928 }
3929
3930 /*
3931 * For asynchronous completions, release the buffer now. The brelse
3932 * will do a wakeup there if necessary - so no need to do a wakeup
3933 * here in the async case. The sync case always needs to do a wakeup.
3934 */
3935
3936 if (bp->b_flags & B_ASYNC) {
3937 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3938 brelse(bp);
3939 else
3940 bqrelse(bp);
3941 } else
3942 bdone(bp);
3943 }
3944
3945 /*
3946 * This routine is called in lieu of iodone in the case of
3947 * incomplete I/O. This keeps the busy status for pages
3948 * consistant.
3949 */
3950 void
3951 vfs_unbusy_pages(struct buf *bp)
3952 {
3953 int i;
3954 vm_object_t obj;
3955 vm_page_t m;
3956
3957 runningbufwakeup(bp);
3958 if (!(bp->b_flags & B_VMIO))
3959 return;
3960
3961 obj = bp->b_bufobj->bo_object;
3962 VM_OBJECT_LOCK(obj);
3963 for (i = 0; i < bp->b_npages; i++) {
3964 m = bp->b_pages[i];
3965 if (m == bogus_page) {
3966 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3967 if (!m)
3968 panic("vfs_unbusy_pages: page missing\n");
3969 bp->b_pages[i] = m;
3970 if ((bp->b_flags & B_UNMAPPED) == 0) {
3971 BUF_CHECK_MAPPED(bp);
3972 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3973 bp->b_pages, bp->b_npages);
3974 } else
3975 BUF_CHECK_UNMAPPED(bp);
3976 }
3977 vm_object_pip_subtract(obj, 1);
3978 vm_page_io_finish(m);
3979 }
3980 vm_object_pip_wakeupn(obj, 0);
3981 VM_OBJECT_UNLOCK(obj);
3982 }
3983
3984 /*
3985 * vfs_page_set_valid:
3986 *
3987 * Set the valid bits in a page based on the supplied offset. The
3988 * range is restricted to the buffer's size.
3989 *
3990 * This routine is typically called after a read completes.
3991 */
3992 static void
3993 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3994 {
3995 vm_ooffset_t eoff;
3996
3997 /*
3998 * Compute the end offset, eoff, such that [off, eoff) does not span a
3999 * page boundary and eoff is not greater than the end of the buffer.
4000 * The end of the buffer, in this case, is our file EOF, not the
4001 * allocation size of the buffer.
4002 */
4003 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4004 if (eoff > bp->b_offset + bp->b_bcount)
4005 eoff = bp->b_offset + bp->b_bcount;
4006
4007 /*
4008 * Set valid range. This is typically the entire buffer and thus the
4009 * entire page.
4010 */
4011 if (eoff > off)
4012 vm_page_set_valid(m, off & PAGE_MASK, eoff - off);
4013 }
4014
4015 /*
4016 * vfs_page_set_validclean:
4017 *
4018 * Set the valid bits and clear the dirty bits in a page based on the
4019 * supplied offset. The range is restricted to the buffer's size.
4020 */
4021 static void
4022 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4023 {
4024 vm_ooffset_t soff, eoff;
4025
4026 /*
4027 * Start and end offsets in buffer. eoff - soff may not cross a
4028 * page boundry or cross the end of the buffer. The end of the
4029 * buffer, in this case, is our file EOF, not the allocation size
4030 * of the buffer.
4031 */
4032 soff = off;
4033 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4034 if (eoff > bp->b_offset + bp->b_bcount)
4035 eoff = bp->b_offset + bp->b_bcount;
4036
4037 /*
4038 * Set valid range. This is typically the entire buffer and thus the
4039 * entire page.
4040 */
4041 if (eoff > soff) {
4042 vm_page_set_validclean(
4043 m,
4044 (vm_offset_t) (soff & PAGE_MASK),
4045 (vm_offset_t) (eoff - soff)
4046 );
4047 }
4048 }
4049
4050 /*
4051 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If
4052 * any page is busy, drain the flag.
4053 */
4054 static void
4055 vfs_drain_busy_pages(struct buf *bp)
4056 {
4057 vm_page_t m;
4058 int i, last_busied;
4059
4060 VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED);
4061 last_busied = 0;
4062 for (i = 0; i < bp->b_npages; i++) {
4063 m = bp->b_pages[i];
4064 if ((m->oflags & VPO_BUSY) != 0) {
4065 for (; last_busied < i; last_busied++)
4066 vm_page_busy(bp->b_pages[last_busied]);
4067 while ((m->oflags & VPO_BUSY) != 0)
4068 vm_page_sleep(m, "vbpage");
4069 }
4070 }
4071 for (i = 0; i < last_busied; i++)
4072 vm_page_wakeup(bp->b_pages[i]);
4073 }
4074
4075 /*
4076 * This routine is called before a device strategy routine.
4077 * It is used to tell the VM system that paging I/O is in
4078 * progress, and treat the pages associated with the buffer
4079 * almost as being VPO_BUSY. Also the object paging_in_progress
4080 * flag is handled to make sure that the object doesn't become
4081 * inconsistant.
4082 *
4083 * Since I/O has not been initiated yet, certain buffer flags
4084 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
4085 * and should be ignored.
4086 */
4087 void
4088 vfs_busy_pages(struct buf *bp, int clear_modify)
4089 {
4090 int i, bogus;
4091 vm_object_t obj;
4092 vm_ooffset_t foff;
4093 vm_page_t m;
4094
4095 if (!(bp->b_flags & B_VMIO))
4096 return;
4097
4098 obj = bp->b_bufobj->bo_object;
4099 foff = bp->b_offset;
4100 KASSERT(bp->b_offset != NOOFFSET,
4101 ("vfs_busy_pages: no buffer offset"));
4102 VM_OBJECT_LOCK(obj);
4103 vfs_drain_busy_pages(bp);
4104 if (bp->b_bufsize != 0)
4105 vfs_setdirty_locked_object(bp);
4106 bogus = 0;
4107 for (i = 0; i < bp->b_npages; i++) {
4108 m = bp->b_pages[i];
4109
4110 if ((bp->b_flags & B_CLUSTER) == 0) {
4111 vm_object_pip_add(obj, 1);
4112 vm_page_io_start(m);
4113 }
4114 /*
4115 * When readying a buffer for a read ( i.e
4116 * clear_modify == 0 ), it is important to do
4117 * bogus_page replacement for valid pages in
4118 * partially instantiated buffers. Partially
4119 * instantiated buffers can, in turn, occur when
4120 * reconstituting a buffer from its VM backing store
4121 * base. We only have to do this if B_CACHE is
4122 * clear ( which causes the I/O to occur in the
4123 * first place ). The replacement prevents the read
4124 * I/O from overwriting potentially dirty VM-backed
4125 * pages. XXX bogus page replacement is, uh, bogus.
4126 * It may not work properly with small-block devices.
4127 * We need to find a better way.
4128 */
4129 if (clear_modify) {
4130 pmap_remove_write(m);
4131 vfs_page_set_validclean(bp, foff, m);
4132 } else if (m->valid == VM_PAGE_BITS_ALL &&
4133 (bp->b_flags & B_CACHE) == 0) {
4134 bp->b_pages[i] = bogus_page;
4135 bogus++;
4136 }
4137 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4138 }
4139 VM_OBJECT_UNLOCK(obj);
4140 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) {
4141 BUF_CHECK_MAPPED(bp);
4142 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4143 bp->b_pages, bp->b_npages);
4144 }
4145 }
4146
4147 /*
4148 * vfs_bio_set_valid:
4149 *
4150 * Set the range within the buffer to valid. The range is
4151 * relative to the beginning of the buffer, b_offset. Note that
4152 * b_offset itself may be offset from the beginning of the first
4153 * page.
4154 */
4155 void
4156 vfs_bio_set_valid(struct buf *bp, int base, int size)
4157 {
4158 int i, n;
4159 vm_page_t m;
4160
4161 if (!(bp->b_flags & B_VMIO))
4162 return;
4163
4164 /*
4165 * Fixup base to be relative to beginning of first page.
4166 * Set initial n to be the maximum number of bytes in the
4167 * first page that can be validated.
4168 */
4169 base += (bp->b_offset & PAGE_MASK);
4170 n = PAGE_SIZE - (base & PAGE_MASK);
4171
4172 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
4173 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4174 m = bp->b_pages[i];
4175 if (n > size)
4176 n = size;
4177 vm_page_set_valid(m, base & PAGE_MASK, n);
4178 base += n;
4179 size -= n;
4180 n = PAGE_SIZE;
4181 }
4182 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
4183 }
4184
4185 /*
4186 * vfs_bio_clrbuf:
4187 *
4188 * If the specified buffer is a non-VMIO buffer, clear the entire
4189 * buffer. If the specified buffer is a VMIO buffer, clear and
4190 * validate only the previously invalid portions of the buffer.
4191 * This routine essentially fakes an I/O, so we need to clear
4192 * BIO_ERROR and B_INVAL.
4193 *
4194 * Note that while we only theoretically need to clear through b_bcount,
4195 * we go ahead and clear through b_bufsize.
4196 */
4197 void
4198 vfs_bio_clrbuf(struct buf *bp)
4199 {
4200 int i, j, mask, sa, ea, slide;
4201
4202 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4203 clrbuf(bp);
4204 return;
4205 }
4206 bp->b_flags &= ~B_INVAL;
4207 bp->b_ioflags &= ~BIO_ERROR;
4208 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
4209 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4210 (bp->b_offset & PAGE_MASK) == 0) {
4211 if (bp->b_pages[0] == bogus_page)
4212 goto unlock;
4213 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4214 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
4215 if ((bp->b_pages[0]->valid & mask) == mask)
4216 goto unlock;
4217 if ((bp->b_pages[0]->valid & mask) == 0) {
4218 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4219 bp->b_pages[0]->valid |= mask;
4220 goto unlock;
4221 }
4222 }
4223 sa = bp->b_offset & PAGE_MASK;
4224 slide = 0;
4225 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4226 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4227 ea = slide & PAGE_MASK;
4228 if (ea == 0)
4229 ea = PAGE_SIZE;
4230 if (bp->b_pages[i] == bogus_page)
4231 continue;
4232 j = sa / DEV_BSIZE;
4233 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4234 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
4235 if ((bp->b_pages[i]->valid & mask) == mask)
4236 continue;
4237 if ((bp->b_pages[i]->valid & mask) == 0)
4238 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4239 else {
4240 for (; sa < ea; sa += DEV_BSIZE, j++) {
4241 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4242 pmap_zero_page_area(bp->b_pages[i],
4243 sa, DEV_BSIZE);
4244 }
4245 }
4246 }
4247 bp->b_pages[i]->valid |= mask;
4248 }
4249 unlock:
4250 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
4251 bp->b_resid = 0;
4252 }
4253
4254 void
4255 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4256 {
4257 vm_page_t m;
4258 int i, n;
4259
4260 if ((bp->b_flags & B_UNMAPPED) == 0) {
4261 BUF_CHECK_MAPPED(bp);
4262 bzero(bp->b_data + base, size);
4263 } else {
4264 BUF_CHECK_UNMAPPED(bp);
4265 n = PAGE_SIZE - (base & PAGE_MASK);
4266 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
4267 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4268 m = bp->b_pages[i];
4269 if (n > size)
4270 n = size;
4271 pmap_zero_page_area(m, base & PAGE_MASK, n);
4272 base += n;
4273 size -= n;
4274 n = PAGE_SIZE;
4275 }
4276 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
4277 }
4278 }
4279
4280 /*
4281 * vm_hold_load_pages and vm_hold_free_pages get pages into
4282 * a buffers address space. The pages are anonymous and are
4283 * not associated with a file object.
4284 */
4285 static void
4286 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4287 {
4288 vm_offset_t pg;
4289 vm_page_t p;
4290 int index;
4291
4292 BUF_CHECK_MAPPED(bp);
4293
4294 to = round_page(to);
4295 from = round_page(from);
4296 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4297
4298 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4299 tryagain:
4300 /*
4301 * note: must allocate system pages since blocking here
4302 * could interfere with paging I/O, no matter which
4303 * process we are.
4304 */
4305 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4306 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
4307 if (p == NULL) {
4308 VM_WAIT;
4309 goto tryagain;
4310 }
4311 pmap_qenter(pg, &p, 1);
4312 bp->b_pages[index] = p;
4313 }
4314 bp->b_npages = index;
4315 }
4316
4317 /* Return pages associated with this buf to the vm system */
4318 static void
4319 vm_hold_free_pages(struct buf *bp, int newbsize)
4320 {
4321 vm_offset_t from;
4322 vm_page_t p;
4323 int index, newnpages;
4324
4325 BUF_CHECK_MAPPED(bp);
4326
4327 from = round_page((vm_offset_t)bp->b_data + newbsize);
4328 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4329 if (bp->b_npages > newnpages)
4330 pmap_qremove(from, bp->b_npages - newnpages);
4331 for (index = newnpages; index < bp->b_npages; index++) {
4332 p = bp->b_pages[index];
4333 bp->b_pages[index] = NULL;
4334 if (p->busy != 0)
4335 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
4336 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
4337 p->wire_count--;
4338 vm_page_free(p);
4339 atomic_subtract_int(&cnt.v_wire_count, 1);
4340 }
4341 bp->b_npages = newnpages;
4342 }
4343
4344 /*
4345 * Map an IO request into kernel virtual address space.
4346 *
4347 * All requests are (re)mapped into kernel VA space.
4348 * Notice that we use b_bufsize for the size of the buffer
4349 * to be mapped. b_bcount might be modified by the driver.
4350 *
4351 * Note that even if the caller determines that the address space should
4352 * be valid, a race or a smaller-file mapped into a larger space may
4353 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4354 * check the return value.
4355 */
4356 int
4357 vmapbuf(struct buf *bp, int mapbuf)
4358 {
4359 caddr_t kva;
4360 vm_prot_t prot;
4361 int pidx;
4362
4363 if (bp->b_bufsize < 0)
4364 return (-1);
4365 prot = VM_PROT_READ;
4366 if (bp->b_iocmd == BIO_READ)
4367 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4368 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4369 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4370 btoc(MAXPHYS))) < 0)
4371 return (-1);
4372 bp->b_npages = pidx;
4373 if (mapbuf || !unmapped_buf_allowed) {
4374 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
4375 kva = bp->b_saveaddr;
4376 bp->b_saveaddr = bp->b_data;
4377 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK);
4378 bp->b_flags &= ~B_UNMAPPED;
4379 } else {
4380 bp->b_flags |= B_UNMAPPED;
4381 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4382 bp->b_saveaddr = bp->b_data;
4383 bp->b_data = unmapped_buf;
4384 }
4385 return(0);
4386 }
4387
4388 /*
4389 * Free the io map PTEs associated with this IO operation.
4390 * We also invalidate the TLB entries and restore the original b_addr.
4391 */
4392 void
4393 vunmapbuf(struct buf *bp)
4394 {
4395 int npages;
4396
4397 npages = bp->b_npages;
4398 if (bp->b_flags & B_UNMAPPED)
4399 bp->b_flags &= ~B_UNMAPPED;
4400 else
4401 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4402 vm_page_unhold_pages(bp->b_pages, npages);
4403
4404 bp->b_data = bp->b_saveaddr;
4405 }
4406
4407 void
4408 bdone(struct buf *bp)
4409 {
4410 struct mtx *mtxp;
4411
4412 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4413 mtx_lock(mtxp);
4414 bp->b_flags |= B_DONE;
4415 wakeup(bp);
4416 mtx_unlock(mtxp);
4417 }
4418
4419 void
4420 bwait(struct buf *bp, u_char pri, const char *wchan)
4421 {
4422 struct mtx *mtxp;
4423
4424 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4425 mtx_lock(mtxp);
4426 while ((bp->b_flags & B_DONE) == 0)
4427 msleep(bp, mtxp, pri, wchan, 0);
4428 mtx_unlock(mtxp);
4429 }
4430
4431 int
4432 bufsync(struct bufobj *bo, int waitfor)
4433 {
4434
4435 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
4436 }
4437
4438 void
4439 bufstrategy(struct bufobj *bo, struct buf *bp)
4440 {
4441 int i = 0;
4442 struct vnode *vp;
4443
4444 vp = bp->b_vp;
4445 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4446 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4447 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4448 i = VOP_STRATEGY(vp, bp);
4449 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4450 }
4451
4452 void
4453 bufobj_wrefl(struct bufobj *bo)
4454 {
4455
4456 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4457 ASSERT_BO_LOCKED(bo);
4458 bo->bo_numoutput++;
4459 }
4460
4461 void
4462 bufobj_wref(struct bufobj *bo)
4463 {
4464
4465 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4466 BO_LOCK(bo);
4467 bo->bo_numoutput++;
4468 BO_UNLOCK(bo);
4469 }
4470
4471 void
4472 bufobj_wdrop(struct bufobj *bo)
4473 {
4474
4475 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
4476 BO_LOCK(bo);
4477 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
4478 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
4479 bo->bo_flag &= ~BO_WWAIT;
4480 wakeup(&bo->bo_numoutput);
4481 }
4482 BO_UNLOCK(bo);
4483 }
4484
4485 int
4486 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
4487 {
4488 int error;
4489
4490 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
4491 ASSERT_BO_LOCKED(bo);
4492 error = 0;
4493 while (bo->bo_numoutput) {
4494 bo->bo_flag |= BO_WWAIT;
4495 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
4496 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
4497 if (error)
4498 break;
4499 }
4500 return (error);
4501 }
4502
4503 void
4504 bpin(struct buf *bp)
4505 {
4506 struct mtx *mtxp;
4507
4508 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4509 mtx_lock(mtxp);
4510 bp->b_pin_count++;
4511 mtx_unlock(mtxp);
4512 }
4513
4514 void
4515 bunpin(struct buf *bp)
4516 {
4517 struct mtx *mtxp;
4518
4519 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4520 mtx_lock(mtxp);
4521 if (--bp->b_pin_count == 0)
4522 wakeup(bp);
4523 mtx_unlock(mtxp);
4524 }
4525
4526 void
4527 bunpin_wait(struct buf *bp)
4528 {
4529 struct mtx *mtxp;
4530
4531 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4532 mtx_lock(mtxp);
4533 while (bp->b_pin_count > 0)
4534 msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
4535 mtx_unlock(mtxp);
4536 }
4537
4538 /*
4539 * Set bio_data or bio_ma for struct bio from the struct buf.
4540 */
4541 void
4542 bdata2bio(struct buf *bp, struct bio *bip)
4543 {
4544
4545 if ((bp->b_flags & B_UNMAPPED) != 0) {
4546 KASSERT(unmapped_buf_allowed, ("unmapped"));
4547 bip->bio_ma = bp->b_pages;
4548 bip->bio_ma_n = bp->b_npages;
4549 bip->bio_data = unmapped_buf;
4550 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
4551 bip->bio_flags |= BIO_UNMAPPED;
4552 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
4553 PAGE_SIZE == bp->b_npages,
4554 ("Buffer %p too short: %d %jd %d", bp, bip->bio_ma_offset,
4555 (uintmax_t)bip->bio_length, bip->bio_ma_n));
4556 } else {
4557 bip->bio_data = bp->b_data;
4558 bip->bio_ma = NULL;
4559 }
4560 }
4561
4562 #include "opt_ddb.h"
4563 #ifdef DDB
4564 #include <ddb/ddb.h>
4565
4566 /* DDB command to show buffer data */
4567 DB_SHOW_COMMAND(buffer, db_show_buffer)
4568 {
4569 /* get args */
4570 struct buf *bp = (struct buf *)addr;
4571
4572 if (!have_addr) {
4573 db_printf("usage: show buffer <addr>\n");
4574 return;
4575 }
4576
4577 db_printf("buf at %p\n", bp);
4578 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
4579 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
4580 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
4581 db_printf(
4582 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
4583 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
4584 "b_dep = %p\n",
4585 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4586 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4587 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
4588 if (bp->b_npages) {
4589 int i;
4590 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4591 for (i = 0; i < bp->b_npages; i++) {
4592 vm_page_t m;
4593 m = bp->b_pages[i];
4594 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4595 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4596 if ((i + 1) < bp->b_npages)
4597 db_printf(",");
4598 }
4599 db_printf("\n");
4600 }
4601 db_printf(" ");
4602 BUF_LOCKPRINTINFO(bp);
4603 }
4604
4605 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4606 {
4607 struct buf *bp;
4608 int i;
4609
4610 for (i = 0; i < nbuf; i++) {
4611 bp = &buf[i];
4612 if (BUF_ISLOCKED(bp)) {
4613 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4614 db_printf("\n");
4615 }
4616 }
4617 }
4618
4619 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
4620 {
4621 struct vnode *vp;
4622 struct buf *bp;
4623
4624 if (!have_addr) {
4625 db_printf("usage: show vnodebufs <addr>\n");
4626 return;
4627 }
4628 vp = (struct vnode *)addr;
4629 db_printf("Clean buffers:\n");
4630 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
4631 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4632 db_printf("\n");
4633 }
4634 db_printf("Dirty buffers:\n");
4635 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
4636 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4637 db_printf("\n");
4638 }
4639 }
4640
4641 DB_COMMAND(countfreebufs, db_coundfreebufs)
4642 {
4643 struct buf *bp;
4644 int i, used = 0, nfree = 0;
4645
4646 if (have_addr) {
4647 db_printf("usage: countfreebufs\n");
4648 return;
4649 }
4650
4651 for (i = 0; i < nbuf; i++) {
4652 bp = &buf[i];
4653 if ((bp->b_vflags & BV_INFREECNT) != 0)
4654 nfree++;
4655 else
4656 used++;
4657 }
4658
4659 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
4660 nfree + used);
4661 db_printf("numfreebuffers is %d\n", numfreebuffers);
4662 }
4663 #endif /* DDB */
Cache object: 48d39179cf509a330f73051b8543df5b
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