1 | /* $NetBSD: vfs_bio.c,v 1.262 2016/10/28 20:17:27 jdolecek Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc. |
5 | * All rights reserved. |
6 | * |
7 | * This code is derived from software contributed to The NetBSD Foundation |
8 | * by Andrew Doran, and by Wasabi Systems, Inc. |
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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
29 | * POSSIBILITY OF SUCH DAMAGE. |
30 | */ |
31 | |
32 | /*- |
33 | * Copyright (c) 1982, 1986, 1989, 1993 |
34 | * The Regents of the University of California. All rights reserved. |
35 | * (c) UNIX System Laboratories, Inc. |
36 | * All or some portions of this file are derived from material licensed |
37 | * to the University of California by American Telephone and Telegraph |
38 | * Co. or Unix System Laboratories, Inc. and are reproduced herein with |
39 | * the permission of UNIX System Laboratories, Inc. |
40 | * |
41 | * Redistribution and use in source and binary forms, with or without |
42 | * modification, are permitted provided that the following conditions |
43 | * are met: |
44 | * 1. Redistributions of source code must retain the above copyright |
45 | * notice, this list of conditions and the following disclaimer. |
46 | * 2. Redistributions in binary form must reproduce the above copyright |
47 | * notice, this list of conditions and the following disclaimer in the |
48 | * documentation and/or other materials provided with the distribution. |
49 | * 3. Neither the name of the University nor the names of its contributors |
50 | * may be used to endorse or promote products derived from this software |
51 | * without specific prior written permission. |
52 | * |
53 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
54 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
55 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
56 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
57 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
58 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
59 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
60 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
61 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
62 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
63 | * SUCH DAMAGE. |
64 | * |
65 | * @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94 |
66 | */ |
67 | |
68 | /*- |
69 | * Copyright (c) 1994 Christopher G. Demetriou |
70 | * |
71 | * Redistribution and use in source and binary forms, with or without |
72 | * modification, are permitted provided that the following conditions |
73 | * are met: |
74 | * 1. Redistributions of source code must retain the above copyright |
75 | * notice, this list of conditions and the following disclaimer. |
76 | * 2. Redistributions in binary form must reproduce the above copyright |
77 | * notice, this list of conditions and the following disclaimer in the |
78 | * documentation and/or other materials provided with the distribution. |
79 | * 3. All advertising materials mentioning features or use of this software |
80 | * must display the following acknowledgement: |
81 | * This product includes software developed by the University of |
82 | * California, Berkeley and its contributors. |
83 | * 4. Neither the name of the University nor the names of its contributors |
84 | * may be used to endorse or promote products derived from this software |
85 | * without specific prior written permission. |
86 | * |
87 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
88 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
89 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
90 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
91 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
92 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
93 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
94 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
95 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
96 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
97 | * SUCH DAMAGE. |
98 | * |
99 | * @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94 |
100 | */ |
101 | |
102 | /* |
103 | * The buffer cache subsystem. |
104 | * |
105 | * Some references: |
106 | * Bach: The Design of the UNIX Operating System (Prentice Hall, 1986) |
107 | * Leffler, et al.: The Design and Implementation of the 4.3BSD |
108 | * UNIX Operating System (Addison Welley, 1989) |
109 | * |
110 | * Locking |
111 | * |
112 | * There are three locks: |
113 | * - bufcache_lock: protects global buffer cache state. |
114 | * - BC_BUSY: a long term per-buffer lock. |
115 | * - buf_t::b_objlock: lock on completion (biowait vs biodone). |
116 | * |
117 | * For buffers associated with vnodes (a most common case) b_objlock points |
118 | * to the vnode_t::v_interlock. Otherwise, it points to generic buffer_lock. |
119 | * |
120 | * Lock order: |
121 | * bufcache_lock -> |
122 | * buf_t::b_objlock |
123 | */ |
124 | |
125 | #include <sys/cdefs.h> |
126 | __KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.262 2016/10/28 20:17:27 jdolecek Exp $" ); |
127 | |
128 | #ifdef _KERNEL_OPT |
129 | #include "opt_bufcache.h" |
130 | #include "opt_dtrace.h" |
131 | #endif |
132 | |
133 | #include <sys/param.h> |
134 | #include <sys/systm.h> |
135 | #include <sys/kernel.h> |
136 | #include <sys/proc.h> |
137 | #include <sys/buf.h> |
138 | #include <sys/vnode.h> |
139 | #include <sys/mount.h> |
140 | #include <sys/resourcevar.h> |
141 | #include <sys/sysctl.h> |
142 | #include <sys/conf.h> |
143 | #include <sys/kauth.h> |
144 | #include <sys/fstrans.h> |
145 | #include <sys/intr.h> |
146 | #include <sys/cpu.h> |
147 | #include <sys/wapbl.h> |
148 | #include <sys/bitops.h> |
149 | #include <sys/cprng.h> |
150 | #include <sys/sdt.h> |
151 | |
152 | #include <uvm/uvm.h> /* extern struct uvm uvm */ |
153 | |
154 | #include <miscfs/specfs/specdev.h> |
155 | |
156 | #ifndef BUFPAGES |
157 | # define BUFPAGES 0 |
158 | #endif |
159 | |
160 | #ifdef BUFCACHE |
161 | # if (BUFCACHE < 5) || (BUFCACHE > 95) |
162 | # error BUFCACHE is not between 5 and 95 |
163 | # endif |
164 | #else |
165 | # define BUFCACHE 15 |
166 | #endif |
167 | |
168 | u_int nbuf; /* desired number of buffer headers */ |
169 | u_int bufpages = BUFPAGES; /* optional hardwired count */ |
170 | u_int bufcache = BUFCACHE; /* max % of RAM to use for buffer cache */ |
171 | |
172 | /* Function prototypes */ |
173 | struct bqueue; |
174 | |
175 | static void buf_setwm(void); |
176 | static int buf_trim(void); |
177 | static void *bufpool_page_alloc(struct pool *, int); |
178 | static void bufpool_page_free(struct pool *, void *); |
179 | static buf_t *bio_doread(struct vnode *, daddr_t, int, int); |
180 | static buf_t *getnewbuf(int, int, int); |
181 | static int buf_lotsfree(void); |
182 | static int buf_canrelease(void); |
183 | static u_long buf_mempoolidx(u_long); |
184 | static u_long buf_roundsize(u_long); |
185 | static void *buf_alloc(size_t); |
186 | static void buf_mrelease(void *, size_t); |
187 | static void binsheadfree(buf_t *, struct bqueue *); |
188 | static void binstailfree(buf_t *, struct bqueue *); |
189 | #ifdef DEBUG |
190 | static int checkfreelist(buf_t *, struct bqueue *, int); |
191 | #endif |
192 | static void biointr(void *); |
193 | static void biodone2(buf_t *); |
194 | static void bref(buf_t *); |
195 | static void brele(buf_t *); |
196 | static void sysctl_kern_buf_setup(void); |
197 | static void sysctl_vm_buf_setup(void); |
198 | |
199 | /* |
200 | * Definitions for the buffer hash lists. |
201 | */ |
202 | #define BUFHASH(dvp, lbn) \ |
203 | (&bufhashtbl[(((long)(dvp) >> 8) + (int)(lbn)) & bufhash]) |
204 | LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; |
205 | u_long bufhash; |
206 | struct bqueue bufqueues[BQUEUES]; |
207 | |
208 | static kcondvar_t needbuffer_cv; |
209 | |
210 | /* |
211 | * Buffer queue lock. |
212 | */ |
213 | kmutex_t bufcache_lock; |
214 | kmutex_t buffer_lock; |
215 | |
216 | /* Software ISR for completed transfers. */ |
217 | static void *biodone_sih; |
218 | |
219 | /* Buffer pool for I/O buffers. */ |
220 | static pool_cache_t buf_cache; |
221 | static pool_cache_t bufio_cache; |
222 | |
223 | #define MEMPOOL_INDEX_OFFSET (ilog2(DEV_BSIZE)) /* smallest pool is 512 bytes */ |
224 | #define NMEMPOOLS (ilog2(MAXBSIZE) - MEMPOOL_INDEX_OFFSET + 1) |
225 | __CTASSERT((1 << (NMEMPOOLS + MEMPOOL_INDEX_OFFSET - 1)) == MAXBSIZE); |
226 | |
227 | /* Buffer memory pools */ |
228 | static struct pool bmempools[NMEMPOOLS]; |
229 | |
230 | static struct vm_map *buf_map; |
231 | |
232 | /* |
233 | * Buffer memory pool allocator. |
234 | */ |
235 | static void * |
236 | bufpool_page_alloc(struct pool *pp, int flags) |
237 | { |
238 | |
239 | return (void *)uvm_km_alloc(buf_map, |
240 | MAXBSIZE, MAXBSIZE, |
241 | ((flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT|UVM_KMF_TRYLOCK) |
242 | | UVM_KMF_WIRED); |
243 | } |
244 | |
245 | static void |
246 | bufpool_page_free(struct pool *pp, void *v) |
247 | { |
248 | |
249 | uvm_km_free(buf_map, (vaddr_t)v, MAXBSIZE, UVM_KMF_WIRED); |
250 | } |
251 | |
252 | static struct pool_allocator bufmempool_allocator = { |
253 | .pa_alloc = bufpool_page_alloc, |
254 | .pa_free = bufpool_page_free, |
255 | .pa_pagesz = MAXBSIZE, |
256 | }; |
257 | |
258 | /* Buffer memory management variables */ |
259 | u_long bufmem_valimit; |
260 | u_long bufmem_hiwater; |
261 | u_long bufmem_lowater; |
262 | u_long bufmem; |
263 | |
264 | /* |
265 | * MD code can call this to set a hard limit on the amount |
266 | * of virtual memory used by the buffer cache. |
267 | */ |
268 | int |
269 | buf_setvalimit(vsize_t sz) |
270 | { |
271 | |
272 | /* We need to accommodate at least NMEMPOOLS of MAXBSIZE each */ |
273 | if (sz < NMEMPOOLS * MAXBSIZE) |
274 | return EINVAL; |
275 | |
276 | bufmem_valimit = sz; |
277 | return 0; |
278 | } |
279 | |
280 | static void |
281 | buf_setwm(void) |
282 | { |
283 | |
284 | bufmem_hiwater = buf_memcalc(); |
285 | /* lowater is approx. 2% of memory (with bufcache = 15) */ |
286 | #define BUFMEM_WMSHIFT 3 |
287 | #define BUFMEM_HIWMMIN (64 * 1024 << BUFMEM_WMSHIFT) |
288 | if (bufmem_hiwater < BUFMEM_HIWMMIN) |
289 | /* Ensure a reasonable minimum value */ |
290 | bufmem_hiwater = BUFMEM_HIWMMIN; |
291 | bufmem_lowater = bufmem_hiwater >> BUFMEM_WMSHIFT; |
292 | } |
293 | |
294 | #ifdef DEBUG |
295 | int debug_verify_freelist = 0; |
296 | static int |
297 | checkfreelist(buf_t *bp, struct bqueue *dp, int ison) |
298 | { |
299 | buf_t *b; |
300 | |
301 | if (!debug_verify_freelist) |
302 | return 1; |
303 | |
304 | TAILQ_FOREACH(b, &dp->bq_queue, b_freelist) { |
305 | if (b == bp) |
306 | return ison ? 1 : 0; |
307 | } |
308 | |
309 | return ison ? 0 : 1; |
310 | } |
311 | #endif |
312 | |
313 | /* |
314 | * Insq/Remq for the buffer hash lists. |
315 | * Call with buffer queue locked. |
316 | */ |
317 | static void |
318 | binsheadfree(buf_t *bp, struct bqueue *dp) |
319 | { |
320 | |
321 | KASSERT(mutex_owned(&bufcache_lock)); |
322 | KASSERT(bp->b_freelistindex == -1); |
323 | TAILQ_INSERT_HEAD(&dp->bq_queue, bp, b_freelist); |
324 | dp->bq_bytes += bp->b_bufsize; |
325 | bp->b_freelistindex = dp - bufqueues; |
326 | } |
327 | |
328 | static void |
329 | binstailfree(buf_t *bp, struct bqueue *dp) |
330 | { |
331 | |
332 | KASSERT(mutex_owned(&bufcache_lock)); |
333 | KASSERTMSG(bp->b_freelistindex == -1, "double free of buffer? " |
334 | "bp=%p, b_freelistindex=%d\n" , bp, bp->b_freelistindex); |
335 | TAILQ_INSERT_TAIL(&dp->bq_queue, bp, b_freelist); |
336 | dp->bq_bytes += bp->b_bufsize; |
337 | bp->b_freelistindex = dp - bufqueues; |
338 | } |
339 | |
340 | void |
341 | bremfree(buf_t *bp) |
342 | { |
343 | struct bqueue *dp; |
344 | int bqidx = bp->b_freelistindex; |
345 | |
346 | KASSERT(mutex_owned(&bufcache_lock)); |
347 | |
348 | KASSERT(bqidx != -1); |
349 | dp = &bufqueues[bqidx]; |
350 | KDASSERT(checkfreelist(bp, dp, 1)); |
351 | KASSERT(dp->bq_bytes >= bp->b_bufsize); |
352 | TAILQ_REMOVE(&dp->bq_queue, bp, b_freelist); |
353 | dp->bq_bytes -= bp->b_bufsize; |
354 | |
355 | /* For the sysctl helper. */ |
356 | if (bp == dp->bq_marker) |
357 | dp->bq_marker = NULL; |
358 | |
359 | #if defined(DIAGNOSTIC) |
360 | bp->b_freelistindex = -1; |
361 | #endif /* defined(DIAGNOSTIC) */ |
362 | } |
363 | |
364 | /* |
365 | * Add a reference to an buffer structure that came from buf_cache. |
366 | */ |
367 | static inline void |
368 | bref(buf_t *bp) |
369 | { |
370 | |
371 | KASSERT(mutex_owned(&bufcache_lock)); |
372 | KASSERT(bp->b_refcnt > 0); |
373 | |
374 | bp->b_refcnt++; |
375 | } |
376 | |
377 | /* |
378 | * Free an unused buffer structure that came from buf_cache. |
379 | */ |
380 | static inline void |
381 | brele(buf_t *bp) |
382 | { |
383 | |
384 | KASSERT(mutex_owned(&bufcache_lock)); |
385 | KASSERT(bp->b_refcnt > 0); |
386 | |
387 | if (bp->b_refcnt-- == 1) { |
388 | buf_destroy(bp); |
389 | #ifdef DEBUG |
390 | memset((char *)bp, 0, sizeof(*bp)); |
391 | #endif |
392 | pool_cache_put(buf_cache, bp); |
393 | } |
394 | } |
395 | |
396 | /* |
397 | * note that for some ports this is used by pmap bootstrap code to |
398 | * determine kva size. |
399 | */ |
400 | u_long |
401 | buf_memcalc(void) |
402 | { |
403 | u_long n; |
404 | vsize_t mapsz = 0; |
405 | |
406 | /* |
407 | * Determine the upper bound of memory to use for buffers. |
408 | * |
409 | * - If bufpages is specified, use that as the number |
410 | * pages. |
411 | * |
412 | * - Otherwise, use bufcache as the percentage of |
413 | * physical memory. |
414 | */ |
415 | if (bufpages != 0) { |
416 | n = bufpages; |
417 | } else { |
418 | if (bufcache < 5) { |
419 | printf("forcing bufcache %d -> 5" , bufcache); |
420 | bufcache = 5; |
421 | } |
422 | if (bufcache > 95) { |
423 | printf("forcing bufcache %d -> 95" , bufcache); |
424 | bufcache = 95; |
425 | } |
426 | if (buf_map != NULL) |
427 | mapsz = vm_map_max(buf_map) - vm_map_min(buf_map); |
428 | n = calc_cache_size(mapsz, bufcache, |
429 | (buf_map != kernel_map) ? 100 : BUFCACHE_VA_MAXPCT) |
430 | / PAGE_SIZE; |
431 | } |
432 | |
433 | n <<= PAGE_SHIFT; |
434 | if (bufmem_valimit != 0 && n > bufmem_valimit) |
435 | n = bufmem_valimit; |
436 | |
437 | return (n); |
438 | } |
439 | |
440 | /* |
441 | * Initialize buffers and hash links for buffers. |
442 | */ |
443 | void |
444 | bufinit(void) |
445 | { |
446 | struct bqueue *dp; |
447 | int use_std; |
448 | u_int i; |
449 | |
450 | biodone_vfs = biodone; |
451 | |
452 | mutex_init(&bufcache_lock, MUTEX_DEFAULT, IPL_NONE); |
453 | mutex_init(&buffer_lock, MUTEX_DEFAULT, IPL_NONE); |
454 | cv_init(&needbuffer_cv, "needbuf" ); |
455 | |
456 | if (bufmem_valimit != 0) { |
457 | vaddr_t minaddr = 0, maxaddr; |
458 | buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr, |
459 | bufmem_valimit, 0, false, 0); |
460 | if (buf_map == NULL) |
461 | panic("bufinit: cannot allocate submap" ); |
462 | } else |
463 | buf_map = kernel_map; |
464 | |
465 | /* |
466 | * Initialize buffer cache memory parameters. |
467 | */ |
468 | bufmem = 0; |
469 | buf_setwm(); |
470 | |
471 | /* On "small" machines use small pool page sizes where possible */ |
472 | use_std = (physmem < atop(16*1024*1024)); |
473 | |
474 | /* |
475 | * Also use them on systems that can map the pool pages using |
476 | * a direct-mapped segment. |
477 | */ |
478 | #ifdef PMAP_MAP_POOLPAGE |
479 | use_std = 1; |
480 | #endif |
481 | |
482 | buf_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, |
483 | "bufpl" , NULL, IPL_SOFTBIO, NULL, NULL, NULL); |
484 | bufio_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, |
485 | "biopl" , NULL, IPL_BIO, NULL, NULL, NULL); |
486 | |
487 | for (i = 0; i < NMEMPOOLS; i++) { |
488 | struct pool_allocator *pa; |
489 | struct pool *pp = &bmempools[i]; |
490 | u_int size = 1 << (i + MEMPOOL_INDEX_OFFSET); |
491 | char *name = kmem_alloc(8, KM_SLEEP); /* XXX: never freed */ |
492 | if (__predict_false(size >= 1048576)) |
493 | (void)snprintf(name, 8, "buf%um" , size / 1048576); |
494 | else if (__predict_true(size >= 1024)) |
495 | (void)snprintf(name, 8, "buf%uk" , size / 1024); |
496 | else |
497 | (void)snprintf(name, 8, "buf%ub" , size); |
498 | pa = (size <= PAGE_SIZE && use_std) |
499 | ? &pool_allocator_nointr |
500 | : &bufmempool_allocator; |
501 | pool_init(pp, size, 0, 0, 0, name, pa, IPL_NONE); |
502 | pool_setlowat(pp, 1); |
503 | pool_sethiwat(pp, 1); |
504 | } |
505 | |
506 | /* Initialize the buffer queues */ |
507 | for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++) { |
508 | TAILQ_INIT(&dp->bq_queue); |
509 | dp->bq_bytes = 0; |
510 | } |
511 | |
512 | /* |
513 | * Estimate hash table size based on the amount of memory we |
514 | * intend to use for the buffer cache. The average buffer |
515 | * size is dependent on our clients (i.e. filesystems). |
516 | * |
517 | * For now, use an empirical 3K per buffer. |
518 | */ |
519 | nbuf = (bufmem_hiwater / 1024) / 3; |
520 | bufhashtbl = hashinit(nbuf, HASH_LIST, true, &bufhash); |
521 | |
522 | sysctl_kern_buf_setup(); |
523 | sysctl_vm_buf_setup(); |
524 | } |
525 | |
526 | void |
527 | bufinit2(void) |
528 | { |
529 | |
530 | biodone_sih = softint_establish(SOFTINT_BIO | SOFTINT_MPSAFE, biointr, |
531 | NULL); |
532 | if (biodone_sih == NULL) |
533 | panic("bufinit2: can't establish soft interrupt" ); |
534 | } |
535 | |
536 | static int |
537 | buf_lotsfree(void) |
538 | { |
539 | u_long guess; |
540 | |
541 | /* Always allocate if less than the low water mark. */ |
542 | if (bufmem < bufmem_lowater) |
543 | return 1; |
544 | |
545 | /* Never allocate if greater than the high water mark. */ |
546 | if (bufmem > bufmem_hiwater) |
547 | return 0; |
548 | |
549 | /* If there's anything on the AGE list, it should be eaten. */ |
550 | if (TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue) != NULL) |
551 | return 0; |
552 | |
553 | /* |
554 | * The probabily of getting a new allocation is inversely |
555 | * proportional to the current size of the cache above |
556 | * the low water mark. Divide the total first to avoid overflows |
557 | * in the product. |
558 | */ |
559 | guess = cprng_fast32() % 16; |
560 | |
561 | if ((bufmem_hiwater - bufmem_lowater) / 16 * guess >= |
562 | (bufmem - bufmem_lowater)) |
563 | return 1; |
564 | |
565 | /* Otherwise don't allocate. */ |
566 | return 0; |
567 | } |
568 | |
569 | /* |
570 | * Return estimate of bytes we think need to be |
571 | * released to help resolve low memory conditions. |
572 | * |
573 | * => called with bufcache_lock held. |
574 | */ |
575 | static int |
576 | buf_canrelease(void) |
577 | { |
578 | int pagedemand, ninvalid = 0; |
579 | |
580 | KASSERT(mutex_owned(&bufcache_lock)); |
581 | |
582 | if (bufmem < bufmem_lowater) |
583 | return 0; |
584 | |
585 | if (bufmem > bufmem_hiwater) |
586 | return bufmem - bufmem_hiwater; |
587 | |
588 | ninvalid += bufqueues[BQ_AGE].bq_bytes; |
589 | |
590 | pagedemand = uvmexp.freetarg - uvmexp.free; |
591 | if (pagedemand < 0) |
592 | return ninvalid; |
593 | return MAX(ninvalid, MIN(2 * MAXBSIZE, |
594 | MIN((bufmem - bufmem_lowater) / 16, pagedemand * PAGE_SIZE))); |
595 | } |
596 | |
597 | /* |
598 | * Buffer memory allocation helper functions |
599 | */ |
600 | static u_long |
601 | buf_mempoolidx(u_long size) |
602 | { |
603 | u_int n = 0; |
604 | |
605 | size -= 1; |
606 | size >>= MEMPOOL_INDEX_OFFSET; |
607 | while (size) { |
608 | size >>= 1; |
609 | n += 1; |
610 | } |
611 | if (n >= NMEMPOOLS) |
612 | panic("buf mem pool index %d" , n); |
613 | return n; |
614 | } |
615 | |
616 | static u_long |
617 | buf_roundsize(u_long size) |
618 | { |
619 | /* Round up to nearest power of 2 */ |
620 | return (1 << (buf_mempoolidx(size) + MEMPOOL_INDEX_OFFSET)); |
621 | } |
622 | |
623 | static void * |
624 | buf_alloc(size_t size) |
625 | { |
626 | u_int n = buf_mempoolidx(size); |
627 | void *addr; |
628 | |
629 | while (1) { |
630 | addr = pool_get(&bmempools[n], PR_NOWAIT); |
631 | if (addr != NULL) |
632 | break; |
633 | |
634 | /* No memory, see if we can free some. If so, try again */ |
635 | mutex_enter(&bufcache_lock); |
636 | if (buf_drain(1) > 0) { |
637 | mutex_exit(&bufcache_lock); |
638 | continue; |
639 | } |
640 | |
641 | if (curlwp == uvm.pagedaemon_lwp) { |
642 | mutex_exit(&bufcache_lock); |
643 | return NULL; |
644 | } |
645 | |
646 | /* Wait for buffers to arrive on the LRU queue */ |
647 | cv_timedwait(&needbuffer_cv, &bufcache_lock, hz / 4); |
648 | mutex_exit(&bufcache_lock); |
649 | } |
650 | |
651 | return addr; |
652 | } |
653 | |
654 | static void |
655 | buf_mrelease(void *addr, size_t size) |
656 | { |
657 | |
658 | pool_put(&bmempools[buf_mempoolidx(size)], addr); |
659 | } |
660 | |
661 | /* |
662 | * bread()/breadn() helper. |
663 | */ |
664 | static buf_t * |
665 | bio_doread(struct vnode *vp, daddr_t blkno, int size, int async) |
666 | { |
667 | buf_t *bp; |
668 | struct mount *mp; |
669 | |
670 | bp = getblk(vp, blkno, size, 0, 0); |
671 | |
672 | /* |
673 | * getblk() may return NULL if we are the pagedaemon. |
674 | */ |
675 | if (bp == NULL) { |
676 | KASSERT(curlwp == uvm.pagedaemon_lwp); |
677 | return NULL; |
678 | } |
679 | |
680 | /* |
681 | * If buffer does not have data valid, start a read. |
682 | * Note that if buffer is BC_INVAL, getblk() won't return it. |
683 | * Therefore, it's valid if its I/O has completed or been delayed. |
684 | */ |
685 | if (!ISSET(bp->b_oflags, (BO_DONE | BO_DELWRI))) { |
686 | /* Start I/O for the buffer. */ |
687 | SET(bp->b_flags, B_READ | async); |
688 | if (async) |
689 | BIO_SETPRIO(bp, BPRIO_TIMELIMITED); |
690 | else |
691 | BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); |
692 | VOP_STRATEGY(vp, bp); |
693 | |
694 | /* Pay for the read. */ |
695 | curlwp->l_ru.ru_inblock++; |
696 | } else if (async) |
697 | brelse(bp, 0); |
698 | |
699 | if (vp->v_type == VBLK) |
700 | mp = spec_node_getmountedfs(vp); |
701 | else |
702 | mp = vp->v_mount; |
703 | |
704 | /* |
705 | * Collect statistics on synchronous and asynchronous reads. |
706 | * Reads from block devices are charged to their associated |
707 | * filesystem (if any). |
708 | */ |
709 | if (mp != NULL) { |
710 | if (async == 0) |
711 | mp->mnt_stat.f_syncreads++; |
712 | else |
713 | mp->mnt_stat.f_asyncreads++; |
714 | } |
715 | |
716 | return (bp); |
717 | } |
718 | |
719 | /* |
720 | * Read a disk block. |
721 | * This algorithm described in Bach (p.54). |
722 | */ |
723 | int |
724 | bread(struct vnode *vp, daddr_t blkno, int size, int flags, buf_t **bpp) |
725 | { |
726 | buf_t *bp; |
727 | int error; |
728 | |
729 | /* Get buffer for block. */ |
730 | bp = *bpp = bio_doread(vp, blkno, size, 0); |
731 | if (bp == NULL) |
732 | return ENOMEM; |
733 | |
734 | /* Wait for the read to complete, and return result. */ |
735 | error = biowait(bp); |
736 | if (error == 0 && (flags & B_MODIFY) != 0) |
737 | error = fscow_run(bp, true); |
738 | if (error) { |
739 | brelse(bp, 0); |
740 | *bpp = NULL; |
741 | } |
742 | |
743 | return error; |
744 | } |
745 | |
746 | /* |
747 | * Read-ahead multiple disk blocks. The first is sync, the rest async. |
748 | * Trivial modification to the breada algorithm presented in Bach (p.55). |
749 | */ |
750 | int |
751 | breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablks, |
752 | int *rasizes, int nrablks, int flags, buf_t **bpp) |
753 | { |
754 | buf_t *bp; |
755 | int error, i; |
756 | |
757 | bp = *bpp = bio_doread(vp, blkno, size, 0); |
758 | if (bp == NULL) |
759 | return ENOMEM; |
760 | |
761 | /* |
762 | * For each of the read-ahead blocks, start a read, if necessary. |
763 | */ |
764 | mutex_enter(&bufcache_lock); |
765 | for (i = 0; i < nrablks; i++) { |
766 | /* If it's in the cache, just go on to next one. */ |
767 | if (incore(vp, rablks[i])) |
768 | continue; |
769 | |
770 | /* Get a buffer for the read-ahead block */ |
771 | mutex_exit(&bufcache_lock); |
772 | (void) bio_doread(vp, rablks[i], rasizes[i], B_ASYNC); |
773 | mutex_enter(&bufcache_lock); |
774 | } |
775 | mutex_exit(&bufcache_lock); |
776 | |
777 | /* Otherwise, we had to start a read for it; wait until it's valid. */ |
778 | error = biowait(bp); |
779 | if (error == 0 && (flags & B_MODIFY) != 0) |
780 | error = fscow_run(bp, true); |
781 | if (error) { |
782 | brelse(bp, 0); |
783 | *bpp = NULL; |
784 | } |
785 | |
786 | return error; |
787 | } |
788 | |
789 | /* |
790 | * Block write. Described in Bach (p.56) |
791 | */ |
792 | int |
793 | bwrite(buf_t *bp) |
794 | { |
795 | int rv, sync, wasdelayed; |
796 | struct vnode *vp; |
797 | struct mount *mp; |
798 | |
799 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
800 | KASSERT(!cv_has_waiters(&bp->b_done)); |
801 | |
802 | vp = bp->b_vp; |
803 | |
804 | /* |
805 | * dholland 20160728 AFAICT vp==NULL must be impossible as it |
806 | * will crash upon reaching VOP_STRATEGY below... see further |
807 | * analysis on tech-kern. |
808 | */ |
809 | KASSERTMSG(vp != NULL, "bwrite given buffer with null vnode" ); |
810 | |
811 | if (vp != NULL) { |
812 | KASSERT(bp->b_objlock == vp->v_interlock); |
813 | if (vp->v_type == VBLK) |
814 | mp = spec_node_getmountedfs(vp); |
815 | else |
816 | mp = vp->v_mount; |
817 | } else { |
818 | mp = NULL; |
819 | } |
820 | |
821 | if (mp && mp->mnt_wapbl) { |
822 | if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { |
823 | bdwrite(bp); |
824 | return 0; |
825 | } |
826 | } |
827 | |
828 | /* |
829 | * Remember buffer type, to switch on it later. If the write was |
830 | * synchronous, but the file system was mounted with MNT_ASYNC, |
831 | * convert it to a delayed write. |
832 | * XXX note that this relies on delayed tape writes being converted |
833 | * to async, not sync writes (which is safe, but ugly). |
834 | */ |
835 | sync = !ISSET(bp->b_flags, B_ASYNC); |
836 | if (sync && mp != NULL && ISSET(mp->mnt_flag, MNT_ASYNC)) { |
837 | bdwrite(bp); |
838 | return (0); |
839 | } |
840 | |
841 | /* |
842 | * Collect statistics on synchronous and asynchronous writes. |
843 | * Writes to block devices are charged to their associated |
844 | * filesystem (if any). |
845 | */ |
846 | if (mp != NULL) { |
847 | if (sync) |
848 | mp->mnt_stat.f_syncwrites++; |
849 | else |
850 | mp->mnt_stat.f_asyncwrites++; |
851 | } |
852 | |
853 | /* |
854 | * Pay for the I/O operation and make sure the buf is on the correct |
855 | * vnode queue. |
856 | */ |
857 | bp->b_error = 0; |
858 | wasdelayed = ISSET(bp->b_oflags, BO_DELWRI); |
859 | CLR(bp->b_flags, B_READ); |
860 | if (wasdelayed) { |
861 | mutex_enter(&bufcache_lock); |
862 | mutex_enter(bp->b_objlock); |
863 | CLR(bp->b_oflags, BO_DONE | BO_DELWRI); |
864 | reassignbuf(bp, bp->b_vp); |
865 | mutex_exit(&bufcache_lock); |
866 | } else { |
867 | curlwp->l_ru.ru_oublock++; |
868 | mutex_enter(bp->b_objlock); |
869 | CLR(bp->b_oflags, BO_DONE | BO_DELWRI); |
870 | } |
871 | if (vp != NULL) |
872 | vp->v_numoutput++; |
873 | mutex_exit(bp->b_objlock); |
874 | |
875 | /* Initiate disk write. */ |
876 | if (sync) |
877 | BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); |
878 | else |
879 | BIO_SETPRIO(bp, BPRIO_TIMELIMITED); |
880 | |
881 | VOP_STRATEGY(vp, bp); |
882 | |
883 | if (sync) { |
884 | /* If I/O was synchronous, wait for it to complete. */ |
885 | rv = biowait(bp); |
886 | |
887 | /* Release the buffer. */ |
888 | brelse(bp, 0); |
889 | |
890 | return (rv); |
891 | } else { |
892 | return (0); |
893 | } |
894 | } |
895 | |
896 | int |
897 | vn_bwrite(void *v) |
898 | { |
899 | struct vop_bwrite_args *ap = v; |
900 | |
901 | return (bwrite(ap->a_bp)); |
902 | } |
903 | |
904 | /* |
905 | * Delayed write. |
906 | * |
907 | * The buffer is marked dirty, but is not queued for I/O. |
908 | * This routine should be used when the buffer is expected |
909 | * to be modified again soon, typically a small write that |
910 | * partially fills a buffer. |
911 | * |
912 | * NB: magnetic tapes cannot be delayed; they must be |
913 | * written in the order that the writes are requested. |
914 | * |
915 | * Described in Leffler, et al. (pp. 208-213). |
916 | */ |
917 | void |
918 | bdwrite(buf_t *bp) |
919 | { |
920 | |
921 | KASSERT(bp->b_vp == NULL || bp->b_vp->v_tag != VT_UFS || |
922 | bp->b_vp->v_type == VBLK || ISSET(bp->b_flags, B_COWDONE)); |
923 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
924 | KASSERT(!cv_has_waiters(&bp->b_done)); |
925 | |
926 | /* If this is a tape block, write the block now. */ |
927 | if (bdev_type(bp->b_dev) == D_TAPE) { |
928 | bawrite(bp); |
929 | return; |
930 | } |
931 | |
932 | if (wapbl_vphaswapbl(bp->b_vp)) { |
933 | struct mount *mp = wapbl_vptomp(bp->b_vp); |
934 | |
935 | if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { |
936 | WAPBL_ADD_BUF(mp, bp); |
937 | } |
938 | } |
939 | |
940 | /* |
941 | * If the block hasn't been seen before: |
942 | * (1) Mark it as having been seen, |
943 | * (2) Charge for the write, |
944 | * (3) Make sure it's on its vnode's correct block list. |
945 | */ |
946 | KASSERT(bp->b_vp == NULL || bp->b_objlock == bp->b_vp->v_interlock); |
947 | |
948 | if (!ISSET(bp->b_oflags, BO_DELWRI)) { |
949 | mutex_enter(&bufcache_lock); |
950 | mutex_enter(bp->b_objlock); |
951 | SET(bp->b_oflags, BO_DELWRI); |
952 | curlwp->l_ru.ru_oublock++; |
953 | reassignbuf(bp, bp->b_vp); |
954 | mutex_exit(&bufcache_lock); |
955 | } else { |
956 | mutex_enter(bp->b_objlock); |
957 | } |
958 | /* Otherwise, the "write" is done, so mark and release the buffer. */ |
959 | CLR(bp->b_oflags, BO_DONE); |
960 | mutex_exit(bp->b_objlock); |
961 | |
962 | brelse(bp, 0); |
963 | } |
964 | |
965 | /* |
966 | * Asynchronous block write; just an asynchronous bwrite(). |
967 | */ |
968 | void |
969 | bawrite(buf_t *bp) |
970 | { |
971 | |
972 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
973 | KASSERT(bp->b_vp != NULL); |
974 | |
975 | SET(bp->b_flags, B_ASYNC); |
976 | VOP_BWRITE(bp->b_vp, bp); |
977 | } |
978 | |
979 | /* |
980 | * Release a buffer on to the free lists. |
981 | * Described in Bach (p. 46). |
982 | */ |
983 | void |
984 | brelsel(buf_t *bp, int set) |
985 | { |
986 | struct bqueue *bufq; |
987 | struct vnode *vp; |
988 | |
989 | KASSERT(bp != NULL); |
990 | KASSERT(mutex_owned(&bufcache_lock)); |
991 | KASSERT(!cv_has_waiters(&bp->b_done)); |
992 | KASSERT(bp->b_refcnt > 0); |
993 | |
994 | SET(bp->b_cflags, set); |
995 | |
996 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
997 | KASSERT(bp->b_iodone == NULL); |
998 | |
999 | /* Wake up any processes waiting for any buffer to become free. */ |
1000 | cv_signal(&needbuffer_cv); |
1001 | |
1002 | /* Wake up any proceeses waiting for _this_ buffer to become free */ |
1003 | if (ISSET(bp->b_cflags, BC_WANTED)) |
1004 | CLR(bp->b_cflags, BC_WANTED|BC_AGE); |
1005 | |
1006 | /* If it's clean clear the copy-on-write flag. */ |
1007 | if (ISSET(bp->b_flags, B_COWDONE)) { |
1008 | mutex_enter(bp->b_objlock); |
1009 | if (!ISSET(bp->b_oflags, BO_DELWRI)) |
1010 | CLR(bp->b_flags, B_COWDONE); |
1011 | mutex_exit(bp->b_objlock); |
1012 | } |
1013 | |
1014 | /* |
1015 | * Determine which queue the buffer should be on, then put it there. |
1016 | */ |
1017 | |
1018 | /* If it's locked, don't report an error; try again later. */ |
1019 | if (ISSET(bp->b_flags, B_LOCKED)) |
1020 | bp->b_error = 0; |
1021 | |
1022 | /* If it's not cacheable, or an error, mark it invalid. */ |
1023 | if (ISSET(bp->b_cflags, BC_NOCACHE) || bp->b_error != 0) |
1024 | SET(bp->b_cflags, BC_INVAL); |
1025 | |
1026 | if (ISSET(bp->b_cflags, BC_VFLUSH)) { |
1027 | /* |
1028 | * This is a delayed write buffer that was just flushed to |
1029 | * disk. It is still on the LRU queue. If it's become |
1030 | * invalid, then we need to move it to a different queue; |
1031 | * otherwise leave it in its current position. |
1032 | */ |
1033 | CLR(bp->b_cflags, BC_VFLUSH); |
1034 | if (!ISSET(bp->b_cflags, BC_INVAL|BC_AGE) && |
1035 | !ISSET(bp->b_flags, B_LOCKED) && bp->b_error == 0) { |
1036 | KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 1)); |
1037 | goto already_queued; |
1038 | } else { |
1039 | bremfree(bp); |
1040 | } |
1041 | } |
1042 | |
1043 | KDASSERT(checkfreelist(bp, &bufqueues[BQ_AGE], 0)); |
1044 | KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 0)); |
1045 | KDASSERT(checkfreelist(bp, &bufqueues[BQ_LOCKED], 0)); |
1046 | |
1047 | if ((bp->b_bufsize <= 0) || ISSET(bp->b_cflags, BC_INVAL)) { |
1048 | /* |
1049 | * If it's invalid or empty, dissociate it from its vnode |
1050 | * and put on the head of the appropriate queue. |
1051 | */ |
1052 | if (ISSET(bp->b_flags, B_LOCKED)) { |
1053 | if (wapbl_vphaswapbl(vp = bp->b_vp)) { |
1054 | struct mount *mp = wapbl_vptomp(vp); |
1055 | |
1056 | KASSERT(bp->b_iodone |
1057 | != mp->mnt_wapbl_op->wo_wapbl_biodone); |
1058 | WAPBL_REMOVE_BUF(mp, bp); |
1059 | } |
1060 | } |
1061 | |
1062 | mutex_enter(bp->b_objlock); |
1063 | CLR(bp->b_oflags, BO_DONE|BO_DELWRI); |
1064 | if ((vp = bp->b_vp) != NULL) { |
1065 | KASSERT(bp->b_objlock == vp->v_interlock); |
1066 | reassignbuf(bp, bp->b_vp); |
1067 | brelvp(bp); |
1068 | mutex_exit(vp->v_interlock); |
1069 | } else { |
1070 | KASSERT(bp->b_objlock == &buffer_lock); |
1071 | mutex_exit(bp->b_objlock); |
1072 | } |
1073 | |
1074 | if (bp->b_bufsize <= 0) |
1075 | /* no data */ |
1076 | goto already_queued; |
1077 | else |
1078 | /* invalid data */ |
1079 | bufq = &bufqueues[BQ_AGE]; |
1080 | binsheadfree(bp, bufq); |
1081 | } else { |
1082 | /* |
1083 | * It has valid data. Put it on the end of the appropriate |
1084 | * queue, so that it'll stick around for as long as possible. |
1085 | * If buf is AGE, but has dependencies, must put it on last |
1086 | * bufqueue to be scanned, ie LRU. This protects against the |
1087 | * livelock where BQ_AGE only has buffers with dependencies, |
1088 | * and we thus never get to the dependent buffers in BQ_LRU. |
1089 | */ |
1090 | if (ISSET(bp->b_flags, B_LOCKED)) { |
1091 | /* locked in core */ |
1092 | bufq = &bufqueues[BQ_LOCKED]; |
1093 | } else if (!ISSET(bp->b_cflags, BC_AGE)) { |
1094 | /* valid data */ |
1095 | bufq = &bufqueues[BQ_LRU]; |
1096 | } else { |
1097 | /* stale but valid data */ |
1098 | bufq = &bufqueues[BQ_AGE]; |
1099 | } |
1100 | binstailfree(bp, bufq); |
1101 | } |
1102 | already_queued: |
1103 | /* Unlock the buffer. */ |
1104 | CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE); |
1105 | CLR(bp->b_flags, B_ASYNC); |
1106 | cv_broadcast(&bp->b_busy); |
1107 | |
1108 | if (bp->b_bufsize <= 0) |
1109 | brele(bp); |
1110 | } |
1111 | |
1112 | void |
1113 | brelse(buf_t *bp, int set) |
1114 | { |
1115 | |
1116 | mutex_enter(&bufcache_lock); |
1117 | brelsel(bp, set); |
1118 | mutex_exit(&bufcache_lock); |
1119 | } |
1120 | |
1121 | /* |
1122 | * Determine if a block is in the cache. |
1123 | * Just look on what would be its hash chain. If it's there, return |
1124 | * a pointer to it, unless it's marked invalid. If it's marked invalid, |
1125 | * we normally don't return the buffer, unless the caller explicitly |
1126 | * wants us to. |
1127 | */ |
1128 | buf_t * |
1129 | incore(struct vnode *vp, daddr_t blkno) |
1130 | { |
1131 | buf_t *bp; |
1132 | |
1133 | KASSERT(mutex_owned(&bufcache_lock)); |
1134 | |
1135 | /* Search hash chain */ |
1136 | LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) { |
1137 | if (bp->b_lblkno == blkno && bp->b_vp == vp && |
1138 | !ISSET(bp->b_cflags, BC_INVAL)) { |
1139 | KASSERT(bp->b_objlock == vp->v_interlock); |
1140 | return (bp); |
1141 | } |
1142 | } |
1143 | |
1144 | return (NULL); |
1145 | } |
1146 | |
1147 | /* |
1148 | * Get a block of requested size that is associated with |
1149 | * a given vnode and block offset. If it is found in the |
1150 | * block cache, mark it as having been found, make it busy |
1151 | * and return it. Otherwise, return an empty block of the |
1152 | * correct size. It is up to the caller to insure that the |
1153 | * cached blocks be of the correct size. |
1154 | */ |
1155 | buf_t * |
1156 | getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo) |
1157 | { |
1158 | int err, preserve; |
1159 | buf_t *bp; |
1160 | |
1161 | mutex_enter(&bufcache_lock); |
1162 | loop: |
1163 | bp = incore(vp, blkno); |
1164 | if (bp != NULL) { |
1165 | err = bbusy(bp, ((slpflag & PCATCH) != 0), slptimeo, NULL); |
1166 | if (err != 0) { |
1167 | if (err == EPASSTHROUGH) |
1168 | goto loop; |
1169 | mutex_exit(&bufcache_lock); |
1170 | return (NULL); |
1171 | } |
1172 | KASSERT(!cv_has_waiters(&bp->b_done)); |
1173 | #ifdef DIAGNOSTIC |
1174 | if (ISSET(bp->b_oflags, BO_DONE|BO_DELWRI) && |
1175 | bp->b_bcount < size && vp->v_type != VBLK) |
1176 | panic("getblk: block size invariant failed" ); |
1177 | #endif |
1178 | bremfree(bp); |
1179 | preserve = 1; |
1180 | } else { |
1181 | if ((bp = getnewbuf(slpflag, slptimeo, 0)) == NULL) |
1182 | goto loop; |
1183 | |
1184 | if (incore(vp, blkno) != NULL) { |
1185 | /* The block has come into memory in the meantime. */ |
1186 | brelsel(bp, 0); |
1187 | goto loop; |
1188 | } |
1189 | |
1190 | LIST_INSERT_HEAD(BUFHASH(vp, blkno), bp, b_hash); |
1191 | bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = blkno; |
1192 | mutex_enter(vp->v_interlock); |
1193 | bgetvp(vp, bp); |
1194 | mutex_exit(vp->v_interlock); |
1195 | preserve = 0; |
1196 | } |
1197 | mutex_exit(&bufcache_lock); |
1198 | |
1199 | /* |
1200 | * LFS can't track total size of B_LOCKED buffer (locked_queue_bytes) |
1201 | * if we re-size buffers here. |
1202 | */ |
1203 | if (ISSET(bp->b_flags, B_LOCKED)) { |
1204 | KASSERT(bp->b_bufsize >= size); |
1205 | } else { |
1206 | if (allocbuf(bp, size, preserve)) { |
1207 | mutex_enter(&bufcache_lock); |
1208 | LIST_REMOVE(bp, b_hash); |
1209 | mutex_exit(&bufcache_lock); |
1210 | brelse(bp, BC_INVAL); |
1211 | return NULL; |
1212 | } |
1213 | } |
1214 | BIO_SETPRIO(bp, BPRIO_DEFAULT); |
1215 | return (bp); |
1216 | } |
1217 | |
1218 | /* |
1219 | * Get an empty, disassociated buffer of given size. |
1220 | */ |
1221 | buf_t * |
1222 | geteblk(int size) |
1223 | { |
1224 | buf_t *bp; |
1225 | int error __diagused; |
1226 | |
1227 | mutex_enter(&bufcache_lock); |
1228 | while ((bp = getnewbuf(0, 0, 0)) == NULL) |
1229 | ; |
1230 | |
1231 | SET(bp->b_cflags, BC_INVAL); |
1232 | LIST_INSERT_HEAD(&invalhash, bp, b_hash); |
1233 | mutex_exit(&bufcache_lock); |
1234 | BIO_SETPRIO(bp, BPRIO_DEFAULT); |
1235 | error = allocbuf(bp, size, 0); |
1236 | KASSERT(error == 0); |
1237 | return (bp); |
1238 | } |
1239 | |
1240 | /* |
1241 | * Expand or contract the actual memory allocated to a buffer. |
1242 | * |
1243 | * If the buffer shrinks, data is lost, so it's up to the |
1244 | * caller to have written it out *first*; this routine will not |
1245 | * start a write. If the buffer grows, it's the callers |
1246 | * responsibility to fill out the buffer's additional contents. |
1247 | */ |
1248 | int |
1249 | allocbuf(buf_t *bp, int size, int preserve) |
1250 | { |
1251 | void *addr; |
1252 | vsize_t oldsize, desired_size; |
1253 | int oldcount; |
1254 | int delta; |
1255 | |
1256 | desired_size = buf_roundsize(size); |
1257 | if (desired_size > MAXBSIZE) |
1258 | printf("allocbuf: buffer larger than MAXBSIZE requested" ); |
1259 | |
1260 | oldcount = bp->b_bcount; |
1261 | |
1262 | bp->b_bcount = size; |
1263 | |
1264 | oldsize = bp->b_bufsize; |
1265 | if (oldsize == desired_size) { |
1266 | /* |
1267 | * Do not short cut the WAPBL resize, as the buffer length |
1268 | * could still have changed and this would corrupt the |
1269 | * tracking of the transaction length. |
1270 | */ |
1271 | goto out; |
1272 | } |
1273 | |
1274 | /* |
1275 | * If we want a buffer of a different size, re-allocate the |
1276 | * buffer's memory; copy old content only if needed. |
1277 | */ |
1278 | addr = buf_alloc(desired_size); |
1279 | if (addr == NULL) |
1280 | return ENOMEM; |
1281 | if (preserve) |
1282 | memcpy(addr, bp->b_data, MIN(oldsize,desired_size)); |
1283 | if (bp->b_data != NULL) |
1284 | buf_mrelease(bp->b_data, oldsize); |
1285 | bp->b_data = addr; |
1286 | bp->b_bufsize = desired_size; |
1287 | |
1288 | /* |
1289 | * Update overall buffer memory counter (protected by bufcache_lock) |
1290 | */ |
1291 | delta = (long)desired_size - (long)oldsize; |
1292 | |
1293 | mutex_enter(&bufcache_lock); |
1294 | if ((bufmem += delta) > bufmem_hiwater) { |
1295 | /* |
1296 | * Need to trim overall memory usage. |
1297 | */ |
1298 | while (buf_canrelease()) { |
1299 | if (curcpu()->ci_schedstate.spc_flags & |
1300 | SPCF_SHOULDYIELD) { |
1301 | mutex_exit(&bufcache_lock); |
1302 | preempt(); |
1303 | mutex_enter(&bufcache_lock); |
1304 | } |
1305 | if (buf_trim() == 0) |
1306 | break; |
1307 | } |
1308 | } |
1309 | mutex_exit(&bufcache_lock); |
1310 | |
1311 | out: |
1312 | if (wapbl_vphaswapbl(bp->b_vp)) |
1313 | WAPBL_RESIZE_BUF(wapbl_vptomp(bp->b_vp), bp, oldsize, oldcount); |
1314 | |
1315 | return 0; |
1316 | } |
1317 | |
1318 | /* |
1319 | * Find a buffer which is available for use. |
1320 | * Select something from a free list. |
1321 | * Preference is to AGE list, then LRU list. |
1322 | * |
1323 | * Called with the buffer queues locked. |
1324 | * Return buffer locked. |
1325 | */ |
1326 | buf_t * |
1327 | getnewbuf(int slpflag, int slptimeo, int from_bufq) |
1328 | { |
1329 | buf_t *bp; |
1330 | struct vnode *vp; |
1331 | |
1332 | start: |
1333 | KASSERT(mutex_owned(&bufcache_lock)); |
1334 | |
1335 | /* |
1336 | * Get a new buffer from the pool. |
1337 | */ |
1338 | if (!from_bufq && buf_lotsfree()) { |
1339 | mutex_exit(&bufcache_lock); |
1340 | bp = pool_cache_get(buf_cache, PR_NOWAIT); |
1341 | if (bp != NULL) { |
1342 | memset((char *)bp, 0, sizeof(*bp)); |
1343 | buf_init(bp); |
1344 | SET(bp->b_cflags, BC_BUSY); /* mark buffer busy */ |
1345 | mutex_enter(&bufcache_lock); |
1346 | #if defined(DIAGNOSTIC) |
1347 | bp->b_freelistindex = -1; |
1348 | #endif /* defined(DIAGNOSTIC) */ |
1349 | return (bp); |
1350 | } |
1351 | mutex_enter(&bufcache_lock); |
1352 | } |
1353 | |
1354 | KASSERT(mutex_owned(&bufcache_lock)); |
1355 | if ((bp = TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue)) != NULL || |
1356 | (bp = TAILQ_FIRST(&bufqueues[BQ_LRU].bq_queue)) != NULL) { |
1357 | KASSERT(!ISSET(bp->b_cflags, BC_BUSY) || ISSET(bp->b_cflags, BC_VFLUSH)); |
1358 | bremfree(bp); |
1359 | |
1360 | /* Buffer is no longer on free lists. */ |
1361 | SET(bp->b_cflags, BC_BUSY); |
1362 | } else { |
1363 | /* |
1364 | * XXX: !from_bufq should be removed. |
1365 | */ |
1366 | if (!from_bufq || curlwp != uvm.pagedaemon_lwp) { |
1367 | /* wait for a free buffer of any kind */ |
1368 | if ((slpflag & PCATCH) != 0) |
1369 | (void)cv_timedwait_sig(&needbuffer_cv, |
1370 | &bufcache_lock, slptimeo); |
1371 | else |
1372 | (void)cv_timedwait(&needbuffer_cv, |
1373 | &bufcache_lock, slptimeo); |
1374 | } |
1375 | return (NULL); |
1376 | } |
1377 | |
1378 | #ifdef DIAGNOSTIC |
1379 | if (bp->b_bufsize <= 0) |
1380 | panic("buffer %p: on queue but empty" , bp); |
1381 | #endif |
1382 | |
1383 | if (ISSET(bp->b_cflags, BC_VFLUSH)) { |
1384 | /* |
1385 | * This is a delayed write buffer being flushed to disk. Make |
1386 | * sure it gets aged out of the queue when it's finished, and |
1387 | * leave it off the LRU queue. |
1388 | */ |
1389 | CLR(bp->b_cflags, BC_VFLUSH); |
1390 | SET(bp->b_cflags, BC_AGE); |
1391 | goto start; |
1392 | } |
1393 | |
1394 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
1395 | KASSERT(bp->b_refcnt > 0); |
1396 | KASSERT(!cv_has_waiters(&bp->b_done)); |
1397 | |
1398 | /* |
1399 | * If buffer was a delayed write, start it and return NULL |
1400 | * (since we might sleep while starting the write). |
1401 | */ |
1402 | if (ISSET(bp->b_oflags, BO_DELWRI)) { |
1403 | /* |
1404 | * This buffer has gone through the LRU, so make sure it gets |
1405 | * reused ASAP. |
1406 | */ |
1407 | SET(bp->b_cflags, BC_AGE); |
1408 | mutex_exit(&bufcache_lock); |
1409 | bawrite(bp); |
1410 | mutex_enter(&bufcache_lock); |
1411 | return (NULL); |
1412 | } |
1413 | |
1414 | vp = bp->b_vp; |
1415 | |
1416 | /* clear out various other fields */ |
1417 | bp->b_cflags = BC_BUSY; |
1418 | bp->b_oflags = 0; |
1419 | bp->b_flags = 0; |
1420 | bp->b_dev = NODEV; |
1421 | bp->b_blkno = 0; |
1422 | bp->b_lblkno = 0; |
1423 | bp->b_rawblkno = 0; |
1424 | bp->b_iodone = 0; |
1425 | bp->b_error = 0; |
1426 | bp->b_resid = 0; |
1427 | bp->b_bcount = 0; |
1428 | |
1429 | LIST_REMOVE(bp, b_hash); |
1430 | |
1431 | /* Disassociate us from our vnode, if we had one... */ |
1432 | if (vp != NULL) { |
1433 | mutex_enter(vp->v_interlock); |
1434 | brelvp(bp); |
1435 | mutex_exit(vp->v_interlock); |
1436 | } |
1437 | |
1438 | return (bp); |
1439 | } |
1440 | |
1441 | /* |
1442 | * Attempt to free an aged buffer off the queues. |
1443 | * Called with queue lock held. |
1444 | * Returns the amount of buffer memory freed. |
1445 | */ |
1446 | static int |
1447 | buf_trim(void) |
1448 | { |
1449 | buf_t *bp; |
1450 | long size; |
1451 | |
1452 | KASSERT(mutex_owned(&bufcache_lock)); |
1453 | |
1454 | /* Instruct getnewbuf() to get buffers off the queues */ |
1455 | if ((bp = getnewbuf(PCATCH, 1, 1)) == NULL) |
1456 | return 0; |
1457 | |
1458 | KASSERT((bp->b_cflags & BC_WANTED) == 0); |
1459 | size = bp->b_bufsize; |
1460 | bufmem -= size; |
1461 | if (size > 0) { |
1462 | buf_mrelease(bp->b_data, size); |
1463 | bp->b_bcount = bp->b_bufsize = 0; |
1464 | } |
1465 | /* brelse() will return the buffer to the global buffer pool */ |
1466 | brelsel(bp, 0); |
1467 | return size; |
1468 | } |
1469 | |
1470 | int |
1471 | buf_drain(int n) |
1472 | { |
1473 | int size = 0, sz; |
1474 | |
1475 | KASSERT(mutex_owned(&bufcache_lock)); |
1476 | |
1477 | while (size < n && bufmem > bufmem_lowater) { |
1478 | sz = buf_trim(); |
1479 | if (sz <= 0) |
1480 | break; |
1481 | size += sz; |
1482 | } |
1483 | |
1484 | return size; |
1485 | } |
1486 | |
1487 | SDT_PROVIDER_DEFINE(io); |
1488 | |
1489 | SDT_PROBE_DEFINE1(io, kernel, , wait__start, "struct buf *" /*bp*/); |
1490 | SDT_PROBE_DEFINE1(io, kernel, , wait__done, "struct buf *" /*bp*/); |
1491 | |
1492 | /* |
1493 | * Wait for operations on the buffer to complete. |
1494 | * When they do, extract and return the I/O's error value. |
1495 | */ |
1496 | int |
1497 | biowait(buf_t *bp) |
1498 | { |
1499 | |
1500 | KASSERT(ISSET(bp->b_cflags, BC_BUSY)); |
1501 | KASSERT(bp->b_refcnt > 0); |
1502 | |
1503 | SDT_PROBE1(io, kernel, , wait__start, bp); |
1504 | |
1505 | mutex_enter(bp->b_objlock); |
1506 | while (!ISSET(bp->b_oflags, BO_DONE | BO_DELWRI)) |
1507 | cv_wait(&bp->b_done, bp->b_objlock); |
1508 | mutex_exit(bp->b_objlock); |
1509 | |
1510 | SDT_PROBE1(io, kernel, , wait__done, bp); |
1511 | |
1512 | return bp->b_error; |
1513 | } |
1514 | |
1515 | /* |
1516 | * Mark I/O complete on a buffer. |
1517 | * |
1518 | * If a callback has been requested, e.g. the pageout |
1519 | * daemon, do so. Otherwise, awaken waiting processes. |
1520 | * |
1521 | * [ Leffler, et al., says on p.247: |
1522 | * "This routine wakes up the blocked process, frees the buffer |
1523 | * for an asynchronous write, or, for a request by the pagedaemon |
1524 | * process, invokes a procedure specified in the buffer structure" ] |
1525 | * |
1526 | * In real life, the pagedaemon (or other system processes) wants |
1527 | * to do async stuff to, and doesn't want the buffer brelse()'d. |
1528 | * (for swap pager, that puts swap buffers on the free lists (!!!), |
1529 | * for the vn device, that puts allocated buffers on the free lists!) |
1530 | */ |
1531 | void |
1532 | biodone(buf_t *bp) |
1533 | { |
1534 | int s; |
1535 | |
1536 | KASSERT(!ISSET(bp->b_oflags, BO_DONE)); |
1537 | |
1538 | if (cpu_intr_p()) { |
1539 | /* From interrupt mode: defer to a soft interrupt. */ |
1540 | s = splvm(); |
1541 | TAILQ_INSERT_TAIL(&curcpu()->ci_data.cpu_biodone, bp, b_actq); |
1542 | softint_schedule(biodone_sih); |
1543 | splx(s); |
1544 | } else { |
1545 | /* Process now - the buffer may be freed soon. */ |
1546 | biodone2(bp); |
1547 | } |
1548 | } |
1549 | |
1550 | SDT_PROBE_DEFINE1(io, kernel, , done, "struct buf *" /*bp*/); |
1551 | |
1552 | static void |
1553 | biodone2(buf_t *bp) |
1554 | { |
1555 | void (*callout)(buf_t *); |
1556 | |
1557 | SDT_PROBE1(io, kernel, ,done, bp); |
1558 | |
1559 | mutex_enter(bp->b_objlock); |
1560 | /* Note that the transfer is done. */ |
1561 | if (ISSET(bp->b_oflags, BO_DONE)) |
1562 | panic("biodone2 already" ); |
1563 | CLR(bp->b_flags, B_COWDONE); |
1564 | SET(bp->b_oflags, BO_DONE); |
1565 | BIO_SETPRIO(bp, BPRIO_DEFAULT); |
1566 | |
1567 | /* Wake up waiting writers. */ |
1568 | if (!ISSET(bp->b_flags, B_READ)) |
1569 | vwakeup(bp); |
1570 | |
1571 | if ((callout = bp->b_iodone) != NULL) { |
1572 | /* Note callout done, then call out. */ |
1573 | KASSERT(!cv_has_waiters(&bp->b_done)); |
1574 | KERNEL_LOCK(1, NULL); /* XXXSMP */ |
1575 | bp->b_iodone = NULL; |
1576 | mutex_exit(bp->b_objlock); |
1577 | (*callout)(bp); |
1578 | KERNEL_UNLOCK_ONE(NULL); /* XXXSMP */ |
1579 | } else if (ISSET(bp->b_flags, B_ASYNC)) { |
1580 | /* If async, release. */ |
1581 | KASSERT(!cv_has_waiters(&bp->b_done)); |
1582 | mutex_exit(bp->b_objlock); |
1583 | brelse(bp, 0); |
1584 | } else { |
1585 | /* Otherwise just wake up waiters in biowait(). */ |
1586 | cv_broadcast(&bp->b_done); |
1587 | mutex_exit(bp->b_objlock); |
1588 | } |
1589 | } |
1590 | |
1591 | static void |
1592 | biointr(void *cookie) |
1593 | { |
1594 | struct cpu_info *ci; |
1595 | buf_t *bp; |
1596 | int s; |
1597 | |
1598 | ci = curcpu(); |
1599 | |
1600 | while (!TAILQ_EMPTY(&ci->ci_data.cpu_biodone)) { |
1601 | KASSERT(curcpu() == ci); |
1602 | |
1603 | s = splvm(); |
1604 | bp = TAILQ_FIRST(&ci->ci_data.cpu_biodone); |
1605 | TAILQ_REMOVE(&ci->ci_data.cpu_biodone, bp, b_actq); |
1606 | splx(s); |
1607 | |
1608 | biodone2(bp); |
1609 | } |
1610 | } |
1611 | |
1612 | /* |
1613 | * Wait for all buffers to complete I/O |
1614 | * Return the number of "stuck" buffers. |
1615 | */ |
1616 | int |
1617 | buf_syncwait(void) |
1618 | { |
1619 | buf_t *bp; |
1620 | int iter, nbusy, nbusy_prev = 0, ihash; |
1621 | |
1622 | for (iter = 0; iter < 20;) { |
1623 | mutex_enter(&bufcache_lock); |
1624 | nbusy = 0; |
1625 | for (ihash = 0; ihash < bufhash+1; ihash++) { |
1626 | LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { |
1627 | if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY) |
1628 | nbusy += ((bp->b_flags & B_READ) == 0); |
1629 | } |
1630 | } |
1631 | mutex_exit(&bufcache_lock); |
1632 | |
1633 | if (nbusy == 0) |
1634 | break; |
1635 | if (nbusy_prev == 0) |
1636 | nbusy_prev = nbusy; |
1637 | printf("%d " , nbusy); |
1638 | kpause("bflush" , false, MAX(1, hz / 25 * iter), NULL); |
1639 | if (nbusy >= nbusy_prev) /* we didn't flush anything */ |
1640 | iter++; |
1641 | else |
1642 | nbusy_prev = nbusy; |
1643 | } |
1644 | |
1645 | if (nbusy) { |
1646 | #if defined(DEBUG) || defined(DEBUG_HALT_BUSY) |
1647 | printf("giving up\nPrinting vnodes for busy buffers\n" ); |
1648 | for (ihash = 0; ihash < bufhash+1; ihash++) { |
1649 | LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { |
1650 | if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY && |
1651 | (bp->b_flags & B_READ) == 0) |
1652 | vprint(NULL, bp->b_vp); |
1653 | } |
1654 | } |
1655 | #endif |
1656 | } |
1657 | |
1658 | return nbusy; |
1659 | } |
1660 | |
1661 | static void |
1662 | sysctl_fillbuf(buf_t *i, struct buf_sysctl *o) |
1663 | { |
1664 | |
1665 | o->b_flags = i->b_flags | i->b_cflags | i->b_oflags; |
1666 | o->b_error = i->b_error; |
1667 | o->b_prio = i->b_prio; |
1668 | o->b_dev = i->b_dev; |
1669 | o->b_bufsize = i->b_bufsize; |
1670 | o->b_bcount = i->b_bcount; |
1671 | o->b_resid = i->b_resid; |
1672 | o->b_addr = PTRTOUINT64(i->b_data); |
1673 | o->b_blkno = i->b_blkno; |
1674 | o->b_rawblkno = i->b_rawblkno; |
1675 | o->b_iodone = PTRTOUINT64(i->b_iodone); |
1676 | o->b_proc = PTRTOUINT64(i->b_proc); |
1677 | o->b_vp = PTRTOUINT64(i->b_vp); |
1678 | o->b_saveaddr = PTRTOUINT64(i->b_saveaddr); |
1679 | o->b_lblkno = i->b_lblkno; |
1680 | } |
1681 | |
1682 | #define KERN_BUFSLOP 20 |
1683 | static int |
1684 | sysctl_dobuf(SYSCTLFN_ARGS) |
1685 | { |
1686 | buf_t *bp; |
1687 | struct buf_sysctl bs; |
1688 | struct bqueue *bq; |
1689 | char *dp; |
1690 | u_int i, op, arg; |
1691 | size_t len, needed, elem_size, out_size; |
1692 | int error, elem_count, retries; |
1693 | |
1694 | if (namelen == 1 && name[0] == CTL_QUERY) |
1695 | return (sysctl_query(SYSCTLFN_CALL(rnode))); |
1696 | |
1697 | if (namelen != 4) |
1698 | return (EINVAL); |
1699 | |
1700 | retries = 100; |
1701 | retry: |
1702 | dp = oldp; |
1703 | len = (oldp != NULL) ? *oldlenp : 0; |
1704 | op = name[0]; |
1705 | arg = name[1]; |
1706 | elem_size = name[2]; |
1707 | elem_count = name[3]; |
1708 | out_size = MIN(sizeof(bs), elem_size); |
1709 | |
1710 | /* |
1711 | * at the moment, these are just "placeholders" to make the |
1712 | * API for retrieving kern.buf data more extensible in the |
1713 | * future. |
1714 | * |
1715 | * XXX kern.buf currently has "netbsd32" issues. hopefully |
1716 | * these will be resolved at a later point. |
1717 | */ |
1718 | if (op != KERN_BUF_ALL || arg != KERN_BUF_ALL || |
1719 | elem_size < 1 || elem_count < 0) |
1720 | return (EINVAL); |
1721 | |
1722 | error = 0; |
1723 | needed = 0; |
1724 | sysctl_unlock(); |
1725 | mutex_enter(&bufcache_lock); |
1726 | for (i = 0; i < BQUEUES; i++) { |
1727 | bq = &bufqueues[i]; |
1728 | TAILQ_FOREACH(bp, &bq->bq_queue, b_freelist) { |
1729 | bq->bq_marker = bp; |
1730 | if (len >= elem_size && elem_count > 0) { |
1731 | sysctl_fillbuf(bp, &bs); |
1732 | mutex_exit(&bufcache_lock); |
1733 | error = copyout(&bs, dp, out_size); |
1734 | mutex_enter(&bufcache_lock); |
1735 | if (error) |
1736 | break; |
1737 | if (bq->bq_marker != bp) { |
1738 | /* |
1739 | * This sysctl node is only for |
1740 | * statistics. Retry; if the |
1741 | * queue keeps changing, then |
1742 | * bail out. |
1743 | */ |
1744 | if (retries-- == 0) { |
1745 | error = EAGAIN; |
1746 | break; |
1747 | } |
1748 | mutex_exit(&bufcache_lock); |
1749 | sysctl_relock(); |
1750 | goto retry; |
1751 | } |
1752 | dp += elem_size; |
1753 | len -= elem_size; |
1754 | } |
1755 | needed += elem_size; |
1756 | if (elem_count > 0 && elem_count != INT_MAX) |
1757 | elem_count--; |
1758 | } |
1759 | if (error != 0) |
1760 | break; |
1761 | } |
1762 | mutex_exit(&bufcache_lock); |
1763 | sysctl_relock(); |
1764 | |
1765 | *oldlenp = needed; |
1766 | if (oldp == NULL) |
1767 | *oldlenp += KERN_BUFSLOP * sizeof(buf_t); |
1768 | |
1769 | return (error); |
1770 | } |
1771 | |
1772 | static int |
1773 | sysctl_bufvm_update(SYSCTLFN_ARGS) |
1774 | { |
1775 | int error, rv; |
1776 | struct sysctlnode node; |
1777 | unsigned int temp_bufcache; |
1778 | unsigned long temp_water; |
1779 | |
1780 | /* Take a copy of the supplied node and its data */ |
1781 | node = *rnode; |
1782 | if (node.sysctl_data == &bufcache) { |
1783 | node.sysctl_data = &temp_bufcache; |
1784 | temp_bufcache = *(unsigned int *)rnode->sysctl_data; |
1785 | } else { |
1786 | node.sysctl_data = &temp_water; |
1787 | temp_water = *(unsigned long *)rnode->sysctl_data; |
1788 | } |
1789 | |
1790 | /* Update the copy */ |
1791 | error = sysctl_lookup(SYSCTLFN_CALL(&node)); |
1792 | if (error || newp == NULL) |
1793 | return (error); |
1794 | |
1795 | if (rnode->sysctl_data == &bufcache) { |
1796 | if (temp_bufcache > 100) |
1797 | return (EINVAL); |
1798 | bufcache = temp_bufcache; |
1799 | buf_setwm(); |
1800 | } else if (rnode->sysctl_data == &bufmem_lowater) { |
1801 | if (bufmem_hiwater - temp_water < 16) |
1802 | return (EINVAL); |
1803 | bufmem_lowater = temp_water; |
1804 | } else if (rnode->sysctl_data == &bufmem_hiwater) { |
1805 | if (temp_water - bufmem_lowater < 16) |
1806 | return (EINVAL); |
1807 | bufmem_hiwater = temp_water; |
1808 | } else |
1809 | return (EINVAL); |
1810 | |
1811 | /* Drain until below new high water mark */ |
1812 | sysctl_unlock(); |
1813 | mutex_enter(&bufcache_lock); |
1814 | while (bufmem > bufmem_hiwater) { |
1815 | rv = buf_drain((bufmem - bufmem_hiwater) / (2 * 1024)); |
1816 | if (rv <= 0) |
1817 | break; |
1818 | } |
1819 | mutex_exit(&bufcache_lock); |
1820 | sysctl_relock(); |
1821 | |
1822 | return 0; |
1823 | } |
1824 | |
1825 | static struct sysctllog *vfsbio_sysctllog; |
1826 | |
1827 | static void |
1828 | sysctl_kern_buf_setup(void) |
1829 | { |
1830 | |
1831 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
1832 | CTLFLAG_PERMANENT, |
1833 | CTLTYPE_NODE, "buf" , |
1834 | SYSCTL_DESCR("Kernel buffer cache information" ), |
1835 | sysctl_dobuf, 0, NULL, 0, |
1836 | CTL_KERN, KERN_BUF, CTL_EOL); |
1837 | } |
1838 | |
1839 | static void |
1840 | sysctl_vm_buf_setup(void) |
1841 | { |
1842 | |
1843 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
1844 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
1845 | CTLTYPE_INT, "bufcache" , |
1846 | SYSCTL_DESCR("Percentage of physical memory to use for " |
1847 | "buffer cache" ), |
1848 | sysctl_bufvm_update, 0, &bufcache, 0, |
1849 | CTL_VM, CTL_CREATE, CTL_EOL); |
1850 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
1851 | CTLFLAG_PERMANENT|CTLFLAG_READONLY, |
1852 | CTLTYPE_LONG, "bufmem" , |
1853 | SYSCTL_DESCR("Amount of kernel memory used by buffer " |
1854 | "cache" ), |
1855 | NULL, 0, &bufmem, 0, |
1856 | CTL_VM, CTL_CREATE, CTL_EOL); |
1857 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
1858 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
1859 | CTLTYPE_LONG, "bufmem_lowater" , |
1860 | SYSCTL_DESCR("Minimum amount of kernel memory to " |
1861 | "reserve for buffer cache" ), |
1862 | sysctl_bufvm_update, 0, &bufmem_lowater, 0, |
1863 | CTL_VM, CTL_CREATE, CTL_EOL); |
1864 | sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, |
1865 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
1866 | CTLTYPE_LONG, "bufmem_hiwater" , |
1867 | SYSCTL_DESCR("Maximum amount of kernel memory to use " |
1868 | "for buffer cache" ), |
1869 | sysctl_bufvm_update, 0, &bufmem_hiwater, 0, |
1870 | CTL_VM, CTL_CREATE, CTL_EOL); |
1871 | } |
1872 | |
1873 | #ifdef DEBUG |
1874 | /* |
1875 | * Print out statistics on the current allocation of the buffer pool. |
1876 | * Can be enabled to print out on every ``sync'' by setting "syncprt" |
1877 | * in vfs_syscalls.c using sysctl. |
1878 | */ |
1879 | void |
1880 | vfs_bufstats(void) |
1881 | { |
1882 | int i, j, count; |
1883 | buf_t *bp; |
1884 | struct bqueue *dp; |
1885 | int counts[MAXBSIZE / MIN_PAGE_SIZE + 1]; |
1886 | static const char *bname[BQUEUES] = { "LOCKED" , "LRU" , "AGE" }; |
1887 | |
1888 | for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) { |
1889 | count = 0; |
1890 | memset(counts, 0, sizeof(counts)); |
1891 | TAILQ_FOREACH(bp, &dp->bq_queue, b_freelist) { |
1892 | counts[bp->b_bufsize / PAGE_SIZE]++; |
1893 | count++; |
1894 | } |
1895 | printf("%s: total-%d" , bname[i], count); |
1896 | for (j = 0; j <= MAXBSIZE / PAGE_SIZE; j++) |
1897 | if (counts[j] != 0) |
1898 | printf(", %d-%d" , j * PAGE_SIZE, counts[j]); |
1899 | printf("\n" ); |
1900 | } |
1901 | } |
1902 | #endif /* DEBUG */ |
1903 | |
1904 | /* ------------------------------ */ |
1905 | |
1906 | buf_t * |
1907 | getiobuf(struct vnode *vp, bool waitok) |
1908 | { |
1909 | buf_t *bp; |
1910 | |
1911 | bp = pool_cache_get(bufio_cache, (waitok ? PR_WAITOK : PR_NOWAIT)); |
1912 | if (bp == NULL) |
1913 | return bp; |
1914 | |
1915 | buf_init(bp); |
1916 | |
1917 | if ((bp->b_vp = vp) == NULL) |
1918 | bp->b_objlock = &buffer_lock; |
1919 | else |
1920 | bp->b_objlock = vp->v_interlock; |
1921 | |
1922 | return bp; |
1923 | } |
1924 | |
1925 | void |
1926 | putiobuf(buf_t *bp) |
1927 | { |
1928 | |
1929 | buf_destroy(bp); |
1930 | pool_cache_put(bufio_cache, bp); |
1931 | } |
1932 | |
1933 | /* |
1934 | * nestiobuf_iodone: b_iodone callback for nested buffers. |
1935 | */ |
1936 | |
1937 | void |
1938 | nestiobuf_iodone(buf_t *bp) |
1939 | { |
1940 | buf_t *mbp = bp->b_private; |
1941 | int error; |
1942 | int donebytes; |
1943 | |
1944 | KASSERT(bp->b_bcount <= bp->b_bufsize); |
1945 | KASSERT(mbp != bp); |
1946 | |
1947 | error = bp->b_error; |
1948 | if (bp->b_error == 0 && |
1949 | (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { |
1950 | /* |
1951 | * Not all got transfered, raise an error. We have no way to |
1952 | * propagate these conditions to mbp. |
1953 | */ |
1954 | error = EIO; |
1955 | } |
1956 | |
1957 | donebytes = bp->b_bufsize; |
1958 | |
1959 | putiobuf(bp); |
1960 | nestiobuf_done(mbp, donebytes, error); |
1961 | } |
1962 | |
1963 | /* |
1964 | * nestiobuf_setup: setup a "nested" buffer. |
1965 | * |
1966 | * => 'mbp' is a "master" buffer which is being divided into sub pieces. |
1967 | * => 'bp' should be a buffer allocated by getiobuf. |
1968 | * => 'offset' is a byte offset in the master buffer. |
1969 | * => 'size' is a size in bytes of this nested buffer. |
1970 | */ |
1971 | |
1972 | void |
1973 | nestiobuf_setup(buf_t *mbp, buf_t *bp, int offset, size_t size) |
1974 | { |
1975 | const int b_read = mbp->b_flags & B_READ; |
1976 | struct vnode *vp = mbp->b_vp; |
1977 | |
1978 | KASSERT(mbp->b_bcount >= offset + size); |
1979 | bp->b_vp = vp; |
1980 | bp->b_dev = mbp->b_dev; |
1981 | bp->b_objlock = mbp->b_objlock; |
1982 | bp->b_cflags = BC_BUSY; |
1983 | bp->b_flags = B_ASYNC | b_read; |
1984 | bp->b_iodone = nestiobuf_iodone; |
1985 | bp->b_data = (char *)mbp->b_data + offset; |
1986 | bp->b_resid = bp->b_bcount = size; |
1987 | bp->b_bufsize = bp->b_bcount; |
1988 | bp->b_private = mbp; |
1989 | BIO_COPYPRIO(bp, mbp); |
1990 | if (!b_read && vp != NULL) { |
1991 | mutex_enter(vp->v_interlock); |
1992 | vp->v_numoutput++; |
1993 | mutex_exit(vp->v_interlock); |
1994 | } |
1995 | } |
1996 | |
1997 | /* |
1998 | * nestiobuf_done: propagate completion to the master buffer. |
1999 | * |
2000 | * => 'donebytes' specifies how many bytes in the 'mbp' is completed. |
2001 | * => 'error' is an errno(2) that 'donebytes' has been completed with. |
2002 | */ |
2003 | |
2004 | void |
2005 | nestiobuf_done(buf_t *mbp, int donebytes, int error) |
2006 | { |
2007 | |
2008 | if (donebytes == 0) { |
2009 | return; |
2010 | } |
2011 | mutex_enter(mbp->b_objlock); |
2012 | KASSERT(mbp->b_resid >= donebytes); |
2013 | mbp->b_resid -= donebytes; |
2014 | if (error) |
2015 | mbp->b_error = error; |
2016 | if (mbp->b_resid == 0) { |
2017 | if (mbp->b_error) |
2018 | mbp->b_resid = mbp->b_bcount; |
2019 | mutex_exit(mbp->b_objlock); |
2020 | biodone(mbp); |
2021 | } else |
2022 | mutex_exit(mbp->b_objlock); |
2023 | } |
2024 | |
2025 | void |
2026 | buf_init(buf_t *bp) |
2027 | { |
2028 | |
2029 | cv_init(&bp->b_busy, "biolock" ); |
2030 | cv_init(&bp->b_done, "biowait" ); |
2031 | bp->b_dev = NODEV; |
2032 | bp->b_error = 0; |
2033 | bp->b_flags = 0; |
2034 | bp->b_cflags = 0; |
2035 | bp->b_oflags = 0; |
2036 | bp->b_objlock = &buffer_lock; |
2037 | bp->b_iodone = NULL; |
2038 | bp->b_refcnt = 1; |
2039 | bp->b_dev = NODEV; |
2040 | bp->b_vnbufs.le_next = NOLIST; |
2041 | BIO_SETPRIO(bp, BPRIO_DEFAULT); |
2042 | } |
2043 | |
2044 | void |
2045 | buf_destroy(buf_t *bp) |
2046 | { |
2047 | |
2048 | cv_destroy(&bp->b_done); |
2049 | cv_destroy(&bp->b_busy); |
2050 | } |
2051 | |
2052 | int |
2053 | bbusy(buf_t *bp, bool intr, int timo, kmutex_t *interlock) |
2054 | { |
2055 | int error; |
2056 | |
2057 | KASSERT(mutex_owned(&bufcache_lock)); |
2058 | |
2059 | if ((bp->b_cflags & BC_BUSY) != 0) { |
2060 | if (curlwp == uvm.pagedaemon_lwp) |
2061 | return EDEADLK; |
2062 | bp->b_cflags |= BC_WANTED; |
2063 | bref(bp); |
2064 | if (interlock != NULL) |
2065 | mutex_exit(interlock); |
2066 | if (intr) { |
2067 | error = cv_timedwait_sig(&bp->b_busy, &bufcache_lock, |
2068 | timo); |
2069 | } else { |
2070 | error = cv_timedwait(&bp->b_busy, &bufcache_lock, |
2071 | timo); |
2072 | } |
2073 | brele(bp); |
2074 | if (interlock != NULL) |
2075 | mutex_enter(interlock); |
2076 | if (error != 0) |
2077 | return error; |
2078 | return EPASSTHROUGH; |
2079 | } |
2080 | bp->b_cflags |= BC_BUSY; |
2081 | |
2082 | return 0; |
2083 | } |
2084 | |