1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1993
5 * The Regents of the University of California. All rights reserved.
6 * Modifications/enhancements:
7 * Copyright (c) 1995 John S. Dyson. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/proc.h>
38 #include <sys/bio.h>
39 #include <sys/buf.h>
40 #include <sys/vnode.h>
41 #include <sys/malloc.h>
42 #include <sys/mount.h>
43 #include <sys/racct.h>
44 #include <sys/resourcevar.h>
45 #include <sys/rwlock.h>
46 #include <sys/vmmeter.h>
47 #include <vm/vm.h>
48 #include <vm/vm_object.h>
49 #include <vm/vm_page.h>
50 #include <sys/sysctl.h>
51
52 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer");
53 static uma_zone_t cluster_pbuf_zone;
54
55 static void cluster_init(void *);
56 static struct cluster_save *cluster_collectbufs(struct vnode *vp,
57 struct vn_clusterw *vnc, struct buf *last_bp, int gbflags);
58 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize,
59 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags,
60 struct buf *fbp);
61 static void cluster_callback(struct buf *);
62
63 static int write_behind = 1;
64 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
65 "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
66
67 static int read_max = 64;
68 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
69 "Cluster read-ahead max block count");
70
71 static int read_min = 1;
72 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0,
73 "Cluster read min block count");
74
75 SYSINIT(cluster, SI_SUB_CPU, SI_ORDER_ANY, cluster_init, NULL);
76
77 static void
cluster_init(void * dummy)78 cluster_init(void *dummy)
79 {
80
81 cluster_pbuf_zone = pbuf_zsecond_create("clpbuf", nswbuf / 2);
82 }
83
84 /*
85 * Read data to a buf, including read-ahead if we find this to be beneficial.
86 * cluster_read replaces bread.
87 */
88 int
cluster_read(struct vnode * vp,u_quad_t filesize,daddr_t lblkno,long size,struct ucred * cred,long totread,int seqcount,int gbflags,struct buf ** bpp)89 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size,
90 struct ucred *cred, long totread, int seqcount, int gbflags,
91 struct buf **bpp)
92 {
93 struct buf *bp, *rbp, *reqbp;
94 struct bufobj *bo;
95 struct thread *td;
96 daddr_t blkno, origblkno;
97 int maxra, racluster;
98 int error, ncontig;
99 int i;
100
101 error = 0;
102 td = curthread;
103 bo = &vp->v_bufobj;
104 if (!unmapped_buf_allowed)
105 gbflags &= ~GB_UNMAPPED;
106
107 /*
108 * Try to limit the amount of read-ahead by a few
109 * ad-hoc parameters. This needs work!!!
110 */
111 racluster = vp->v_mount->mnt_iosize_max / size;
112 maxra = seqcount;
113 maxra = min(read_max, maxra);
114 maxra = min(nbuf/8, maxra);
115 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize)
116 maxra = (filesize / size) - lblkno;
117
118 /*
119 * get the requested block
120 */
121 error = getblkx(vp, lblkno, lblkno, size, 0, 0, gbflags, &bp);
122 if (error != 0) {
123 *bpp = NULL;
124 return (error);
125 }
126 gbflags &= ~GB_NOSPARSE;
127 origblkno = lblkno;
128 *bpp = reqbp = bp;
129
130 /*
131 * if it is in the cache, then check to see if the reads have been
132 * sequential. If they have, then try some read-ahead, otherwise
133 * back-off on prospective read-aheads.
134 */
135 if (bp->b_flags & B_CACHE) {
136 if (!seqcount) {
137 return 0;
138 } else if ((bp->b_flags & B_RAM) == 0) {
139 return 0;
140 } else {
141 bp->b_flags &= ~B_RAM;
142 BO_RLOCK(bo);
143 for (i = 1; i < maxra; i++) {
144 /*
145 * Stop if the buffer does not exist or it
146 * is invalid (about to go away?)
147 */
148 rbp = gbincore(&vp->v_bufobj, lblkno+i);
149 if (rbp == NULL || (rbp->b_flags & B_INVAL))
150 break;
151
152 /*
153 * Set another read-ahead mark so we know
154 * to check again. (If we can lock the
155 * buffer without waiting)
156 */
157 if ((((i % racluster) == (racluster - 1)) ||
158 (i == (maxra - 1)))
159 && (0 == BUF_LOCK(rbp,
160 LK_EXCLUSIVE | LK_NOWAIT, NULL))) {
161 rbp->b_flags |= B_RAM;
162 BUF_UNLOCK(rbp);
163 }
164 }
165 BO_RUNLOCK(bo);
166 if (i >= maxra) {
167 return 0;
168 }
169 lblkno += i;
170 }
171 reqbp = bp = NULL;
172 /*
173 * If it isn't in the cache, then get a chunk from
174 * disk if sequential, otherwise just get the block.
175 */
176 } else {
177 off_t firstread = bp->b_offset;
178 int nblks;
179 long minread;
180
181 KASSERT(bp->b_offset != NOOFFSET,
182 ("cluster_read: no buffer offset"));
183
184 ncontig = 0;
185
186 /*
187 * Adjust totread if needed
188 */
189 minread = read_min * size;
190 if (minread > totread)
191 totread = minread;
192
193 /*
194 * Compute the total number of blocks that we should read
195 * synchronously.
196 */
197 if (firstread + totread > filesize)
198 totread = filesize - firstread;
199 nblks = howmany(totread, size);
200 if (nblks > racluster)
201 nblks = racluster;
202
203 /*
204 * Now compute the number of contiguous blocks.
205 */
206 if (nblks > 1) {
207 error = VOP_BMAP(vp, lblkno, NULL,
208 &blkno, &ncontig, NULL);
209 /*
210 * If this failed to map just do the original block.
211 */
212 if (error || blkno == -1)
213 ncontig = 0;
214 }
215
216 /*
217 * If we have contiguous data available do a cluster
218 * otherwise just read the requested block.
219 */
220 if (ncontig) {
221 /* Account for our first block. */
222 ncontig = min(ncontig + 1, nblks);
223 if (ncontig < nblks)
224 nblks = ncontig;
225 bp = cluster_rbuild(vp, filesize, lblkno,
226 blkno, size, nblks, gbflags, bp);
227 lblkno += (bp->b_bufsize / size);
228 } else {
229 bp->b_flags |= B_RAM;
230 bp->b_iocmd = BIO_READ;
231 lblkno += 1;
232 }
233 }
234
235 /*
236 * handle the synchronous read so that it is available ASAP.
237 */
238 if (bp) {
239 if ((bp->b_flags & B_CLUSTER) == 0) {
240 vfs_busy_pages(bp, 0);
241 }
242 bp->b_flags &= ~B_INVAL;
243 bp->b_ioflags &= ~BIO_ERROR;
244 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
245 BUF_KERNPROC(bp);
246 bp->b_iooffset = dbtob(bp->b_blkno);
247 bstrategy(bp);
248 #ifdef RACCT
249 if (racct_enable) {
250 PROC_LOCK(td->td_proc);
251 racct_add_buf(td->td_proc, bp, 0);
252 PROC_UNLOCK(td->td_proc);
253 }
254 #endif /* RACCT */
255 td->td_ru.ru_inblock++;
256 }
257
258 /*
259 * If we have been doing sequential I/O, then do some read-ahead.
260 */
261 while (lblkno < (origblkno + maxra)) {
262 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
263 if (error)
264 break;
265
266 if (blkno == -1)
267 break;
268
269 /*
270 * We could throttle ncontig here by maxra but we might as
271 * well read the data if it is contiguous. We're throttled
272 * by racluster anyway.
273 */
274 if (ncontig) {
275 ncontig = min(ncontig + 1, racluster);
276 rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
277 size, ncontig, gbflags, NULL);
278 lblkno += (rbp->b_bufsize / size);
279 if (rbp->b_flags & B_DELWRI) {
280 bqrelse(rbp);
281 continue;
282 }
283 } else {
284 rbp = getblk(vp, lblkno, size, 0, 0, gbflags);
285 lblkno += 1;
286 if (rbp->b_flags & B_DELWRI) {
287 bqrelse(rbp);
288 continue;
289 }
290 rbp->b_flags |= B_ASYNC | B_RAM;
291 rbp->b_iocmd = BIO_READ;
292 rbp->b_blkno = blkno;
293 }
294 if (rbp->b_flags & B_CACHE) {
295 rbp->b_flags &= ~B_ASYNC;
296 bqrelse(rbp);
297 continue;
298 }
299 if ((rbp->b_flags & B_CLUSTER) == 0) {
300 vfs_busy_pages(rbp, 0);
301 }
302 rbp->b_flags &= ~B_INVAL;
303 rbp->b_ioflags &= ~BIO_ERROR;
304 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
305 BUF_KERNPROC(rbp);
306 rbp->b_iooffset = dbtob(rbp->b_blkno);
307 bstrategy(rbp);
308 #ifdef RACCT
309 if (racct_enable) {
310 PROC_LOCK(td->td_proc);
311 racct_add_buf(td->td_proc, rbp, 0);
312 PROC_UNLOCK(td->td_proc);
313 }
314 #endif /* RACCT */
315 td->td_ru.ru_inblock++;
316 }
317
318 if (reqbp) {
319 /*
320 * Like bread, always brelse() the buffer when
321 * returning an error.
322 */
323 error = bufwait(reqbp);
324 if (error != 0) {
325 brelse(reqbp);
326 *bpp = NULL;
327 }
328 }
329 return (error);
330 }
331
332 /*
333 * If blocks are contiguous on disk, use this to provide clustered
334 * read ahead. We will read as many blocks as possible sequentially
335 * and then parcel them up into logical blocks in the buffer hash table.
336 */
337 static struct buf *
cluster_rbuild(struct vnode * vp,u_quad_t filesize,daddr_t lbn,daddr_t blkno,long size,int run,int gbflags,struct buf * fbp)338 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
339 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp)
340 {
341 struct buf *bp, *tbp;
342 daddr_t bn;
343 off_t off;
344 long tinc, tsize;
345 int i, inc, j, k, toff;
346
347 KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
348 ("cluster_rbuild: size %ld != f_iosize %jd\n",
349 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
350
351 /*
352 * avoid a division
353 */
354 while ((u_quad_t) size * (lbn + run) > filesize) {
355 --run;
356 }
357
358 if (fbp) {
359 tbp = fbp;
360 tbp->b_iocmd = BIO_READ;
361 } else {
362 tbp = getblk(vp, lbn, size, 0, 0, gbflags);
363 if (tbp->b_flags & B_CACHE)
364 return tbp;
365 tbp->b_flags |= B_ASYNC | B_RAM;
366 tbp->b_iocmd = BIO_READ;
367 }
368 tbp->b_blkno = blkno;
369 if ( (tbp->b_flags & B_MALLOC) ||
370 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
371 return tbp;
372
373 bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT);
374 if (bp == NULL)
375 return tbp;
376 MPASS((bp->b_flags & B_MAXPHYS) != 0);
377
378 /*
379 * We are synthesizing a buffer out of vm_page_t's, but
380 * if the block size is not page aligned then the starting
381 * address may not be either. Inherit the b_data offset
382 * from the original buffer.
383 */
384 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
385 if ((gbflags & GB_UNMAPPED) != 0) {
386 bp->b_data = unmapped_buf;
387 } else {
388 bp->b_data = (char *)((vm_offset_t)bp->b_data |
389 ((vm_offset_t)tbp->b_data & PAGE_MASK));
390 }
391 bp->b_iocmd = BIO_READ;
392 bp->b_iodone = cluster_callback;
393 bp->b_blkno = blkno;
394 bp->b_lblkno = lbn;
395 bp->b_offset = tbp->b_offset;
396 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
397 pbgetvp(vp, bp);
398
399 TAILQ_INIT(&bp->b_cluster.cluster_head);
400
401 bp->b_bcount = 0;
402 bp->b_bufsize = 0;
403 bp->b_npages = 0;
404
405 inc = btodb(size);
406 for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
407 if (i == 0) {
408 vm_object_pip_add(tbp->b_bufobj->bo_object,
409 tbp->b_npages);
410 vfs_busy_pages_acquire(tbp);
411 } else {
412 if ((bp->b_npages * PAGE_SIZE) +
413 round_page(size) > vp->v_mount->mnt_iosize_max) {
414 break;
415 }
416
417 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT |
418 (gbflags & GB_UNMAPPED));
419
420 /* Don't wait around for locked bufs. */
421 if (tbp == NULL)
422 break;
423
424 /*
425 * Stop scanning if the buffer is fully valid
426 * (marked B_CACHE), or locked (may be doing a
427 * background write), or if the buffer is not
428 * VMIO backed. The clustering code can only deal
429 * with VMIO-backed buffers. The bo lock is not
430 * required for the BKGRDINPROG check since it
431 * can not be set without the buf lock.
432 */
433 if ((tbp->b_vflags & BV_BKGRDINPROG) ||
434 (tbp->b_flags & B_CACHE) ||
435 (tbp->b_flags & B_VMIO) == 0) {
436 bqrelse(tbp);
437 break;
438 }
439
440 /*
441 * The buffer must be completely invalid in order to
442 * take part in the cluster. If it is partially valid
443 * then we stop.
444 */
445 off = tbp->b_offset;
446 tsize = size;
447 for (j = 0; tsize > 0; j++) {
448 toff = off & PAGE_MASK;
449 tinc = tsize;
450 if (toff + tinc > PAGE_SIZE)
451 tinc = PAGE_SIZE - toff;
452 if (vm_page_trysbusy(tbp->b_pages[j]) == 0)
453 break;
454 if ((tbp->b_pages[j]->valid &
455 vm_page_bits(toff, tinc)) != 0) {
456 vm_page_sunbusy(tbp->b_pages[j]);
457 break;
458 }
459 vm_object_pip_add(tbp->b_bufobj->bo_object, 1);
460 off += tinc;
461 tsize -= tinc;
462 }
463 if (tsize > 0) {
464 clean_sbusy:
465 vm_object_pip_wakeupn(tbp->b_bufobj->bo_object,
466 j);
467 for (k = 0; k < j; k++)
468 vm_page_sunbusy(tbp->b_pages[k]);
469 bqrelse(tbp);
470 break;
471 }
472
473 /*
474 * Set a read-ahead mark as appropriate
475 */
476 if ((fbp && (i == 1)) || (i == (run - 1)))
477 tbp->b_flags |= B_RAM;
478
479 /*
480 * Set the buffer up for an async read (XXX should
481 * we do this only if we do not wind up brelse()ing?).
482 * Set the block number if it isn't set, otherwise
483 * if it is make sure it matches the block number we
484 * expect.
485 */
486 tbp->b_flags |= B_ASYNC;
487 tbp->b_iocmd = BIO_READ;
488 if (tbp->b_blkno == tbp->b_lblkno) {
489 tbp->b_blkno = bn;
490 } else if (tbp->b_blkno != bn) {
491 goto clean_sbusy;
492 }
493 }
494 /*
495 * XXX fbp from caller may not be B_ASYNC, but we are going
496 * to biodone() it in cluster_callback() anyway
497 */
498 BUF_KERNPROC(tbp);
499 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
500 tbp, b_cluster.cluster_entry);
501 for (j = 0; j < tbp->b_npages; j += 1) {
502 vm_page_t m;
503
504 m = tbp->b_pages[j];
505 if ((bp->b_npages == 0) ||
506 (bp->b_pages[bp->b_npages-1] != m)) {
507 bp->b_pages[bp->b_npages] = m;
508 bp->b_npages++;
509 }
510 if (vm_page_all_valid(m))
511 tbp->b_pages[j] = bogus_page;
512 }
513
514 /*
515 * Don't inherit tbp->b_bufsize as it may be larger due to
516 * a non-page-aligned size. Instead just aggregate using
517 * 'size'.
518 */
519 if (tbp->b_bcount != size)
520 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
521 if (tbp->b_bufsize != size)
522 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
523 bp->b_bcount += size;
524 bp->b_bufsize += size;
525 }
526
527 /*
528 * Fully valid pages in the cluster are already good and do not need
529 * to be re-read from disk. Replace the page with bogus_page
530 */
531 for (j = 0; j < bp->b_npages; j++) {
532 if (vm_page_all_valid(bp->b_pages[j]))
533 bp->b_pages[j] = bogus_page;
534 }
535 if (bp->b_bufsize > bp->b_kvasize)
536 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
537 bp->b_bufsize, bp->b_kvasize);
538
539 if (buf_mapped(bp)) {
540 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
541 (vm_page_t *)bp->b_pages, bp->b_npages);
542 }
543 return (bp);
544 }
545
546 /*
547 * Cleanup after a clustered read or write.
548 * This is complicated by the fact that any of the buffers might have
549 * extra memory (if there were no empty buffer headers at allocbuf time)
550 * that we will need to shift around.
551 */
552 static void
cluster_callback(struct buf * bp)553 cluster_callback(struct buf *bp)
554 {
555 struct buf *nbp, *tbp;
556 int error = 0;
557
558 /*
559 * Must propagate errors to all the components.
560 */
561 if (bp->b_ioflags & BIO_ERROR)
562 error = bp->b_error;
563
564 if (buf_mapped(bp)) {
565 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
566 bp->b_npages);
567 }
568 /*
569 * Move memory from the large cluster buffer into the component
570 * buffers and mark IO as done on these.
571 */
572 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
573 tbp; tbp = nbp) {
574 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
575 if (error) {
576 tbp->b_ioflags |= BIO_ERROR;
577 tbp->b_error = error;
578 } else {
579 tbp->b_dirtyoff = tbp->b_dirtyend = 0;
580 tbp->b_flags &= ~B_INVAL;
581 tbp->b_ioflags &= ~BIO_ERROR;
582 /*
583 * XXX the bdwrite()/bqrelse() issued during
584 * cluster building clears B_RELBUF (see bqrelse()
585 * comment). If direct I/O was specified, we have
586 * to restore it here to allow the buffer and VM
587 * to be freed.
588 */
589 if (tbp->b_flags & B_DIRECT)
590 tbp->b_flags |= B_RELBUF;
591 }
592 bufdone(tbp);
593 }
594 pbrelvp(bp);
595 uma_zfree(cluster_pbuf_zone, bp);
596 }
597
598 /*
599 * cluster_wbuild_wb:
600 *
601 * Implement modified write build for cluster.
602 *
603 * write_behind = 0 write behind disabled
604 * write_behind = 1 write behind normal (default)
605 * write_behind = 2 write behind backed-off
606 */
607
608 static __inline int
cluster_wbuild_wb(struct vnode * vp,long size,daddr_t start_lbn,int len,int gbflags)609 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len,
610 int gbflags)
611 {
612 int r = 0;
613
614 switch (write_behind) {
615 case 2:
616 if (start_lbn < len)
617 break;
618 start_lbn -= len;
619 /* FALLTHROUGH */
620 case 1:
621 r = cluster_wbuild(vp, size, start_lbn, len, gbflags);
622 /* FALLTHROUGH */
623 default:
624 /* FALLTHROUGH */
625 break;
626 }
627 return(r);
628 }
629
630 /*
631 * Do clustered write for FFS.
632 *
633 * Three cases:
634 * 1. Write is not sequential (write asynchronously)
635 * Write is sequential:
636 * 2. beginning of cluster - begin cluster
637 * 3. middle of a cluster - add to cluster
638 * 4. end of a cluster - asynchronously write cluster
639 */
640 void
cluster_write(struct vnode * vp,struct vn_clusterw * vnc,struct buf * bp,u_quad_t filesize,int seqcount,int gbflags)641 cluster_write(struct vnode *vp, struct vn_clusterw *vnc, struct buf *bp,
642 u_quad_t filesize, int seqcount, int gbflags)
643 {
644 daddr_t lbn, pbn;
645 int maxclen, cursize;
646 int lblocksize;
647 int async;
648
649 if (!unmapped_buf_allowed)
650 gbflags &= ~GB_UNMAPPED;
651
652 if (vp->v_type == VREG) {
653 async = DOINGASYNC(vp);
654 lblocksize = vp->v_mount->mnt_stat.f_iosize;
655 } else {
656 async = 0;
657 lblocksize = bp->b_bufsize;
658 }
659 lbn = bp->b_lblkno;
660 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
661
662 /* Initialize vnode to beginning of file. */
663 if (lbn == 0)
664 vnc->v_lasta = vnc->v_clen = vnc->v_cstart = vnc->v_lastw = 0;
665
666 if (vnc->v_clen == 0 || lbn != vnc->v_lastw + 1 ||
667 (bp->b_blkno != vnc->v_lasta + btodb(lblocksize))) {
668 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
669 if (vnc->v_clen != 0) {
670 /*
671 * Next block is not sequential.
672 *
673 * If we are not writing at end of file, the process
674 * seeked to another point in the file since its last
675 * write, or we have reached our maximum cluster size,
676 * then push the previous cluster. Otherwise try
677 * reallocating to make it sequential.
678 *
679 * Change to algorithm: only push previous cluster if
680 * it was sequential from the point of view of the
681 * seqcount heuristic, otherwise leave the buffer
682 * intact so we can potentially optimize the I/O
683 * later on in the buf_daemon or update daemon
684 * flush.
685 */
686 cursize = vnc->v_lastw - vnc->v_cstart + 1;
687 if ((u_quad_t)bp->b_offset + lblocksize != filesize ||
688 lbn != vnc->v_lastw + 1 || vnc->v_clen <= cursize) {
689 if (!async && seqcount > 0) {
690 cluster_wbuild_wb(vp, lblocksize,
691 vnc->v_cstart, cursize, gbflags);
692 }
693 } else {
694 struct buf **bpp, **endbp;
695 struct cluster_save *buflist;
696
697 buflist = cluster_collectbufs(vp, vnc, bp,
698 gbflags);
699 if (buflist == NULL) {
700 /*
701 * Cluster build failed so just write
702 * it now.
703 */
704 bawrite(bp);
705 return;
706 }
707 endbp = &buflist->bs_children
708 [buflist->bs_nchildren - 1];
709 if (VOP_REALLOCBLKS(vp, buflist)) {
710 /*
711 * Failed, push the previous cluster
712 * if *really* writing sequentially
713 * in the logical file (seqcount > 1),
714 * otherwise delay it in the hopes that
715 * the low level disk driver can
716 * optimize the write ordering.
717 */
718 for (bpp = buflist->bs_children;
719 bpp < endbp; bpp++)
720 brelse(*bpp);
721 free(buflist, M_SEGMENT);
722 if (seqcount > 1) {
723 cluster_wbuild_wb(vp,
724 lblocksize, vnc->v_cstart,
725 cursize, gbflags);
726 }
727 } else {
728 /*
729 * Succeeded, keep building cluster.
730 */
731 for (bpp = buflist->bs_children;
732 bpp <= endbp; bpp++)
733 bdwrite(*bpp);
734 free(buflist, M_SEGMENT);
735 vnc->v_lastw = lbn;
736 vnc->v_lasta = bp->b_blkno;
737 return;
738 }
739 }
740 }
741 /*
742 * Consider beginning a cluster. If at end of file, make
743 * cluster as large as possible, otherwise find size of
744 * existing cluster.
745 */
746 if (vp->v_type == VREG &&
747 (u_quad_t) bp->b_offset + lblocksize != filesize &&
748 bp->b_blkno == bp->b_lblkno &&
749 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen,
750 NULL) != 0 || bp->b_blkno == -1)) {
751 pbn = bp->b_blkno;
752 bawrite(bp);
753 vnc->v_clen = 0;
754 vnc->v_lasta = pbn;
755 vnc->v_cstart = lbn + 1;
756 vnc->v_lastw = lbn;
757 return;
758 }
759 vnc->v_clen = maxclen;
760 pbn = bp->b_blkno;
761 if (!async && maxclen == 0) { /* I/O not contiguous */
762 vnc->v_cstart = lbn + 1;
763 bawrite(bp);
764 } else { /* Wait for rest of cluster */
765 vnc->v_cstart = lbn;
766 bdwrite(bp);
767 }
768 } else if (lbn == vnc->v_cstart + vnc->v_clen) {
769 /*
770 * At end of cluster, write it out if seqcount tells us we
771 * are operating sequentially, otherwise let the buf or
772 * update daemon handle it.
773 */
774 pbn = bp->b_blkno;
775 bdwrite(bp);
776 if (seqcount > 1) {
777 cluster_wbuild_wb(vp, lblocksize, vnc->v_cstart,
778 vnc->v_clen + 1, gbflags);
779 }
780 vnc->v_clen = 0;
781 vnc->v_cstart = lbn + 1;
782 } else if (vm_page_count_severe()) {
783 /*
784 * We are low on memory, get it going NOW
785 */
786 pbn = bp->b_blkno;
787 bawrite(bp);
788 } else {
789 /*
790 * In the middle of a cluster, so just delay the I/O for now.
791 */
792 pbn = bp->b_blkno;
793 bdwrite(bp);
794 }
795 vnc->v_lastw = lbn;
796 vnc->v_lasta = pbn;
797 }
798
799 /*
800 * This is an awful lot like cluster_rbuild...wish they could be combined.
801 * The last lbn argument is the current block on which I/O is being
802 * performed. Check to see that it doesn't fall in the middle of
803 * the current block (if last_bp == NULL).
804 */
805 int
cluster_wbuild(struct vnode * vp,long size,daddr_t start_lbn,int len,int gbflags)806 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len,
807 int gbflags)
808 {
809 struct buf *bp, *tbp;
810 struct bufobj *bo;
811 int i, j;
812 int totalwritten = 0;
813 int dbsize = btodb(size);
814
815 if (!unmapped_buf_allowed)
816 gbflags &= ~GB_UNMAPPED;
817
818 bo = &vp->v_bufobj;
819 while (len > 0) {
820 /*
821 * If the buffer is not delayed-write (i.e. dirty), or it
822 * is delayed-write but either locked or inval, it cannot
823 * partake in the clustered write.
824 */
825 BO_LOCK(bo);
826 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
827 (tbp->b_vflags & BV_BKGRDINPROG)) {
828 BO_UNLOCK(bo);
829 ++start_lbn;
830 --len;
831 continue;
832 }
833 if (BUF_LOCK(tbp,
834 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) {
835 ++start_lbn;
836 --len;
837 continue;
838 }
839 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
840 BUF_UNLOCK(tbp);
841 ++start_lbn;
842 --len;
843 continue;
844 }
845 bremfree(tbp);
846 tbp->b_flags &= ~B_DONE;
847
848 /*
849 * Extra memory in the buffer, punt on this buffer.
850 * XXX we could handle this in most cases, but we would
851 * have to push the extra memory down to after our max
852 * possible cluster size and then potentially pull it back
853 * up if the cluster was terminated prematurely--too much
854 * hassle.
855 */
856 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
857 (B_CLUSTEROK | B_VMIO)) ||
858 (tbp->b_bcount != tbp->b_bufsize) ||
859 (tbp->b_bcount != size) ||
860 (len == 1) ||
861 ((bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT)) == NULL)) {
862 totalwritten += tbp->b_bufsize;
863 bawrite(tbp);
864 ++start_lbn;
865 --len;
866 continue;
867 }
868 MPASS((bp->b_flags & B_MAXPHYS) != 0);
869
870 /*
871 * We got a pbuf to make the cluster in.
872 * so initialise it.
873 */
874 TAILQ_INIT(&bp->b_cluster.cluster_head);
875 bp->b_bcount = 0;
876 bp->b_bufsize = 0;
877 bp->b_npages = 0;
878 if (tbp->b_wcred != NOCRED)
879 bp->b_wcred = crhold(tbp->b_wcred);
880
881 bp->b_blkno = tbp->b_blkno;
882 bp->b_lblkno = tbp->b_lblkno;
883 bp->b_offset = tbp->b_offset;
884
885 /*
886 * We are synthesizing a buffer out of vm_page_t's, but
887 * if the block size is not page aligned then the starting
888 * address may not be either. Inherit the b_data offset
889 * from the original buffer.
890 */
891 if ((gbflags & GB_UNMAPPED) == 0 ||
892 (tbp->b_flags & B_VMIO) == 0) {
893 bp->b_data = (char *)((vm_offset_t)bp->b_data |
894 ((vm_offset_t)tbp->b_data & PAGE_MASK));
895 } else {
896 bp->b_data = unmapped_buf;
897 }
898 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO |
899 B_NEEDCOMMIT));
900 bp->b_iodone = cluster_callback;
901 pbgetvp(vp, bp);
902 /*
903 * From this location in the file, scan forward to see
904 * if there are buffers with adjacent data that need to
905 * be written as well.
906 */
907 for (i = 0; i < len; ++i, ++start_lbn) {
908 if (i != 0) { /* If not the first buffer */
909 /*
910 * If the adjacent data is not even in core it
911 * can't need to be written.
912 */
913 BO_LOCK(bo);
914 if ((tbp = gbincore(bo, start_lbn)) == NULL ||
915 (tbp->b_vflags & BV_BKGRDINPROG)) {
916 BO_UNLOCK(bo);
917 break;
918 }
919
920 /*
921 * If it IS in core, but has different
922 * characteristics, or is locked (which
923 * means it could be undergoing a background
924 * I/O or be in a weird state), then don't
925 * cluster with it.
926 */
927 if (BUF_LOCK(tbp,
928 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
929 BO_LOCKPTR(bo)))
930 break;
931
932 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
933 B_INVAL | B_DELWRI | B_NEEDCOMMIT))
934 != (B_DELWRI | B_CLUSTEROK |
935 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
936 tbp->b_wcred != bp->b_wcred) {
937 BUF_UNLOCK(tbp);
938 break;
939 }
940
941 /*
942 * Check that the combined cluster
943 * would make sense with regard to pages
944 * and would not be too large
945 */
946 if ((tbp->b_bcount != size) ||
947 ((bp->b_blkno + (dbsize * i)) !=
948 tbp->b_blkno) ||
949 ((tbp->b_npages + bp->b_npages) >
950 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
951 BUF_UNLOCK(tbp);
952 break;
953 }
954
955 /*
956 * Ok, it's passed all the tests,
957 * so remove it from the free list
958 * and mark it busy. We will use it.
959 */
960 bremfree(tbp);
961 tbp->b_flags &= ~B_DONE;
962 } /* end of code for non-first buffers only */
963 /*
964 * If the IO is via the VM then we do some
965 * special VM hackery (yuck). Since the buffer's
966 * block size may not be page-aligned it is possible
967 * for a page to be shared between two buffers. We
968 * have to get rid of the duplication when building
969 * the cluster.
970 */
971 if (tbp->b_flags & B_VMIO) {
972 vm_page_t m;
973
974 if (i == 0) {
975 vfs_busy_pages_acquire(tbp);
976 } else { /* if not first buffer */
977 for (j = 0; j < tbp->b_npages; j += 1) {
978 m = tbp->b_pages[j];
979 if (vm_page_trysbusy(m) == 0) {
980 for (j--; j >= 0; j--)
981 vm_page_sunbusy(
982 tbp->b_pages[j]);
983 bqrelse(tbp);
984 goto finishcluster;
985 }
986 }
987 }
988 vm_object_pip_add(tbp->b_bufobj->bo_object,
989 tbp->b_npages);
990 for (j = 0; j < tbp->b_npages; j += 1) {
991 m = tbp->b_pages[j];
992 if ((bp->b_npages == 0) ||
993 (bp->b_pages[bp->b_npages - 1] != m)) {
994 bp->b_pages[bp->b_npages] = m;
995 bp->b_npages++;
996 }
997 }
998 }
999 bp->b_bcount += size;
1000 bp->b_bufsize += size;
1001 /*
1002 * If any of the clustered buffers have their
1003 * B_BARRIER flag set, transfer that request to
1004 * the cluster.
1005 */
1006 bp->b_flags |= (tbp->b_flags & B_BARRIER);
1007 tbp->b_flags &= ~(B_DONE | B_BARRIER);
1008 tbp->b_flags |= B_ASYNC;
1009 tbp->b_ioflags &= ~BIO_ERROR;
1010 tbp->b_iocmd = BIO_WRITE;
1011 bundirty(tbp);
1012 reassignbuf(tbp); /* put on clean list */
1013 bufobj_wref(tbp->b_bufobj);
1014 BUF_KERNPROC(tbp);
1015 buf_track(tbp, __func__);
1016 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
1017 tbp, b_cluster.cluster_entry);
1018 }
1019 finishcluster:
1020 if (buf_mapped(bp)) {
1021 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1022 (vm_page_t *)bp->b_pages, bp->b_npages);
1023 }
1024 if (bp->b_bufsize > bp->b_kvasize)
1025 panic(
1026 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
1027 bp->b_bufsize, bp->b_kvasize);
1028 totalwritten += bp->b_bufsize;
1029 bp->b_dirtyoff = 0;
1030 bp->b_dirtyend = bp->b_bufsize;
1031 bawrite(bp);
1032
1033 len -= i;
1034 }
1035 return totalwritten;
1036 }
1037
1038 /*
1039 * Collect together all the buffers in a cluster.
1040 * Plus add one additional buffer.
1041 */
1042 static struct cluster_save *
cluster_collectbufs(struct vnode * vp,struct vn_clusterw * vnc,struct buf * last_bp,int gbflags)1043 cluster_collectbufs(struct vnode *vp, struct vn_clusterw *vnc,
1044 struct buf *last_bp, int gbflags)
1045 {
1046 struct cluster_save *buflist;
1047 struct buf *bp;
1048 daddr_t lbn;
1049 int i, j, len, error;
1050
1051 len = vnc->v_lastw - vnc->v_cstart + 1;
1052 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1053 M_SEGMENT, M_WAITOK);
1054 buflist->bs_nchildren = 0;
1055 buflist->bs_children = (struct buf **) (buflist + 1);
1056 for (lbn = vnc->v_cstart, i = 0; i < len; lbn++, i++) {
1057 error = bread_gb(vp, lbn, last_bp->b_bcount, NOCRED,
1058 gbflags, &bp);
1059 if (error != 0) {
1060 /*
1061 * If read fails, release collected buffers
1062 * and return failure.
1063 */
1064 for (j = 0; j < i; j++)
1065 brelse(buflist->bs_children[j]);
1066 free(buflist, M_SEGMENT);
1067 return (NULL);
1068 }
1069 buflist->bs_children[i] = bp;
1070 if (bp->b_blkno == bp->b_lblkno)
1071 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
1072 NULL, NULL);
1073 }
1074 buflist->bs_children[i] = bp = last_bp;
1075 if (bp->b_blkno == bp->b_lblkno)
1076 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1077 buflist->bs_nchildren = i + 1;
1078 return (buflist);
1079 }
1080
1081 void
cluster_init_vn(struct vn_clusterw * vnc)1082 cluster_init_vn(struct vn_clusterw *vnc)
1083 {
1084 vnc->v_lasta = 0;
1085 vnc->v_clen = 0;
1086 vnc->v_cstart = 0;
1087 vnc->v_lastw = 0;
1088 }
1089