1 /*-
2 * Copyright (c) 1993
3 * The Regents of the University of California. All rights reserved.
4 * Modifications/enhancements:
5 * Copyright (c) 1995 John S. Dyson. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94
36 */
37
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD: releng/5.2/sys/kern/vfs_cluster.c 122537 2003-11-12 08:01:40Z mckusick $");
40
41 #include "opt_debug_cluster.h"
42
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/kernel.h>
46 #include <sys/proc.h>
47 #include <sys/bio.h>
48 #include <sys/buf.h>
49 #include <sys/vnode.h>
50 #include <sys/malloc.h>
51 #include <sys/mount.h>
52 #include <sys/resourcevar.h>
53 #include <sys/vmmeter.h>
54 #include <vm/vm.h>
55 #include <vm/vm_object.h>
56 #include <vm/vm_page.h>
57 #include <sys/sysctl.h>
58
59 #if defined(CLUSTERDEBUG)
60 static int rcluster= 0;
61 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0,
62 "Debug VFS clustering code");
63 #endif
64
65 static MALLOC_DEFINE(M_SEGMENT, "cluster_save buffer", "cluster_save buffer");
66
67 static struct cluster_save *
68 cluster_collectbufs(struct vnode *vp, struct buf *last_bp);
69 static struct buf *
70 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
71 daddr_t blkno, long size, int run, struct buf *fbp);
72
73 static int write_behind = 1;
74 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
75 "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
76
77 static int read_max = 8;
78 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
79 "Cluster read-ahead max block count");
80
81 /* Page expended to mark partially backed buffers */
82 extern vm_page_t bogus_page;
83
84 /*
85 * Number of physical bufs (pbufs) this subsystem is allowed.
86 * Manipulated by vm_pager.c
87 */
88 extern int cluster_pbuf_freecnt;
89
90 /*
91 * Read data to a buf, including read-ahead if we find this to be beneficial.
92 * cluster_read replaces bread.
93 */
94 int
95 cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
96 struct vnode *vp;
97 u_quad_t filesize;
98 daddr_t lblkno;
99 long size;
100 struct ucred *cred;
101 long totread;
102 int seqcount;
103 struct buf **bpp;
104 {
105 struct buf *bp, *rbp, *reqbp;
106 daddr_t blkno, origblkno;
107 int maxra, racluster;
108 int error, ncontig;
109 int i;
110
111 error = 0;
112
113 /*
114 * Try to limit the amount of read-ahead by a few
115 * ad-hoc parameters. This needs work!!!
116 */
117 racluster = vp->v_mount->mnt_iosize_max / size;
118 maxra = seqcount;
119 maxra = min(read_max, maxra);
120 maxra = min(nbuf/8, maxra);
121 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize)
122 maxra = (filesize / size) - lblkno;
123
124 /*
125 * get the requested block
126 */
127 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, 0);
128 origblkno = lblkno;
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 int s;
142 bp->b_flags &= ~B_RAM;
143 /*
144 * We do the spl here so that there is no window
145 * between the incore and the b_usecount increment
146 * below. We opt to keep the spl out of the loop
147 * for efficiency.
148 */
149 s = splbio();
150 VI_LOCK(vp);
151 for (i = 1; i < maxra; i++) {
152 /*
153 * Stop if the buffer does not exist or it
154 * is invalid (about to go away?)
155 */
156 rbp = gbincore(vp, lblkno+i);
157 if (rbp == NULL || (rbp->b_flags & B_INVAL))
158 break;
159
160 /*
161 * Set another read-ahead mark so we know
162 * to check again.
163 */
164 if (((i % racluster) == (racluster - 1)) ||
165 (i == (maxra - 1)))
166 rbp->b_flags |= B_RAM;
167 }
168 VI_UNLOCK(vp);
169 splx(s);
170 if (i >= maxra) {
171 return 0;
172 }
173 lblkno += i;
174 }
175 reqbp = bp = NULL;
176 /*
177 * If it isn't in the cache, then get a chunk from
178 * disk if sequential, otherwise just get the block.
179 */
180 } else {
181 off_t firstread = bp->b_offset;
182 int nblks;
183
184 KASSERT(bp->b_offset != NOOFFSET,
185 ("cluster_read: no buffer offset"));
186
187 ncontig = 0;
188
189 /*
190 * Compute the total number of blocks that we should read
191 * synchronously.
192 */
193 if (firstread + totread > filesize)
194 totread = filesize - firstread;
195 nblks = howmany(totread, size);
196 if (nblks > racluster)
197 nblks = racluster;
198
199 /*
200 * Now compute the number of contiguous blocks.
201 */
202 if (nblks > 1) {
203 error = VOP_BMAP(vp, lblkno, NULL,
204 &blkno, &ncontig, NULL);
205 /*
206 * If this failed to map just do the original block.
207 */
208 if (error || blkno == -1)
209 ncontig = 0;
210 }
211
212 /*
213 * If we have contiguous data available do a cluster
214 * otherwise just read the requested block.
215 */
216 if (ncontig) {
217 /* Account for our first block. */
218 ncontig = min(ncontig + 1, nblks);
219 if (ncontig < nblks)
220 nblks = ncontig;
221 bp = cluster_rbuild(vp, filesize, lblkno,
222 blkno, size, nblks, bp);
223 lblkno += (bp->b_bufsize / size);
224 } else {
225 bp->b_flags |= B_RAM;
226 bp->b_iocmd = BIO_READ;
227 lblkno += 1;
228 }
229 }
230
231 /*
232 * handle the synchronous read so that it is available ASAP.
233 */
234 if (bp) {
235 if ((bp->b_flags & B_CLUSTER) == 0) {
236 vfs_busy_pages(bp, 0);
237 }
238 bp->b_flags &= ~B_INVAL;
239 bp->b_ioflags &= ~BIO_ERROR;
240 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
241 BUF_KERNPROC(bp);
242 bp->b_iooffset = dbtob(bp->b_blkno);
243 error = VOP_STRATEGY(vp, bp);
244 curproc->p_stats->p_ru.ru_inblock++;
245 if (error)
246 return (error);
247 }
248
249 /*
250 * If we have been doing sequential I/O, then do some read-ahead.
251 */
252 while (lblkno < (origblkno + maxra)) {
253 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
254 if (error)
255 break;
256
257 if (blkno == -1)
258 break;
259
260 /*
261 * We could throttle ncontig here by maxra but we might as
262 * well read the data if it is contiguous. We're throttled
263 * by racluster anyway.
264 */
265 if (ncontig) {
266 ncontig = min(ncontig + 1, racluster);
267 rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
268 size, ncontig, NULL);
269 lblkno += (rbp->b_bufsize / size);
270 if (rbp->b_flags & B_DELWRI) {
271 bqrelse(rbp);
272 continue;
273 }
274 } else {
275 rbp = getblk(vp, lblkno, size, 0, 0, 0);
276 lblkno += 1;
277 if (rbp->b_flags & B_DELWRI) {
278 bqrelse(rbp);
279 continue;
280 }
281 rbp->b_flags |= B_ASYNC | B_RAM;
282 rbp->b_iocmd = BIO_READ;
283 rbp->b_blkno = blkno;
284 }
285 if (rbp->b_flags & B_CACHE) {
286 rbp->b_flags &= ~B_ASYNC;
287 bqrelse(rbp);
288 continue;
289 }
290 if ((rbp->b_flags & B_CLUSTER) == 0) {
291 vfs_busy_pages(rbp, 0);
292 }
293 rbp->b_flags &= ~B_INVAL;
294 rbp->b_ioflags &= ~BIO_ERROR;
295 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
296 BUF_KERNPROC(rbp);
297 rbp->b_iooffset = dbtob(rbp->b_blkno);
298 (void) VOP_STRATEGY(vp, rbp);
299 curproc->p_stats->p_ru.ru_inblock++;
300 }
301
302 if (reqbp)
303 return (bufwait(reqbp));
304 else
305 return (error);
306 }
307
308 /*
309 * If blocks are contiguous on disk, use this to provide clustered
310 * read ahead. We will read as many blocks as possible sequentially
311 * and then parcel them up into logical blocks in the buffer hash table.
312 */
313 static struct buf *
314 cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
315 struct vnode *vp;
316 u_quad_t filesize;
317 daddr_t lbn;
318 daddr_t blkno;
319 long size;
320 int run;
321 struct buf *fbp;
322 {
323 struct buf *bp, *tbp;
324 daddr_t bn;
325 int i, inc, j;
326
327 GIANT_REQUIRED;
328
329 KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
330 ("cluster_rbuild: size %ld != filesize %jd\n",
331 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
332
333 /*
334 * avoid a division
335 */
336 while ((u_quad_t) size * (lbn + run) > filesize) {
337 --run;
338 }
339
340 if (fbp) {
341 tbp = fbp;
342 tbp->b_iocmd = BIO_READ;
343 } else {
344 tbp = getblk(vp, lbn, size, 0, 0, 0);
345 if (tbp->b_flags & B_CACHE)
346 return tbp;
347 tbp->b_flags |= B_ASYNC | B_RAM;
348 tbp->b_iocmd = BIO_READ;
349 }
350
351 tbp->b_blkno = blkno;
352 if( (tbp->b_flags & B_MALLOC) ||
353 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
354 return tbp;
355
356 bp = trypbuf(&cluster_pbuf_freecnt);
357 if (bp == 0)
358 return tbp;
359
360 /*
361 * We are synthesizing a buffer out of vm_page_t's, but
362 * if the block size is not page aligned then the starting
363 * address may not be either. Inherit the b_data offset
364 * from the original buffer.
365 */
366 bp->b_data = (char *)((vm_offset_t)bp->b_data |
367 ((vm_offset_t)tbp->b_data & PAGE_MASK));
368 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
369 bp->b_iocmd = BIO_READ;
370 bp->b_iodone = cluster_callback;
371 bp->b_blkno = blkno;
372 bp->b_lblkno = lbn;
373 bp->b_offset = tbp->b_offset;
374 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
375 pbgetvp(vp, bp);
376
377 TAILQ_INIT(&bp->b_cluster.cluster_head);
378
379 bp->b_bcount = 0;
380 bp->b_bufsize = 0;
381 bp->b_npages = 0;
382
383 inc = btodb(size);
384 for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
385 if (i != 0) {
386 if ((bp->b_npages * PAGE_SIZE) +
387 round_page(size) > vp->v_mount->mnt_iosize_max) {
388 break;
389 }
390
391 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT);
392
393 /* Don't wait around for locked bufs. */
394 if (tbp == NULL)
395 break;
396
397 /*
398 * Stop scanning if the buffer is fully valid
399 * (marked B_CACHE), or locked (may be doing a
400 * background write), or if the buffer is not
401 * VMIO backed. The clustering code can only deal
402 * with VMIO-backed buffers.
403 */
404 VI_LOCK(bp->b_vp);
405 if ((tbp->b_vflags & BV_BKGRDINPROG) ||
406 (tbp->b_flags & B_CACHE) ||
407 (tbp->b_flags & B_VMIO) == 0) {
408 VI_UNLOCK(bp->b_vp);
409 bqrelse(tbp);
410 break;
411 }
412 VI_UNLOCK(bp->b_vp);
413
414 /*
415 * The buffer must be completely invalid in order to
416 * take part in the cluster. If it is partially valid
417 * then we stop.
418 */
419 VM_OBJECT_LOCK(tbp->b_object);
420 for (j = 0;j < tbp->b_npages; j++) {
421 VM_OBJECT_LOCK_ASSERT(tbp->b_pages[j]->object,
422 MA_OWNED);
423 if (tbp->b_pages[j]->valid)
424 break;
425 }
426 VM_OBJECT_UNLOCK(tbp->b_object);
427 if (j != tbp->b_npages) {
428 bqrelse(tbp);
429 break;
430 }
431
432 /*
433 * Set a read-ahead mark as appropriate
434 */
435 if ((fbp && (i == 1)) || (i == (run - 1)))
436 tbp->b_flags |= B_RAM;
437
438 /*
439 * Set the buffer up for an async read (XXX should
440 * we do this only if we do not wind up brelse()ing?).
441 * Set the block number if it isn't set, otherwise
442 * if it is make sure it matches the block number we
443 * expect.
444 */
445 tbp->b_flags |= B_ASYNC;
446 tbp->b_iocmd = BIO_READ;
447 if (tbp->b_blkno == tbp->b_lblkno) {
448 tbp->b_blkno = bn;
449 } else if (tbp->b_blkno != bn) {
450 brelse(tbp);
451 break;
452 }
453 }
454 /*
455 * XXX fbp from caller may not be B_ASYNC, but we are going
456 * to biodone() it in cluster_callback() anyway
457 */
458 BUF_KERNPROC(tbp);
459 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
460 tbp, b_cluster.cluster_entry);
461 VM_OBJECT_LOCK(tbp->b_object);
462 vm_page_lock_queues();
463 for (j = 0; j < tbp->b_npages; j += 1) {
464 vm_page_t m;
465 m = tbp->b_pages[j];
466 vm_page_io_start(m);
467 vm_object_pip_add(m->object, 1);
468 if ((bp->b_npages == 0) ||
469 (bp->b_pages[bp->b_npages-1] != m)) {
470 bp->b_pages[bp->b_npages] = m;
471 bp->b_npages++;
472 }
473 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
474 tbp->b_pages[j] = bogus_page;
475 }
476 vm_page_unlock_queues();
477 VM_OBJECT_UNLOCK(tbp->b_object);
478 /*
479 * XXX shouldn't this be += size for both, like in
480 * cluster_wbuild()?
481 *
482 * Don't inherit tbp->b_bufsize as it may be larger due to
483 * a non-page-aligned size. Instead just aggregate using
484 * 'size'.
485 */
486 if (tbp->b_bcount != size)
487 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
488 if (tbp->b_bufsize != size)
489 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
490 bp->b_bcount += size;
491 bp->b_bufsize += size;
492 }
493
494 /*
495 * Fully valid pages in the cluster are already good and do not need
496 * to be re-read from disk. Replace the page with bogus_page
497 */
498 VM_OBJECT_LOCK(bp->b_object);
499 for (j = 0; j < bp->b_npages; j++) {
500 VM_OBJECT_LOCK_ASSERT(bp->b_pages[j]->object, MA_OWNED);
501 if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) ==
502 VM_PAGE_BITS_ALL) {
503 bp->b_pages[j] = bogus_page;
504 }
505 }
506 VM_OBJECT_UNLOCK(bp->b_object);
507 if (bp->b_bufsize > bp->b_kvasize)
508 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
509 bp->b_bufsize, bp->b_kvasize);
510 bp->b_kvasize = bp->b_bufsize;
511
512 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
513 (vm_page_t *)bp->b_pages, bp->b_npages);
514 return (bp);
515 }
516
517 /*
518 * Cleanup after a clustered read or write.
519 * This is complicated by the fact that any of the buffers might have
520 * extra memory (if there were no empty buffer headers at allocbuf time)
521 * that we will need to shift around.
522 */
523 void
524 cluster_callback(bp)
525 struct buf *bp;
526 {
527 struct buf *nbp, *tbp;
528 int error = 0;
529
530 GIANT_REQUIRED;
531
532 /*
533 * Must propogate errors to all the components.
534 */
535 if (bp->b_ioflags & BIO_ERROR)
536 error = bp->b_error;
537
538 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
539 /*
540 * Move memory from the large cluster buffer into the component
541 * buffers and mark IO as done on these.
542 */
543 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
544 tbp; tbp = nbp) {
545 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
546 if (error) {
547 tbp->b_ioflags |= BIO_ERROR;
548 tbp->b_error = error;
549 } else {
550 tbp->b_dirtyoff = tbp->b_dirtyend = 0;
551 tbp->b_flags &= ~B_INVAL;
552 tbp->b_ioflags &= ~BIO_ERROR;
553 /*
554 * XXX the bdwrite()/bqrelse() issued during
555 * cluster building clears B_RELBUF (see bqrelse()
556 * comment). If direct I/O was specified, we have
557 * to restore it here to allow the buffer and VM
558 * to be freed.
559 */
560 if (tbp->b_flags & B_DIRECT)
561 tbp->b_flags |= B_RELBUF;
562 }
563 bufdone(tbp);
564 }
565 relpbuf(bp, &cluster_pbuf_freecnt);
566 }
567
568 /*
569 * cluster_wbuild_wb:
570 *
571 * Implement modified write build for cluster.
572 *
573 * write_behind = 0 write behind disabled
574 * write_behind = 1 write behind normal (default)
575 * write_behind = 2 write behind backed-off
576 */
577
578 static __inline int
579 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len)
580 {
581 int r = 0;
582
583 switch(write_behind) {
584 case 2:
585 if (start_lbn < len)
586 break;
587 start_lbn -= len;
588 /* FALLTHROUGH */
589 case 1:
590 r = cluster_wbuild(vp, size, start_lbn, len);
591 /* FALLTHROUGH */
592 default:
593 /* FALLTHROUGH */
594 break;
595 }
596 return(r);
597 }
598
599 /*
600 * Do clustered write for FFS.
601 *
602 * Three cases:
603 * 1. Write is not sequential (write asynchronously)
604 * Write is sequential:
605 * 2. beginning of cluster - begin cluster
606 * 3. middle of a cluster - add to cluster
607 * 4. end of a cluster - asynchronously write cluster
608 */
609 void
610 cluster_write(bp, filesize, seqcount)
611 struct buf *bp;
612 u_quad_t filesize;
613 int seqcount;
614 {
615 struct vnode *vp;
616 daddr_t lbn;
617 int maxclen, cursize;
618 int lblocksize;
619 int async;
620
621 vp = bp->b_vp;
622 if (vp->v_type == VREG) {
623 async = vp->v_mount->mnt_flag & MNT_ASYNC;
624 lblocksize = vp->v_mount->mnt_stat.f_iosize;
625 } else {
626 async = 0;
627 lblocksize = bp->b_bufsize;
628 }
629 lbn = bp->b_lblkno;
630 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
631
632 /* Initialize vnode to beginning of file. */
633 if (lbn == 0)
634 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
635
636 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
637 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
638 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
639 if (vp->v_clen != 0) {
640 /*
641 * Next block is not sequential.
642 *
643 * If we are not writing at end of file, the process
644 * seeked to another point in the file since its last
645 * write, or we have reached our maximum cluster size,
646 * then push the previous cluster. Otherwise try
647 * reallocating to make it sequential.
648 *
649 * Change to algorithm: only push previous cluster if
650 * it was sequential from the point of view of the
651 * seqcount heuristic, otherwise leave the buffer
652 * intact so we can potentially optimize the I/O
653 * later on in the buf_daemon or update daemon
654 * flush.
655 */
656 cursize = vp->v_lastw - vp->v_cstart + 1;
657 if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
658 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
659 if (!async && seqcount > 0) {
660 cluster_wbuild_wb(vp, lblocksize,
661 vp->v_cstart, cursize);
662 }
663 } else {
664 struct buf **bpp, **endbp;
665 struct cluster_save *buflist;
666
667 buflist = cluster_collectbufs(vp, bp);
668 endbp = &buflist->bs_children
669 [buflist->bs_nchildren - 1];
670 if (VOP_REALLOCBLKS(vp, buflist)) {
671 /*
672 * Failed, push the previous cluster
673 * if *really* writing sequentially
674 * in the logical file (seqcount > 1),
675 * otherwise delay it in the hopes that
676 * the low level disk driver can
677 * optimize the write ordering.
678 */
679 for (bpp = buflist->bs_children;
680 bpp < endbp; bpp++)
681 brelse(*bpp);
682 free(buflist, M_SEGMENT);
683 if (seqcount > 1) {
684 cluster_wbuild_wb(vp,
685 lblocksize, vp->v_cstart,
686 cursize);
687 }
688 } else {
689 /*
690 * Succeeded, keep building cluster.
691 */
692 for (bpp = buflist->bs_children;
693 bpp <= endbp; bpp++)
694 bdwrite(*bpp);
695 free(buflist, M_SEGMENT);
696 vp->v_lastw = lbn;
697 vp->v_lasta = bp->b_blkno;
698 return;
699 }
700 }
701 }
702 /*
703 * Consider beginning a cluster. If at end of file, make
704 * cluster as large as possible, otherwise find size of
705 * existing cluster.
706 */
707 if ((vp->v_type == VREG) &&
708 ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
709 (bp->b_blkno == bp->b_lblkno) &&
710 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
711 bp->b_blkno == -1)) {
712 bawrite(bp);
713 vp->v_clen = 0;
714 vp->v_lasta = bp->b_blkno;
715 vp->v_cstart = lbn + 1;
716 vp->v_lastw = lbn;
717 return;
718 }
719 vp->v_clen = maxclen;
720 if (!async && maxclen == 0) { /* I/O not contiguous */
721 vp->v_cstart = lbn + 1;
722 bawrite(bp);
723 } else { /* Wait for rest of cluster */
724 vp->v_cstart = lbn;
725 bdwrite(bp);
726 }
727 } else if (lbn == vp->v_cstart + vp->v_clen) {
728 /*
729 * At end of cluster, write it out if seqcount tells us we
730 * are operating sequentially, otherwise let the buf or
731 * update daemon handle it.
732 */
733 bdwrite(bp);
734 if (seqcount > 1)
735 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1);
736 vp->v_clen = 0;
737 vp->v_cstart = lbn + 1;
738 } else if (vm_page_count_severe()) {
739 /*
740 * We are low on memory, get it going NOW
741 */
742 bawrite(bp);
743 } else {
744 /*
745 * In the middle of a cluster, so just delay the I/O for now.
746 */
747 bdwrite(bp);
748 }
749 vp->v_lastw = lbn;
750 vp->v_lasta = bp->b_blkno;
751 }
752
753
754 /*
755 * This is an awful lot like cluster_rbuild...wish they could be combined.
756 * The last lbn argument is the current block on which I/O is being
757 * performed. Check to see that it doesn't fall in the middle of
758 * the current block (if last_bp == NULL).
759 */
760 int
761 cluster_wbuild(vp, size, start_lbn, len)
762 struct vnode *vp;
763 long size;
764 daddr_t start_lbn;
765 int len;
766 {
767 struct buf *bp, *tbp;
768 int i, j, s;
769 int totalwritten = 0;
770 int dbsize = btodb(size);
771
772 GIANT_REQUIRED;
773
774 while (len > 0) {
775 s = splbio();
776 /*
777 * If the buffer is not delayed-write (i.e. dirty), or it
778 * is delayed-write but either locked or inval, it cannot
779 * partake in the clustered write.
780 */
781 VI_LOCK(vp);
782 if ((tbp = gbincore(vp, start_lbn)) == NULL ||
783 (tbp->b_vflags & BV_BKGRDINPROG)) {
784 VI_UNLOCK(vp);
785 ++start_lbn;
786 --len;
787 splx(s);
788 continue;
789 }
790 if (BUF_LOCK(tbp,
791 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, VI_MTX(vp))) {
792 ++start_lbn;
793 --len;
794 splx(s);
795 continue;
796 }
797 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
798 BUF_UNLOCK(tbp);
799 ++start_lbn;
800 --len;
801 splx(s);
802 continue;
803 }
804 bremfree(tbp);
805 tbp->b_flags &= ~B_DONE;
806 splx(s);
807
808 /*
809 * Extra memory in the buffer, punt on this buffer.
810 * XXX we could handle this in most cases, but we would
811 * have to push the extra memory down to after our max
812 * possible cluster size and then potentially pull it back
813 * up if the cluster was terminated prematurely--too much
814 * hassle.
815 */
816 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
817 (B_CLUSTEROK | B_VMIO)) ||
818 (tbp->b_bcount != tbp->b_bufsize) ||
819 (tbp->b_bcount != size) ||
820 (len == 1) ||
821 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
822 totalwritten += tbp->b_bufsize;
823 bawrite(tbp);
824 ++start_lbn;
825 --len;
826 continue;
827 }
828
829 /*
830 * We got a pbuf to make the cluster in.
831 * so initialise it.
832 */
833 TAILQ_INIT(&bp->b_cluster.cluster_head);
834 bp->b_bcount = 0;
835 bp->b_magic = tbp->b_magic;
836 bp->b_op = tbp->b_op;
837 bp->b_bufsize = 0;
838 bp->b_npages = 0;
839 if (tbp->b_wcred != NOCRED)
840 bp->b_wcred = crhold(tbp->b_wcred);
841
842 bp->b_blkno = tbp->b_blkno;
843 bp->b_lblkno = tbp->b_lblkno;
844 bp->b_offset = tbp->b_offset;
845
846 /*
847 * We are synthesizing a buffer out of vm_page_t's, but
848 * if the block size is not page aligned then the starting
849 * address may not be either. Inherit the b_data offset
850 * from the original buffer.
851 */
852 bp->b_data = (char *)((vm_offset_t)bp->b_data |
853 ((vm_offset_t)tbp->b_data & PAGE_MASK));
854 bp->b_flags |= B_CLUSTER |
855 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
856 bp->b_iodone = cluster_callback;
857 pbgetvp(vp, bp);
858 /*
859 * From this location in the file, scan forward to see
860 * if there are buffers with adjacent data that need to
861 * be written as well.
862 */
863 for (i = 0; i < len; ++i, ++start_lbn) {
864 if (i != 0) { /* If not the first buffer */
865 s = splbio();
866 /*
867 * If the adjacent data is not even in core it
868 * can't need to be written.
869 */
870 VI_LOCK(vp);
871 if ((tbp = gbincore(vp, start_lbn)) == NULL ||
872 (tbp->b_vflags & BV_BKGRDINPROG)) {
873 VI_UNLOCK(vp);
874 splx(s);
875 break;
876 }
877
878 /*
879 * If it IS in core, but has different
880 * characteristics, or is locked (which
881 * means it could be undergoing a background
882 * I/O or be in a weird state), then don't
883 * cluster with it.
884 */
885 if (BUF_LOCK(tbp,
886 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
887 VI_MTX(vp))) {
888 splx(s);
889 break;
890 }
891
892 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
893 B_INVAL | B_DELWRI | B_NEEDCOMMIT))
894 != (B_DELWRI | B_CLUSTEROK |
895 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
896 tbp->b_wcred != bp->b_wcred) {
897 BUF_UNLOCK(tbp);
898 splx(s);
899 break;
900 }
901
902 /*
903 * Check that the combined cluster
904 * would make sense with regard to pages
905 * and would not be too large
906 */
907 if ((tbp->b_bcount != size) ||
908 ((bp->b_blkno + (dbsize * i)) !=
909 tbp->b_blkno) ||
910 ((tbp->b_npages + bp->b_npages) >
911 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
912 BUF_UNLOCK(tbp);
913 splx(s);
914 break;
915 }
916 /*
917 * Ok, it's passed all the tests,
918 * so remove it from the free list
919 * and mark it busy. We will use it.
920 */
921 bremfree(tbp);
922 tbp->b_flags &= ~B_DONE;
923 splx(s);
924 } /* end of code for non-first buffers only */
925 /* check for latent dependencies to be handled */
926 if ((LIST_FIRST(&tbp->b_dep)) != NULL) {
927 tbp->b_iocmd = BIO_WRITE;
928 buf_start(tbp);
929 }
930 /*
931 * If the IO is via the VM then we do some
932 * special VM hackery (yuck). Since the buffer's
933 * block size may not be page-aligned it is possible
934 * for a page to be shared between two buffers. We
935 * have to get rid of the duplication when building
936 * the cluster.
937 */
938 if (tbp->b_flags & B_VMIO) {
939 vm_page_t m;
940
941 if (i != 0) { /* if not first buffer */
942 for (j = 0; j < tbp->b_npages; j += 1) {
943 m = tbp->b_pages[j];
944 if (m->flags & PG_BUSY) {
945 bqrelse(tbp);
946 goto finishcluster;
947 }
948 }
949 }
950 if (tbp->b_object != NULL)
951 VM_OBJECT_LOCK(tbp->b_object);
952 vm_page_lock_queues();
953 for (j = 0; j < tbp->b_npages; j += 1) {
954 m = tbp->b_pages[j];
955 vm_page_io_start(m);
956 vm_object_pip_add(m->object, 1);
957 if ((bp->b_npages == 0) ||
958 (bp->b_pages[bp->b_npages - 1] != m)) {
959 bp->b_pages[bp->b_npages] = m;
960 bp->b_npages++;
961 }
962 }
963 vm_page_unlock_queues();
964 if (tbp->b_object != NULL)
965 VM_OBJECT_UNLOCK(tbp->b_object);
966 }
967 bp->b_bcount += size;
968 bp->b_bufsize += size;
969
970 s = splbio();
971 bundirty(tbp);
972 tbp->b_flags &= ~B_DONE;
973 tbp->b_ioflags &= ~BIO_ERROR;
974 tbp->b_flags |= B_ASYNC;
975 tbp->b_iocmd = BIO_WRITE;
976 reassignbuf(tbp, tbp->b_vp); /* put on clean list */
977 VI_LOCK(tbp->b_vp);
978 ++tbp->b_vp->v_numoutput;
979 VI_UNLOCK(tbp->b_vp);
980 splx(s);
981 BUF_KERNPROC(tbp);
982 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
983 tbp, b_cluster.cluster_entry);
984 }
985 finishcluster:
986 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
987 (vm_page_t *) bp->b_pages, bp->b_npages);
988 if (bp->b_bufsize > bp->b_kvasize)
989 panic(
990 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
991 bp->b_bufsize, bp->b_kvasize);
992 bp->b_kvasize = bp->b_bufsize;
993 totalwritten += bp->b_bufsize;
994 bp->b_dirtyoff = 0;
995 bp->b_dirtyend = bp->b_bufsize;
996 bawrite(bp);
997
998 len -= i;
999 }
1000 return totalwritten;
1001 }
1002
1003 /*
1004 * Collect together all the buffers in a cluster.
1005 * Plus add one additional buffer.
1006 */
1007 static struct cluster_save *
1008 cluster_collectbufs(vp, last_bp)
1009 struct vnode *vp;
1010 struct buf *last_bp;
1011 {
1012 struct cluster_save *buflist;
1013 struct buf *bp;
1014 daddr_t lbn;
1015 int i, len;
1016
1017 len = vp->v_lastw - vp->v_cstart + 1;
1018 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1019 M_SEGMENT, M_WAITOK);
1020 buflist->bs_nchildren = 0;
1021 buflist->bs_children = (struct buf **) (buflist + 1);
1022 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1023 (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp);
1024 buflist->bs_children[i] = bp;
1025 if (bp->b_blkno == bp->b_lblkno)
1026 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno,
1027 NULL, NULL);
1028 }
1029 buflist->bs_children[i] = bp = last_bp;
1030 if (bp->b_blkno == bp->b_lblkno)
1031 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno,
1032 NULL, NULL);
1033 buflist->bs_nchildren = i + 1;
1034 return (buflist);
1035 }
Cache object: edb6e3c4a0d79b8c519be2893ef3af28
|