summaryrefslogtreecommitdiffstats
path: root/sys/kern/vfs_cluster.c
blob: 3d82c5e95a493e03b63a7eed9e5bad732e7664ef (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
/*-
 * Copyright (c) 1993
 *	The Regents of the University of California.  All rights reserved.
 * Modifications/enhancements:
 * 	Copyright (c) 1995 John S. Dyson.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)vfs_cluster.c	8.7 (Berkeley) 2/13/94
 * $Id: vfs_cluster.c,v 1.49 1997/11/07 08:53:05 phk Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/resourcevar.h>
#include <vm/vm.h>
#include <vm/vm_prot.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>

#if defined(CLUSTERDEBUG)
#include <sys/sysctl.h>
#include <sys/kernel.h>
static int	rcluster= 0;
SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
#endif

#ifdef notyet_block_reallocation_enabled
static struct cluster_save *
	cluster_collectbufs __P((struct vnode *vp, struct buf *last_bp));
#endif
static struct buf *
	cluster_rbuild __P((struct vnode *vp, u_quad_t filesize, daddr_t lbn,
			    daddr_t blkno, long size, int run, struct buf *fbp));

extern vm_page_t	bogus_page;

/*
 * Maximum number of blocks for read-ahead.
 */
#define MAXRA 32

/*
 * This replaces bread.
 */
int
cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
	struct vnode *vp;
	u_quad_t filesize;
	daddr_t lblkno;
	long size;
	struct ucred *cred;
	long totread;
	int seqcount;
	struct buf **bpp;
{
	struct buf *bp, *rbp, *reqbp;
	daddr_t blkno, origblkno;
	int error, num_ra;
	int i;
	int maxra, racluster;
	long origtotread;

	error = 0;

	/*
	 * Try to limit the amount of read-ahead by a few
	 * ad-hoc parameters.  This needs work!!!
	 */
	racluster = MAXPHYS/size;
	maxra = 2 * racluster + (totread / size);
	if (maxra > MAXRA)
		maxra = MAXRA;
	if (maxra > nbuf/8)
		maxra = nbuf/8;

	/*
	 * get the requested block
	 */
	*bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0);
	origblkno = lblkno;
	origtotread = totread;

	/*
	 * if it is in the cache, then check to see if the reads have been
	 * sequential.  If they have, then try some read-ahead, otherwise
	 * back-off on prospective read-aheads.
	 */
	if (bp->b_flags & B_CACHE) {
		if (!seqcount) {
			return 0;
		} else if ((bp->b_flags & B_RAM) == 0) {
			return 0;
		} else {
			int s;
			struct buf *tbp;
			bp->b_flags &= ~B_RAM;
			/*
			 * We do the spl here so that there is no window
			 * between the incore and the b_usecount increment
			 * below.  We opt to keep the spl out of the loop
			 * for efficiency.
			 */
			s = splbio();
			for(i=1;i<maxra;i++) {

				if (!(tbp = incore(vp, lblkno+i))) {
					break;
				}

				/*
				 * Set another read-ahead mark so we know to check
				 * again.
				 */
				if (((i % racluster) == (racluster - 1)) ||
					(i == (maxra - 1)))
					tbp->b_flags |= B_RAM;

#if 0
				if (tbp->b_usecount == 0) {
					/*
					 * Make sure that the soon-to-be used readaheads
					 * are still there.  The getblk/bqrelse pair will
					 * boost the priority of the buffer.
					 */
					tbp = getblk(vp, lblkno+i, size, 0, 0);
					bqrelse(tbp);
				}
#endif
			}
			splx(s);
			if (i >= maxra) {
				return 0;
			}
			lblkno += i;
		}
		reqbp = bp = NULL;
	} else {
		u_quad_t firstread;
		firstread = (u_quad_t) lblkno * size;
		if (firstread + totread > filesize)
			totread = filesize - firstread;
		if (totread > size) {
			int nblks = 0;
			int ncontigafter;
			while (totread > 0) {
				nblks++;
				totread -= size;
			}
			if (nblks == 1)
				goto single_block_read;
			if (nblks > racluster)
				nblks = racluster;

	    		error = VOP_BMAP(vp, lblkno, NULL,
				&blkno, &ncontigafter, NULL);
			if (error)
				goto single_block_read;
			if (blkno == -1)
				goto single_block_read;
			if (ncontigafter == 0)
				goto single_block_read;
			if (ncontigafter + 1 < nblks)
				nblks = ncontigafter + 1;

			bp = cluster_rbuild(vp, filesize, lblkno,
				blkno, size, nblks, bp);
			lblkno += nblks;
		} else {
single_block_read:
			/*
			 * if it isn't in the cache, then get a chunk from
			 * disk if sequential, otherwise just get the block.
			 */
			bp->b_flags |= B_READ | B_RAM;
			lblkno += 1;
		}
	}

	/*
	 * if we have been doing sequential I/O, then do some read-ahead
	 */
	rbp = NULL;
	/* if (seqcount && (lblkno < (origblkno + maxra))) { */
	if (seqcount && (lblkno < (origblkno + seqcount))) {
		/*
		 * we now build the read-ahead buffer if it is desirable.
		 */
		if (((u_quad_t)(lblkno + 1) * size) <= filesize &&
		    !(error = VOP_BMAP(vp, lblkno, NULL, &blkno, &num_ra, NULL)) &&
		    blkno != -1) {
			int nblksread;
			int ntoread = num_ra + 1;
			nblksread = (origtotread + size - 1) / size;
			if (seqcount < nblksread)
				seqcount = nblksread;
			if (seqcount < ntoread)
				ntoread = seqcount;
			if (num_ra) {
				rbp = cluster_rbuild(vp, filesize, lblkno,
					blkno, size, ntoread, NULL);
			} else {
				rbp = getblk(vp, lblkno, size, 0, 0);
				rbp->b_flags |= B_READ | B_ASYNC | B_RAM;
				rbp->b_blkno = blkno;
			}
		}
	}

	/*
	 * handle the synchronous read
	 */
	if (bp) {
		if (bp->b_flags & (B_DONE | B_DELWRI)) {
			panic("cluster_read: DONE bp");
		} else {
#if defined(CLUSTERDEBUG)
			if (rcluster)
				printf("S(%d,%d,%d) ",
					bp->b_lblkno, bp->b_bcount, seqcount);
#endif
			if ((bp->b_flags & B_CLUSTER) == 0)
				vfs_busy_pages(bp, 0);
			error = VOP_STRATEGY(bp);
			curproc->p_stats->p_ru.ru_inblock++;
		}
	}
	/*
	 * and if we have read-aheads, do them too
	 */
	if (rbp) {
		if (error) {
			rbp->b_flags &= ~(B_ASYNC | B_READ);
			brelse(rbp);
		} else if (rbp->b_flags & B_CACHE) {
			rbp->b_flags &= ~(B_ASYNC | B_READ);
			bqrelse(rbp);
		} else {
#if defined(CLUSTERDEBUG)
			if (rcluster) {
				if (bp)
					printf("A+(%d,%d,%d,%d) ",
					rbp->b_lblkno, rbp->b_bcount,
					rbp->b_lblkno - origblkno,
					seqcount);
				else
					printf("A(%d,%d,%d,%d) ",
					rbp->b_lblkno, rbp->b_bcount,
					rbp->b_lblkno - origblkno,
					seqcount);
			}
#endif

			if ((rbp->b_flags & B_CLUSTER) == 0)
				vfs_busy_pages(rbp, 0);
			(void) VOP_STRATEGY(rbp);
			curproc->p_stats->p_ru.ru_inblock++;
		}
	}
	if (reqbp)
		return (biowait(reqbp));
	else
		return (error);
}

/*
 * If blocks are contiguous on disk, use this to provide clustered
 * read ahead.  We will read as many blocks as possible sequentially
 * and then parcel them up into logical blocks in the buffer hash table.
 */
static struct buf *
cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
	struct vnode *vp;
	u_quad_t filesize;
	daddr_t lbn;
	daddr_t blkno;
	long size;
	int run;
	struct buf *fbp;
{
	struct buf *bp, *tbp;
	daddr_t bn;
	int i, inc, j;

#ifdef DIAGNOSTIC
	if (size != vp->v_mount->mnt_stat.f_iosize)
		panic("cluster_rbuild: size %d != filesize %d\n",
		    size, vp->v_mount->mnt_stat.f_iosize);
#endif
	/*
	 * avoid a division
	 */
	while ((u_quad_t) size * (lbn + run) > filesize) {
		--run;
	}

	if (fbp) {
		tbp = fbp;
		tbp->b_flags |= B_READ; 
	} else {
		tbp = getblk(vp, lbn, size, 0, 0);
		if (tbp->b_flags & B_CACHE)
			return tbp;
		tbp->b_flags |= B_ASYNC | B_READ | B_RAM;
	}

	tbp->b_blkno = blkno;
	if( (tbp->b_flags & B_MALLOC) ||
		((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
		return tbp;

	bp = trypbuf();
	if (bp == 0)
		return tbp;

	(vm_offset_t) bp->b_data |= ((vm_offset_t) tbp->b_data) & PAGE_MASK;
	bp->b_flags = B_ASYNC | B_READ | B_CALL | B_BUSY | B_CLUSTER | B_VMIO;
	bp->b_iodone = cluster_callback;
	bp->b_blkno = blkno;
	bp->b_lblkno = lbn;
	pbgetvp(vp, bp);

	TAILQ_INIT(&bp->b_cluster.cluster_head);

	bp->b_bcount = 0;
	bp->b_bufsize = 0;
	bp->b_npages = 0;

	inc = btodb(size);
	for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
		if (i != 0) {
			if ((bp->b_npages * PAGE_SIZE) +
				round_page(size) > MAXPHYS)
				break;

			if (incore(vp, lbn + i))
				break;

			tbp = getblk(vp, lbn + i, size, 0, 0);

			if ((tbp->b_flags & B_CACHE) ||
				(tbp->b_flags & B_VMIO) == 0) {
				bqrelse(tbp);
				break;
			}

			for (j=0;j<tbp->b_npages;j++) {
				if (tbp->b_pages[j]->valid) {
					break;
				}
			}

			if (j != tbp->b_npages) {
				/*
				 * force buffer to be re-constituted later
				 */
				tbp->b_flags |= B_RELBUF;
				brelse(tbp);
				break;
			}

			if ((fbp && (i == 1)) || (i == (run - 1)))
				tbp->b_flags |= B_RAM;
			tbp->b_flags |= B_READ | B_ASYNC;
			if (tbp->b_blkno == tbp->b_lblkno) {
				tbp->b_blkno = bn;
			} else if (tbp->b_blkno != bn) {
				brelse(tbp);
				break;
			}
		}
		TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
			tbp, b_cluster.cluster_entry);
		for (j = 0; j < tbp->b_npages; j += 1) {
			vm_page_t m;
			m = tbp->b_pages[j];
			++m->busy;
			++m->object->paging_in_progress;
			if ((bp->b_npages == 0) ||
				(bp->b_pages[bp->b_npages-1] != m)) {
				bp->b_pages[bp->b_npages] = m;
				bp->b_npages++;
			}
			if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
				tbp->b_pages[j] = bogus_page;
		}
		bp->b_bcount += tbp->b_bcount;
		bp->b_bufsize += tbp->b_bufsize;
	}

	for(j=0;j<bp->b_npages;j++) {
		if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) ==
			VM_PAGE_BITS_ALL)
			bp->b_pages[j] = bogus_page;
	}
	if (bp->b_bufsize > bp->b_kvasize)
		panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)\n",
			bp->b_bufsize, bp->b_kvasize);
	bp->b_kvasize = bp->b_bufsize;

	pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
		(vm_page_t *)bp->b_pages, bp->b_npages);
	return (bp);
}

/*
 * Cleanup after a clustered read or write.
 * This is complicated by the fact that any of the buffers might have
 * extra memory (if there were no empty buffer headers at allocbuf time)
 * that we will need to shift around.
 */
void
cluster_callback(bp)
	struct buf *bp;
{
	struct buf *nbp, *tbp;
	int error = 0;

	/*
	 * Must propogate errors to all the components.
	 */
	if (bp->b_flags & B_ERROR)
		error = bp->b_error;

	pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
	/*
	 * Move memory from the large cluster buffer into the component
	 * buffers and mark IO as done on these.
	 */
	for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
		tbp; tbp = nbp) {
		nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
		if (error) {
			tbp->b_flags |= B_ERROR;
			tbp->b_error = error;
		} else
		    tbp->b_dirtyoff = tbp->b_dirtyend = 0;
		biodone(tbp);
	}
	relpbuf(bp);
}

/*
 * Do clustered write for FFS.
 *
 * Three cases:
 *	1. Write is not sequential (write asynchronously)
 *	Write is sequential:
 *	2.	beginning of cluster - begin cluster
 *	3.	middle of a cluster - add to cluster
 *	4.	end of a cluster - asynchronously write cluster
 */
void
cluster_write(bp, filesize)
	struct buf *bp;
	u_quad_t filesize;
{
	struct vnode *vp;
	daddr_t lbn;
	int maxclen, cursize;
	int lblocksize;
	int async;

	vp = bp->b_vp;
	if (vp->v_type == VREG) {
		async = vp->v_mount->mnt_flag & MNT_ASYNC;
		lblocksize = vp->v_mount->mnt_stat.f_iosize;
	} else {
		async = 0;
		lblocksize = bp->b_bufsize;
	}
	lbn = bp->b_lblkno;

	/* Initialize vnode to beginning of file. */
	if (lbn == 0)
		vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;

	if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
	    (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
		maxclen = MAXPHYS / lblocksize - 1;
		if (vp->v_clen != 0) {
			/*
			 * Next block is not sequential.
			 *
			 * If we are not writing at end of file, the process
			 * seeked to another point in the file since its last
			 * write, or we have reached our maximum cluster size,
			 * then push the previous cluster. Otherwise try
			 * reallocating to make it sequential.
			 */
			cursize = vp->v_lastw - vp->v_cstart + 1;
#ifndef notyet_block_reallocation_enabled
			if (((u_quad_t)(lbn + 1) * lblocksize) != filesize ||
				lbn != vp->v_lastw + 1 ||
				vp->v_clen <= cursize) {
				if (!async)
					cluster_wbuild(vp, lblocksize,
						vp->v_cstart, cursize);
			}
#else
			if ((lbn + 1) * lblocksize != filesize ||
			    lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
				if (!async)
					cluster_wbuild(vp, lblocksize,
						vp->v_cstart, cursize);
			} else {
				struct buf **bpp, **endbp;
				struct cluster_save *buflist;

				buflist = cluster_collectbufs(vp, bp);
				endbp = &buflist->bs_children
				    [buflist->bs_nchildren - 1];
				if (VOP_REALLOCBLKS(vp, buflist)) {
					/*
					 * Failed, push the previous cluster.
					 */
					for (bpp = buflist->bs_children;
					     bpp < endbp; bpp++)
						brelse(*bpp);
					free(buflist, M_SEGMENT);
					cluster_wbuild(vp, lblocksize,
					    vp->v_cstart, cursize);
				} else {
					/*
					 * Succeeded, keep building cluster.
					 */
					for (bpp = buflist->bs_children;
					     bpp <= endbp; bpp++)
						bdwrite(*bpp);
					free(buflist, M_SEGMENT);
					vp->v_lastw = lbn;
					vp->v_lasta = bp->b_blkno;
					return;
				}
			}
#endif /* notyet_block_reallocation_enabled */
		}
		/*
		 * Consider beginning a cluster. If at end of file, make
		 * cluster as large as possible, otherwise find size of
		 * existing cluster.
		 */
		if ((vp->v_type == VREG) &&
			((u_quad_t) (lbn + 1) * lblocksize) != filesize &&
		    (bp->b_blkno == bp->b_lblkno) &&
		    (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
		     bp->b_blkno == -1)) {
			bawrite(bp);
			vp->v_clen = 0;
			vp->v_lasta = bp->b_blkno;
			vp->v_cstart = lbn + 1;
			vp->v_lastw = lbn;
			return;
		}
		vp->v_clen = maxclen;
		if (!async && maxclen == 0) {	/* I/O not contiguous */
			vp->v_cstart = lbn + 1;
			bawrite(bp);
		} else {	/* Wait for rest of cluster */
			vp->v_cstart = lbn;
			bdwrite(bp);
		}
	} else if (lbn == vp->v_cstart + vp->v_clen) {
		/*
		 * At end of cluster, write it out.
		 */
		bdwrite(bp);
		cluster_wbuild(vp, lblocksize, vp->v_cstart, vp->v_clen + 1);
		vp->v_clen = 0;
		vp->v_cstart = lbn + 1;
	} else
		/*
		 * In the middle of a cluster, so just delay the I/O for now.
		 */
		bdwrite(bp);
	vp->v_lastw = lbn;
	vp->v_lasta = bp->b_blkno;
}


/*
 * This is an awful lot like cluster_rbuild...wish they could be combined.
 * The last lbn argument is the current block on which I/O is being
 * performed.  Check to see that it doesn't fall in the middle of
 * the current block (if last_bp == NULL).
 */
int
cluster_wbuild(vp, size, start_lbn, len)
	struct vnode *vp;
	long size;
	daddr_t start_lbn;
	int len;
{
	struct buf *bp, *tbp;
	int i, j, s;
	int totalwritten = 0;
	int dbsize = btodb(size);
	while (len > 0) {
		s = splbio();
		if (((tbp = gbincore(vp, start_lbn)) == NULL) ||
			((tbp->b_flags & (B_INVAL|B_BUSY|B_DELWRI)) != B_DELWRI)) {
			++start_lbn;
			--len;
			splx(s);
			continue;
		}
		bremfree(tbp);
		tbp->b_flags |= B_BUSY;
		tbp->b_flags &= ~B_DONE;
		splx(s);

	/*
	 * Extra memory in the buffer, punt on this buffer. XXX we could
	 * handle this in most cases, but we would have to push the extra
	 * memory down to after our max possible cluster size and then
	 * potentially pull it back up if the cluster was terminated
	 * prematurely--too much hassle.
	 */
		if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
			(tbp->b_bcount != tbp->b_bufsize) ||
			(tbp->b_bcount != size) ||
			len == 1) {
			totalwritten += tbp->b_bufsize;
			bawrite(tbp);
			++start_lbn;
			--len;
			continue;
		}

		bp = trypbuf();
		if (bp == NULL) {
			totalwritten += tbp->b_bufsize;
			bawrite(tbp);
			++start_lbn;
			--len;
			continue;
		}

		TAILQ_INIT(&bp->b_cluster.cluster_head);
		bp->b_bcount = 0;
		bp->b_bufsize = 0;
		bp->b_npages = 0;
		if (tbp->b_wcred != NOCRED) {
		    bp->b_wcred = tbp->b_wcred;
		    crhold(bp->b_wcred);
		}

		bp->b_blkno = tbp->b_blkno;
		bp->b_lblkno = tbp->b_lblkno;
		(vm_offset_t) bp->b_data |= ((vm_offset_t) tbp->b_data) & PAGE_MASK;
		bp->b_flags |= B_CALL | B_BUSY | B_CLUSTER |
						(tbp->b_flags & (B_VMIO|B_NEEDCOMMIT));
		bp->b_iodone = cluster_callback;
		pbgetvp(vp, bp);

		for (i = 0; i < len; ++i, ++start_lbn) {
			if (i != 0) {
				s = splbio();
				if ((tbp = gbincore(vp, start_lbn)) == NULL) {
					splx(s);
					break;
				}

				if ((tbp->b_flags & (B_VMIO|B_CLUSTEROK|B_INVAL|B_BUSY|B_DELWRI|B_NEEDCOMMIT)) != (B_DELWRI|B_CLUSTEROK|(bp->b_flags & (B_VMIO|B_NEEDCOMMIT)))) {
					splx(s);
					break;
				}

				if (tbp->b_wcred != bp->b_wcred) {
					splx(s);
					break;
				}

				if ((tbp->b_bcount != size) ||
					((bp->b_blkno + dbsize * i) != tbp->b_blkno) ||
					((tbp->b_npages + bp->b_npages) > (MAXPHYS / PAGE_SIZE))) {
					splx(s);
					break;
				}
				bremfree(tbp);
				tbp->b_flags |= B_BUSY;
				tbp->b_flags &= ~B_DONE;
				splx(s);
			}
			if (tbp->b_flags & B_VMIO) {
				for (j = 0; j < tbp->b_npages; j += 1) {
					vm_page_t m;
					m = tbp->b_pages[j];
					++m->busy;
					++m->object->paging_in_progress;
					if ((bp->b_npages == 0) ||
						(bp->b_pages[bp->b_npages - 1] != m)) {
						bp->b_pages[bp->b_npages] = m;
						bp->b_npages++;
					}
				}
			}
			bp->b_bcount += size;
			bp->b_bufsize += size;

			--numdirtybuffers;
			tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI);
			tbp->b_flags |= B_ASYNC;
			s = splbio();
			reassignbuf(tbp, tbp->b_vp);	/* put on clean list */
			++tbp->b_vp->v_numoutput;
			splx(s);
			TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
				tbp, b_cluster.cluster_entry);
		}
		pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
			(vm_page_t *) bp->b_pages, bp->b_npages);
		if (bp->b_bufsize > bp->b_kvasize)
			panic("cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
				bp->b_bufsize, bp->b_kvasize);
		bp->b_kvasize = bp->b_bufsize;
		totalwritten += bp->b_bufsize;
		bp->b_dirtyoff = 0;
		bp->b_dirtyend = bp->b_bufsize;
		bawrite(bp);

		len -= i;
	}
	return totalwritten;
}

#ifdef notyet_block_reallocation_enabled
/*
 * Collect together all the buffers in a cluster.
 * Plus add one additional buffer.
 */
static struct cluster_save *
cluster_collectbufs(vp, last_bp)
	struct vnode *vp;
	struct buf *last_bp;
{
	struct cluster_save *buflist;
	daddr_t lbn;
	int i, len;

	len = vp->v_lastw - vp->v_cstart + 1;
	buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
	    M_SEGMENT, M_WAITOK);
	buflist->bs_nchildren = 0;
	buflist->bs_children = (struct buf **) (buflist + 1);
	for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++)
		(void) bread(vp, lbn, last_bp->b_bcount, NOCRED,
		    &buflist->bs_children[i]);
	buflist->bs_children[i] = last_bp;
	buflist->bs_nchildren = i + 1;
	return (buflist);
}
#endif /* notyet_block_reallocation_enabled */
OpenPOWER on IntegriCloud