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 * 4. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include "opt_debug_cluster.h"
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/kernel.h>
42 #include <sys/proc.h>
43 #include <sys/bio.h>
44 #include <sys/buf.h>
45 #include <sys/vnode.h>
46 #include <sys/malloc.h>
47 #include <sys/mount.h>
48 #include <sys/resourcevar.h>
49 #include <sys/rwlock.h>
50 #include <sys/vmmeter.h>
51 #include <vm/vm.h>
52 #include <vm/vm_object.h>
53 #include <vm/vm_page.h>
54 #include <sys/sysctl.h>
55
56 #if defined(CLUSTERDEBUG)
57 static int rcluster= 0;
58 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0,
59 "Debug VFS clustering code");
60 #endif
61
62 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer");
63
64 static struct cluster_save *cluster_collectbufs(struct vnode *vp,
65 struct buf *last_bp, int gbflags);
66 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize,
67 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags,
68 struct buf *fbp);
69 static void cluster_callback(struct buf *);
70
71 static int write_behind = 1;
72 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
73 "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
74
75 static int read_max = 64;
76 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
77 "Cluster read-ahead max block count");
78
79 static int read_min = 1;
80 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0,
81 "Cluster read min block count");
82
83 /* Page expended to mark partially backed buffers */
84 extern vm_page_t bogus_page;
85
86 /*
87 * Read data to a buf, including read-ahead if we find this to be beneficial.
88 * cluster_read replaces bread.
89 */
90 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)91 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size,
92 struct ucred *cred, long totread, int seqcount, int gbflags,
93 struct buf **bpp)
94 {
95 struct buf *bp, *rbp, *reqbp;
96 struct bufobj *bo;
97 daddr_t blkno, origblkno;
98 int maxra, racluster;
99 int error, ncontig;
100 int i;
101
102 error = 0;
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 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, gbflags);
122 origblkno = lblkno;
123
124 /*
125 * if it is in the cache, then check to see if the reads have been
126 * sequential. If they have, then try some read-ahead, otherwise
127 * back-off on prospective read-aheads.
128 */
129 if (bp->b_flags & B_CACHE) {
130 if (!seqcount) {
131 return 0;
132 } else if ((bp->b_flags & B_RAM) == 0) {
133 return 0;
134 } else {
135 bp->b_flags &= ~B_RAM;
136 BO_RLOCK(bo);
137 for (i = 1; i < maxra; i++) {
138 /*
139 * Stop if the buffer does not exist or it
140 * is invalid (about to go away?)
141 */
142 rbp = gbincore(&vp->v_bufobj, lblkno+i);
143 if (rbp == NULL || (rbp->b_flags & B_INVAL))
144 break;
145
146 /*
147 * Set another read-ahead mark so we know
148 * to check again. (If we can lock the
149 * buffer without waiting)
150 */
151 if ((((i % racluster) == (racluster - 1)) ||
152 (i == (maxra - 1)))
153 && (0 == BUF_LOCK(rbp,
154 LK_EXCLUSIVE | LK_NOWAIT, NULL))) {
155 rbp->b_flags |= B_RAM;
156 BUF_UNLOCK(rbp);
157 }
158 }
159 BO_RUNLOCK(bo);
160 if (i >= maxra) {
161 return 0;
162 }
163 lblkno += i;
164 }
165 reqbp = bp = NULL;
166 /*
167 * If it isn't in the cache, then get a chunk from
168 * disk if sequential, otherwise just get the block.
169 */
170 } else {
171 off_t firstread = bp->b_offset;
172 int nblks;
173 long minread;
174
175 KASSERT(bp->b_offset != NOOFFSET,
176 ("cluster_read: no buffer offset"));
177
178 ncontig = 0;
179
180 /*
181 * Adjust totread if needed
182 */
183 minread = read_min * size;
184 if (minread > totread)
185 totread = minread;
186
187 /*
188 * Compute the total number of blocks that we should read
189 * synchronously.
190 */
191 if (firstread + totread > filesize)
192 totread = filesize - firstread;
193 nblks = howmany(totread, size);
194 if (nblks > racluster)
195 nblks = racluster;
196
197 /*
198 * Now compute the number of contiguous blocks.
199 */
200 if (nblks > 1) {
201 error = VOP_BMAP(vp, lblkno, NULL,
202 &blkno, &ncontig, NULL);
203 /*
204 * If this failed to map just do the original block.
205 */
206 if (error || blkno == -1)
207 ncontig = 0;
208 }
209
210 /*
211 * If we have contiguous data available do a cluster
212 * otherwise just read the requested block.
213 */
214 if (ncontig) {
215 /* Account for our first block. */
216 ncontig = min(ncontig + 1, nblks);
217 if (ncontig < nblks)
218 nblks = ncontig;
219 bp = cluster_rbuild(vp, filesize, lblkno,
220 blkno, size, nblks, gbflags, bp);
221 lblkno += (bp->b_bufsize / size);
222 } else {
223 bp->b_flags |= B_RAM;
224 bp->b_iocmd = BIO_READ;
225 lblkno += 1;
226 }
227 }
228
229 /*
230 * handle the synchronous read so that it is available ASAP.
231 */
232 if (bp) {
233 if ((bp->b_flags & B_CLUSTER) == 0) {
234 vfs_busy_pages(bp, 0);
235 }
236 bp->b_flags &= ~B_INVAL;
237 bp->b_ioflags &= ~BIO_ERROR;
238 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
239 BUF_KERNPROC(bp);
240 bp->b_iooffset = dbtob(bp->b_blkno);
241 bstrategy(bp);
242 curthread->td_ru.ru_inblock++;
243 }
244
245 /*
246 * If we have been doing sequential I/O, then do some read-ahead.
247 */
248 while (lblkno < (origblkno + maxra)) {
249 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
250 if (error)
251 break;
252
253 if (blkno == -1)
254 break;
255
256 /*
257 * We could throttle ncontig here by maxra but we might as
258 * well read the data if it is contiguous. We're throttled
259 * by racluster anyway.
260 */
261 if (ncontig) {
262 ncontig = min(ncontig + 1, racluster);
263 rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
264 size, ncontig, gbflags, NULL);
265 lblkno += (rbp->b_bufsize / size);
266 if (rbp->b_flags & B_DELWRI) {
267 bqrelse(rbp);
268 continue;
269 }
270 } else {
271 rbp = getblk(vp, lblkno, size, 0, 0, gbflags);
272 lblkno += 1;
273 if (rbp->b_flags & B_DELWRI) {
274 bqrelse(rbp);
275 continue;
276 }
277 rbp->b_flags |= B_ASYNC | B_RAM;
278 rbp->b_iocmd = BIO_READ;
279 rbp->b_blkno = blkno;
280 }
281 if (rbp->b_flags & B_CACHE) {
282 rbp->b_flags &= ~B_ASYNC;
283 bqrelse(rbp);
284 continue;
285 }
286 if ((rbp->b_flags & B_CLUSTER) == 0) {
287 vfs_busy_pages(rbp, 0);
288 }
289 rbp->b_flags &= ~B_INVAL;
290 rbp->b_ioflags &= ~BIO_ERROR;
291 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
292 BUF_KERNPROC(rbp);
293 rbp->b_iooffset = dbtob(rbp->b_blkno);
294 bstrategy(rbp);
295 curthread->td_ru.ru_inblock++;
296 }
297
298 if (reqbp)
299 return (bufwait(reqbp));
300 else
301 return (error);
302 }
303
304 /*
305 * If blocks are contiguous on disk, use this to provide clustered
306 * read ahead. We will read as many blocks as possible sequentially
307 * and then parcel them up into logical blocks in the buffer hash table.
308 */
309 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)310 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
311 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp)
312 {
313 struct buf *bp, *tbp;
314 daddr_t bn;
315 off_t off;
316 long tinc, tsize;
317 int i, inc, j, k, toff;
318
319 KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
320 ("cluster_rbuild: size %ld != f_iosize %jd\n",
321 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
322
323 /*
324 * avoid a division
325 */
326 while ((u_quad_t) size * (lbn + run) > filesize) {
327 --run;
328 }
329
330 if (fbp) {
331 tbp = fbp;
332 tbp->b_iocmd = BIO_READ;
333 } else {
334 tbp = getblk(vp, lbn, size, 0, 0, gbflags);
335 if (tbp->b_flags & B_CACHE)
336 return tbp;
337 tbp->b_flags |= B_ASYNC | B_RAM;
338 tbp->b_iocmd = BIO_READ;
339 }
340 tbp->b_blkno = blkno;
341 if( (tbp->b_flags & B_MALLOC) ||
342 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
343 return tbp;
344
345 bp = trypbuf(&cluster_pbuf_freecnt);
346 if (bp == 0)
347 return tbp;
348
349 /*
350 * We are synthesizing a buffer out of vm_page_t's, but
351 * if the block size is not page aligned then the starting
352 * address may not be either. Inherit the b_data offset
353 * from the original buffer.
354 */
355 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
356 if ((gbflags & GB_UNMAPPED) != 0) {
357 bp->b_data = unmapped_buf;
358 } else {
359 bp->b_data = (char *)((vm_offset_t)bp->b_data |
360 ((vm_offset_t)tbp->b_data & PAGE_MASK));
361 }
362 bp->b_iocmd = BIO_READ;
363 bp->b_iodone = cluster_callback;
364 bp->b_blkno = blkno;
365 bp->b_lblkno = lbn;
366 bp->b_offset = tbp->b_offset;
367 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
368 pbgetvp(vp, bp);
369
370 TAILQ_INIT(&bp->b_cluster.cluster_head);
371
372 bp->b_bcount = 0;
373 bp->b_bufsize = 0;
374 bp->b_npages = 0;
375
376 inc = btodb(size);
377 for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
378 if (i == 0) {
379 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
380 vfs_drain_busy_pages(tbp);
381 vm_object_pip_add(tbp->b_bufobj->bo_object,
382 tbp->b_npages);
383 for (k = 0; k < tbp->b_npages; k++)
384 vm_page_sbusy(tbp->b_pages[k]);
385 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
386 } else {
387 if ((bp->b_npages * PAGE_SIZE) +
388 round_page(size) > vp->v_mount->mnt_iosize_max) {
389 break;
390 }
391
392 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT |
393 (gbflags & GB_UNMAPPED));
394
395 /* Don't wait around for locked bufs. */
396 if (tbp == NULL)
397 break;
398
399 /*
400 * Stop scanning if the buffer is fully valid
401 * (marked B_CACHE), or locked (may be doing a
402 * background write), or if the buffer is not
403 * VMIO backed. The clustering code can only deal
404 * with VMIO-backed buffers. The bo lock is not
405 * required for the BKGRDINPROG check since it
406 * can not be set without the buf lock.
407 */
408 if ((tbp->b_vflags & BV_BKGRDINPROG) ||
409 (tbp->b_flags & B_CACHE) ||
410 (tbp->b_flags & B_VMIO) == 0) {
411 bqrelse(tbp);
412 break;
413 }
414
415 /*
416 * The buffer must be completely invalid in order to
417 * take part in the cluster. If it is partially valid
418 * then we stop.
419 */
420 off = tbp->b_offset;
421 tsize = size;
422 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
423 for (j = 0; tsize > 0; j++) {
424 toff = off & PAGE_MASK;
425 tinc = tsize;
426 if (toff + tinc > PAGE_SIZE)
427 tinc = PAGE_SIZE - toff;
428 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object);
429 if ((tbp->b_pages[j]->valid &
430 vm_page_bits(toff, tinc)) != 0)
431 break;
432 if (vm_page_xbusied(tbp->b_pages[j]))
433 break;
434 vm_object_pip_add(tbp->b_bufobj->bo_object, 1);
435 vm_page_sbusy(tbp->b_pages[j]);
436 off += tinc;
437 tsize -= tinc;
438 }
439 if (tsize > 0) {
440 clean_sbusy:
441 vm_object_pip_add(tbp->b_bufobj->bo_object, -j);
442 for (k = 0; k < j; k++)
443 vm_page_sunbusy(tbp->b_pages[k]);
444 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
445 bqrelse(tbp);
446 break;
447 }
448 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
449
450 /*
451 * Set a read-ahead mark as appropriate
452 */
453 if ((fbp && (i == 1)) || (i == (run - 1)))
454 tbp->b_flags |= B_RAM;
455
456 /*
457 * Set the buffer up for an async read (XXX should
458 * we do this only if we do not wind up brelse()ing?).
459 * Set the block number if it isn't set, otherwise
460 * if it is make sure it matches the block number we
461 * expect.
462 */
463 tbp->b_flags |= B_ASYNC;
464 tbp->b_iocmd = BIO_READ;
465 if (tbp->b_blkno == tbp->b_lblkno) {
466 tbp->b_blkno = bn;
467 } else if (tbp->b_blkno != bn) {
468 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
469 goto clean_sbusy;
470 }
471 }
472 /*
473 * XXX fbp from caller may not be B_ASYNC, but we are going
474 * to biodone() it in cluster_callback() anyway
475 */
476 BUF_KERNPROC(tbp);
477 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
478 tbp, b_cluster.cluster_entry);
479 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
480 for (j = 0; j < tbp->b_npages; j += 1) {
481 vm_page_t m;
482 m = tbp->b_pages[j];
483 if ((bp->b_npages == 0) ||
484 (bp->b_pages[bp->b_npages-1] != m)) {
485 bp->b_pages[bp->b_npages] = m;
486 bp->b_npages++;
487 }
488 if (m->valid == VM_PAGE_BITS_ALL)
489 tbp->b_pages[j] = bogus_page;
490 }
491 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
492 /*
493 * Don't inherit tbp->b_bufsize as it may be larger due to
494 * a non-page-aligned size. Instead just aggregate using
495 * 'size'.
496 */
497 if (tbp->b_bcount != size)
498 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
499 if (tbp->b_bufsize != size)
500 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
501 bp->b_bcount += size;
502 bp->b_bufsize += size;
503 }
504
505 /*
506 * Fully valid pages in the cluster are already good and do not need
507 * to be re-read from disk. Replace the page with bogus_page
508 */
509 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
510 for (j = 0; j < bp->b_npages; j++) {
511 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object);
512 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL)
513 bp->b_pages[j] = bogus_page;
514 }
515 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
516 if (bp->b_bufsize > bp->b_kvasize)
517 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
518 bp->b_bufsize, bp->b_kvasize);
519
520 if (buf_mapped(bp)) {
521 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
522 (vm_page_t *)bp->b_pages, bp->b_npages);
523 }
524 return (bp);
525 }
526
527 /*
528 * Cleanup after a clustered read or write.
529 * This is complicated by the fact that any of the buffers might have
530 * extra memory (if there were no empty buffer headers at allocbuf time)
531 * that we will need to shift around.
532 */
533 static void
cluster_callback(bp)534 cluster_callback(bp)
535 struct buf *bp;
536 {
537 struct buf *nbp, *tbp;
538 int error = 0;
539
540 /*
541 * Must propogate errors to all the components.
542 */
543 if (bp->b_ioflags & BIO_ERROR)
544 error = bp->b_error;
545
546 if (buf_mapped(bp)) {
547 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
548 bp->b_npages);
549 }
550 /*
551 * Move memory from the large cluster buffer into the component
552 * buffers and mark IO as done on these.
553 */
554 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
555 tbp; tbp = nbp) {
556 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
557 if (error) {
558 tbp->b_ioflags |= BIO_ERROR;
559 tbp->b_error = error;
560 } else {
561 tbp->b_dirtyoff = tbp->b_dirtyend = 0;
562 tbp->b_flags &= ~B_INVAL;
563 tbp->b_ioflags &= ~BIO_ERROR;
564 /*
565 * XXX the bdwrite()/bqrelse() issued during
566 * cluster building clears B_RELBUF (see bqrelse()
567 * comment). If direct I/O was specified, we have
568 * to restore it here to allow the buffer and VM
569 * to be freed.
570 */
571 if (tbp->b_flags & B_DIRECT)
572 tbp->b_flags |= B_RELBUF;
573 }
574 bufdone(tbp);
575 }
576 pbrelvp(bp);
577 relpbuf(bp, &cluster_pbuf_freecnt);
578 }
579
580 /*
581 * cluster_wbuild_wb:
582 *
583 * Implement modified write build for cluster.
584 *
585 * write_behind = 0 write behind disabled
586 * write_behind = 1 write behind normal (default)
587 * write_behind = 2 write behind backed-off
588 */
589
590 static __inline int
cluster_wbuild_wb(struct vnode * vp,long size,daddr_t start_lbn,int len,int gbflags)591 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len,
592 int gbflags)
593 {
594 int r = 0;
595
596 switch (write_behind) {
597 case 2:
598 if (start_lbn < len)
599 break;
600 start_lbn -= len;
601 /* FALLTHROUGH */
602 case 1:
603 r = cluster_wbuild(vp, size, start_lbn, len, gbflags);
604 /* FALLTHROUGH */
605 default:
606 /* FALLTHROUGH */
607 break;
608 }
609 return(r);
610 }
611
612 /*
613 * Do clustered write for FFS.
614 *
615 * Three cases:
616 * 1. Write is not sequential (write asynchronously)
617 * Write is sequential:
618 * 2. beginning of cluster - begin cluster
619 * 3. middle of a cluster - add to cluster
620 * 4. end of a cluster - asynchronously write cluster
621 */
622 void
cluster_write(struct vnode * vp,struct buf * bp,u_quad_t filesize,int seqcount,int gbflags)623 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount,
624 int gbflags)
625 {
626 daddr_t lbn;
627 int maxclen, cursize;
628 int lblocksize;
629 int async;
630
631 if (!unmapped_buf_allowed)
632 gbflags &= ~GB_UNMAPPED;
633
634 if (vp->v_type == VREG) {
635 async = DOINGASYNC(vp);
636 lblocksize = vp->v_mount->mnt_stat.f_iosize;
637 } else {
638 async = 0;
639 lblocksize = bp->b_bufsize;
640 }
641 lbn = bp->b_lblkno;
642 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
643
644 /* Initialize vnode to beginning of file. */
645 if (lbn == 0)
646 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
647
648 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
649 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
650 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
651 if (vp->v_clen != 0) {
652 /*
653 * Next block is not sequential.
654 *
655 * If we are not writing at end of file, the process
656 * seeked to another point in the file since its last
657 * write, or we have reached our maximum cluster size,
658 * then push the previous cluster. Otherwise try
659 * reallocating to make it sequential.
660 *
661 * Change to algorithm: only push previous cluster if
662 * it was sequential from the point of view of the
663 * seqcount heuristic, otherwise leave the buffer
664 * intact so we can potentially optimize the I/O
665 * later on in the buf_daemon or update daemon
666 * flush.
667 */
668 cursize = vp->v_lastw - vp->v_cstart + 1;
669 if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
670 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
671 if (!async && seqcount > 0) {
672 cluster_wbuild_wb(vp, lblocksize,
673 vp->v_cstart, cursize, gbflags);
674 }
675 } else {
676 struct buf **bpp, **endbp;
677 struct cluster_save *buflist;
678
679 buflist = cluster_collectbufs(vp, bp, gbflags);
680 endbp = &buflist->bs_children
681 [buflist->bs_nchildren - 1];
682 if (VOP_REALLOCBLKS(vp, buflist)) {
683 /*
684 * Failed, push the previous cluster
685 * if *really* writing sequentially
686 * in the logical file (seqcount > 1),
687 * otherwise delay it in the hopes that
688 * the low level disk driver can
689 * optimize the write ordering.
690 */
691 for (bpp = buflist->bs_children;
692 bpp < endbp; bpp++)
693 brelse(*bpp);
694 free(buflist, M_SEGMENT);
695 if (seqcount > 1) {
696 cluster_wbuild_wb(vp,
697 lblocksize, vp->v_cstart,
698 cursize, gbflags);
699 }
700 } else {
701 /*
702 * Succeeded, keep building cluster.
703 */
704 for (bpp = buflist->bs_children;
705 bpp <= endbp; bpp++)
706 bdwrite(*bpp);
707 free(buflist, M_SEGMENT);
708 vp->v_lastw = lbn;
709 vp->v_lasta = bp->b_blkno;
710 return;
711 }
712 }
713 }
714 /*
715 * Consider beginning a cluster. If at end of file, make
716 * cluster as large as possible, otherwise find size of
717 * existing cluster.
718 */
719 if ((vp->v_type == VREG) &&
720 ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
721 (bp->b_blkno == bp->b_lblkno) &&
722 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
723 bp->b_blkno == -1)) {
724 bawrite(bp);
725 vp->v_clen = 0;
726 vp->v_lasta = bp->b_blkno;
727 vp->v_cstart = lbn + 1;
728 vp->v_lastw = lbn;
729 return;
730 }
731 vp->v_clen = maxclen;
732 if (!async && maxclen == 0) { /* I/O not contiguous */
733 vp->v_cstart = lbn + 1;
734 bawrite(bp);
735 } else { /* Wait for rest of cluster */
736 vp->v_cstart = lbn;
737 bdwrite(bp);
738 }
739 } else if (lbn == vp->v_cstart + vp->v_clen) {
740 /*
741 * At end of cluster, write it out if seqcount tells us we
742 * are operating sequentially, otherwise let the buf or
743 * update daemon handle it.
744 */
745 bdwrite(bp);
746 if (seqcount > 1) {
747 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
748 vp->v_clen + 1, gbflags);
749 }
750 vp->v_clen = 0;
751 vp->v_cstart = lbn + 1;
752 } else if (vm_page_count_severe()) {
753 /*
754 * We are low on memory, get it going NOW
755 */
756 bawrite(bp);
757 } else {
758 /*
759 * In the middle of a cluster, so just delay the I/O for now.
760 */
761 bdwrite(bp);
762 }
763 vp->v_lastw = lbn;
764 vp->v_lasta = bp->b_blkno;
765 }
766
767
768 /*
769 * This is an awful lot like cluster_rbuild...wish they could be combined.
770 * The last lbn argument is the current block on which I/O is being
771 * performed. Check to see that it doesn't fall in the middle of
772 * the current block (if last_bp == NULL).
773 */
774 int
cluster_wbuild(struct vnode * vp,long size,daddr_t start_lbn,int len,int gbflags)775 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len,
776 int gbflags)
777 {
778 struct buf *bp, *tbp;
779 struct bufobj *bo;
780 int i, j;
781 int totalwritten = 0;
782 int dbsize = btodb(size);
783
784 if (!unmapped_buf_allowed)
785 gbflags &= ~GB_UNMAPPED;
786
787 bo = &vp->v_bufobj;
788 while (len > 0) {
789 /*
790 * If the buffer is not delayed-write (i.e. dirty), or it
791 * is delayed-write but either locked or inval, it cannot
792 * partake in the clustered write.
793 */
794 BO_LOCK(bo);
795 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
796 (tbp->b_vflags & BV_BKGRDINPROG)) {
797 BO_UNLOCK(bo);
798 ++start_lbn;
799 --len;
800 continue;
801 }
802 if (BUF_LOCK(tbp,
803 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) {
804 ++start_lbn;
805 --len;
806 continue;
807 }
808 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
809 BUF_UNLOCK(tbp);
810 ++start_lbn;
811 --len;
812 continue;
813 }
814 if (tbp->b_pin_count > 0) {
815 BUF_UNLOCK(tbp);
816 ++start_lbn;
817 --len;
818 continue;
819 }
820 bremfree(tbp);
821 tbp->b_flags &= ~B_DONE;
822
823 /*
824 * Extra memory in the buffer, punt on this buffer.
825 * XXX we could handle this in most cases, but we would
826 * have to push the extra memory down to after our max
827 * possible cluster size and then potentially pull it back
828 * up if the cluster was terminated prematurely--too much
829 * hassle.
830 */
831 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
832 (B_CLUSTEROK | B_VMIO)) ||
833 (tbp->b_bcount != tbp->b_bufsize) ||
834 (tbp->b_bcount != size) ||
835 (len == 1) ||
836 ((bp = (vp->v_vflag & VV_MD) != 0 ?
837 trypbuf(&cluster_pbuf_freecnt) :
838 getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
839 totalwritten += tbp->b_bufsize;
840 bawrite(tbp);
841 ++start_lbn;
842 --len;
843 continue;
844 }
845
846 /*
847 * We got a pbuf to make the cluster in.
848 * so initialise it.
849 */
850 TAILQ_INIT(&bp->b_cluster.cluster_head);
851 bp->b_bcount = 0;
852 bp->b_bufsize = 0;
853 bp->b_npages = 0;
854 if (tbp->b_wcred != NOCRED)
855 bp->b_wcred = crhold(tbp->b_wcred);
856
857 bp->b_blkno = tbp->b_blkno;
858 bp->b_lblkno = tbp->b_lblkno;
859 bp->b_offset = tbp->b_offset;
860
861 /*
862 * We are synthesizing a buffer out of vm_page_t's, but
863 * if the block size is not page aligned then the starting
864 * address may not be either. Inherit the b_data offset
865 * from the original buffer.
866 */
867 if ((gbflags & GB_UNMAPPED) == 0 ||
868 (tbp->b_flags & B_VMIO) == 0) {
869 bp->b_data = (char *)((vm_offset_t)bp->b_data |
870 ((vm_offset_t)tbp->b_data & PAGE_MASK));
871 } else {
872 bp->b_data = unmapped_buf;
873 }
874 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO |
875 B_NEEDCOMMIT));
876 bp->b_iodone = cluster_callback;
877 pbgetvp(vp, bp);
878 /*
879 * From this location in the file, scan forward to see
880 * if there are buffers with adjacent data that need to
881 * be written as well.
882 */
883 for (i = 0; i < len; ++i, ++start_lbn) {
884 if (i != 0) { /* If not the first buffer */
885 /*
886 * If the adjacent data is not even in core it
887 * can't need to be written.
888 */
889 BO_LOCK(bo);
890 if ((tbp = gbincore(bo, start_lbn)) == NULL ||
891 (tbp->b_vflags & BV_BKGRDINPROG)) {
892 BO_UNLOCK(bo);
893 break;
894 }
895
896 /*
897 * If it IS in core, but has different
898 * characteristics, or is locked (which
899 * means it could be undergoing a background
900 * I/O or be in a weird state), then don't
901 * cluster with it.
902 */
903 if (BUF_LOCK(tbp,
904 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
905 BO_LOCKPTR(bo)))
906 break;
907
908 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
909 B_INVAL | B_DELWRI | B_NEEDCOMMIT))
910 != (B_DELWRI | B_CLUSTEROK |
911 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
912 tbp->b_wcred != bp->b_wcred) {
913 BUF_UNLOCK(tbp);
914 break;
915 }
916
917 /*
918 * Check that the combined cluster
919 * would make sense with regard to pages
920 * and would not be too large
921 */
922 if ((tbp->b_bcount != size) ||
923 ((bp->b_blkno + (dbsize * i)) !=
924 tbp->b_blkno) ||
925 ((tbp->b_npages + bp->b_npages) >
926 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
927 BUF_UNLOCK(tbp);
928 break;
929 }
930
931 /*
932 * Do not pull in pinned buffers.
933 */
934 if (tbp->b_pin_count > 0) {
935 BUF_UNLOCK(tbp);
936 break;
937 }
938
939 /*
940 * Ok, it's passed all the tests,
941 * so remove it from the free list
942 * and mark it busy. We will use it.
943 */
944 bremfree(tbp);
945 tbp->b_flags &= ~B_DONE;
946 } /* end of code for non-first buffers only */
947 /*
948 * If the IO is via the VM then we do some
949 * special VM hackery (yuck). Since the buffer's
950 * block size may not be page-aligned it is possible
951 * for a page to be shared between two buffers. We
952 * have to get rid of the duplication when building
953 * the cluster.
954 */
955 if (tbp->b_flags & B_VMIO) {
956 vm_page_t m;
957
958 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
959 if (i == 0) {
960 vfs_drain_busy_pages(tbp);
961 } else { /* if not first buffer */
962 for (j = 0; j < tbp->b_npages; j += 1) {
963 m = tbp->b_pages[j];
964 if (vm_page_xbusied(m)) {
965 VM_OBJECT_WUNLOCK(
966 tbp->b_object);
967 bqrelse(tbp);
968 goto finishcluster;
969 }
970 }
971 }
972 for (j = 0; j < tbp->b_npages; j += 1) {
973 m = tbp->b_pages[j];
974 vm_page_sbusy(m);
975 vm_object_pip_add(m->object, 1);
976 if ((bp->b_npages == 0) ||
977 (bp->b_pages[bp->b_npages - 1] != m)) {
978 bp->b_pages[bp->b_npages] = m;
979 bp->b_npages++;
980 }
981 }
982 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
983 }
984 bp->b_bcount += size;
985 bp->b_bufsize += size;
986 /*
987 * If any of the clustered buffers have their
988 * B_BARRIER flag set, transfer that request to
989 * the cluster.
990 */
991 bp->b_flags |= (tbp->b_flags & B_BARRIER);
992 tbp->b_flags &= ~(B_DONE | B_BARRIER);
993 tbp->b_flags |= B_ASYNC;
994 tbp->b_ioflags &= ~BIO_ERROR;
995 tbp->b_iocmd = BIO_WRITE;
996 bundirty(tbp);
997 reassignbuf(tbp); /* put on clean list */
998 bufobj_wref(tbp->b_bufobj);
999 BUF_KERNPROC(tbp);
1000 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
1001 tbp, b_cluster.cluster_entry);
1002 }
1003 finishcluster:
1004 if (buf_mapped(bp)) {
1005 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1006 (vm_page_t *)bp->b_pages, bp->b_npages);
1007 }
1008 if (bp->b_bufsize > bp->b_kvasize)
1009 panic(
1010 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
1011 bp->b_bufsize, bp->b_kvasize);
1012 totalwritten += bp->b_bufsize;
1013 bp->b_dirtyoff = 0;
1014 bp->b_dirtyend = bp->b_bufsize;
1015 bawrite(bp);
1016
1017 len -= i;
1018 }
1019 return totalwritten;
1020 }
1021
1022 /*
1023 * Collect together all the buffers in a cluster.
1024 * Plus add one additional buffer.
1025 */
1026 static struct cluster_save *
cluster_collectbufs(struct vnode * vp,struct buf * last_bp,int gbflags)1027 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags)
1028 {
1029 struct cluster_save *buflist;
1030 struct buf *bp;
1031 daddr_t lbn;
1032 int i, len;
1033
1034 len = vp->v_lastw - vp->v_cstart + 1;
1035 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1036 M_SEGMENT, M_WAITOK);
1037 buflist->bs_nchildren = 0;
1038 buflist->bs_children = (struct buf **) (buflist + 1);
1039 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1040 (void)bread_gb(vp, lbn, last_bp->b_bcount, NOCRED,
1041 gbflags, &bp);
1042 buflist->bs_children[i] = bp;
1043 if (bp->b_blkno == bp->b_lblkno)
1044 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
1045 NULL, NULL);
1046 }
1047 buflist->bs_children[i] = bp = last_bp;
1048 if (bp->b_blkno == bp->b_lblkno)
1049 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1050 buflist->bs_nchildren = i + 1;
1051 return (buflist);
1052 }
1053