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: releng/11.1/sys/kern/vfs_cluster.c 298819 2016-04-29 22:15:33Z pfg $");
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/racct.h>
49 #include <sys/resourcevar.h>
50 #include <sys/rwlock.h>
51 #include <sys/vmmeter.h>
52 #include <vm/vm.h>
53 #include <vm/vm_object.h>
54 #include <vm/vm_page.h>
55 #include <sys/sysctl.h>
56
57 #if defined(CLUSTERDEBUG)
58 static int rcluster= 0;
59 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0,
60 "Debug VFS clustering code");
61 #endif
62
63 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer");
64
65 static struct cluster_save *cluster_collectbufs(struct vnode *vp,
66 struct buf *last_bp, int gbflags);
67 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize,
68 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags,
69 struct buf *fbp);
70 static void cluster_callback(struct buf *);
71
72 static int write_behind = 1;
73 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
74 "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
75
76 static int read_max = 64;
77 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
78 "Cluster read-ahead max block count");
79
80 static int read_min = 1;
81 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0,
82 "Cluster read min block count");
83
84 /* Page expended to mark partially backed buffers */
85 extern vm_page_t bogus_page;
86
87 /*
88 * Read data to a buf, including read-ahead if we find this to be beneficial.
89 * cluster_read replaces bread.
90 */
91 int
92 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size,
93 struct ucred *cred, long totread, int seqcount, int gbflags,
94 struct buf **bpp)
95 {
96 struct buf *bp, *rbp, *reqbp;
97 struct bufobj *bo;
98 daddr_t blkno, origblkno;
99 int maxra, racluster;
100 int error, ncontig;
101 int i;
102
103 error = 0;
104 bo = &vp->v_bufobj;
105 if (!unmapped_buf_allowed)
106 gbflags &= ~GB_UNMAPPED;
107
108 /*
109 * Try to limit the amount of read-ahead by a few
110 * ad-hoc parameters. This needs work!!!
111 */
112 racluster = vp->v_mount->mnt_iosize_max / size;
113 maxra = seqcount;
114 maxra = min(read_max, maxra);
115 maxra = min(nbuf/8, maxra);
116 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize)
117 maxra = (filesize / size) - lblkno;
118
119 /*
120 * get the requested block
121 */
122 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, gbflags);
123 if (bp == NULL)
124 return (EBUSY);
125 origblkno = lblkno;
126
127 /*
128 * if it is in the cache, then check to see if the reads have been
129 * sequential. If they have, then try some read-ahead, otherwise
130 * back-off on prospective read-aheads.
131 */
132 if (bp->b_flags & B_CACHE) {
133 if (!seqcount) {
134 return 0;
135 } else if ((bp->b_flags & B_RAM) == 0) {
136 return 0;
137 } else {
138 bp->b_flags &= ~B_RAM;
139 BO_RLOCK(bo);
140 for (i = 1; i < maxra; i++) {
141 /*
142 * Stop if the buffer does not exist or it
143 * is invalid (about to go away?)
144 */
145 rbp = gbincore(&vp->v_bufobj, lblkno+i);
146 if (rbp == NULL || (rbp->b_flags & B_INVAL))
147 break;
148
149 /*
150 * Set another read-ahead mark so we know
151 * to check again. (If we can lock the
152 * buffer without waiting)
153 */
154 if ((((i % racluster) == (racluster - 1)) ||
155 (i == (maxra - 1)))
156 && (0 == BUF_LOCK(rbp,
157 LK_EXCLUSIVE | LK_NOWAIT, NULL))) {
158 rbp->b_flags |= B_RAM;
159 BUF_UNLOCK(rbp);
160 }
161 }
162 BO_RUNLOCK(bo);
163 if (i >= maxra) {
164 return 0;
165 }
166 lblkno += i;
167 }
168 reqbp = bp = NULL;
169 /*
170 * If it isn't in the cache, then get a chunk from
171 * disk if sequential, otherwise just get the block.
172 */
173 } else {
174 off_t firstread = bp->b_offset;
175 int nblks;
176 long minread;
177
178 KASSERT(bp->b_offset != NOOFFSET,
179 ("cluster_read: no buffer offset"));
180
181 ncontig = 0;
182
183 /*
184 * Adjust totread if needed
185 */
186 minread = read_min * size;
187 if (minread > totread)
188 totread = minread;
189
190 /*
191 * Compute the total number of blocks that we should read
192 * synchronously.
193 */
194 if (firstread + totread > filesize)
195 totread = filesize - firstread;
196 nblks = howmany(totread, size);
197 if (nblks > racluster)
198 nblks = racluster;
199
200 /*
201 * Now compute the number of contiguous blocks.
202 */
203 if (nblks > 1) {
204 error = VOP_BMAP(vp, lblkno, NULL,
205 &blkno, &ncontig, NULL);
206 /*
207 * If this failed to map just do the original block.
208 */
209 if (error || blkno == -1)
210 ncontig = 0;
211 }
212
213 /*
214 * If we have contiguous data available do a cluster
215 * otherwise just read the requested block.
216 */
217 if (ncontig) {
218 /* Account for our first block. */
219 ncontig = min(ncontig + 1, nblks);
220 if (ncontig < nblks)
221 nblks = ncontig;
222 bp = cluster_rbuild(vp, filesize, lblkno,
223 blkno, size, nblks, gbflags, bp);
224 lblkno += (bp->b_bufsize / size);
225 } else {
226 bp->b_flags |= B_RAM;
227 bp->b_iocmd = BIO_READ;
228 lblkno += 1;
229 }
230 }
231
232 /*
233 * handle the synchronous read so that it is available ASAP.
234 */
235 if (bp) {
236 if ((bp->b_flags & B_CLUSTER) == 0) {
237 vfs_busy_pages(bp, 0);
238 }
239 bp->b_flags &= ~B_INVAL;
240 bp->b_ioflags &= ~BIO_ERROR;
241 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
242 BUF_KERNPROC(bp);
243 bp->b_iooffset = dbtob(bp->b_blkno);
244 bstrategy(bp);
245 #ifdef RACCT
246 if (racct_enable) {
247 PROC_LOCK(curproc);
248 racct_add_buf(curproc, bp, 0);
249 PROC_UNLOCK(curproc);
250 }
251 #endif /* RACCT */
252 curthread->td_ru.ru_inblock++;
253 }
254
255 /*
256 * If we have been doing sequential I/O, then do some read-ahead.
257 */
258 while (lblkno < (origblkno + maxra)) {
259 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
260 if (error)
261 break;
262
263 if (blkno == -1)
264 break;
265
266 /*
267 * We could throttle ncontig here by maxra but we might as
268 * well read the data if it is contiguous. We're throttled
269 * by racluster anyway.
270 */
271 if (ncontig) {
272 ncontig = min(ncontig + 1, racluster);
273 rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
274 size, ncontig, gbflags, NULL);
275 lblkno += (rbp->b_bufsize / size);
276 if (rbp->b_flags & B_DELWRI) {
277 bqrelse(rbp);
278 continue;
279 }
280 } else {
281 rbp = getblk(vp, lblkno, size, 0, 0, gbflags);
282 lblkno += 1;
283 if (rbp->b_flags & B_DELWRI) {
284 bqrelse(rbp);
285 continue;
286 }
287 rbp->b_flags |= B_ASYNC | B_RAM;
288 rbp->b_iocmd = BIO_READ;
289 rbp->b_blkno = blkno;
290 }
291 if (rbp->b_flags & B_CACHE) {
292 rbp->b_flags &= ~B_ASYNC;
293 bqrelse(rbp);
294 continue;
295 }
296 if ((rbp->b_flags & B_CLUSTER) == 0) {
297 vfs_busy_pages(rbp, 0);
298 }
299 rbp->b_flags &= ~B_INVAL;
300 rbp->b_ioflags &= ~BIO_ERROR;
301 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
302 BUF_KERNPROC(rbp);
303 rbp->b_iooffset = dbtob(rbp->b_blkno);
304 bstrategy(rbp);
305 #ifdef RACCT
306 if (racct_enable) {
307 PROC_LOCK(curproc);
308 racct_add_buf(curproc, rbp, 0);
309 PROC_UNLOCK(curproc);
310 }
311 #endif /* RACCT */
312 curthread->td_ru.ru_inblock++;
313 }
314
315 if (reqbp) {
316 /*
317 * Like bread, always brelse() the buffer when
318 * returning an error.
319 */
320 error = bufwait(reqbp);
321 if (error != 0) {
322 brelse(reqbp);
323 *bpp = NULL;
324 }
325 }
326 return (error);
327 }
328
329 /*
330 * If blocks are contiguous on disk, use this to provide clustered
331 * read ahead. We will read as many blocks as possible sequentially
332 * and then parcel them up into logical blocks in the buffer hash table.
333 */
334 static struct buf *
335 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
336 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp)
337 {
338 struct buf *bp, *tbp;
339 daddr_t bn;
340 off_t off;
341 long tinc, tsize;
342 int i, inc, j, k, toff;
343
344 KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
345 ("cluster_rbuild: size %ld != f_iosize %jd\n",
346 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
347
348 /*
349 * avoid a division
350 */
351 while ((u_quad_t) size * (lbn + run) > filesize) {
352 --run;
353 }
354
355 if (fbp) {
356 tbp = fbp;
357 tbp->b_iocmd = BIO_READ;
358 } else {
359 tbp = getblk(vp, lbn, size, 0, 0, gbflags);
360 if (tbp->b_flags & B_CACHE)
361 return tbp;
362 tbp->b_flags |= B_ASYNC | B_RAM;
363 tbp->b_iocmd = BIO_READ;
364 }
365 tbp->b_blkno = blkno;
366 if( (tbp->b_flags & B_MALLOC) ||
367 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
368 return tbp;
369
370 bp = trypbuf(&cluster_pbuf_freecnt);
371 if (bp == NULL)
372 return tbp;
373
374 /*
375 * We are synthesizing a buffer out of vm_page_t's, but
376 * if the block size is not page aligned then the starting
377 * address may not be either. Inherit the b_data offset
378 * from the original buffer.
379 */
380 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
381 if ((gbflags & GB_UNMAPPED) != 0) {
382 bp->b_data = unmapped_buf;
383 } else {
384 bp->b_data = (char *)((vm_offset_t)bp->b_data |
385 ((vm_offset_t)tbp->b_data & PAGE_MASK));
386 }
387 bp->b_iocmd = BIO_READ;
388 bp->b_iodone = cluster_callback;
389 bp->b_blkno = blkno;
390 bp->b_lblkno = lbn;
391 bp->b_offset = tbp->b_offset;
392 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
393 pbgetvp(vp, bp);
394
395 TAILQ_INIT(&bp->b_cluster.cluster_head);
396
397 bp->b_bcount = 0;
398 bp->b_bufsize = 0;
399 bp->b_npages = 0;
400
401 inc = btodb(size);
402 for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
403 if (i == 0) {
404 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
405 vfs_drain_busy_pages(tbp);
406 vm_object_pip_add(tbp->b_bufobj->bo_object,
407 tbp->b_npages);
408 for (k = 0; k < tbp->b_npages; k++)
409 vm_page_sbusy(tbp->b_pages[k]);
410 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
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 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
448 for (j = 0; tsize > 0; j++) {
449 toff = off & PAGE_MASK;
450 tinc = tsize;
451 if (toff + tinc > PAGE_SIZE)
452 tinc = PAGE_SIZE - toff;
453 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object);
454 if ((tbp->b_pages[j]->valid &
455 vm_page_bits(toff, tinc)) != 0)
456 break;
457 if (vm_page_xbusied(tbp->b_pages[j]))
458 break;
459 vm_object_pip_add(tbp->b_bufobj->bo_object, 1);
460 vm_page_sbusy(tbp->b_pages[j]);
461 off += tinc;
462 tsize -= tinc;
463 }
464 if (tsize > 0) {
465 clean_sbusy:
466 vm_object_pip_add(tbp->b_bufobj->bo_object, -j);
467 for (k = 0; k < j; k++)
468 vm_page_sunbusy(tbp->b_pages[k]);
469 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
470 bqrelse(tbp);
471 break;
472 }
473 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
474
475 /*
476 * Set a read-ahead mark as appropriate
477 */
478 if ((fbp && (i == 1)) || (i == (run - 1)))
479 tbp->b_flags |= B_RAM;
480
481 /*
482 * Set the buffer up for an async read (XXX should
483 * we do this only if we do not wind up brelse()ing?).
484 * Set the block number if it isn't set, otherwise
485 * if it is make sure it matches the block number we
486 * expect.
487 */
488 tbp->b_flags |= B_ASYNC;
489 tbp->b_iocmd = BIO_READ;
490 if (tbp->b_blkno == tbp->b_lblkno) {
491 tbp->b_blkno = bn;
492 } else if (tbp->b_blkno != bn) {
493 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
494 goto clean_sbusy;
495 }
496 }
497 /*
498 * XXX fbp from caller may not be B_ASYNC, but we are going
499 * to biodone() it in cluster_callback() anyway
500 */
501 BUF_KERNPROC(tbp);
502 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
503 tbp, b_cluster.cluster_entry);
504 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
505 for (j = 0; j < tbp->b_npages; j += 1) {
506 vm_page_t m;
507 m = tbp->b_pages[j];
508 if ((bp->b_npages == 0) ||
509 (bp->b_pages[bp->b_npages-1] != m)) {
510 bp->b_pages[bp->b_npages] = m;
511 bp->b_npages++;
512 }
513 if (m->valid == VM_PAGE_BITS_ALL)
514 tbp->b_pages[j] = bogus_page;
515 }
516 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
517 /*
518 * Don't inherit tbp->b_bufsize as it may be larger due to
519 * a non-page-aligned size. Instead just aggregate using
520 * 'size'.
521 */
522 if (tbp->b_bcount != size)
523 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
524 if (tbp->b_bufsize != size)
525 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
526 bp->b_bcount += size;
527 bp->b_bufsize += size;
528 }
529
530 /*
531 * Fully valid pages in the cluster are already good and do not need
532 * to be re-read from disk. Replace the page with bogus_page
533 */
534 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
535 for (j = 0; j < bp->b_npages; j++) {
536 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object);
537 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL)
538 bp->b_pages[j] = bogus_page;
539 }
540 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
541 if (bp->b_bufsize > bp->b_kvasize)
542 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
543 bp->b_bufsize, bp->b_kvasize);
544
545 if (buf_mapped(bp)) {
546 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
547 (vm_page_t *)bp->b_pages, bp->b_npages);
548 }
549 return (bp);
550 }
551
552 /*
553 * Cleanup after a clustered read or write.
554 * This is complicated by the fact that any of the buffers might have
555 * extra memory (if there were no empty buffer headers at allocbuf time)
556 * that we will need to shift around.
557 */
558 static void
559 cluster_callback(bp)
560 struct buf *bp;
561 {
562 struct buf *nbp, *tbp;
563 int error = 0;
564
565 /*
566 * Must propagate errors to all the components.
567 */
568 if (bp->b_ioflags & BIO_ERROR)
569 error = bp->b_error;
570
571 if (buf_mapped(bp)) {
572 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
573 bp->b_npages);
574 }
575 /*
576 * Move memory from the large cluster buffer into the component
577 * buffers and mark IO as done on these.
578 */
579 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
580 tbp; tbp = nbp) {
581 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
582 if (error) {
583 tbp->b_ioflags |= BIO_ERROR;
584 tbp->b_error = error;
585 } else {
586 tbp->b_dirtyoff = tbp->b_dirtyend = 0;
587 tbp->b_flags &= ~B_INVAL;
588 tbp->b_ioflags &= ~BIO_ERROR;
589 /*
590 * XXX the bdwrite()/bqrelse() issued during
591 * cluster building clears B_RELBUF (see bqrelse()
592 * comment). If direct I/O was specified, we have
593 * to restore it here to allow the buffer and VM
594 * to be freed.
595 */
596 if (tbp->b_flags & B_DIRECT)
597 tbp->b_flags |= B_RELBUF;
598 }
599 bufdone(tbp);
600 }
601 pbrelvp(bp);
602 relpbuf(bp, &cluster_pbuf_freecnt);
603 }
604
605 /*
606 * cluster_wbuild_wb:
607 *
608 * Implement modified write build for cluster.
609 *
610 * write_behind = 0 write behind disabled
611 * write_behind = 1 write behind normal (default)
612 * write_behind = 2 write behind backed-off
613 */
614
615 static __inline int
616 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len,
617 int gbflags)
618 {
619 int r = 0;
620
621 switch (write_behind) {
622 case 2:
623 if (start_lbn < len)
624 break;
625 start_lbn -= len;
626 /* FALLTHROUGH */
627 case 1:
628 r = cluster_wbuild(vp, size, start_lbn, len, gbflags);
629 /* FALLTHROUGH */
630 default:
631 /* FALLTHROUGH */
632 break;
633 }
634 return(r);
635 }
636
637 /*
638 * Do clustered write for FFS.
639 *
640 * Three cases:
641 * 1. Write is not sequential (write asynchronously)
642 * Write is sequential:
643 * 2. beginning of cluster - begin cluster
644 * 3. middle of a cluster - add to cluster
645 * 4. end of a cluster - asynchronously write cluster
646 */
647 void
648 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount,
649 int gbflags)
650 {
651 daddr_t lbn;
652 int maxclen, cursize;
653 int lblocksize;
654 int async;
655
656 if (!unmapped_buf_allowed)
657 gbflags &= ~GB_UNMAPPED;
658
659 if (vp->v_type == VREG) {
660 async = DOINGASYNC(vp);
661 lblocksize = vp->v_mount->mnt_stat.f_iosize;
662 } else {
663 async = 0;
664 lblocksize = bp->b_bufsize;
665 }
666 lbn = bp->b_lblkno;
667 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
668
669 /* Initialize vnode to beginning of file. */
670 if (lbn == 0)
671 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
672
673 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
674 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
675 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
676 if (vp->v_clen != 0) {
677 /*
678 * Next block is not sequential.
679 *
680 * If we are not writing at end of file, the process
681 * seeked to another point in the file since its last
682 * write, or we have reached our maximum cluster size,
683 * then push the previous cluster. Otherwise try
684 * reallocating to make it sequential.
685 *
686 * Change to algorithm: only push previous cluster if
687 * it was sequential from the point of view of the
688 * seqcount heuristic, otherwise leave the buffer
689 * intact so we can potentially optimize the I/O
690 * later on in the buf_daemon or update daemon
691 * flush.
692 */
693 cursize = vp->v_lastw - vp->v_cstart + 1;
694 if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
695 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
696 if (!async && seqcount > 0) {
697 cluster_wbuild_wb(vp, lblocksize,
698 vp->v_cstart, cursize, gbflags);
699 }
700 } else {
701 struct buf **bpp, **endbp;
702 struct cluster_save *buflist;
703
704 buflist = cluster_collectbufs(vp, bp, gbflags);
705 endbp = &buflist->bs_children
706 [buflist->bs_nchildren - 1];
707 if (VOP_REALLOCBLKS(vp, buflist)) {
708 /*
709 * Failed, push the previous cluster
710 * if *really* writing sequentially
711 * in the logical file (seqcount > 1),
712 * otherwise delay it in the hopes that
713 * the low level disk driver can
714 * optimize the write ordering.
715 */
716 for (bpp = buflist->bs_children;
717 bpp < endbp; bpp++)
718 brelse(*bpp);
719 free(buflist, M_SEGMENT);
720 if (seqcount > 1) {
721 cluster_wbuild_wb(vp,
722 lblocksize, vp->v_cstart,
723 cursize, gbflags);
724 }
725 } else {
726 /*
727 * Succeeded, keep building cluster.
728 */
729 for (bpp = buflist->bs_children;
730 bpp <= endbp; bpp++)
731 bdwrite(*bpp);
732 free(buflist, M_SEGMENT);
733 vp->v_lastw = lbn;
734 vp->v_lasta = bp->b_blkno;
735 return;
736 }
737 }
738 }
739 /*
740 * Consider beginning a cluster. If at end of file, make
741 * cluster as large as possible, otherwise find size of
742 * existing cluster.
743 */
744 if ((vp->v_type == VREG) &&
745 ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
746 (bp->b_blkno == bp->b_lblkno) &&
747 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
748 bp->b_blkno == -1)) {
749 bawrite(bp);
750 vp->v_clen = 0;
751 vp->v_lasta = bp->b_blkno;
752 vp->v_cstart = lbn + 1;
753 vp->v_lastw = lbn;
754 return;
755 }
756 vp->v_clen = maxclen;
757 if (!async && maxclen == 0) { /* I/O not contiguous */
758 vp->v_cstart = lbn + 1;
759 bawrite(bp);
760 } else { /* Wait for rest of cluster */
761 vp->v_cstart = lbn;
762 bdwrite(bp);
763 }
764 } else if (lbn == vp->v_cstart + vp->v_clen) {
765 /*
766 * At end of cluster, write it out if seqcount tells us we
767 * are operating sequentially, otherwise let the buf or
768 * update daemon handle it.
769 */
770 bdwrite(bp);
771 if (seqcount > 1) {
772 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
773 vp->v_clen + 1, gbflags);
774 }
775 vp->v_clen = 0;
776 vp->v_cstart = lbn + 1;
777 } else if (vm_page_count_severe()) {
778 /*
779 * We are low on memory, get it going NOW
780 */
781 bawrite(bp);
782 } else {
783 /*
784 * In the middle of a cluster, so just delay the I/O for now.
785 */
786 bdwrite(bp);
787 }
788 vp->v_lastw = lbn;
789 vp->v_lasta = bp->b_blkno;
790 }
791
792
793 /*
794 * This is an awful lot like cluster_rbuild...wish they could be combined.
795 * The last lbn argument is the current block on which I/O is being
796 * performed. Check to see that it doesn't fall in the middle of
797 * the current block (if last_bp == NULL).
798 */
799 int
800 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len,
801 int gbflags)
802 {
803 struct buf *bp, *tbp;
804 struct bufobj *bo;
805 int i, j;
806 int totalwritten = 0;
807 int dbsize = btodb(size);
808
809 if (!unmapped_buf_allowed)
810 gbflags &= ~GB_UNMAPPED;
811
812 bo = &vp->v_bufobj;
813 while (len > 0) {
814 /*
815 * If the buffer is not delayed-write (i.e. dirty), or it
816 * is delayed-write but either locked or inval, it cannot
817 * partake in the clustered write.
818 */
819 BO_LOCK(bo);
820 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
821 (tbp->b_vflags & BV_BKGRDINPROG)) {
822 BO_UNLOCK(bo);
823 ++start_lbn;
824 --len;
825 continue;
826 }
827 if (BUF_LOCK(tbp,
828 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) {
829 ++start_lbn;
830 --len;
831 continue;
832 }
833 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
834 BUF_UNLOCK(tbp);
835 ++start_lbn;
836 --len;
837 continue;
838 }
839 if (tbp->b_pin_count > 0) {
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 = (vp->v_vflag & VV_MD) != 0 ?
862 trypbuf(&cluster_pbuf_freecnt) :
863 getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
864 totalwritten += tbp->b_bufsize;
865 bawrite(tbp);
866 ++start_lbn;
867 --len;
868 continue;
869 }
870
871 /*
872 * We got a pbuf to make the cluster in.
873 * so initialise it.
874 */
875 TAILQ_INIT(&bp->b_cluster.cluster_head);
876 bp->b_bcount = 0;
877 bp->b_bufsize = 0;
878 bp->b_npages = 0;
879 if (tbp->b_wcred != NOCRED)
880 bp->b_wcred = crhold(tbp->b_wcred);
881
882 bp->b_blkno = tbp->b_blkno;
883 bp->b_lblkno = tbp->b_lblkno;
884 bp->b_offset = tbp->b_offset;
885
886 /*
887 * We are synthesizing a buffer out of vm_page_t's, but
888 * if the block size is not page aligned then the starting
889 * address may not be either. Inherit the b_data offset
890 * from the original buffer.
891 */
892 if ((gbflags & GB_UNMAPPED) == 0 ||
893 (tbp->b_flags & B_VMIO) == 0) {
894 bp->b_data = (char *)((vm_offset_t)bp->b_data |
895 ((vm_offset_t)tbp->b_data & PAGE_MASK));
896 } else {
897 bp->b_data = unmapped_buf;
898 }
899 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO |
900 B_NEEDCOMMIT));
901 bp->b_iodone = cluster_callback;
902 pbgetvp(vp, bp);
903 /*
904 * From this location in the file, scan forward to see
905 * if there are buffers with adjacent data that need to
906 * be written as well.
907 */
908 for (i = 0; i < len; ++i, ++start_lbn) {
909 if (i != 0) { /* If not the first buffer */
910 /*
911 * If the adjacent data is not even in core it
912 * can't need to be written.
913 */
914 BO_LOCK(bo);
915 if ((tbp = gbincore(bo, start_lbn)) == NULL ||
916 (tbp->b_vflags & BV_BKGRDINPROG)) {
917 BO_UNLOCK(bo);
918 break;
919 }
920
921 /*
922 * If it IS in core, but has different
923 * characteristics, or is locked (which
924 * means it could be undergoing a background
925 * I/O or be in a weird state), then don't
926 * cluster with it.
927 */
928 if (BUF_LOCK(tbp,
929 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
930 BO_LOCKPTR(bo)))
931 break;
932
933 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
934 B_INVAL | B_DELWRI | B_NEEDCOMMIT))
935 != (B_DELWRI | B_CLUSTEROK |
936 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
937 tbp->b_wcred != bp->b_wcred) {
938 BUF_UNLOCK(tbp);
939 break;
940 }
941
942 /*
943 * Check that the combined cluster
944 * would make sense with regard to pages
945 * and would not be too large
946 */
947 if ((tbp->b_bcount != size) ||
948 ((bp->b_blkno + (dbsize * i)) !=
949 tbp->b_blkno) ||
950 ((tbp->b_npages + bp->b_npages) >
951 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
952 BUF_UNLOCK(tbp);
953 break;
954 }
955
956 /*
957 * Do not pull in pinned buffers.
958 */
959 if (tbp->b_pin_count > 0) {
960 BUF_UNLOCK(tbp);
961 break;
962 }
963
964 /*
965 * Ok, it's passed all the tests,
966 * so remove it from the free list
967 * and mark it busy. We will use it.
968 */
969 bremfree(tbp);
970 tbp->b_flags &= ~B_DONE;
971 } /* end of code for non-first buffers only */
972 /*
973 * If the IO is via the VM then we do some
974 * special VM hackery (yuck). Since the buffer's
975 * block size may not be page-aligned it is possible
976 * for a page to be shared between two buffers. We
977 * have to get rid of the duplication when building
978 * the cluster.
979 */
980 if (tbp->b_flags & B_VMIO) {
981 vm_page_t m;
982
983 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
984 if (i == 0) {
985 vfs_drain_busy_pages(tbp);
986 } else { /* if not first buffer */
987 for (j = 0; j < tbp->b_npages; j += 1) {
988 m = tbp->b_pages[j];
989 if (vm_page_xbusied(m)) {
990 VM_OBJECT_WUNLOCK(
991 tbp->b_object);
992 bqrelse(tbp);
993 goto finishcluster;
994 }
995 }
996 }
997 for (j = 0; j < tbp->b_npages; j += 1) {
998 m = tbp->b_pages[j];
999 vm_page_sbusy(m);
1000 vm_object_pip_add(m->object, 1);
1001 if ((bp->b_npages == 0) ||
1002 (bp->b_pages[bp->b_npages - 1] != m)) {
1003 bp->b_pages[bp->b_npages] = m;
1004 bp->b_npages++;
1005 }
1006 }
1007 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
1008 }
1009 bp->b_bcount += size;
1010 bp->b_bufsize += size;
1011 /*
1012 * If any of the clustered buffers have their
1013 * B_BARRIER flag set, transfer that request to
1014 * the cluster.
1015 */
1016 bp->b_flags |= (tbp->b_flags & B_BARRIER);
1017 tbp->b_flags &= ~(B_DONE | B_BARRIER);
1018 tbp->b_flags |= B_ASYNC;
1019 tbp->b_ioflags &= ~BIO_ERROR;
1020 tbp->b_iocmd = BIO_WRITE;
1021 bundirty(tbp);
1022 reassignbuf(tbp); /* put on clean list */
1023 bufobj_wref(tbp->b_bufobj);
1024 BUF_KERNPROC(tbp);
1025 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
1026 tbp, b_cluster.cluster_entry);
1027 }
1028 finishcluster:
1029 if (buf_mapped(bp)) {
1030 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1031 (vm_page_t *)bp->b_pages, bp->b_npages);
1032 }
1033 if (bp->b_bufsize > bp->b_kvasize)
1034 panic(
1035 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
1036 bp->b_bufsize, bp->b_kvasize);
1037 totalwritten += bp->b_bufsize;
1038 bp->b_dirtyoff = 0;
1039 bp->b_dirtyend = bp->b_bufsize;
1040 bawrite(bp);
1041
1042 len -= i;
1043 }
1044 return totalwritten;
1045 }
1046
1047 /*
1048 * Collect together all the buffers in a cluster.
1049 * Plus add one additional buffer.
1050 */
1051 static struct cluster_save *
1052 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags)
1053 {
1054 struct cluster_save *buflist;
1055 struct buf *bp;
1056 daddr_t lbn;
1057 int i, len;
1058
1059 len = vp->v_lastw - vp->v_cstart + 1;
1060 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1061 M_SEGMENT, M_WAITOK);
1062 buflist->bs_nchildren = 0;
1063 buflist->bs_children = (struct buf **) (buflist + 1);
1064 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1065 (void)bread_gb(vp, lbn, last_bp->b_bcount, NOCRED,
1066 gbflags, &bp);
1067 buflist->bs_children[i] = bp;
1068 if (bp->b_blkno == bp->b_lblkno)
1069 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
1070 NULL, NULL);
1071 }
1072 buflist->bs_children[i] = bp = last_bp;
1073 if (bp->b_blkno == bp->b_lblkno)
1074 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1075 buflist->bs_nchildren = i + 1;
1076 return (buflist);
1077 }
Cache object: 535d2a4f6169417ed3a8a0bc84746590
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