kernel - Add many sysctl definitions, sysv, vfs, nfs, etc.
[dragonfly.git] / sys / kern / vfs_cluster.c
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  * $FreeBSD: src/sys/kern/vfs_cluster.c,v 1.92.2.9 2001/11/18 07:10:59 dillon Exp $
37  * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.40 2008/07/14 03:09:00 dillon Exp $
38  */
39
40 #include "opt_debug_cluster.h"
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
45 #include <sys/proc.h>
46 #include <sys/buf.h>
47 #include <sys/vnode.h>
48 #include <sys/malloc.h>
49 #include <sys/mount.h>
50 #include <sys/resourcevar.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 #include <sys/buf2.h>
57 #include <vm/vm_page2.h>
58
59 #include <machine/limits.h>
60
61 #if defined(CLUSTERDEBUG)
62 #include <sys/sysctl.h>
63 static int      rcluster= 0;
64 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
65 #endif
66
67 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
68
69 static struct cluster_save *
70         cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
71                             int blksize);
72 static struct buf *
73         cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
74                             off_t doffset, int blksize, int run, 
75                             struct buf *fbp);
76 static void cluster_callback (struct bio *);
77 static void cluster_setram (struct buf *);
78
79 static int write_behind = 1;
80 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
81     "Cluster write-behind setting");
82 static int max_readahead = 2 * 1024 * 1024;
83 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0,
84     "Limit in bytes for desired cluster read-ahead");
85
86 extern vm_page_t        bogus_page;
87
88 extern int cluster_pbuf_freecnt;
89
90 /*
91  * This replaces bread.
92  *
93  * filesize     - read-ahead @ blksize will not cross this boundary
94  * loffset      - loffset for returned *bpp
95  * blksize      - blocksize for returned *bpp and read-ahead bps
96  * minreq       - minimum (not a hard minimum) in bytes, typically reflects
97  *                a higher level uio resid.
98  * maxreq       - maximum (sequential heuristic) in bytes (highet typ ~2MB)
99  * bpp          - return buffer (*bpp) for (loffset,blksize)
100  */
101 int
102 cluster_read(struct vnode *vp, off_t filesize, off_t loffset, 
103              int blksize, size_t minreq, size_t maxreq, struct buf **bpp)
104 {
105         struct buf *bp, *rbp, *reqbp;
106         off_t origoffset;
107         off_t doffset;
108         int error;
109         int i;
110         int maxra;
111         int maxrbuild;
112
113         error = 0;
114
115         /*
116          * Calculate the desired read-ahead in blksize'd blocks (maxra).
117          * To do this we calculate maxreq.
118          *
119          * maxreq typically starts out as a sequential heuristic.  If the
120          * high level uio/resid is bigger (minreq), we pop maxreq up to
121          * minreq.  This represents the case where random I/O is being
122          * performed by the userland is issuing big read()'s.
123          *
124          * Then we limit maxreq to max_readahead to ensure it is a reasonable
125          * value.
126          *
127          * Finally we must ensure that (loffset + maxreq) does not cross the
128          * boundary (filesize) for the current blocksize.  If we allowed it
129          * to cross we could end up with buffers past the boundary with the
130          * wrong block size (HAMMER large-data areas use mixed block sizes).
131          * minreq is also absolutely limited to filesize.
132          */
133         if (maxreq < minreq)
134                 maxreq = minreq;
135         /* minreq not used beyond this point */
136
137         if (maxreq > max_readahead) {
138                 maxreq = max_readahead;
139                 if (maxreq > 16 * 1024 * 1024)
140                         maxreq = 16 * 1024 * 1024;
141         }
142         if (maxreq < blksize)
143                 maxreq = blksize;
144         if (loffset + maxreq > filesize) {
145                 if (loffset > filesize)
146                         maxreq = 0;
147                 else
148                         maxreq = filesize - loffset;
149         }
150
151         maxra = (int)(maxreq / blksize);
152
153         /*
154          * Get the requested block.
155          */
156         *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
157         origoffset = loffset;
158
159         /*
160          * Calculate the maximum cluster size for a single I/O, used
161          * by cluster_rbuild().
162          */
163         maxrbuild = vmaxiosize(vp) / blksize;
164
165         /*
166          * if it is in the cache, then check to see if the reads have been
167          * sequential.  If they have, then try some read-ahead, otherwise
168          * back-off on prospective read-aheads.
169          */
170         if (bp->b_flags & B_CACHE) {
171                 /*
172                  * Not sequential, do not do any read-ahead
173                  */
174                 if (maxra <= 1)
175                         return 0;
176
177                 /*
178                  * No read-ahead mark, do not do any read-ahead
179                  * yet.
180                  */
181                 if ((bp->b_flags & B_RAM) == 0)
182                         return 0;
183
184                 /*
185                  * We hit a read-ahead-mark, figure out how much read-ahead
186                  * to do (maxra) and where to start (loffset).
187                  *
188                  * Shortcut the scan.  Typically the way this works is that
189                  * we've built up all the blocks inbetween except for the
190                  * last in previous iterations, so if the second-to-last
191                  * block is present we just skip ahead to it.
192                  *
193                  * This algorithm has O(1) cpu in the steady state no
194                  * matter how large maxra is.
195                  */
196                 bp->b_flags &= ~B_RAM;
197
198                 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
199                         i = maxra - 1;
200                 else
201                         i = 1;
202                 while (i < maxra) {
203                         if (findblk(vp, loffset + i * blksize,
204                                     FINDBLK_TEST) == NULL) {
205                                 break;
206                         }
207                         ++i;
208                 }
209
210                 /*
211                  * We got everything or everything is in the cache, no
212                  * point continuing.
213                  */
214                 if (i >= maxra)
215                         return 0;
216                 maxra -= i;
217                 loffset += i * blksize;
218                 reqbp = bp = NULL;
219         } else {
220                 __debugvar off_t firstread = bp->b_loffset;
221                 int nblks;
222
223                 /*
224                  * Set-up synchronous read for bp.
225                  */
226                 bp->b_cmd = BUF_CMD_READ;
227                 bp->b_bio1.bio_done = biodone_sync;
228                 bp->b_bio1.bio_flags |= BIO_SYNC;
229
230                 KASSERT(firstread != NOOFFSET, 
231                         ("cluster_read: no buffer offset"));
232
233                 /*
234                  * nblks is our cluster_rbuild request size, limited
235                  * primarily by the device.
236                  */
237                 if ((nblks = maxra) > maxrbuild)
238                         nblks = maxrbuild;
239
240                 if (nblks > 1) {
241                         int burstbytes;
242
243                         error = VOP_BMAP(vp, loffset, &doffset,
244                                          &burstbytes, NULL, BUF_CMD_READ);
245                         if (error)
246                                 goto single_block_read;
247                         if (nblks > burstbytes / blksize)
248                                 nblks = burstbytes / blksize;
249                         if (doffset == NOOFFSET)
250                                 goto single_block_read;
251                         if (nblks <= 1)
252                                 goto single_block_read;
253
254                         bp = cluster_rbuild(vp, filesize, loffset,
255                                             doffset, blksize, nblks, bp);
256                         loffset += bp->b_bufsize;
257                         maxra -= bp->b_bufsize / blksize;
258                 } else {
259 single_block_read:
260                         /*
261                          * If it isn't in the cache, then get a chunk from
262                          * disk if sequential, otherwise just get the block.
263                          */
264                         cluster_setram(bp);
265                         loffset += blksize;
266                         --maxra;
267                 }
268         }
269
270         /*
271          * If B_CACHE was not set issue bp.  bp will either be an
272          * asynchronous cluster buf or a synchronous single-buf.
273          * If it is a single buf it will be the same as reqbp.
274          *
275          * NOTE: Once an async cluster buf is issued bp becomes invalid.
276          */
277         if (bp) {
278 #if defined(CLUSTERDEBUG)
279                 if (rcluster)
280                         kprintf("S(%012jx,%d,%d)\n",
281                             (intmax_t)bp->b_loffset, bp->b_bcount, maxra);
282 #endif
283                 if ((bp->b_flags & B_CLUSTER) == 0)
284                         vfs_busy_pages(vp, bp);
285                 bp->b_flags &= ~(B_ERROR|B_INVAL);
286                 vn_strategy(vp, &bp->b_bio1);
287                 error = 0;
288                 /* bp invalid now */
289         }
290
291         /*
292          * If we have been doing sequential I/O, then do some read-ahead.
293          * The code above us should have positioned us at the next likely
294          * offset.
295          *
296          * Only mess with buffers which we can immediately lock.  HAMMER
297          * will do device-readahead irrespective of what the blocks
298          * represent.
299          */
300         while (error == 0 && maxra > 0) {
301                 int burstbytes;
302                 int tmp_error;
303                 int nblks;
304
305                 rbp = getblk(vp, loffset, blksize,
306                              GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
307                 if (rbp == NULL)
308                         goto no_read_ahead;
309                 if ((rbp->b_flags & B_CACHE)) {
310                         bqrelse(rbp);
311                         goto no_read_ahead;
312                 }
313
314                 /*
315                  * An error from the read-ahead bmap has nothing to do
316                  * with the caller's original request.
317                  */
318                 tmp_error = VOP_BMAP(vp, loffset, &doffset,
319                                      &burstbytes, NULL, BUF_CMD_READ);
320                 if (tmp_error || doffset == NOOFFSET) {
321                         rbp->b_flags |= B_INVAL;
322                         brelse(rbp);
323                         rbp = NULL;
324                         goto no_read_ahead;
325                 }
326                 if ((nblks = maxra) > maxrbuild)
327                         nblks = maxrbuild;
328                 if (nblks > burstbytes / blksize)
329                         nblks = burstbytes / blksize;
330
331                 /*
332                  * rbp: async read
333                  */
334                 rbp->b_cmd = BUF_CMD_READ;
335                 /*rbp->b_flags |= B_AGE*/;
336                 cluster_setram(rbp);
337
338                 if (nblks > 1) {
339                         rbp = cluster_rbuild(vp, filesize, loffset,
340                                              doffset, blksize, 
341                                              nblks, rbp);
342                 } else {
343                         rbp->b_bio2.bio_offset = doffset;
344                 }
345
346 #if defined(CLUSTERDEBUG)
347                 if (rcluster) {
348                         if (bp) {
349                                 kprintf("A+(%012jx,%d,%jd) "
350                                         "doff=%012jx minr=%zd ra=%d\n",
351                                     (intmax_t)loffset, rbp->b_bcount,
352                                     (intmax_t)(loffset - origoffset),
353                                     (intmax_t)doffset, minreq, maxra);
354                         } else {
355                                 kprintf("A-(%012jx,%d,%jd) "
356                                         "doff=%012jx minr=%zd ra=%d\n",
357                                     (intmax_t)rbp->b_loffset, rbp->b_bcount,
358                                     (intmax_t)(loffset - origoffset),
359                                     (intmax_t)doffset, minreq, maxra);
360                         }
361                 }
362 #endif
363                 rbp->b_flags &= ~(B_ERROR|B_INVAL);
364
365                 if ((rbp->b_flags & B_CLUSTER) == 0)
366                         vfs_busy_pages(vp, rbp);
367                 BUF_KERNPROC(rbp);
368                 loffset += rbp->b_bufsize;
369                 maxra -= rbp->b_bufsize / blksize;
370                 vn_strategy(vp, &rbp->b_bio1);
371                 /* rbp invalid now */
372         }
373
374         /*
375          * Wait for our original buffer to complete its I/O.  reqbp will
376          * be NULL if the original buffer was B_CACHE.  We are returning
377          * (*bpp) which is the same as reqbp when reqbp != NULL.
378          */
379 no_read_ahead:
380         if (reqbp) {
381                 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC);
382                 error = biowait(&reqbp->b_bio1, "clurd");
383         }
384         return (error);
385 }
386
387 /*
388  * If blocks are contiguous on disk, use this to provide clustered
389  * read ahead.  We will read as many blocks as possible sequentially
390  * and then parcel them up into logical blocks in the buffer hash table.
391  *
392  * This function either returns a cluster buf or it returns fbp.  fbp is
393  * already expected to be set up as a synchronous or asynchronous request.
394  *
395  * If a cluster buf is returned it will always be async.
396  */
397 static struct buf *
398 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset,
399                int blksize, int run, struct buf *fbp)
400 {
401         struct buf *bp, *tbp;
402         off_t boffset;
403         int i, j;
404         int maxiosize = vmaxiosize(vp);
405
406         /*
407          * avoid a division
408          */
409         while (loffset + run * blksize > filesize) {
410                 --run;
411         }
412
413         tbp = fbp;
414         tbp->b_bio2.bio_offset = doffset;
415         if((tbp->b_flags & B_MALLOC) ||
416             ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
417                 return tbp;
418         }
419
420         bp = trypbuf_kva(&cluster_pbuf_freecnt);
421         if (bp == NULL) {
422                 return tbp;
423         }
424
425         /*
426          * We are synthesizing a buffer out of vm_page_t's, but
427          * if the block size is not page aligned then the starting
428          * address may not be either.  Inherit the b_data offset
429          * from the original buffer.
430          */
431         bp->b_data = (char *)((vm_offset_t)bp->b_data |
432             ((vm_offset_t)tbp->b_data & PAGE_MASK));
433         bp->b_flags |= B_CLUSTER | B_VMIO;
434         bp->b_cmd = BUF_CMD_READ;
435         bp->b_bio1.bio_done = cluster_callback;         /* default to async */
436         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
437         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
438         bp->b_loffset = loffset;
439         bp->b_bio2.bio_offset = doffset;
440         KASSERT(bp->b_loffset != NOOFFSET,
441                 ("cluster_rbuild: no buffer offset"));
442
443         bp->b_bcount = 0;
444         bp->b_bufsize = 0;
445         bp->b_xio.xio_npages = 0;
446
447         for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) {
448                 if (i) {
449                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
450                             round_page(blksize) > maxiosize) {
451                                 break;
452                         }
453
454                         /*
455                          * Shortcut some checks and try to avoid buffers that
456                          * would block in the lock.  The same checks have to
457                          * be made again after we officially get the buffer.
458                          */
459                         tbp = getblk(vp, loffset + i * blksize, blksize,
460                                      GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
461                         if (tbp == NULL)
462                                 break;
463                         for (j = 0; j < tbp->b_xio.xio_npages; j++) {
464                                 if (tbp->b_xio.xio_pages[j]->valid)
465                                         break;
466                         }
467                         if (j != tbp->b_xio.xio_npages) {
468                                 bqrelse(tbp);
469                                 break;
470                         }
471
472                         /*
473                          * Stop scanning if the buffer is fuly valid 
474                          * (marked B_CACHE), or locked (may be doing a
475                          * background write), or if the buffer is not
476                          * VMIO backed.  The clustering code can only deal
477                          * with VMIO-backed buffers.
478                          */
479                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
480                             (tbp->b_flags & B_VMIO) == 0 ||
481                             (LIST_FIRST(&tbp->b_dep) != NULL &&
482                              buf_checkread(tbp))
483                         ) {
484                                 bqrelse(tbp);
485                                 break;
486                         }
487
488                         /*
489                          * The buffer must be completely invalid in order to
490                          * take part in the cluster.  If it is partially valid
491                          * then we stop.
492                          */
493                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
494                                 if (tbp->b_xio.xio_pages[j]->valid)
495                                         break;
496                         }
497                         if (j != tbp->b_xio.xio_npages) {
498                                 bqrelse(tbp);
499                                 break;
500                         }
501
502                         /*
503                          * Set a read-ahead mark as appropriate
504                          */
505                         if (i == 1 || i == (run - 1))
506                                 cluster_setram(tbp);
507
508                         /*
509                          * Depress the priority of buffers not explicitly
510                          * requested.
511                          */
512                         /* tbp->b_flags |= B_AGE; */
513
514                         /*
515                          * Set the block number if it isn't set, otherwise
516                          * if it is make sure it matches the block number we
517                          * expect.
518                          */
519                         if (tbp->b_bio2.bio_offset == NOOFFSET) {
520                                 tbp->b_bio2.bio_offset = boffset;
521                         } else if (tbp->b_bio2.bio_offset != boffset) {
522                                 brelse(tbp);
523                                 break;
524                         }
525                 }
526
527                 /*
528                  * The passed-in tbp (i == 0) will already be set up for
529                  * async or sync operation.  All other tbp's acquire in
530                  * our loop are set up for async operation.
531                  */
532                 tbp->b_cmd = BUF_CMD_READ;
533                 BUF_KERNPROC(tbp);
534                 cluster_append(&bp->b_bio1, tbp);
535                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
536                         vm_page_t m;
537                         m = tbp->b_xio.xio_pages[j];
538                         vm_page_io_start(m);
539                         vm_object_pip_add(m->object, 1);
540                         if ((bp->b_xio.xio_npages == 0) ||
541                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
542                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
543                                 bp->b_xio.xio_npages++;
544                         }
545                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
546                                 tbp->b_xio.xio_pages[j] = bogus_page;
547                 }
548                 /*
549                  * XXX shouldn't this be += size for both, like in 
550                  * cluster_wbuild()?
551                  *
552                  * Don't inherit tbp->b_bufsize as it may be larger due to
553                  * a non-page-aligned size.  Instead just aggregate using
554                  * 'size'.
555                  */
556                 if (tbp->b_bcount != blksize)
557                     kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize);
558                 if (tbp->b_bufsize != blksize)
559                     kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize);
560                 bp->b_bcount += blksize;
561                 bp->b_bufsize += blksize;
562         }
563
564         /*
565          * Fully valid pages in the cluster are already good and do not need
566          * to be re-read from disk.  Replace the page with bogus_page
567          */
568         for (j = 0; j < bp->b_xio.xio_npages; j++) {
569                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
570                     VM_PAGE_BITS_ALL) {
571                         bp->b_xio.xio_pages[j] = bogus_page;
572                 }
573         }
574         if (bp->b_bufsize > bp->b_kvasize) {
575                 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
576                     bp->b_bufsize, bp->b_kvasize);
577         }
578         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
579                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
580         BUF_KERNPROC(bp);
581         return (bp);
582 }
583
584 /*
585  * Cleanup after a clustered read or write.
586  * This is complicated by the fact that any of the buffers might have
587  * extra memory (if there were no empty buffer headers at allocbuf time)
588  * that we will need to shift around.
589  *
590  * The returned bio is &bp->b_bio1
591  */
592 void
593 cluster_callback(struct bio *bio)
594 {
595         struct buf *bp = bio->bio_buf;
596         struct buf *tbp;
597         int error = 0;
598
599         /*
600          * Must propogate errors to all the components.  A short read (EOF)
601          * is a critical error.
602          */
603         if (bp->b_flags & B_ERROR) {
604                 error = bp->b_error;
605         } else if (bp->b_bcount != bp->b_bufsize) {
606                 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
607         }
608
609         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
610         /*
611          * Move memory from the large cluster buffer into the component
612          * buffers and mark IO as done on these.  Since the memory map
613          * is the same, no actual copying is required.
614          */
615         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
616                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
617                 if (error) {
618                         tbp->b_flags |= B_ERROR | B_IODEBUG;
619                         tbp->b_error = error;
620                 } else {
621                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
622                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
623                         tbp->b_flags |= B_IODEBUG;
624                         /*
625                          * XXX the bdwrite()/bqrelse() issued during
626                          * cluster building clears B_RELBUF (see bqrelse()
627                          * comment).  If direct I/O was specified, we have
628                          * to restore it here to allow the buffer and VM
629                          * to be freed.
630                          */
631                         if (tbp->b_flags & B_DIRECT)
632                                 tbp->b_flags |= B_RELBUF;
633                 }
634                 biodone(&tbp->b_bio1);
635         }
636         relpbuf(bp, &cluster_pbuf_freecnt);
637 }
638
639 /*
640  *      cluster_wbuild_wb:
641  *
642  *      Implement modified write build for cluster.
643  *
644  *              write_behind = 0        write behind disabled
645  *              write_behind = 1        write behind normal (default)
646  *              write_behind = 2        write behind backed-off
647  */
648
649 static __inline int
650 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len)
651 {
652         int r = 0;
653
654         switch(write_behind) {
655         case 2:
656                 if (start_loffset < len)
657                         break;
658                 start_loffset -= len;
659                 /* fall through */
660         case 1:
661                 r = cluster_wbuild(vp, blksize, start_loffset, len);
662                 /* fall through */
663         default:
664                 /* fall through */
665                 break;
666         }
667         return(r);
668 }
669
670 /*
671  * Do clustered write for FFS.
672  *
673  * Three cases:
674  *      1. Write is not sequential (write asynchronously)
675  *      Write is sequential:
676  *      2.      beginning of cluster - begin cluster
677  *      3.      middle of a cluster - add to cluster
678  *      4.      end of a cluster - asynchronously write cluster
679  */
680 void
681 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount)
682 {
683         struct vnode *vp;
684         off_t loffset;
685         int maxclen, cursize;
686         int async;
687
688         vp = bp->b_vp;
689         if (vp->v_type == VREG)
690                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
691         else
692                 async = 0;
693         loffset = bp->b_loffset;
694         KASSERT(bp->b_loffset != NOOFFSET, 
695                 ("cluster_write: no buffer offset"));
696
697         /* Initialize vnode to beginning of file. */
698         if (loffset == 0)
699                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
700
701         if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize ||
702             bp->b_bio2.bio_offset == NOOFFSET ||
703             (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) {
704                 maxclen = vmaxiosize(vp);
705                 if (vp->v_clen != 0) {
706                         /*
707                          * Next block is not sequential.
708                          *
709                          * If we are not writing at end of file, the process
710                          * seeked to another point in the file since its last
711                          * write, or we have reached our maximum cluster size,
712                          * then push the previous cluster. Otherwise try
713                          * reallocating to make it sequential.
714                          *
715                          * Change to algorithm: only push previous cluster if
716                          * it was sequential from the point of view of the
717                          * seqcount heuristic, otherwise leave the buffer 
718                          * intact so we can potentially optimize the I/O
719                          * later on in the buf_daemon or update daemon
720                          * flush.
721                          */
722                         cursize = vp->v_lastw - vp->v_cstart + blksize;
723                         if (bp->b_loffset + blksize != filesize ||
724                             loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) {
725                                 if (!async && seqcount > 0) {
726                                         cluster_wbuild_wb(vp, blksize,
727                                                 vp->v_cstart, cursize);
728                                 }
729                         } else {
730                                 struct buf **bpp, **endbp;
731                                 struct cluster_save *buflist;
732
733                                 buflist = cluster_collectbufs(vp, bp, blksize);
734                                 endbp = &buflist->bs_children
735                                     [buflist->bs_nchildren - 1];
736                                 if (VOP_REALLOCBLKS(vp, buflist)) {
737                                         /*
738                                          * Failed, push the previous cluster
739                                          * if *really* writing sequentially
740                                          * in the logical file (seqcount > 1),
741                                          * otherwise delay it in the hopes that
742                                          * the low level disk driver can
743                                          * optimize the write ordering.
744                                          */
745                                         for (bpp = buflist->bs_children;
746                                              bpp < endbp; bpp++)
747                                                 brelse(*bpp);
748                                         kfree(buflist, M_SEGMENT);
749                                         if (seqcount > 1) {
750                                                 cluster_wbuild_wb(vp, 
751                                                     blksize, vp->v_cstart, 
752                                                     cursize);
753                                         }
754                                 } else {
755                                         /*
756                                          * Succeeded, keep building cluster.
757                                          */
758                                         for (bpp = buflist->bs_children;
759                                              bpp <= endbp; bpp++)
760                                                 bdwrite(*bpp);
761                                         kfree(buflist, M_SEGMENT);
762                                         vp->v_lastw = loffset;
763                                         vp->v_lasta = bp->b_bio2.bio_offset;
764                                         return;
765                                 }
766                         }
767                 }
768                 /*
769                  * Consider beginning a cluster. If at end of file, make
770                  * cluster as large as possible, otherwise find size of
771                  * existing cluster.
772                  */
773                 if ((vp->v_type == VREG) &&
774                     bp->b_loffset + blksize != filesize &&
775                     (bp->b_bio2.bio_offset == NOOFFSET) &&
776                     (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) ||
777                      bp->b_bio2.bio_offset == NOOFFSET)) {
778                         bawrite(bp);
779                         vp->v_clen = 0;
780                         vp->v_lasta = bp->b_bio2.bio_offset;
781                         vp->v_cstart = loffset + blksize;
782                         vp->v_lastw = loffset;
783                         return;
784                 }
785                 if (maxclen > blksize)
786                         vp->v_clen = maxclen - blksize;
787                 else
788                         vp->v_clen = 0;
789                 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
790                         vp->v_cstart = loffset + blksize;
791                         bawrite(bp);
792                 } else {        /* Wait for rest of cluster */
793                         vp->v_cstart = loffset;
794                         bdwrite(bp);
795                 }
796         } else if (loffset == vp->v_cstart + vp->v_clen) {
797                 /*
798                  * At end of cluster, write it out if seqcount tells us we
799                  * are operating sequentially, otherwise let the buf or
800                  * update daemon handle it.
801                  */
802                 bdwrite(bp);
803                 if (seqcount > 1)
804                         cluster_wbuild_wb(vp, blksize, vp->v_cstart,
805                                           vp->v_clen + blksize);
806                 vp->v_clen = 0;
807                 vp->v_cstart = loffset + blksize;
808         } else if (vm_page_count_severe()) {
809                 /*
810                  * We are low on memory, get it going NOW
811                  */
812                 bawrite(bp);
813         } else {
814                 /*
815                  * In the middle of a cluster, so just delay the I/O for now.
816                  */
817                 bdwrite(bp);
818         }
819         vp->v_lastw = loffset;
820         vp->v_lasta = bp->b_bio2.bio_offset;
821 }
822
823
824 /*
825  * This is an awful lot like cluster_rbuild...wish they could be combined.
826  * The last lbn argument is the current block on which I/O is being
827  * performed.  Check to see that it doesn't fall in the middle of
828  * the current block (if last_bp == NULL).
829  */
830 int
831 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes)
832 {
833         struct buf *bp, *tbp;
834         int i, j;
835         int totalwritten = 0;
836         int maxiosize = vmaxiosize(vp);
837
838         while (bytes > 0) {
839                 /*
840                  * If the buffer is not delayed-write (i.e. dirty), or it 
841                  * is delayed-write but either locked or inval, it cannot 
842                  * partake in the clustered write.
843                  */
844                 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK);
845                 if (tbp == NULL ||
846                     (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI ||
847                     (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) {
848                         if (tbp)
849                                 BUF_UNLOCK(tbp);
850                         start_loffset += blksize;
851                         bytes -= blksize;
852                         continue;
853                 }
854                 bremfree(tbp);
855                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
856
857                 /*
858                  * Extra memory in the buffer, punt on this buffer.
859                  * XXX we could handle this in most cases, but we would
860                  * have to push the extra memory down to after our max
861                  * possible cluster size and then potentially pull it back
862                  * up if the cluster was terminated prematurely--too much
863                  * hassle.
864                  */
865                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
866                     (tbp->b_bcount != tbp->b_bufsize) ||
867                     (tbp->b_bcount != blksize) ||
868                     (bytes == blksize) ||
869                     ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) {
870                         totalwritten += tbp->b_bufsize;
871                         bawrite(tbp);
872                         start_loffset += blksize;
873                         bytes -= blksize;
874                         continue;
875                 }
876
877                 /*
878                  * Set up the pbuf.  Track our append point with b_bcount
879                  * and b_bufsize.  b_bufsize is not used by the device but
880                  * our caller uses it to loop clusters and we use it to
881                  * detect a premature EOF on the block device.
882                  */
883                 bp->b_bcount = 0;
884                 bp->b_bufsize = 0;
885                 bp->b_xio.xio_npages = 0;
886                 bp->b_loffset = tbp->b_loffset;
887                 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
888
889                 /*
890                  * We are synthesizing a buffer out of vm_page_t's, but
891                  * if the block size is not page aligned then the starting
892                  * address may not be either.  Inherit the b_data offset
893                  * from the original buffer.
894                  */
895                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
896                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
897                 bp->b_flags &= ~B_ERROR;
898                 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
899                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
900                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
901                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
902
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 < bytes; (i += blksize), (start_loffset += blksize)) {
909                         if (i != 0) { /* If not the first buffer */
910                                 tbp = findblk(vp, start_loffset,
911                                               FINDBLK_NBLOCK);
912                                 /*
913                                  * Buffer not found or could not be locked
914                                  * non-blocking.
915                                  */
916                                 if (tbp == NULL)
917                                         break;
918
919                                 /*
920                                  * If it IS in core, but has different
921                                  * characteristics, then don't cluster
922                                  * with it.
923                                  */
924                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
925                                      B_INVAL | B_DELWRI | B_NEEDCOMMIT))
926                                     != (B_DELWRI | B_CLUSTEROK |
927                                      (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
928                                     (tbp->b_flags & B_LOCKED) ||
929                                     (LIST_FIRST(&tbp->b_dep) &&
930                                      buf_checkwrite(tbp))
931                                 ) {
932                                         BUF_UNLOCK(tbp);
933                                         break;
934                                 }
935
936                                 /*
937                                  * Check that the combined cluster
938                                  * would make sense with regard to pages
939                                  * and would not be too large
940                                  */
941                                 if ((tbp->b_bcount != blksize) ||
942                                   ((bp->b_bio2.bio_offset + i) !=
943                                     tbp->b_bio2.bio_offset) ||
944                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
945                                     (maxiosize / PAGE_SIZE))) {
946                                         BUF_UNLOCK(tbp);
947                                         break;
948                                 }
949                                 /*
950                                  * Ok, it's passed all the tests,
951                                  * so remove it from the free list
952                                  * and mark it busy. We will use it.
953                                  */
954                                 bremfree(tbp);
955                                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
956                         } /* end of code for non-first buffers only */
957
958                         /*
959                          * If the IO is via the VM then we do some
960                          * special VM hackery (yuck).  Since the buffer's
961                          * block size may not be page-aligned it is possible
962                          * for a page to be shared between two buffers.  We
963                          * have to get rid of the duplication when building
964                          * the cluster.
965                          */
966                         if (tbp->b_flags & B_VMIO) {
967                                 vm_page_t m;
968
969                                 if (i != 0) { /* if not first buffer */
970                                         for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
971                                                 m = tbp->b_xio.xio_pages[j];
972                                                 if (m->flags & PG_BUSY) {
973                                                         bqrelse(tbp);
974                                                         goto finishcluster;
975                                                 }
976                                         }
977                                 }
978                                         
979                                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
980                                         m = tbp->b_xio.xio_pages[j];
981                                         vm_page_io_start(m);
982                                         vm_object_pip_add(m->object, 1);
983                                         if ((bp->b_xio.xio_npages == 0) ||
984                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
985                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
986                                                 bp->b_xio.xio_npages++;
987                                         }
988                                 }
989                         }
990                         bp->b_bcount += blksize;
991                         bp->b_bufsize += blksize;
992
993                         bundirty(tbp);
994                         tbp->b_flags &= ~B_ERROR;
995                         tbp->b_cmd = BUF_CMD_WRITE;
996                         BUF_KERNPROC(tbp);
997                         cluster_append(&bp->b_bio1, tbp);
998
999                         /*
1000                          * check for latent dependencies to be handled 
1001                          */
1002                         if (LIST_FIRST(&tbp->b_dep) != NULL)
1003                                 buf_start(tbp);
1004                 }
1005         finishcluster:
1006                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1007                         (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
1008                 if (bp->b_bufsize > bp->b_kvasize) {
1009                         panic(
1010                             "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
1011                             bp->b_bufsize, bp->b_kvasize);
1012                 }
1013                 totalwritten += bp->b_bufsize;
1014                 bp->b_dirtyoff = 0;
1015                 bp->b_dirtyend = bp->b_bufsize;
1016                 bp->b_bio1.bio_done = cluster_callback;
1017                 bp->b_cmd = BUF_CMD_WRITE;
1018
1019                 vfs_busy_pages(vp, bp);
1020                 bsetrunningbufspace(bp, bp->b_bufsize);
1021                 BUF_KERNPROC(bp);
1022                 vn_strategy(vp, &bp->b_bio1);
1023
1024                 bytes -= i;
1025         }
1026         return totalwritten;
1027 }
1028
1029 /*
1030  * Collect together all the buffers in a cluster.
1031  * Plus add one additional buffer.
1032  */
1033 static struct cluster_save *
1034 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize)
1035 {
1036         struct cluster_save *buflist;
1037         struct buf *bp;
1038         off_t loffset;
1039         int i, len;
1040
1041         len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize;
1042         buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1043                          M_SEGMENT, M_WAITOK);
1044         buflist->bs_nchildren = 0;
1045         buflist->bs_children = (struct buf **) (buflist + 1);
1046         for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) {
1047                 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
1048                 buflist->bs_children[i] = bp;
1049                 if (bp->b_bio2.bio_offset == NOOFFSET) {
1050                         VOP_BMAP(bp->b_vp, bp->b_loffset,
1051                                  &bp->b_bio2.bio_offset,
1052                                  NULL, NULL, BUF_CMD_WRITE);
1053                 }
1054         }
1055         buflist->bs_children[i] = bp = last_bp;
1056         if (bp->b_bio2.bio_offset == NOOFFSET) {
1057                 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1058                          NULL, NULL, BUF_CMD_WRITE);
1059         }
1060         buflist->bs_nchildren = i + 1;
1061         return (buflist);
1062 }
1063
1064 void
1065 cluster_append(struct bio *bio, struct buf *tbp)
1066 {
1067         tbp->b_cluster_next = NULL;
1068         if (bio->bio_caller_info1.cluster_head == NULL) {
1069                 bio->bio_caller_info1.cluster_head = tbp;
1070                 bio->bio_caller_info2.cluster_tail = tbp;
1071         } else {
1072                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1073                 bio->bio_caller_info2.cluster_tail = tbp;
1074         }
1075 }
1076
1077 static
1078 void
1079 cluster_setram (struct buf *bp)
1080 {
1081         bp->b_flags |= B_RAM;
1082         if (bp->b_xio.xio_npages)
1083                 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM);
1084 }