3 * The Regents of the University of California. All rights reserved.
4 * Modifications/enhancements:
5 * Copyright (c) 1995 John S. Dyson. All rights reserved.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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.
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
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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
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 $
40 #include "opt_debug_cluster.h"
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.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>
53 #include <vm/vm_object.h>
54 #include <vm/vm_page.h>
55 #include <sys/sysctl.h>
57 #include <vm/vm_page2.h>
59 #include <machine/limits.h>
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, "");
67 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
69 static struct cluster_save *
70 cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
73 cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
74 off_t doffset, int blksize, int run,
76 static void cluster_callback (struct bio *);
77 static void cluster_setram (struct buf *);
79 static int write_behind = 1;
80 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, "");
82 extern vm_page_t bogus_page;
84 extern int cluster_pbuf_freecnt;
87 * Maximum number of blocks for read-ahead.
92 * This replaces bread.
95 cluster_read(struct vnode *vp, off_t filesize, off_t loffset,
96 int blksize, size_t resid, int seqcount, struct buf **bpp)
98 struct buf *bp, *rbp, *reqbp;
103 int maxra, racluster;
107 totread = (resid > INT_MAX) ? INT_MAX : (int)resid;
110 * racluster - calculate maximum cluster IO size (limited by
111 * backing block device).
113 * Try to limit the amount of read-ahead by a few ad-hoc parameters.
116 * NOTE! The BMAP operations may involve synchronous I/O so we
117 * really want several cluster IOs in progress to absorb
120 racluster = vmaxiosize(vp) / blksize;
121 maxra = 2 * racluster + (totread / blksize);
124 if (maxra > nbuf / 8)
128 * Get the requested block.
130 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
131 origoffset = loffset;
134 * if it is in the cache, then check to see if the reads have been
135 * sequential. If they have, then try some read-ahead, otherwise
136 * back-off on prospective read-aheads.
138 if (bp->b_flags & B_CACHE) {
140 * Not sequential, do not do any read-ahead
142 seqcount -= (bp->b_bufsize + BKVASIZE - 1) / BKVASIZE;
143 if (seqcount <= 0 || maxra == 0)
147 * No read-ahead mark, do not do any read-ahead
150 if ((bp->b_flags & B_RAM) == 0)
154 * We hit a read-ahead-mark, figure out how much read-ahead
155 * to do (maxra) and where to start (loffset).
157 * Shortcut the scan. Typically the way this works is that
158 * we've built up all the blocks inbetween except for the
159 * last in previous iterations, so if the second-to-last
160 * block is present we just skip ahead to it.
162 * This algorithm has O(1) cpu in the steady state no
163 * matter how large maxra is.
165 bp->b_flags &= ~B_RAM;
167 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
172 if (findblk(vp, loffset + i * blksize,
173 FINDBLK_TEST) == NULL) {
181 loffset += i * blksize;
184 off_t firstread = bp->b_loffset;
188 * Set-up synchronous read for bp.
190 bp->b_cmd = BUF_CMD_READ;
191 bp->b_bio1.bio_done = biodone_sync;
192 bp->b_bio1.bio_flags |= BIO_SYNC;
194 KASSERT(firstread != NOOFFSET,
195 ("cluster_read: no buffer offset"));
196 if (firstread + totread > filesize)
197 totread = (int)(filesize - firstread);
198 nblks = totread / blksize;
202 if (nblks > racluster)
205 error = VOP_BMAP(vp, loffset, &doffset,
206 &burstbytes, NULL, BUF_CMD_READ);
208 goto single_block_read;
209 if (doffset == NOOFFSET)
210 goto single_block_read;
211 if (burstbytes < blksize * 2)
212 goto single_block_read;
213 if (nblks > burstbytes / blksize)
214 nblks = burstbytes / blksize;
216 bp = cluster_rbuild(vp, filesize, loffset,
217 doffset, blksize, nblks, bp);
218 loffset += bp->b_bufsize;
219 maxra -= (bp->b_bufsize - blksize) / blksize;
223 * if it isn't in the cache, then get a chunk from
224 * disk if sequential, otherwise just get the block.
232 * If B_CACHE was not set issue bp. bp will either be an
233 * asynchronous cluster buf or a synchronous single-buf.
234 * If it is a single buf it will be the same as reqbp.
236 * NOTE: Once an async cluster buf is issued bp becomes invalid.
239 #if defined(CLUSTERDEBUG)
241 kprintf("S(%lld,%d,%d)\n",
242 bp->b_loffset, bp->b_bcount, seqcount);
244 if ((bp->b_flags & B_CLUSTER) == 0)
245 vfs_busy_pages(vp, bp);
246 bp->b_flags &= ~(B_ERROR|B_INVAL);
247 seqcount -= (bp->b_bufsize + BKVASIZE - 1) / BKVASIZE;
248 vn_strategy(vp, &bp->b_bio1);
254 * If we have been doing sequential I/O, then do some read-ahead.
255 * The code above us should have positioned us at the next likely
258 * Only mess with buffers which we can immediately lock. HAMMER
259 * will do device-readahead irrespective of what the blocks
262 while (!error && seqcount > 0 && maxra > 0 &&
263 loffset + blksize <= filesize) {
269 rbp = getblk(vp, loffset, blksize,
270 GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
273 if ((rbp->b_flags & B_CACHE)) {
279 * An error from the read-ahead bmap has nothing to do
280 * with the caller's original request.
282 tmp_error = VOP_BMAP(vp, loffset, &doffset,
283 &burstbytes, NULL, BUF_CMD_READ);
284 if (tmp_error || doffset == NOOFFSET) {
285 rbp->b_flags |= B_INVAL;
290 ntoread = burstbytes / blksize;
291 nblksread = (totread + blksize - 1) / blksize;
292 if (seqcount < nblksread)
293 seqcount = nblksread;
294 if (ntoread > seqcount)
300 rbp->b_cmd = BUF_CMD_READ;
301 /*rbp->b_flags |= B_AGE*/;
305 rbp = cluster_rbuild(vp, filesize, loffset,
309 rbp->b_bio2.bio_offset = doffset;
311 seqcount -= (rbp->b_bufsize + BKVASIZE - 1) / BKVASIZE;
312 #if defined(CLUSTERDEBUG)
315 kprintf("A+(%lld,%d,%lld,%d) ra=%d\n",
316 rbp->b_loffset, rbp->b_bcount,
317 rbp->b_loffset - origoffset,
320 kprintf("A-(%lld,%d,%lld,%d) ra=%d\n",
321 rbp->b_loffset, rbp->b_bcount,
322 rbp->b_loffset - origoffset,
326 rbp->b_flags &= ~(B_ERROR|B_INVAL);
328 if ((rbp->b_flags & B_CLUSTER) == 0)
329 vfs_busy_pages(vp, rbp);
331 loffset += rbp->b_bufsize;
332 maxra -= rbp->b_bufsize / blksize;
333 vn_strategy(vp, &rbp->b_bio1);
334 /* rbp invalid now */
338 * Wait for our original buffer to complete its I/O. reqbp will
339 * be NULL if the original buffer was B_CACHE. We are returning
340 * (*bpp) which is the same as reqbp when reqbp != NULL.
344 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC);
345 error = biowait(&reqbp->b_bio1, "clurd");
351 * If blocks are contiguous on disk, use this to provide clustered
352 * read ahead. We will read as many blocks as possible sequentially
353 * and then parcel them up into logical blocks in the buffer hash table.
355 * This function either returns a cluster buf or it returns fbp. fbp is
356 * already expected to be set up as a synchronous or asynchronous request.
358 * If a cluster buf is returned it will always be async.
361 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset,
362 int blksize, int run, struct buf *fbp)
364 struct buf *bp, *tbp;
367 int maxiosize = vmaxiosize(vp);
372 while (loffset + run * blksize > filesize) {
377 tbp->b_bio2.bio_offset = doffset;
378 if((tbp->b_flags & B_MALLOC) ||
379 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
383 bp = trypbuf(&cluster_pbuf_freecnt);
389 * We are synthesizing a buffer out of vm_page_t's, but
390 * if the block size is not page aligned then the starting
391 * address may not be either. Inherit the b_data offset
392 * from the original buffer.
394 bp->b_data = (char *)((vm_offset_t)bp->b_data |
395 ((vm_offset_t)tbp->b_data & PAGE_MASK));
396 bp->b_flags |= B_CLUSTER | B_VMIO;
397 bp->b_cmd = BUF_CMD_READ;
398 bp->b_bio1.bio_done = cluster_callback; /* default to async */
399 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
400 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
401 bp->b_loffset = loffset;
402 bp->b_bio2.bio_offset = doffset;
403 KASSERT(bp->b_loffset != NOOFFSET,
404 ("cluster_rbuild: no buffer offset"));
408 bp->b_xio.xio_npages = 0;
410 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) {
412 if ((bp->b_xio.xio_npages * PAGE_SIZE) +
413 round_page(blksize) > maxiosize) {
418 * Shortcut some checks and try to avoid buffers that
419 * would block in the lock. The same checks have to
420 * be made again after we officially get the buffer.
422 tbp = getblk(vp, loffset + i * blksize, blksize,
423 GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
426 for (j = 0; j < tbp->b_xio.xio_npages; j++) {
427 if (tbp->b_xio.xio_pages[j]->valid)
430 if (j != tbp->b_xio.xio_npages) {
436 * Stop scanning if the buffer is fuly valid
437 * (marked B_CACHE), or locked (may be doing a
438 * background write), or if the buffer is not
439 * VMIO backed. The clustering code can only deal
440 * with VMIO-backed buffers.
442 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
443 (tbp->b_flags & B_VMIO) == 0 ||
444 (LIST_FIRST(&tbp->b_dep) != NULL &&
452 * The buffer must be completely invalid in order to
453 * take part in the cluster. If it is partially valid
456 for (j = 0;j < tbp->b_xio.xio_npages; j++) {
457 if (tbp->b_xio.xio_pages[j]->valid)
460 if (j != tbp->b_xio.xio_npages) {
466 * Set a read-ahead mark as appropriate
468 if (i == 1 || i == (run - 1))
472 * Depress the priority of buffers not explicitly
475 /* tbp->b_flags |= B_AGE; */
478 * Set the block number if it isn't set, otherwise
479 * if it is make sure it matches the block number we
482 if (tbp->b_bio2.bio_offset == NOOFFSET) {
483 tbp->b_bio2.bio_offset = boffset;
484 } else if (tbp->b_bio2.bio_offset != boffset) {
491 * The passed-in tbp (i == 0) will already be set up for
492 * async or sync operation. All other tbp's acquire in
493 * our loop are set up for async operation.
495 tbp->b_cmd = BUF_CMD_READ;
497 cluster_append(&bp->b_bio1, tbp);
498 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
500 m = tbp->b_xio.xio_pages[j];
502 vm_object_pip_add(m->object, 1);
503 if ((bp->b_xio.xio_npages == 0) ||
504 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
505 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
506 bp->b_xio.xio_npages++;
508 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
509 tbp->b_xio.xio_pages[j] = bogus_page;
512 * XXX shouldn't this be += size for both, like in
515 * Don't inherit tbp->b_bufsize as it may be larger due to
516 * a non-page-aligned size. Instead just aggregate using
519 if (tbp->b_bcount != blksize)
520 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize);
521 if (tbp->b_bufsize != blksize)
522 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize);
523 bp->b_bcount += blksize;
524 bp->b_bufsize += blksize;
528 * Fully valid pages in the cluster are already good and do not need
529 * to be re-read from disk. Replace the page with bogus_page
531 for (j = 0; j < bp->b_xio.xio_npages; j++) {
532 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
534 bp->b_xio.xio_pages[j] = bogus_page;
537 if (bp->b_bufsize > bp->b_kvasize) {
538 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
539 bp->b_bufsize, bp->b_kvasize);
541 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
542 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
548 * Cleanup after a clustered read or write.
549 * This is complicated by the fact that any of the buffers might have
550 * extra memory (if there were no empty buffer headers at allocbuf time)
551 * that we will need to shift around.
553 * The returned bio is &bp->b_bio1
556 cluster_callback(struct bio *bio)
558 struct buf *bp = bio->bio_buf;
563 * Must propogate errors to all the components. A short read (EOF)
564 * is a critical error.
566 if (bp->b_flags & B_ERROR) {
568 } else if (bp->b_bcount != bp->b_bufsize) {
569 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
572 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
574 * Move memory from the large cluster buffer into the component
575 * buffers and mark IO as done on these. Since the memory map
576 * is the same, no actual copying is required.
578 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
579 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
581 tbp->b_flags |= B_ERROR;
582 tbp->b_error = error;
584 tbp->b_dirtyoff = tbp->b_dirtyend = 0;
585 tbp->b_flags &= ~(B_ERROR|B_INVAL);
587 * XXX the bdwrite()/bqrelse() issued during
588 * cluster building clears B_RELBUF (see bqrelse()
589 * comment). If direct I/O was specified, we have
590 * to restore it here to allow the buffer and VM
593 if (tbp->b_flags & B_DIRECT)
594 tbp->b_flags |= B_RELBUF;
596 biodone(&tbp->b_bio1);
598 relpbuf(bp, &cluster_pbuf_freecnt);
604 * Implement modified write build for cluster.
606 * write_behind = 0 write behind disabled
607 * write_behind = 1 write behind normal (default)
608 * write_behind = 2 write behind backed-off
612 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len)
616 switch(write_behind) {
618 if (start_loffset < len)
620 start_loffset -= len;
623 r = cluster_wbuild(vp, blksize, start_loffset, len);
633 * Do clustered write for FFS.
636 * 1. Write is not sequential (write asynchronously)
637 * Write is sequential:
638 * 2. beginning of cluster - begin cluster
639 * 3. middle of a cluster - add to cluster
640 * 4. end of a cluster - asynchronously write cluster
643 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount)
647 int maxclen, cursize;
651 if (vp->v_type == VREG)
652 async = vp->v_mount->mnt_flag & MNT_ASYNC;
655 loffset = bp->b_loffset;
656 KASSERT(bp->b_loffset != NOOFFSET,
657 ("cluster_write: no buffer offset"));
659 /* Initialize vnode to beginning of file. */
661 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
663 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize ||
664 bp->b_bio2.bio_offset == NOOFFSET ||
665 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) {
666 maxclen = vmaxiosize(vp);
667 if (vp->v_clen != 0) {
669 * Next block is not sequential.
671 * If we are not writing at end of file, the process
672 * seeked to another point in the file since its last
673 * write, or we have reached our maximum cluster size,
674 * then push the previous cluster. Otherwise try
675 * reallocating to make it sequential.
677 * Change to algorithm: only push previous cluster if
678 * it was sequential from the point of view of the
679 * seqcount heuristic, otherwise leave the buffer
680 * intact so we can potentially optimize the I/O
681 * later on in the buf_daemon or update daemon
684 cursize = vp->v_lastw - vp->v_cstart + blksize;
685 if (bp->b_loffset + blksize != filesize ||
686 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) {
687 if (!async && seqcount > 0) {
688 cluster_wbuild_wb(vp, blksize,
689 vp->v_cstart, cursize);
692 struct buf **bpp, **endbp;
693 struct cluster_save *buflist;
695 buflist = cluster_collectbufs(vp, bp, blksize);
696 endbp = &buflist->bs_children
697 [buflist->bs_nchildren - 1];
698 if (VOP_REALLOCBLKS(vp, buflist)) {
700 * Failed, push the previous cluster
701 * if *really* writing sequentially
702 * in the logical file (seqcount > 1),
703 * otherwise delay it in the hopes that
704 * the low level disk driver can
705 * optimize the write ordering.
707 for (bpp = buflist->bs_children;
710 kfree(buflist, M_SEGMENT);
712 cluster_wbuild_wb(vp,
713 blksize, vp->v_cstart,
718 * Succeeded, keep building cluster.
720 for (bpp = buflist->bs_children;
723 kfree(buflist, M_SEGMENT);
724 vp->v_lastw = loffset;
725 vp->v_lasta = bp->b_bio2.bio_offset;
731 * Consider beginning a cluster. If at end of file, make
732 * cluster as large as possible, otherwise find size of
735 if ((vp->v_type == VREG) &&
736 bp->b_loffset + blksize != filesize &&
737 (bp->b_bio2.bio_offset == NOOFFSET) &&
738 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) ||
739 bp->b_bio2.bio_offset == NOOFFSET)) {
742 vp->v_lasta = bp->b_bio2.bio_offset;
743 vp->v_cstart = loffset + blksize;
744 vp->v_lastw = loffset;
747 if (maxclen > blksize)
748 vp->v_clen = maxclen - blksize;
751 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
752 vp->v_cstart = loffset + blksize;
754 } else { /* Wait for rest of cluster */
755 vp->v_cstart = loffset;
758 } else if (loffset == vp->v_cstart + vp->v_clen) {
760 * At end of cluster, write it out if seqcount tells us we
761 * are operating sequentially, otherwise let the buf or
762 * update daemon handle it.
766 cluster_wbuild_wb(vp, blksize, vp->v_cstart,
767 vp->v_clen + blksize);
769 vp->v_cstart = loffset + blksize;
770 } else if (vm_page_count_severe()) {
772 * We are low on memory, get it going NOW
777 * In the middle of a cluster, so just delay the I/O for now.
781 vp->v_lastw = loffset;
782 vp->v_lasta = bp->b_bio2.bio_offset;
787 * This is an awful lot like cluster_rbuild...wish they could be combined.
788 * The last lbn argument is the current block on which I/O is being
789 * performed. Check to see that it doesn't fall in the middle of
790 * the current block (if last_bp == NULL).
793 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes)
795 struct buf *bp, *tbp;
797 int totalwritten = 0;
798 int maxiosize = vmaxiosize(vp);
802 * If the buffer is not delayed-write (i.e. dirty), or it
803 * is delayed-write but either locked or inval, it cannot
804 * partake in the clustered write.
806 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK);
808 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI ||
809 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) {
812 start_loffset += blksize;
817 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
820 * Extra memory in the buffer, punt on this buffer.
821 * XXX we could handle this in most cases, but we would
822 * have to push the extra memory down to after our max
823 * possible cluster size and then potentially pull it back
824 * up if the cluster was terminated prematurely--too much
827 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
828 (tbp->b_bcount != tbp->b_bufsize) ||
829 (tbp->b_bcount != blksize) ||
830 (bytes == blksize) ||
831 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
832 totalwritten += tbp->b_bufsize;
834 start_loffset += blksize;
840 * Set up the pbuf. Track our append point with b_bcount
841 * and b_bufsize. b_bufsize is not used by the device but
842 * our caller uses it to loop clusters and we use it to
843 * detect a premature EOF on the block device.
847 bp->b_xio.xio_npages = 0;
848 bp->b_loffset = tbp->b_loffset;
849 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
852 * We are synthesizing a buffer out of vm_page_t's, but
853 * if the block size is not page aligned then the starting
854 * address may not be either. Inherit the b_data offset
855 * from the original buffer.
857 bp->b_data = (char *)((vm_offset_t)bp->b_data |
858 ((vm_offset_t)tbp->b_data & PAGE_MASK));
859 bp->b_flags &= ~B_ERROR;
860 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
861 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
862 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
863 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
866 * From this location in the file, scan forward to see
867 * if there are buffers with adjacent data that need to
868 * be written as well.
870 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) {
871 if (i != 0) { /* If not the first buffer */
872 tbp = findblk(vp, start_loffset,
875 * Buffer not found or could not be locked
882 * If it IS in core, but has different
883 * characteristics, then don't cluster
886 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
887 B_INVAL | B_DELWRI | B_NEEDCOMMIT))
888 != (B_DELWRI | B_CLUSTEROK |
889 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
890 (tbp->b_flags & B_LOCKED) ||
891 (LIST_FIRST(&tbp->b_dep) &&
899 * Check that the combined cluster
900 * would make sense with regard to pages
901 * and would not be too large
903 if ((tbp->b_bcount != blksize) ||
904 ((bp->b_bio2.bio_offset + i) !=
905 tbp->b_bio2.bio_offset) ||
906 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
907 (maxiosize / PAGE_SIZE))) {
912 * Ok, it's passed all the tests,
913 * so remove it from the free list
914 * and mark it busy. We will use it.
917 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
918 } /* end of code for non-first buffers only */
921 * If the IO is via the VM then we do some
922 * special VM hackery (yuck). Since the buffer's
923 * block size may not be page-aligned it is possible
924 * for a page to be shared between two buffers. We
925 * have to get rid of the duplication when building
928 if (tbp->b_flags & B_VMIO) {
931 if (i != 0) { /* if not first buffer */
932 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
933 m = tbp->b_xio.xio_pages[j];
934 if (m->flags & PG_BUSY) {
941 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
942 m = tbp->b_xio.xio_pages[j];
944 vm_object_pip_add(m->object, 1);
945 if ((bp->b_xio.xio_npages == 0) ||
946 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
947 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
948 bp->b_xio.xio_npages++;
952 bp->b_bcount += blksize;
953 bp->b_bufsize += blksize;
956 tbp->b_flags &= ~B_ERROR;
957 tbp->b_cmd = BUF_CMD_WRITE;
959 cluster_append(&bp->b_bio1, tbp);
962 * check for latent dependencies to be handled
964 if (LIST_FIRST(&tbp->b_dep) != NULL)
968 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
969 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
970 if (bp->b_bufsize > bp->b_kvasize) {
972 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
973 bp->b_bufsize, bp->b_kvasize);
975 totalwritten += bp->b_bufsize;
977 bp->b_dirtyend = bp->b_bufsize;
978 bp->b_bio1.bio_done = cluster_callback;
979 bp->b_cmd = BUF_CMD_WRITE;
981 vfs_busy_pages(vp, bp);
982 bp->b_runningbufspace = bp->b_bufsize;
983 if (bp->b_runningbufspace) {
984 runningbufspace += bp->b_runningbufspace;
988 vn_strategy(vp, &bp->b_bio1);
996 * Collect together all the buffers in a cluster.
997 * Plus add one additional buffer.
999 static struct cluster_save *
1000 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize)
1002 struct cluster_save *buflist;
1007 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize;
1008 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1009 M_SEGMENT, M_WAITOK);
1010 buflist->bs_nchildren = 0;
1011 buflist->bs_children = (struct buf **) (buflist + 1);
1012 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) {
1013 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
1014 buflist->bs_children[i] = bp;
1015 if (bp->b_bio2.bio_offset == NOOFFSET) {
1016 VOP_BMAP(bp->b_vp, bp->b_loffset,
1017 &bp->b_bio2.bio_offset,
1018 NULL, NULL, BUF_CMD_WRITE);
1021 buflist->bs_children[i] = bp = last_bp;
1022 if (bp->b_bio2.bio_offset == NOOFFSET) {
1023 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1024 NULL, NULL, BUF_CMD_WRITE);
1026 buflist->bs_nchildren = i + 1;
1031 cluster_append(struct bio *bio, struct buf *tbp)
1033 tbp->b_cluster_next = NULL;
1034 if (bio->bio_caller_info1.cluster_head == NULL) {
1035 bio->bio_caller_info1.cluster_head = tbp;
1036 bio->bio_caller_info2.cluster_tail = tbp;
1038 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1039 bio->bio_caller_info2.cluster_tail = tbp;
1045 cluster_setram (struct buf *bp)
1047 bp->b_flags |= B_RAM;
1048 if (bp->b_xio.xio_npages)
1049 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM);