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
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11 * notice, this list of conditions and the following disclaimer.
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13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
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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
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25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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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>
62 #if defined(CLUSTERDEBUG)
63 #include <sys/sysctl.h>
64 static int rcluster= 0;
65 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
68 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
70 static struct cluster_save *
71 cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
74 cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
75 off_t doffset, int blksize, int run,
77 static void cluster_callback (struct bio *);
78 static void cluster_setram (struct buf *);
80 static int write_behind = 1;
81 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, "");
82 static int max_readahead = 2 * 1024 * 1024;
83 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0, "");
85 extern vm_page_t bogus_page;
87 extern int cluster_pbuf_freecnt;
90 * This replaces bread.
92 * filesize - read-ahead @ blksize will not cross this boundary
93 * loffset - loffset for returned *bpp
94 * blksize - blocksize for returned *bpp and read-ahead bps
95 * minreq - minimum (not a hard minimum) in bytes, typically reflects
96 * a higher level uio resid.
97 * maxreq - maximum (sequential heuristic) in bytes (highet typ ~2MB)
98 * bpp - return buffer (*bpp) for (loffset,blksize)
101 cluster_read(struct vnode *vp, off_t filesize, off_t loffset,
102 int blksize, size_t minreq, size_t maxreq, struct buf **bpp)
104 struct buf *bp, *rbp, *reqbp;
115 * Calculate the desired read-ahead in blksize'd blocks (maxra).
116 * To do this we calculate maxreq.
118 * maxreq typically starts out as a sequential heuristic. If the
119 * high level uio/resid is bigger (minreq), we pop maxreq up to
120 * minreq. This represents the case where random I/O is being
121 * performed by the userland is issuing big read()'s.
123 * Then we limit maxreq to max_readahead to ensure it is a reasonable
126 * Finally we must ensure that loffset + maxreq does not cross the
127 * boundary (filesize) for the current blocksize. If we allowed it
128 * to cross we could end up with buffers past the boundary with the
129 * wrong block size (HAMMER large-data areas use mixed block sizes).
133 if (maxreq > max_readahead) {
134 maxreq = max_readahead;
135 if (maxreq > 16 * 1024 * 1024)
136 maxreq = 16 * 1024 * 1024;
138 if (maxreq < blksize)
140 if (loffset + maxreq > filesize) {
141 if (loffset > filesize)
144 maxreq = filesize - loffset;
147 maxra = (int)(maxreq / blksize);
150 * Get the requested block.
152 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
153 origoffset = loffset;
156 * Calculate the maximum cluster size for a single I/O, used
157 * by cluster_rbuild().
159 maxrbuild = vmaxiosize(vp) / blksize;
162 * if it is in the cache, then check to see if the reads have been
163 * sequential. If they have, then try some read-ahead, otherwise
164 * back-off on prospective read-aheads.
166 if (bp->b_flags & B_CACHE) {
168 * Not sequential, do not do any read-ahead
174 * No read-ahead mark, do not do any read-ahead
177 if ((bp->b_flags & B_RAM) == 0)
181 * We hit a read-ahead-mark, figure out how much read-ahead
182 * to do (maxra) and where to start (loffset).
184 * Shortcut the scan. Typically the way this works is that
185 * we've built up all the blocks inbetween except for the
186 * last in previous iterations, so if the second-to-last
187 * block is present we just skip ahead to it.
189 * This algorithm has O(1) cpu in the steady state no
190 * matter how large maxra is.
192 bp->b_flags &= ~B_RAM;
194 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
199 if (findblk(vp, loffset + i * blksize,
200 FINDBLK_TEST) == NULL) {
207 * We got everything or everything is in the cache, no
213 loffset += i * blksize;
216 off_t firstread = bp->b_loffset;
220 * Set-up synchronous read for bp.
222 bp->b_cmd = BUF_CMD_READ;
223 bp->b_bio1.bio_done = biodone_sync;
224 bp->b_bio1.bio_flags |= BIO_SYNC;
226 KASSERT(firstread != NOOFFSET,
227 ("cluster_read: no buffer offset"));
230 * nblks is our cluster_rbuild request size, limited
231 * primarily by the device.
233 if ((nblks = maxra) > maxrbuild)
239 error = VOP_BMAP(vp, loffset, &doffset,
240 &burstbytes, NULL, BUF_CMD_READ);
242 goto single_block_read;
243 if (nblks > burstbytes / blksize)
244 nblks = burstbytes / blksize;
245 if (doffset == NOOFFSET)
246 goto single_block_read;
248 goto single_block_read;
250 bp = cluster_rbuild(vp, filesize, loffset,
251 doffset, blksize, nblks, bp);
252 loffset += bp->b_bufsize;
253 maxra -= bp->b_bufsize / blksize;
257 * If it isn't in the cache, then get a chunk from
258 * disk if sequential, otherwise just get the block.
267 * If B_CACHE was not set issue bp. bp will either be an
268 * asynchronous cluster buf or a synchronous single-buf.
269 * If it is a single buf it will be the same as reqbp.
271 * NOTE: Once an async cluster buf is issued bp becomes invalid.
274 #if defined(CLUSTERDEBUG)
276 kprintf("S(%012jx,%d,%d)\n",
277 (intmax_t)bp->b_loffset, bp->b_bcount, maxra);
279 if ((bp->b_flags & B_CLUSTER) == 0)
280 vfs_busy_pages(vp, bp);
281 bp->b_flags &= ~(B_ERROR|B_INVAL);
282 vn_strategy(vp, &bp->b_bio1);
288 * If we have been doing sequential I/O, then do some read-ahead.
289 * The code above us should have positioned us at the next likely
292 * Only mess with buffers which we can immediately lock. HAMMER
293 * will do device-readahead irrespective of what the blocks
296 while (error == 0 && maxra > 0) {
301 rbp = getblk(vp, loffset, blksize,
302 GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
305 if ((rbp->b_flags & B_CACHE)) {
311 * An error from the read-ahead bmap has nothing to do
312 * with the caller's original request.
314 tmp_error = VOP_BMAP(vp, loffset, &doffset,
315 &burstbytes, NULL, BUF_CMD_READ);
316 if (tmp_error || doffset == NOOFFSET) {
317 rbp->b_flags |= B_INVAL;
322 if ((nblks = maxra) > maxrbuild)
324 if (nblks > burstbytes / blksize)
325 nblks = burstbytes / blksize;
330 rbp->b_cmd = BUF_CMD_READ;
331 /*rbp->b_flags |= B_AGE*/;
335 rbp = cluster_rbuild(vp, filesize, loffset,
339 rbp->b_bio2.bio_offset = doffset;
342 #if defined(CLUSTERDEBUG)
345 kprintf("A+(%012jx,%d,%jd) "
346 "doff=%012jx minr=%zd ra=%d\n",
347 (intmax_t)loffset, rbp->b_bcount,
348 (intmax_t)(loffset - origoffset),
349 (intmax_t)doffset, minreq, maxra);
351 kprintf("A-(%012jx,%d,%jd) "
352 "doff=%012jx minr=%zd ra=%d\n",
353 (intmax_t)rbp->b_loffset, rbp->b_bcount,
354 (intmax_t)(loffset - origoffset),
355 (intmax_t)doffset, minreq, maxra);
359 rbp->b_flags &= ~(B_ERROR|B_INVAL);
361 if ((rbp->b_flags & B_CLUSTER) == 0)
362 vfs_busy_pages(vp, rbp);
364 loffset += rbp->b_bufsize;
365 maxra -= rbp->b_bufsize / blksize;
366 vn_strategy(vp, &rbp->b_bio1);
367 /* rbp invalid now */
371 * Wait for our original buffer to complete its I/O. reqbp will
372 * be NULL if the original buffer was B_CACHE. We are returning
373 * (*bpp) which is the same as reqbp when reqbp != NULL.
377 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC);
378 error = biowait(&reqbp->b_bio1, "clurd");
384 * If blocks are contiguous on disk, use this to provide clustered
385 * read ahead. We will read as many blocks as possible sequentially
386 * and then parcel them up into logical blocks in the buffer hash table.
388 * This function either returns a cluster buf or it returns fbp. fbp is
389 * already expected to be set up as a synchronous or asynchronous request.
391 * If a cluster buf is returned it will always be async.
394 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset,
395 int blksize, int run, struct buf *fbp)
397 struct buf *bp, *tbp;
400 int maxiosize = vmaxiosize(vp);
405 while (loffset + run * blksize > filesize) {
410 tbp->b_bio2.bio_offset = doffset;
411 if((tbp->b_flags & B_MALLOC) ||
412 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
416 bp = trypbuf_kva(&cluster_pbuf_freecnt);
422 * We are synthesizing a buffer out of vm_page_t's, but
423 * if the block size is not page aligned then the starting
424 * address may not be either. Inherit the b_data offset
425 * from the original buffer.
427 bp->b_data = (char *)((vm_offset_t)bp->b_data |
428 ((vm_offset_t)tbp->b_data & PAGE_MASK));
429 bp->b_flags |= B_CLUSTER | B_VMIO;
430 bp->b_cmd = BUF_CMD_READ;
431 bp->b_bio1.bio_done = cluster_callback; /* default to async */
432 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
433 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
434 bp->b_loffset = loffset;
435 bp->b_bio2.bio_offset = doffset;
436 KASSERT(bp->b_loffset != NOOFFSET,
437 ("cluster_rbuild: no buffer offset"));
441 bp->b_xio.xio_npages = 0;
443 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) {
445 if ((bp->b_xio.xio_npages * PAGE_SIZE) +
446 round_page(blksize) > maxiosize) {
451 * Shortcut some checks and try to avoid buffers that
452 * would block in the lock. The same checks have to
453 * be made again after we officially get the buffer.
455 tbp = getblk(vp, loffset + i * blksize, blksize,
456 GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
459 for (j = 0; j < tbp->b_xio.xio_npages; j++) {
460 if (tbp->b_xio.xio_pages[j]->valid)
463 if (j != tbp->b_xio.xio_npages) {
469 * Stop scanning if the buffer is fuly valid
470 * (marked B_CACHE), or locked (may be doing a
471 * background write), or if the buffer is not
472 * VMIO backed. The clustering code can only deal
473 * with VMIO-backed buffers.
475 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
476 (tbp->b_flags & B_VMIO) == 0 ||
477 (LIST_FIRST(&tbp->b_dep) != NULL &&
485 * The buffer must be completely invalid in order to
486 * take part in the cluster. If it is partially valid
489 for (j = 0;j < tbp->b_xio.xio_npages; j++) {
490 if (tbp->b_xio.xio_pages[j]->valid)
493 if (j != tbp->b_xio.xio_npages) {
499 * Set a read-ahead mark as appropriate
501 if (i == 1 || i == (run - 1))
505 * Depress the priority of buffers not explicitly
508 /* tbp->b_flags |= B_AGE; */
511 * Set the block number if it isn't set, otherwise
512 * if it is make sure it matches the block number we
515 if (tbp->b_bio2.bio_offset == NOOFFSET) {
516 tbp->b_bio2.bio_offset = boffset;
517 } else if (tbp->b_bio2.bio_offset != boffset) {
524 * The passed-in tbp (i == 0) will already be set up for
525 * async or sync operation. All other tbp's acquire in
526 * our loop are set up for async operation.
528 tbp->b_cmd = BUF_CMD_READ;
530 cluster_append(&bp->b_bio1, tbp);
531 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
533 m = tbp->b_xio.xio_pages[j];
535 vm_object_pip_add(m->object, 1);
536 if ((bp->b_xio.xio_npages == 0) ||
537 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
538 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
539 bp->b_xio.xio_npages++;
541 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
542 tbp->b_xio.xio_pages[j] = bogus_page;
545 * XXX shouldn't this be += size for both, like in
548 * Don't inherit tbp->b_bufsize as it may be larger due to
549 * a non-page-aligned size. Instead just aggregate using
552 if (tbp->b_bcount != blksize)
553 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize);
554 if (tbp->b_bufsize != blksize)
555 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize);
556 bp->b_bcount += blksize;
557 bp->b_bufsize += blksize;
561 * Fully valid pages in the cluster are already good and do not need
562 * to be re-read from disk. Replace the page with bogus_page
564 for (j = 0; j < bp->b_xio.xio_npages; j++) {
565 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
567 bp->b_xio.xio_pages[j] = bogus_page;
570 if (bp->b_bufsize > bp->b_kvasize) {
571 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
572 bp->b_bufsize, bp->b_kvasize);
574 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
575 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
581 * Cleanup after a clustered read or write.
582 * This is complicated by the fact that any of the buffers might have
583 * extra memory (if there were no empty buffer headers at allocbuf time)
584 * that we will need to shift around.
586 * The returned bio is &bp->b_bio1
589 cluster_callback(struct bio *bio)
591 struct buf *bp = bio->bio_buf;
596 * Must propogate errors to all the components. A short read (EOF)
597 * is a critical error.
599 if (bp->b_flags & B_ERROR) {
601 } else if (bp->b_bcount != bp->b_bufsize) {
602 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
605 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
607 * Move memory from the large cluster buffer into the component
608 * buffers and mark IO as done on these. Since the memory map
609 * is the same, no actual copying is required.
611 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
612 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
614 tbp->b_flags |= B_ERROR;
615 tbp->b_error = error;
617 tbp->b_dirtyoff = tbp->b_dirtyend = 0;
618 tbp->b_flags &= ~(B_ERROR|B_INVAL);
620 * XXX the bdwrite()/bqrelse() issued during
621 * cluster building clears B_RELBUF (see bqrelse()
622 * comment). If direct I/O was specified, we have
623 * to restore it here to allow the buffer and VM
626 if (tbp->b_flags & B_DIRECT)
627 tbp->b_flags |= B_RELBUF;
629 biodone(&tbp->b_bio1);
631 relpbuf(bp, &cluster_pbuf_freecnt);
637 * Implement modified write build for cluster.
639 * write_behind = 0 write behind disabled
640 * write_behind = 1 write behind normal (default)
641 * write_behind = 2 write behind backed-off
645 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len)
649 switch(write_behind) {
651 if (start_loffset < len)
653 start_loffset -= len;
656 r = cluster_wbuild(vp, blksize, start_loffset, len);
666 * Do clustered write for FFS.
669 * 1. Write is not sequential (write asynchronously)
670 * Write is sequential:
671 * 2. beginning of cluster - begin cluster
672 * 3. middle of a cluster - add to cluster
673 * 4. end of a cluster - asynchronously write cluster
676 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount)
680 int maxclen, cursize;
684 if (vp->v_type == VREG)
685 async = vp->v_mount->mnt_flag & MNT_ASYNC;
688 loffset = bp->b_loffset;
689 KASSERT(bp->b_loffset != NOOFFSET,
690 ("cluster_write: no buffer offset"));
692 /* Initialize vnode to beginning of file. */
694 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
696 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize ||
697 bp->b_bio2.bio_offset == NOOFFSET ||
698 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) {
699 maxclen = vmaxiosize(vp);
700 if (vp->v_clen != 0) {
702 * Next block is not sequential.
704 * If we are not writing at end of file, the process
705 * seeked to another point in the file since its last
706 * write, or we have reached our maximum cluster size,
707 * then push the previous cluster. Otherwise try
708 * reallocating to make it sequential.
710 * Change to algorithm: only push previous cluster if
711 * it was sequential from the point of view of the
712 * seqcount heuristic, otherwise leave the buffer
713 * intact so we can potentially optimize the I/O
714 * later on in the buf_daemon or update daemon
717 cursize = vp->v_lastw - vp->v_cstart + blksize;
718 if (bp->b_loffset + blksize != filesize ||
719 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) {
720 if (!async && seqcount > 0) {
721 cluster_wbuild_wb(vp, blksize,
722 vp->v_cstart, cursize);
725 struct buf **bpp, **endbp;
726 struct cluster_save *buflist;
728 buflist = cluster_collectbufs(vp, bp, blksize);
729 endbp = &buflist->bs_children
730 [buflist->bs_nchildren - 1];
731 if (VOP_REALLOCBLKS(vp, buflist)) {
733 * Failed, push the previous cluster
734 * if *really* writing sequentially
735 * in the logical file (seqcount > 1),
736 * otherwise delay it in the hopes that
737 * the low level disk driver can
738 * optimize the write ordering.
740 for (bpp = buflist->bs_children;
743 kfree(buflist, M_SEGMENT);
745 cluster_wbuild_wb(vp,
746 blksize, vp->v_cstart,
751 * Succeeded, keep building cluster.
753 for (bpp = buflist->bs_children;
756 kfree(buflist, M_SEGMENT);
757 vp->v_lastw = loffset;
758 vp->v_lasta = bp->b_bio2.bio_offset;
764 * Consider beginning a cluster. If at end of file, make
765 * cluster as large as possible, otherwise find size of
768 if ((vp->v_type == VREG) &&
769 bp->b_loffset + blksize != filesize &&
770 (bp->b_bio2.bio_offset == NOOFFSET) &&
771 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) ||
772 bp->b_bio2.bio_offset == NOOFFSET)) {
775 vp->v_lasta = bp->b_bio2.bio_offset;
776 vp->v_cstart = loffset + blksize;
777 vp->v_lastw = loffset;
780 if (maxclen > blksize)
781 vp->v_clen = maxclen - blksize;
784 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
785 vp->v_cstart = loffset + blksize;
787 } else { /* Wait for rest of cluster */
788 vp->v_cstart = loffset;
791 } else if (loffset == vp->v_cstart + vp->v_clen) {
793 * At end of cluster, write it out if seqcount tells us we
794 * are operating sequentially, otherwise let the buf or
795 * update daemon handle it.
799 cluster_wbuild_wb(vp, blksize, vp->v_cstart,
800 vp->v_clen + blksize);
802 vp->v_cstart = loffset + blksize;
803 } else if (vm_page_count_severe()) {
805 * We are low on memory, get it going NOW
810 * In the middle of a cluster, so just delay the I/O for now.
814 vp->v_lastw = loffset;
815 vp->v_lasta = bp->b_bio2.bio_offset;
820 * This is an awful lot like cluster_rbuild...wish they could be combined.
821 * The last lbn argument is the current block on which I/O is being
822 * performed. Check to see that it doesn't fall in the middle of
823 * the current block (if last_bp == NULL).
826 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes)
828 struct buf *bp, *tbp;
830 int totalwritten = 0;
831 int maxiosize = vmaxiosize(vp);
835 * If the buffer is not delayed-write (i.e. dirty), or it
836 * is delayed-write but either locked or inval, it cannot
837 * partake in the clustered write.
839 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK);
841 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI ||
842 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) {
845 start_loffset += blksize;
850 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
853 * Extra memory in the buffer, punt on this buffer.
854 * XXX we could handle this in most cases, but we would
855 * have to push the extra memory down to after our max
856 * possible cluster size and then potentially pull it back
857 * up if the cluster was terminated prematurely--too much
860 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
861 (tbp->b_bcount != tbp->b_bufsize) ||
862 (tbp->b_bcount != blksize) ||
863 (bytes == blksize) ||
864 ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) {
865 totalwritten += tbp->b_bufsize;
867 start_loffset += blksize;
873 * Set up the pbuf. Track our append point with b_bcount
874 * and b_bufsize. b_bufsize is not used by the device but
875 * our caller uses it to loop clusters and we use it to
876 * detect a premature EOF on the block device.
880 bp->b_xio.xio_npages = 0;
881 bp->b_loffset = tbp->b_loffset;
882 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
885 * We are synthesizing a buffer out of vm_page_t's, but
886 * if the block size is not page aligned then the starting
887 * address may not be either. Inherit the b_data offset
888 * from the original buffer.
890 bp->b_data = (char *)((vm_offset_t)bp->b_data |
891 ((vm_offset_t)tbp->b_data & PAGE_MASK));
892 bp->b_flags &= ~B_ERROR;
893 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
894 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
895 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
896 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
899 * From this location in the file, scan forward to see
900 * if there are buffers with adjacent data that need to
901 * be written as well.
903 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) {
904 if (i != 0) { /* If not the first buffer */
905 tbp = findblk(vp, start_loffset,
908 * Buffer not found or could not be locked
915 * If it IS in core, but has different
916 * characteristics, then don't cluster
919 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
920 B_INVAL | B_DELWRI | B_NEEDCOMMIT))
921 != (B_DELWRI | B_CLUSTEROK |
922 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
923 (tbp->b_flags & B_LOCKED) ||
924 (LIST_FIRST(&tbp->b_dep) &&
932 * Check that the combined cluster
933 * would make sense with regard to pages
934 * and would not be too large
936 if ((tbp->b_bcount != blksize) ||
937 ((bp->b_bio2.bio_offset + i) !=
938 tbp->b_bio2.bio_offset) ||
939 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
940 (maxiosize / PAGE_SIZE))) {
945 * Ok, it's passed all the tests,
946 * so remove it from the free list
947 * and mark it busy. We will use it.
950 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
951 } /* end of code for non-first buffers only */
954 * If the IO is via the VM then we do some
955 * special VM hackery (yuck). Since the buffer's
956 * block size may not be page-aligned it is possible
957 * for a page to be shared between two buffers. We
958 * have to get rid of the duplication when building
961 if (tbp->b_flags & B_VMIO) {
964 if (i != 0) { /* if not first buffer */
965 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
966 m = tbp->b_xio.xio_pages[j];
967 if (m->flags & PG_BUSY) {
974 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
975 m = tbp->b_xio.xio_pages[j];
977 vm_object_pip_add(m->object, 1);
978 if ((bp->b_xio.xio_npages == 0) ||
979 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
980 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
981 bp->b_xio.xio_npages++;
985 bp->b_bcount += blksize;
986 bp->b_bufsize += blksize;
989 tbp->b_flags &= ~B_ERROR;
990 tbp->b_cmd = BUF_CMD_WRITE;
992 cluster_append(&bp->b_bio1, tbp);
995 * check for latent dependencies to be handled
997 if (LIST_FIRST(&tbp->b_dep) != NULL)
1001 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1002 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
1003 if (bp->b_bufsize > bp->b_kvasize) {
1005 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
1006 bp->b_bufsize, bp->b_kvasize);
1008 totalwritten += bp->b_bufsize;
1010 bp->b_dirtyend = bp->b_bufsize;
1011 bp->b_bio1.bio_done = cluster_callback;
1012 bp->b_cmd = BUF_CMD_WRITE;
1014 vfs_busy_pages(vp, bp);
1015 bp->b_runningbufspace = bp->b_bufsize;
1016 if (bp->b_runningbufspace) {
1017 runningbufspace += bp->b_runningbufspace;
1021 vn_strategy(vp, &bp->b_bio1);
1025 return totalwritten;
1029 * Collect together all the buffers in a cluster.
1030 * Plus add one additional buffer.
1032 static struct cluster_save *
1033 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize)
1035 struct cluster_save *buflist;
1040 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize;
1041 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1042 M_SEGMENT, M_WAITOK);
1043 buflist->bs_nchildren = 0;
1044 buflist->bs_children = (struct buf **) (buflist + 1);
1045 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) {
1046 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
1047 buflist->bs_children[i] = bp;
1048 if (bp->b_bio2.bio_offset == NOOFFSET) {
1049 VOP_BMAP(bp->b_vp, bp->b_loffset,
1050 &bp->b_bio2.bio_offset,
1051 NULL, NULL, BUF_CMD_WRITE);
1054 buflist->bs_children[i] = bp = last_bp;
1055 if (bp->b_bio2.bio_offset == NOOFFSET) {
1056 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1057 NULL, NULL, BUF_CMD_WRITE);
1059 buflist->bs_nchildren = i + 1;
1064 cluster_append(struct bio *bio, struct buf *tbp)
1066 tbp->b_cluster_next = NULL;
1067 if (bio->bio_caller_info1.cluster_head == NULL) {
1068 bio->bio_caller_info1.cluster_head = tbp;
1069 bio->bio_caller_info2.cluster_tail = tbp;
1071 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1072 bio->bio_caller_info2.cluster_tail = tbp;
1078 cluster_setram (struct buf *bp)
1080 bp->b_flags |= B_RAM;
1081 if (bp->b_xio.xio_npages)
1082 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM);