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Diffstat (limited to 'sys/kern/vfs_cluster.c')
| -rw-r--r-- | sys/kern/vfs_cluster.c | 1024 |
1 files changed, 1024 insertions, 0 deletions
diff --git a/sys/kern/vfs_cluster.c b/sys/kern/vfs_cluster.c new file mode 100644 index 0000000..ad0b55d --- /dev/null +++ b/sys/kern/vfs_cluster.c @@ -0,0 +1,1024 @@ +/*- + * Copyright (c) 1993 + * The Regents of the University of California. All rights reserved. + * Modifications/enhancements: + * Copyright (c) 1995 John S. Dyson. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94 + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_debug_cluster.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/kernel.h> +#include <sys/proc.h> +#include <sys/bio.h> +#include <sys/buf.h> +#include <sys/vnode.h> +#include <sys/malloc.h> +#include <sys/mount.h> +#include <sys/resourcevar.h> +#include <sys/vmmeter.h> +#include <vm/vm.h> +#include <vm/vm_object.h> +#include <vm/vm_page.h> +#include <sys/sysctl.h> + +#if defined(CLUSTERDEBUG) +static int rcluster= 0; +SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, + "Debug VFS clustering code"); +#endif + +static MALLOC_DEFINE(M_SEGMENT, "cluster_save buffer", "cluster_save buffer"); + +static struct cluster_save * + cluster_collectbufs(struct vnode *vp, struct buf *last_bp); +static struct buf * + cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, + daddr_t blkno, long size, int run, struct buf *fbp); + +static int write_behind = 1; +SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, + "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); + +static int read_max = 8; +SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, + "Cluster read-ahead max block count"); + +/* Page expended to mark partially backed buffers */ +extern vm_page_t bogus_page; + +/* + * Number of physical bufs (pbufs) this subsystem is allowed. + * Manipulated by vm_pager.c + */ +extern int cluster_pbuf_freecnt; + +/* + * Read data to a buf, including read-ahead if we find this to be beneficial. + * cluster_read replaces bread. + */ +int +cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp) + struct vnode *vp; + u_quad_t filesize; + daddr_t lblkno; + long size; + struct ucred *cred; + long totread; + int seqcount; + struct buf **bpp; +{ + struct buf *bp, *rbp, *reqbp; + daddr_t blkno, origblkno; + int maxra, racluster; + int error, ncontig; + int i; + + error = 0; + + /* + * Try to limit the amount of read-ahead by a few + * ad-hoc parameters. This needs work!!! + */ + racluster = vp->v_mount->mnt_iosize_max / size; + maxra = seqcount; + maxra = min(read_max, maxra); + maxra = min(nbuf/8, maxra); + if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) + maxra = (filesize / size) - lblkno; + + /* + * get the requested block + */ + *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, 0); + origblkno = lblkno; + + /* + * if it is in the cache, then check to see if the reads have been + * sequential. If they have, then try some read-ahead, otherwise + * back-off on prospective read-aheads. + */ + if (bp->b_flags & B_CACHE) { + if (!seqcount) { + return 0; + } else if ((bp->b_flags & B_RAM) == 0) { + return 0; + } else { + int s; + bp->b_flags &= ~B_RAM; + /* + * We do the spl here so that there is no window + * between the incore and the b_usecount increment + * below. We opt to keep the spl out of the loop + * for efficiency. + */ + s = splbio(); + VI_LOCK(vp); + for (i = 1; i < maxra; i++) { + /* + * Stop if the buffer does not exist or it + * is invalid (about to go away?) + */ + rbp = gbincore(vp, lblkno+i); + if (rbp == NULL || (rbp->b_flags & B_INVAL)) + break; + + /* + * Set another read-ahead mark so we know + * to check again. + */ + if (((i % racluster) == (racluster - 1)) || + (i == (maxra - 1))) + rbp->b_flags |= B_RAM; + } + VI_UNLOCK(vp); + splx(s); + if (i >= maxra) { + return 0; + } + lblkno += i; + } + reqbp = bp = NULL; + /* + * If it isn't in the cache, then get a chunk from + * disk if sequential, otherwise just get the block. + */ + } else { + off_t firstread = bp->b_offset; + int nblks; + + KASSERT(bp->b_offset != NOOFFSET, + ("cluster_read: no buffer offset")); + + ncontig = 0; + + /* + * Compute the total number of blocks that we should read + * synchronously. + */ + if (firstread + totread > filesize) + totread = filesize - firstread; + nblks = howmany(totread, size); + if (nblks > racluster) + nblks = racluster; + + /* + * Now compute the number of contiguous blocks. + */ + if (nblks > 1) { + error = VOP_BMAP(vp, lblkno, NULL, + &blkno, &ncontig, NULL); + /* + * If this failed to map just do the original block. + */ + if (error || blkno == -1) + ncontig = 0; + } + + /* + * If we have contiguous data available do a cluster + * otherwise just read the requested block. + */ + if (ncontig) { + /* Account for our first block. */ + ncontig = min(ncontig + 1, nblks); + if (ncontig < nblks) + nblks = ncontig; + bp = cluster_rbuild(vp, filesize, lblkno, + blkno, size, nblks, bp); + lblkno += (bp->b_bufsize / size); + } else { + bp->b_flags |= B_RAM; + bp->b_iocmd = BIO_READ; + lblkno += 1; + } + } + + /* + * handle the synchronous read so that it is available ASAP. + */ + if (bp) { + if ((bp->b_flags & B_CLUSTER) == 0) { + vfs_busy_pages(bp, 0); + } + bp->b_flags &= ~B_INVAL; + bp->b_ioflags &= ~BIO_ERROR; + if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) + BUF_KERNPROC(bp); + error = VOP_STRATEGY(vp, bp); + curproc->p_stats->p_ru.ru_inblock++; + if (error) + return (error); + } + + /* + * If we have been doing sequential I/O, then do some read-ahead. + */ + while (lblkno < (origblkno + maxra)) { + error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); + if (error) + break; + + if (blkno == -1) + break; + + /* + * We could throttle ncontig here by maxra but we might as + * well read the data if it is contiguous. We're throttled + * by racluster anyway. + */ + if (ncontig) { + ncontig = min(ncontig + 1, racluster); + rbp = cluster_rbuild(vp, filesize, lblkno, blkno, + size, ncontig, NULL); + lblkno += (rbp->b_bufsize / size); + if (rbp->b_flags & B_DELWRI) { + bqrelse(rbp); + continue; + } + } else { + rbp = getblk(vp, lblkno, size, 0, 0, 0); + lblkno += 1; + if (rbp->b_flags & B_DELWRI) { + bqrelse(rbp); + continue; + } + rbp->b_flags |= B_ASYNC | B_RAM; + rbp->b_iocmd = BIO_READ; + rbp->b_blkno = blkno; + } + if (rbp->b_flags & B_CACHE) { + rbp->b_flags &= ~B_ASYNC; + bqrelse(rbp); + continue; + } + if ((rbp->b_flags & B_CLUSTER) == 0) { + vfs_busy_pages(rbp, 0); + } + rbp->b_flags &= ~B_INVAL; + rbp->b_ioflags &= ~BIO_ERROR; + if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) + BUF_KERNPROC(rbp); + (void) VOP_STRATEGY(vp, rbp); + curproc->p_stats->p_ru.ru_inblock++; + } + + if (reqbp) + return (bufwait(reqbp)); + else + return (error); +} + +/* + * If blocks are contiguous on disk, use this to provide clustered + * read ahead. We will read as many blocks as possible sequentially + * and then parcel them up into logical blocks in the buffer hash table. + */ +static struct buf * +cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp) + struct vnode *vp; + u_quad_t filesize; + daddr_t lbn; + daddr_t blkno; + long size; + int run; + struct buf *fbp; +{ + struct buf *bp, *tbp; + daddr_t bn; + int i, inc, j; + + GIANT_REQUIRED; + + KASSERT(size == vp->v_mount->mnt_stat.f_iosize, + ("cluster_rbuild: size %ld != filesize %ld\n", + size, vp->v_mount->mnt_stat.f_iosize)); + + /* + * avoid a division + */ + while ((u_quad_t) size * (lbn + run) > filesize) { + --run; + } + + if (fbp) { + tbp = fbp; + tbp->b_iocmd = BIO_READ; + } else { + tbp = getblk(vp, lbn, size, 0, 0, 0); + if (tbp->b_flags & B_CACHE) + return tbp; + tbp->b_flags |= B_ASYNC | B_RAM; + tbp->b_iocmd = BIO_READ; + } + + tbp->b_blkno = blkno; + if( (tbp->b_flags & B_MALLOC) || + ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) + return tbp; + + bp = trypbuf(&cluster_pbuf_freecnt); + if (bp == 0) + return tbp; + + /* + * We are synthesizing a buffer out of vm_page_t's, but + * if the block size is not page aligned then the starting + * address may not be either. Inherit the b_data offset + * from the original buffer. + */ + bp->b_data = (char *)((vm_offset_t)bp->b_data | + ((vm_offset_t)tbp->b_data & PAGE_MASK)); + bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; + bp->b_iocmd = BIO_READ; + bp->b_iodone = cluster_callback; + bp->b_blkno = blkno; + bp->b_lblkno = lbn; + bp->b_offset = tbp->b_offset; + KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); + pbgetvp(vp, bp); + + TAILQ_INIT(&bp->b_cluster.cluster_head); + + bp->b_bcount = 0; + bp->b_bufsize = 0; + bp->b_npages = 0; + + inc = btodb(size); + for (bn = blkno, i = 0; i < run; ++i, bn += inc) { + if (i != 0) { + if ((bp->b_npages * PAGE_SIZE) + + round_page(size) > vp->v_mount->mnt_iosize_max) { + break; + } + + tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT); + + /* Don't wait around for locked bufs. */ + if (tbp == NULL) + break; + + /* + * Stop scanning if the buffer is fully valid + * (marked B_CACHE), or locked (may be doing a + * background write), or if the buffer is not + * VMIO backed. The clustering code can only deal + * with VMIO-backed buffers. + */ + if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || + (tbp->b_flags & B_VMIO) == 0) { + bqrelse(tbp); + break; + } + + /* + * The buffer must be completely invalid in order to + * take part in the cluster. If it is partially valid + * then we stop. + */ + for (j = 0;j < tbp->b_npages; j++) { + if (tbp->b_pages[j]->valid) + break; + } + if (j != tbp->b_npages) { + bqrelse(tbp); + break; + } + + /* + * Set a read-ahead mark as appropriate + */ + if ((fbp && (i == 1)) || (i == (run - 1))) + tbp->b_flags |= B_RAM; + + /* + * Set the buffer up for an async read (XXX should + * we do this only if we do not wind up brelse()ing?). + * Set the block number if it isn't set, otherwise + * if it is make sure it matches the block number we + * expect. + */ + tbp->b_flags |= B_ASYNC; + tbp->b_iocmd = BIO_READ; + if (tbp->b_blkno == tbp->b_lblkno) { + tbp->b_blkno = bn; + } else if (tbp->b_blkno != bn) { + brelse(tbp); + break; + } + } + /* + * XXX fbp from caller may not be B_ASYNC, but we are going + * to biodone() it in cluster_callback() anyway + */ + BUF_KERNPROC(tbp); + TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, + tbp, b_cluster.cluster_entry); + if (tbp->b_object != NULL) + VM_OBJECT_LOCK(tbp->b_object); + vm_page_lock_queues(); + for (j = 0; j < tbp->b_npages; j += 1) { + vm_page_t m; + m = tbp->b_pages[j]; + vm_page_io_start(m); + vm_object_pip_add(m->object, 1); + if ((bp->b_npages == 0) || + (bp->b_pages[bp->b_npages-1] != m)) { + bp->b_pages[bp->b_npages] = m; + bp->b_npages++; + } + if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) + tbp->b_pages[j] = bogus_page; + } + vm_page_unlock_queues(); + if (tbp->b_object != NULL) + VM_OBJECT_UNLOCK(tbp->b_object); + /* + * XXX shouldn't this be += size for both, like in + * cluster_wbuild()? + * + * Don't inherit tbp->b_bufsize as it may be larger due to + * a non-page-aligned size. Instead just aggregate using + * 'size'. + */ + if (tbp->b_bcount != size) + printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); + if (tbp->b_bufsize != size) + printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); + bp->b_bcount += size; + bp->b_bufsize += size; + } + + /* + * Fully valid pages in the cluster are already good and do not need + * to be re-read from disk. Replace the page with bogus_page + */ + for (j = 0; j < bp->b_npages; j++) { + if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) == + VM_PAGE_BITS_ALL) { + bp->b_pages[j] = bogus_page; + } + } + if (bp->b_bufsize > bp->b_kvasize) + panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", + bp->b_bufsize, bp->b_kvasize); + bp->b_kvasize = bp->b_bufsize; + + pmap_qenter(trunc_page((vm_offset_t) bp->b_data), + (vm_page_t *)bp->b_pages, bp->b_npages); + return (bp); +} + +/* + * Cleanup after a clustered read or write. + * This is complicated by the fact that any of the buffers might have + * extra memory (if there were no empty buffer headers at allocbuf time) + * that we will need to shift around. + */ +void +cluster_callback(bp) + struct buf *bp; +{ + struct buf *nbp, *tbp; + int error = 0; + + GIANT_REQUIRED; + + /* + * Must propogate errors to all the components. + */ + if (bp->b_ioflags & BIO_ERROR) + error = bp->b_error; + + pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); + /* + * Move memory from the large cluster buffer into the component + * buffers and mark IO as done on these. + */ + for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); + tbp; tbp = nbp) { + nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); + if (error) { + tbp->b_ioflags |= BIO_ERROR; + tbp->b_error = error; + } else { + tbp->b_dirtyoff = tbp->b_dirtyend = 0; + tbp->b_flags &= ~B_INVAL; + tbp->b_ioflags &= ~BIO_ERROR; + /* + * XXX the bdwrite()/bqrelse() issued during + * cluster building clears B_RELBUF (see bqrelse() + * comment). If direct I/O was specified, we have + * to restore it here to allow the buffer and VM + * to be freed. + */ + if (tbp->b_flags & B_DIRECT) + tbp->b_flags |= B_RELBUF; + } + bufdone(tbp); + } + relpbuf(bp, &cluster_pbuf_freecnt); +} + +/* + * cluster_wbuild_wb: + * + * Implement modified write build for cluster. + * + * write_behind = 0 write behind disabled + * write_behind = 1 write behind normal (default) + * write_behind = 2 write behind backed-off + */ + +static __inline int +cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) +{ + int r = 0; + + switch(write_behind) { + case 2: + if (start_lbn < len) + break; + start_lbn -= len; + /* FALLTHROUGH */ + case 1: + r = cluster_wbuild(vp, size, start_lbn, len); + /* FALLTHROUGH */ + default: + /* FALLTHROUGH */ + break; + } + return(r); +} + +/* + * Do clustered write for FFS. + * + * Three cases: + * 1. Write is not sequential (write asynchronously) + * Write is sequential: + * 2. beginning of cluster - begin cluster + * 3. middle of a cluster - add to cluster + * 4. end of a cluster - asynchronously write cluster + */ +void +cluster_write(bp, filesize, seqcount) + struct buf *bp; + u_quad_t filesize; + int seqcount; +{ + struct vnode *vp; + daddr_t lbn; + int maxclen, cursize; + int lblocksize; + int async; + + vp = bp->b_vp; + if (vp->v_type == VREG) { + async = vp->v_mount->mnt_flag & MNT_ASYNC; + lblocksize = vp->v_mount->mnt_stat.f_iosize; + } else { + async = 0; + lblocksize = bp->b_bufsize; + } + lbn = bp->b_lblkno; + KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); + + /* Initialize vnode to beginning of file. */ + if (lbn == 0) + vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; + + if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || + (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { + maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; + if (vp->v_clen != 0) { + /* + * Next block is not sequential. + * + * If we are not writing at end of file, the process + * seeked to another point in the file since its last + * write, or we have reached our maximum cluster size, + * then push the previous cluster. Otherwise try + * reallocating to make it sequential. + * + * Change to algorithm: only push previous cluster if + * it was sequential from the point of view of the + * seqcount heuristic, otherwise leave the buffer + * intact so we can potentially optimize the I/O + * later on in the buf_daemon or update daemon + * flush. + */ + cursize = vp->v_lastw - vp->v_cstart + 1; + if (((u_quad_t) bp->b_offset + lblocksize) != filesize || + lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { + if (!async && seqcount > 0) { + cluster_wbuild_wb(vp, lblocksize, + vp->v_cstart, cursize); + } + } else { + struct buf **bpp, **endbp; + struct cluster_save *buflist; + + buflist = cluster_collectbufs(vp, bp); + endbp = &buflist->bs_children + [buflist->bs_nchildren - 1]; + if (VOP_REALLOCBLKS(vp, buflist)) { + /* + * Failed, push the previous cluster + * if *really* writing sequentially + * in the logical file (seqcount > 1), + * otherwise delay it in the hopes that + * the low level disk driver can + * optimize the write ordering. + */ + for (bpp = buflist->bs_children; + bpp < endbp; bpp++) + brelse(*bpp); + free(buflist, M_SEGMENT); + if (seqcount > 1) { + cluster_wbuild_wb(vp, + lblocksize, vp->v_cstart, + cursize); + } + } else { + /* + * Succeeded, keep building cluster. + */ + for (bpp = buflist->bs_children; + bpp <= endbp; bpp++) + bdwrite(*bpp); + free(buflist, M_SEGMENT); + vp->v_lastw = lbn; + vp->v_lasta = bp->b_blkno; + return; + } + } + } + /* + * Consider beginning a cluster. If at end of file, make + * cluster as large as possible, otherwise find size of + * existing cluster. + */ + if ((vp->v_type == VREG) && + ((u_quad_t) bp->b_offset + lblocksize) != filesize && + (bp->b_blkno == bp->b_lblkno) && + (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || + bp->b_blkno == -1)) { + bawrite(bp); + vp->v_clen = 0; + vp->v_lasta = bp->b_blkno; + vp->v_cstart = lbn + 1; + vp->v_lastw = lbn; + return; + } + vp->v_clen = maxclen; + if (!async && maxclen == 0) { /* I/O not contiguous */ + vp->v_cstart = lbn + 1; + bawrite(bp); + } else { /* Wait for rest of cluster */ + vp->v_cstart = lbn; + bdwrite(bp); + } + } else if (lbn == vp->v_cstart + vp->v_clen) { + /* + * At end of cluster, write it out if seqcount tells us we + * are operating sequentially, otherwise let the buf or + * update daemon handle it. + */ + bdwrite(bp); + if (seqcount > 1) + cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); + vp->v_clen = 0; + vp->v_cstart = lbn + 1; + } else if (vm_page_count_severe()) { + /* + * We are low on memory, get it going NOW + */ + bawrite(bp); + } else { + /* + * In the middle of a cluster, so just delay the I/O for now. + */ + bdwrite(bp); + } + vp->v_lastw = lbn; + vp->v_lasta = bp->b_blkno; +} + + +/* + * This is an awful lot like cluster_rbuild...wish they could be combined. + * The last lbn argument is the current block on which I/O is being + * performed. Check to see that it doesn't fall in the middle of + * the current block (if last_bp == NULL). + */ +int +cluster_wbuild(vp, size, start_lbn, len) + struct vnode *vp; + long size; + daddr_t start_lbn; + int len; +{ + struct buf *bp, *tbp; + int i, j, s; + int totalwritten = 0; + int dbsize = btodb(size); + + GIANT_REQUIRED; + + while (len > 0) { + s = splbio(); + /* + * If the buffer is not delayed-write (i.e. dirty), or it + * is delayed-write but either locked or inval, it cannot + * partake in the clustered write. + */ + VI_LOCK(vp); + if ((tbp = gbincore(vp, start_lbn)) == NULL) { + VI_UNLOCK(vp); + ++start_lbn; + --len; + splx(s); + continue; + } + if (BUF_LOCK(tbp, + LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, VI_MTX(vp))) { + ++start_lbn; + --len; + splx(s); + continue; + } + if ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != + B_DELWRI) { + BUF_UNLOCK(tbp); + ++start_lbn; + --len; + splx(s); + continue; + } + bremfree(tbp); + tbp->b_flags &= ~B_DONE; + splx(s); + + /* + * Extra memory in the buffer, punt on this buffer. + * XXX we could handle this in most cases, but we would + * have to push the extra memory down to after our max + * possible cluster size and then potentially pull it back + * up if the cluster was terminated prematurely--too much + * hassle. + */ + if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != + (B_CLUSTEROK | B_VMIO)) || + (tbp->b_bcount != tbp->b_bufsize) || + (tbp->b_bcount != size) || + (len == 1) || + ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { + totalwritten += tbp->b_bufsize; + bawrite(tbp); + ++start_lbn; + --len; + continue; + } + + /* + * We got a pbuf to make the cluster in. + * so initialise it. + */ + TAILQ_INIT(&bp->b_cluster.cluster_head); + bp->b_bcount = 0; + bp->b_magic = tbp->b_magic; + bp->b_op = tbp->b_op; + bp->b_bufsize = 0; + bp->b_npages = 0; + if (tbp->b_wcred != NOCRED) + bp->b_wcred = crhold(tbp->b_wcred); + + bp->b_blkno = tbp->b_blkno; + bp->b_lblkno = tbp->b_lblkno; + bp->b_offset = tbp->b_offset; + + /* + * We are synthesizing a buffer out of vm_page_t's, but + * if the block size is not page aligned then the starting + * address may not be either. Inherit the b_data offset + * from the original buffer. + */ + bp->b_data = (char *)((vm_offset_t)bp->b_data | + ((vm_offset_t)tbp->b_data & PAGE_MASK)); + bp->b_flags |= B_CLUSTER | + (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); + bp->b_iodone = cluster_callback; + pbgetvp(vp, bp); + /* + * From this location in the file, scan forward to see + * if there are buffers with adjacent data that need to + * be written as well. + */ + for (i = 0; i < len; ++i, ++start_lbn) { + if (i != 0) { /* If not the first buffer */ + s = splbio(); + /* + * If the adjacent data is not even in core it + * can't need to be written. + */ + VI_LOCK(vp); + if ((tbp = gbincore(vp, start_lbn)) == NULL) { + VI_UNLOCK(vp); + splx(s); + break; + } + + /* + * If it IS in core, but has different + * characteristics, or is locked (which + * means it could be undergoing a background + * I/O or be in a weird state), then don't + * cluster with it. + */ + if (BUF_LOCK(tbp, + LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, + VI_MTX(vp))) { + splx(s); + break; + } + + if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | + B_INVAL | B_DELWRI | B_NEEDCOMMIT)) + != (B_DELWRI | B_CLUSTEROK | + (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || + (tbp->b_flags & B_LOCKED) || + tbp->b_wcred != bp->b_wcred) { + BUF_UNLOCK(tbp); + splx(s); + break; + } + + /* + * Check that the combined cluster + * would make sense with regard to pages + * and would not be too large + */ + if ((tbp->b_bcount != size) || + ((bp->b_blkno + (dbsize * i)) != + tbp->b_blkno) || + ((tbp->b_npages + bp->b_npages) > + (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { + BUF_UNLOCK(tbp); + splx(s); + break; + } + /* + * Ok, it's passed all the tests, + * so remove it from the free list + * and mark it busy. We will use it. + */ + bremfree(tbp); + tbp->b_flags &= ~B_DONE; + splx(s); + } /* end of code for non-first buffers only */ + /* check for latent dependencies to be handled */ + if ((LIST_FIRST(&tbp->b_dep)) != NULL) { + tbp->b_iocmd = BIO_WRITE; + buf_start(tbp); + } + /* + * If the IO is via the VM then we do some + * special VM hackery (yuck). Since the buffer's + * block size may not be page-aligned it is possible + * for a page to be shared between two buffers. We + * have to get rid of the duplication when building + * the cluster. + */ + if (tbp->b_flags & B_VMIO) { + vm_page_t m; + + if (i != 0) { /* if not first buffer */ + for (j = 0; j < tbp->b_npages; j += 1) { + m = tbp->b_pages[j]; + if (m->flags & PG_BUSY) { + bqrelse(tbp); + goto finishcluster; + } + } + } + if (tbp->b_object != NULL) + VM_OBJECT_LOCK(tbp->b_object); + vm_page_lock_queues(); + for (j = 0; j < tbp->b_npages; j += 1) { + m = tbp->b_pages[j]; + vm_page_io_start(m); + vm_object_pip_add(m->object, 1); + if ((bp->b_npages == 0) || + (bp->b_pages[bp->b_npages - 1] != m)) { + bp->b_pages[bp->b_npages] = m; + bp->b_npages++; + } + } + vm_page_unlock_queues(); + if (tbp->b_object != NULL) + VM_OBJECT_UNLOCK(tbp->b_object); + } + bp->b_bcount += size; + bp->b_bufsize += size; + + s = splbio(); + bundirty(tbp); + tbp->b_flags &= ~B_DONE; + tbp->b_ioflags &= ~BIO_ERROR; + tbp->b_flags |= B_ASYNC; + tbp->b_iocmd = BIO_WRITE; + reassignbuf(tbp, tbp->b_vp); /* put on clean list */ + VI_LOCK(tbp->b_vp); + ++tbp->b_vp->v_numoutput; + VI_UNLOCK(tbp->b_vp); + splx(s); + BUF_KERNPROC(tbp); + TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, + tbp, b_cluster.cluster_entry); + } + finishcluster: + pmap_qenter(trunc_page((vm_offset_t) bp->b_data), + (vm_page_t *) bp->b_pages, bp->b_npages); + if (bp->b_bufsize > bp->b_kvasize) + panic( + "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", + bp->b_bufsize, bp->b_kvasize); + bp->b_kvasize = bp->b_bufsize; + totalwritten += bp->b_bufsize; + bp->b_dirtyoff = 0; + bp->b_dirtyend = bp->b_bufsize; + bawrite(bp); + + len -= i; + } + return totalwritten; +} + +/* + * Collect together all the buffers in a cluster. + * Plus add one additional buffer. + */ +static struct cluster_save * +cluster_collectbufs(vp, last_bp) + struct vnode *vp; + struct buf *last_bp; +{ + struct cluster_save *buflist; + struct buf *bp; + daddr_t lbn; + int i, len; + + len = vp->v_lastw - vp->v_cstart + 1; + buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), + M_SEGMENT, M_WAITOK); + buflist->bs_nchildren = 0; + buflist->bs_children = (struct buf **) (buflist + 1); + for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { + (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp); + buflist->bs_children[i] = bp; + if (bp->b_blkno == bp->b_lblkno) + VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, + NULL, NULL); + } + buflist->bs_children[i] = bp = last_bp; + if (bp->b_blkno == bp->b_lblkno) + VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, + NULL, NULL); + buflist->bs_nchildren = i + 1; + return (buflist); +} |
