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freebsd-dev/sys/kern/vfs_cluster.c
Kirk McKusick ad8ac923fa These changes appear to give us benefits with both small (32MB) and 
large (1G) memory machine configurations.  I was able to run 'dbench 32'
on a 32MB system without bring the machine to a grinding halt.

    * buffer cache hash table now dynamically allocated.  This will
      have no effect on memory consumption for smaller systems and
      will help scale the buffer cache for larger systems.

    * minor enhancement to pmap_clearbit().  I noticed that
      all the calls to it used constant arguments.  Making
      it an inline allows the constants to propogate to
      deeper inlines and should produce better code.

    * removal of inherent vfs_ioopt support through the emplacement
      of appropriate #ifdef's, with John's permission.  If we do not
      find a use for it by the end of the year we will remove it entirely.

    * removal of getnewbufloops* counters & sysctl's - no longer
      necessary for debugging, getnewbuf() is now optimal.

    * buffer hash table functions removed from sys/buf.h and localized
      to vfs_bio.c

    * VFS_BIO_NEED_DIRTYFLUSH flag and support code added
      ( bwillwrite() ), allowing processes to block when too many dirty
      buffers are present in the system.

    * removal of a softdep test in bdwrite() that is no longer necessary
      now that bdwrite() no longer attempts to flush dirty buffers.

    * slight optimization added to bqrelse() - there is no reason
      to test for available buffer space on B_DELWRI buffers.

    * addition of reverse-scanning code to vfs_bio_awrite().
      vfs_bio_awrite() will attempt to locate clusterable areas
      in both the forward and reverse direction relative to the
      offset of the buffer passed to it.  This will probably not
      make much of a difference now, but I believe we will start
      to rely on it heavily in the future if we decide to shift
      some of the burden of the clustering closer to the actual
      I/O initiation.

    * Removal of the newbufcnt and lastnewbuf counters that Kirk
      added.  They do not fix any race conditions that haven't already
      been fixed by the gbincore() test done after the only call
      to getnewbuf().  getnewbuf() is a static, so there is no chance
      of it being misused by other modules.  ( Unless Kirk can think
      of a specific thing that this code fixes.  I went through it
      very carefully and didn't see anything ).

    * removal of VOP_ISLOCKED() check in flushbufqueues().  I do not
      think this check is necessary, the buffer should flush properly
      whether the vnode is locked or not. ( yes? ).

    * removal of extra arguments passed to getnewbuf() that are not
      necessary.

    * missed cluster_wbuild() that had to be a cluster_wbuild_wb() in
      vfs_cluster.c

    * vn_write() now calls bwillwrite() *PRIOR* to locking the vnode,
      which should greatly aid flushing operations in heavy load
      situations - both the pageout and update daemons will be able
      to operate more efficiently.

    * removal of b_usecount.  We may add it back in later but for now
      it is useless.  Prior implementations of the buffer cache never
      had enough buffers for it to be useful, and current implementations
      which make more buffers available might not benefit relative to
      the amount of sophistication required to implement a b_usecount.
      Straight LRU should work just as well, especially when most things
      are VMIO backed.  I expect that (even though John will not like
      this assumption) directories will become VMIO backed some point soon.

Submitted by:	Matthew Dillon <dillon@backplane.com>
Reviewed by:	Kirk McKusick <mckusick@mckusick.com>
1999-07-08 06:06:00 +00:00

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/*-
* 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
* $Id: vfs_cluster.c,v 1.86 1999/07/04 00:31:17 mckusick Exp $
*/
#include "opt_debug_cluster.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/resourcevar.h>
#include <vm/vm.h>
#include <vm/vm_prot.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <sys/sysctl.h>
#if defined(CLUSTERDEBUG)
#include <sys/sysctl.h>
static int rcluster= 0;
SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
#endif
static MALLOC_DEFINE(M_SEGMENT, "cluster_save buffer", "cluster_save buffer");
static struct cluster_save *
cluster_collectbufs __P((struct vnode *vp, struct buf *last_bp));
static struct buf *
cluster_rbuild __P((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, "");
extern vm_page_t bogus_page;
extern int cluster_pbuf_freecnt;
/*
* Maximum number of blocks for read-ahead.
*/
#define MAXRA 32
/*
* This 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 error, num_ra;
int i;
int maxra, racluster;
long origtotread;
error = 0;
if (vp->v_maxio == 0)
vp->v_maxio = DFLTPHYS;
/*
* Try to limit the amount of read-ahead by a few
* ad-hoc parameters. This needs work!!!
*/
racluster = vp->v_maxio/size;
maxra = 2 * racluster + (totread / size);
if (maxra > MAXRA)
maxra = MAXRA;
if (maxra > nbuf/8)
maxra = nbuf/8;
/*
* get the requested block
*/
*bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0);
origblkno = lblkno;
origtotread = totread;
/*
* 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;
struct buf *tbp;
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();
for (i = 1; i < maxra; i++) {
if (!(tbp = incore(vp, lblkno+i))) {
break;
}
/*
* Set another read-ahead mark so we know
* to check again.
*/
if (((i % racluster) == (racluster - 1)) ||
(i == (maxra - 1)))
tbp->b_flags |= B_RAM;
}
splx(s);
if (i >= maxra) {
return 0;
}
lblkno += i;
}
reqbp = bp = NULL;
} else {
off_t firstread = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("cluster_read: no buffer offset"));
if (firstread + totread > filesize)
totread = filesize - firstread;
if (totread > size) {
int nblks = 0;
int ncontigafter;
while (totread > 0) {
nblks++;
totread -= size;
}
if (nblks == 1)
goto single_block_read;
if (nblks > racluster)
nblks = racluster;
error = VOP_BMAP(vp, lblkno, NULL,
&blkno, &ncontigafter, NULL);
if (error)
goto single_block_read;
if (blkno == -1)
goto single_block_read;
if (ncontigafter == 0)
goto single_block_read;
if (ncontigafter + 1 < nblks)
nblks = ncontigafter + 1;
bp = cluster_rbuild(vp, filesize, lblkno,
blkno, size, nblks, bp);
lblkno += (bp->b_bufsize / size);
} else {
single_block_read:
/*
* if it isn't in the cache, then get a chunk from
* disk if sequential, otherwise just get the block.
*/
bp->b_flags |= B_READ | B_RAM;
lblkno += 1;
}
}
/*
* if we have been doing sequential I/O, then do some read-ahead
*/
rbp = NULL;
if (seqcount && (lblkno < (origblkno + seqcount))) {
/*
* we now build the read-ahead buffer if it is desirable.
*/
if (((u_quad_t)(lblkno + 1) * size) <= filesize &&
!(error = VOP_BMAP(vp, lblkno, NULL, &blkno, &num_ra, NULL)) &&
blkno != -1) {
int nblksread;
int ntoread = num_ra + 1;
nblksread = (origtotread + size - 1) / size;
if (seqcount < nblksread)
seqcount = nblksread;
if (seqcount < ntoread)
ntoread = seqcount;
if (num_ra) {
rbp = cluster_rbuild(vp, filesize, lblkno,
blkno, size, ntoread, NULL);
} else {
rbp = getblk(vp, lblkno, size, 0, 0);
rbp->b_flags |= B_READ | B_ASYNC | B_RAM;
rbp->b_blkno = blkno;
}
}
}
/*
* handle the synchronous read
*/
if (bp) {
#if defined(CLUSTERDEBUG)
if (rcluster)
printf("S(%ld,%ld,%d) ",
(long)bp->b_lblkno, bp->b_bcount, seqcount);
#endif
if ((bp->b_flags & B_CLUSTER) == 0)
vfs_busy_pages(bp, 0);
bp->b_flags &= ~(B_ERROR|B_INVAL);
if (bp->b_flags & (B_ASYNC|B_CALL))
BUF_KERNPROC(bp);
error = VOP_STRATEGY(vp, bp);
curproc->p_stats->p_ru.ru_inblock++;
}
/*
* and if we have read-aheads, do them too
*/
if (rbp) {
if (error) {
rbp->b_flags &= ~(B_ASYNC | B_READ);
brelse(rbp);
} else if (rbp->b_flags & B_CACHE) {
rbp->b_flags &= ~(B_ASYNC | B_READ);
bqrelse(rbp);
} else {
#if defined(CLUSTERDEBUG)
if (rcluster) {
if (bp)
printf("A+(%ld,%ld,%ld,%d) ",
(long)rbp->b_lblkno, rbp->b_bcount,
(long)(rbp->b_lblkno - origblkno),
seqcount);
else
printf("A(%ld,%ld,%ld,%d) ",
(long)rbp->b_lblkno, rbp->b_bcount,
(long)(rbp->b_lblkno - origblkno),
seqcount);
}
#endif
if ((rbp->b_flags & B_CLUSTER) == 0)
vfs_busy_pages(rbp, 0);
rbp->b_flags &= ~(B_ERROR|B_INVAL);
if (rbp->b_flags & (B_ASYNC|B_CALL))
BUF_KERNPROC(rbp);
(void) VOP_STRATEGY(vp, rbp);
curproc->p_stats->p_ru.ru_inblock++;
}
}
if (reqbp)
return (biowait(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;
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_flags |= B_READ;
} else {
tbp = getblk(vp, lbn, size, 0, 0);
if (tbp->b_flags & B_CACHE)
return tbp;
tbp->b_flags |= B_ASYNC | B_READ | B_RAM;
}
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;
bp->b_data = (char *)((vm_offset_t)bp->b_data |
((vm_offset_t)tbp->b_data & PAGE_MASK));
bp->b_flags = B_ASYNC | B_READ | B_CALL | B_CLUSTER | B_VMIO;
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;
if (vp->v_maxio == 0)
vp->v_maxio = DFLTPHYS;
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_maxio)
break;
if ((tbp = incore(vp, lbn + i)) != NULL) {
if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT))
break;
BUF_UNLOCK(tbp);
for (j = 0; j < tbp->b_npages; j++)
if (tbp->b_pages[j]->valid)
break;
if (j != tbp->b_npages)
break;
if (tbp->b_bcount != size)
break;
}
tbp = getblk(vp, lbn + i, size, 0, 0);
if ((tbp->b_flags & B_CACHE) ||
(tbp->b_flags & B_VMIO) == 0) {
bqrelse(tbp);
break;
}
for (j = 0;j < tbp->b_npages; j++)
if (tbp->b_pages[j]->valid)
break;
if (j != tbp->b_npages) {
bqrelse(tbp);
break;
}
if ((fbp && (i == 1)) || (i == (run - 1)))
tbp->b_flags |= B_RAM;
tbp->b_flags |= B_READ | B_ASYNC;
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);
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;
}
bp->b_bcount += tbp->b_bcount;
bp->b_bufsize += tbp->b_bufsize;
}
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;
/*
* Must propogate errors to all the components.
*/
if (bp->b_flags & B_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_flags |= B_ERROR;
tbp->b_error = error;
} else {
tbp->b_dirtyoff = tbp->b_dirtyend = 0;
tbp->b_flags &= ~(B_ERROR|B_INVAL);
}
biodone(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;
/* fall through */
case 1:
r = cluster_wbuild(vp, size, start_lbn, len);
/* fall through */
default:
/* fall through */
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)
struct buf *bp;
u_quad_t filesize;
{
struct vnode *vp;
daddr_t lbn;
int maxclen, cursize;
int lblocksize;
int async;
vp = bp->b_vp;
if (vp->v_maxio == 0)
vp->v_maxio = DFLTPHYS;
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_maxio / 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.
*/
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)
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.
*/
for (bpp = buflist->bs_children;
bpp < endbp; bpp++)
brelse(*bpp);
free(buflist, M_SEGMENT);
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.
*/
bdwrite(bp);
cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1);
vp->v_clen = 0;
vp->v_cstart = lbn + 1;
} 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);
if (vp->v_maxio == 0)
vp->v_maxio = DFLTPHYS;
while (len > 0) {
s = splbio();
if (((tbp = gbincore(vp, start_lbn)) == NULL) ||
((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) ||
BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) {
++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_CLUSTEROK) ||
(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_bufsize = 0;
bp->b_npages = 0;
if (tbp->b_wcred != NOCRED) {
bp->b_wcred = tbp->b_wcred;
crhold(bp->b_wcred);
}
bp->b_blkno = tbp->b_blkno;
bp->b_lblkno = tbp->b_lblkno;
bp->b_offset = tbp->b_offset;
bp->b_data = (char *)((vm_offset_t)bp->b_data |
((vm_offset_t)tbp->b_data & PAGE_MASK));
bp->b_flags |= B_CALL | 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.
*/
if ((tbp = gbincore(vp, start_lbn)) == NULL) {
splx(s);
break;
}
/*
* If it IS in core, but has different
* characteristics, don't cluster with it.
*/
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_wcred != bp->b_wcred ||
BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) {
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_maxio / 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 &&
bioops.io_start)
(*bioops.io_start)(tbp);
/*
* If the IO is via the VM then we do some
* special VM hackery. (yuck)
*/
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)
goto finishcluster;
}
}
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++;
}
}
}
bp->b_bcount += size;
bp->b_bufsize += size;
s = splbio();
bundirty(tbp);
tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
tbp->b_flags |= B_ASYNC;
reassignbuf(tbp, tbp->b_vp); /* put on clean list */
++tbp->b_vp->v_numoutput;
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);
}
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