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freebsd/sys/kern/vfs_cluster.c
Matthew Dillon ac8f990bde This patch implements O_DIRECT about 80% of the way. It takes a patchset 
Tor created a while ago, removes the raw I/O piece (that has cache coherency
problems), and adds a buffer cache / VM freeing piece.

Essentially this patch causes O_DIRECT I/O to not be left in the cache, but
does not prevent it from going through the cache, hence the 80%.  For
the last 20% we need a method by which the I/O can be issued directly to
buffer supplied by the user process and bypass the buffer cache entirely,
but still maintain cache coherency.

I also have the code working under -stable but the changes made to sys/file.h
may not be MFCable, so an MFC is not on the table yet.

Submitted by:	tegge, dillon
2001-05-24 07:22:27 +00:00

951 lines
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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
* $FreeBSD$
*/
#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)
#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;
/*
* 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 = 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_RAM;
bp->b_iocmd = BIO_READ;
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_ASYNC | B_RAM;
rbp->b_iocmd = BIO_READ;
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_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++;
}
/*
* and if we have read-aheads, do them too
*/
if (rbp) {
if (error) {
rbp->b_flags &= ~B_ASYNC;
brelse(rbp);
} else if (rbp->b_flags & B_CACHE) {
rbp->b_flags &= ~B_ASYNC;
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_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;
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);
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;
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;
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 the buffer is already fully valid or locked
* (which could also mean that a background write is
* in progress), or the buffer is not backed by VMIO,
* stop.
*/
if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
(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_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);
mtx_lock(&vm_mtx);
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;
}
mtx_unlock(&vm_mtx);
bp->b_bcount += tbp->b_bcount;
bp->b_bufsize += tbp->b_bufsize;
}
mtx_lock(&vm_mtx);
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);
mtx_unlock(&vm_mtx);
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_ioflags & BIO_ERROR)
error = bp->b_error;
mtx_lock(&vm_mtx);
pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
mtx_unlock(&vm_mtx);
/*
* 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;
/* 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, 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);
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.
*/
if (((tbp = gbincore(vp, start_lbn)) == NULL) ||
((tbp->b_flags & (B_LOCKED | 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_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 = 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_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, 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 ((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_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_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)
buf_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) {
bqrelse(tbp);
goto finishcluster;
}
}
}
mtx_lock(&vm_mtx);
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++;
}
}
mtx_unlock(&vm_mtx);
}
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 */
++tbp->b_vp->v_numoutput;
splx(s);
BUF_KERNPROC(tbp);
TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
tbp, b_cluster.cluster_entry);
}
finishcluster:
mtx_lock(&vm_mtx);
pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
(vm_page_t *) bp->b_pages, bp->b_npages);
mtx_unlock(&vm_mtx);
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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