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freebsd-dev/sys/kern/vfs_cluster.c
Kirk McKusick 0d2af52141 Introduce the new 64-bit size disk block, daddr64_t. Change 
the bio and buffer structures to have daddr64_t bio_pblkno,
b_blkno, and b_lblkno fields which allows access to disks
larger than a Terabyte in size. This change also requires
that the VOP_BMAP vnode operation accept and return daddr64_t
blocks. This delta should not affect system operation in
any way. It merely sets up the necessary interfaces to allow
the development of disk drivers that work with these larger
disk block addresses. It also allows for the development of
UFS2 which will use 64-bit block addresses.
2002-03-15 18:49:47 +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
* $FreeBSD$
*/
#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,
"Debug VFS clustering code");
#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,
daddr64_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");
/* 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;
/*
* Maximum number of blocks for read-ahead.
*/
#define MAXRA 32
/*
* 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;
daddr64_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;
daddr64_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);
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;
}
/*
* Shortcut some checks and try to avoid buffers that
* would block in the lock. The same checks have to
* be made again after we officially get the buffer.
*/
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);
/*
* 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);
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;
}
/*
* 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;
/* 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);
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.
*/
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 = 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 | B_NOWDRAIN));
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). 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;
}
}
}
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_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:
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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