4.4BSD/usr/src/sys/kern/vfs_cluster.c
/*-
* Copyright (c) 1993
* The Regents of the University of California. 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 8.1 (Berkeley) 6/10/93
*/
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/trace.h>
#include <sys/malloc.h>
#include <sys/resourcevar.h>
#include <libkern/libkern.h>
/*
* Local declarations
*/
struct buf *cluster_newbuf __P((struct vnode *, struct buf *, long, daddr_t,
daddr_t, long, int));
struct buf *cluster_rbuild __P((struct vnode *, u_quad_t, struct buf *,
daddr_t, daddr_t, long, int, long));
void cluster_wbuild __P((struct vnode *, struct buf *, long size,
daddr_t start_lbn, int len, daddr_t lbn));
/*
* We could optimize this by keeping track of where the last read-ahead
* was, but it would involve adding fields to the vnode. For now, let's
* just get it working.
*
* This replaces bread. If this is a bread at the beginning of a file and
* lastr is 0, we assume this is the first read and we'll read up to two
* blocks if they are sequential. After that, we'll do regular read ahead
* in clustered chunks.
*
* There are 4 or 5 cases depending on how you count:
* Desired block is in the cache:
* 1 Not sequential access (0 I/Os).
* 2 Access is sequential, do read-ahead (1 ASYNC).
* Desired block is not in cache:
* 3 Not sequential access (1 SYNC).
* 4 Sequential access, next block is contiguous (1 SYNC).
* 5 Sequential access, next block is not contiguous (1 SYNC, 1 ASYNC)
*
* There are potentially two buffers that require I/O.
* bp is the block requested.
* rbp is the read-ahead block.
* If either is NULL, then you don't have to do the I/O.
*/
cluster_read(vp, filesize, lblkno, size, cred, bpp)
struct vnode *vp;
u_quad_t filesize;
daddr_t lblkno;
long size;
struct ucred *cred;
struct buf **bpp;
{
struct buf *bp, *rbp;
daddr_t blkno, ioblkno;
long flags;
int error, num_ra, alreadyincore;
#ifdef DIAGNOSTIC
if (size == 0)
panic("cluster_read: size = 0");
#endif
error = 0;
flags = B_READ;
*bpp = bp = getblk(vp, lblkno, size, 0, 0);
if (bp->b_flags & (B_CACHE | B_DONE | B_DELWRI)) {
/*
* Desired block is in cache; do any readahead ASYNC.
* Case 1, 2.
*/
trace(TR_BREADHIT, pack(vp, size), lblkno);
flags |= B_ASYNC;
ioblkno = lblkno +
(lblkno < vp->v_ralen ? vp->v_ralen >> 1 : vp->v_ralen);
alreadyincore = (int)incore(vp, ioblkno);
bp = NULL;
} else {
/* Block wasn't in cache, case 3, 4, 5. */
trace(TR_BREADMISS, pack(vp, size), lblkno);
ioblkno = lblkno;
bp->b_flags |= flags;
alreadyincore = 0;
curproc->p_stats->p_ru.ru_inblock++; /* XXX */
}
/*
* XXX
* Replace 1 with a window size based on some permutation of
* maxcontig and rot_delay. This will let you figure out how
* many blocks you should read-ahead (case 2, 4, 5).
*
* If the access isn't sequential, cut the window size in half.
*/
rbp = NULL;
if (lblkno != vp->v_lastr + 1 && lblkno != 0)
vp->v_ralen = max(vp->v_ralen >> 1, 1);
else if ((ioblkno + 1) * size < filesize && !alreadyincore &&
!(error = VOP_BMAP(vp, ioblkno, NULL, &blkno, &num_ra))) {
/*
* Reading sequentially, and the next block is not in the
* cache. We are going to try reading ahead. If this is
* the first read of a file, then limit read-ahead to a
* single block, else read as much as we're allowed.
*/
if (num_ra > vp->v_ralen) {
num_ra = vp->v_ralen;
vp->v_ralen = min(MAXPHYS / size, vp->v_ralen << 1);
} else
vp->v_ralen = num_ra + 1;
if (num_ra) /* case 2, 4 */
rbp = cluster_rbuild(vp, filesize,
bp, ioblkno, blkno, size, num_ra, flags);
else if (lblkno != 0 && ioblkno == lblkno) {
/* Case 5: check how many blocks to read ahead */
++ioblkno;
if ((ioblkno + 1) * size > filesize ||
(error = VOP_BMAP(vp,
ioblkno, NULL, &blkno, &num_ra)))
goto skip_readahead;
flags |= B_ASYNC;
if (num_ra)
rbp = cluster_rbuild(vp, filesize,
NULL, ioblkno, blkno, size, num_ra, flags);
else {
rbp = getblk(vp, ioblkno, size, 0, 0);
rbp->b_flags |= flags;
rbp->b_blkno = blkno;
}
} else if (lblkno != 0) {
/* case 2; read ahead single block */
rbp = getblk(vp, ioblkno, size, 0, 0);
rbp->b_flags |= flags;
rbp->b_blkno = blkno;
} else if (bp) /* case 1, 3, block 0 */
bp->b_blkno = blkno;
/* Case 1 on block 0; not really doing sequential I/O */
if (rbp == bp) /* case 4 */
rbp = NULL;
else if (rbp) { /* case 2, 5 */
trace(TR_BREADMISSRA,
pack(vp, (num_ra + 1) * size), ioblkno);
curproc->p_stats->p_ru.ru_inblock++; /* XXX */
}
}
/* XXX Kirk, do we need to make sure the bp has creds? */
skip_readahead:
if (bp)
if (bp->b_flags & (B_DONE | B_DELWRI))
panic("cluster_read: DONE bp");
else
error = VOP_STRATEGY(bp);
if (rbp)
if (error || rbp->b_flags & (B_DONE | B_DELWRI)) {
rbp->b_flags &= ~(B_ASYNC | B_READ);
brelse(rbp);
} else
(void) VOP_STRATEGY(rbp);
if (bp)
return(biowait(bp));
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.
*/
struct buf *
cluster_rbuild(vp, filesize, bp, lbn, blkno, size, run, flags)
struct vnode *vp;
u_quad_t filesize;
struct buf *bp;
daddr_t lbn;
daddr_t blkno;
long size;
int run;
long flags;
{
struct cluster_save *b_save;
struct buf *tbp;
daddr_t bn;
int i, inc;
#ifdef DIAGNOSTIC
if (size != vp->v_mount->mnt_stat.f_iosize)
panic("cluster_rbuild: size %d != filesize %d\n",
size, vp->v_mount->mnt_stat.f_iosize);
#endif
if (size * (lbn + run + 1) > filesize)
--run;
if (run == 0) {
if (!bp) {
bp = getblk(vp, lbn, size, 0, 0);
bp->b_blkno = blkno;
bp->b_flags |= flags;
}
return(bp);
}
bp = cluster_newbuf(vp, bp, flags, blkno, lbn, size, run + 1);
if (bp->b_flags & (B_DONE | B_DELWRI))
return (bp);
b_save = malloc(sizeof(struct buf *) * run + sizeof(struct cluster_save),
M_SEGMENT, M_WAITOK);
b_save->bs_bufsize = b_save->bs_bcount = size;
b_save->bs_nchildren = 0;
b_save->bs_children = (struct buf **)(b_save + 1);
b_save->bs_saveaddr = bp->b_saveaddr;
bp->b_saveaddr = (caddr_t) b_save;
inc = size / DEV_BSIZE;
for (bn = blkno + inc, i = 1; i <= run; ++i, bn += inc) {
if (incore(vp, lbn + i)) {
if (i == 1) {
bp->b_saveaddr = b_save->bs_saveaddr;
bp->b_flags &= ~B_CALL;
bp->b_iodone = NULL;
allocbuf(bp, size);
free(b_save, M_SEGMENT);
} else
allocbuf(bp, size * i);
break;
}
tbp = getblk(vp, lbn + i, 0, 0, 0);
tbp->b_bcount = tbp->b_bufsize = size;
tbp->b_blkno = bn;
tbp->b_flags |= flags | B_READ | B_ASYNC;
++b_save->bs_nchildren;
b_save->bs_children[i - 1] = tbp;
}
if (!(bp->b_flags & B_ASYNC))
vp->v_ralen = max(vp->v_ralen - 1, 1);
return(bp);
}
/*
* Either get a new buffer or grow the existing one.
*/
struct buf *
cluster_newbuf(vp, bp, flags, blkno, lblkno, size, run)
struct vnode *vp;
struct buf *bp;
long flags;
daddr_t blkno;
daddr_t lblkno;
long size;
int run;
{
if (!bp) {
bp = getblk(vp, lblkno, size, 0, 0);
if (bp->b_flags & (B_DONE | B_DELWRI)) {
bp->b_blkno = blkno;
return(bp);
}
}
allocbuf(bp, run * size);
bp->b_blkno = blkno;
bp->b_iodone = cluster_callback;
bp->b_flags |= flags | B_CALL;
return(bp);
}
/*
* Cleanup after a clustered read or write.
*/
void
cluster_callback(bp)
struct buf *bp;
{
struct cluster_save *b_save;
struct buf **tbp;
long bsize;
caddr_t cp;
b_save = (struct cluster_save *)(bp->b_saveaddr);
bp->b_saveaddr = b_save->bs_saveaddr;
cp = bp->b_un.b_addr + b_save->bs_bufsize;
for (tbp = b_save->bs_children; b_save->bs_nchildren--; ++tbp) {
pagemove(cp, (*tbp)->b_un.b_addr, (*tbp)->b_bufsize);
cp += (*tbp)->b_bufsize;
bp->b_bufsize -= (*tbp)->b_bufsize;
biodone(*tbp);
}
#ifdef DIAGNOSTIC
if (bp->b_bufsize != b_save->bs_bufsize)
panic ("cluster_callback: more space to reclaim");
#endif
bp->b_bcount = bp->b_bufsize;
bp->b_iodone = NULL;
free(b_save, M_SEGMENT);
if (bp->b_flags & B_ASYNC)
brelse(bp);
else
wakeup((caddr_t)bp);
}
/*
* 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 clen;
vp = bp->b_vp;
lbn = bp->b_lblkno;
/* 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 + bp->b_bcount / DEV_BSIZE)) {
if (vp->v_clen != 0)
/*
* Write is not sequential.
*/
cluster_wbuild(vp, NULL, bp->b_bcount, vp->v_cstart,
vp->v_lastw - vp->v_cstart + 1, lbn);
/*
* Consider beginning a cluster.
*/
if ((lbn + 1) * bp->b_bcount == filesize)
/* End of file, make cluster as large as possible */
clen = MAXBSIZE / vp->v_mount->mnt_stat.f_iosize - 1;
else if (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &clen)) {
bawrite(bp);
vp->v_clen = 0;
vp->v_lasta = bp->b_blkno;
vp->v_cstart = lbn + 1;
vp->v_lastw = lbn;
return;
} else
clen = 0;
vp->v_clen = clen;
if (clen == 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.
*/
cluster_wbuild(vp, bp, bp->b_bcount, vp->v_cstart,
vp->v_clen + 1, lbn);
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.
*/
void
cluster_wbuild(vp, last_bp, size, start_lbn, len, lbn)
struct vnode *vp;
struct buf *last_bp;
long size;
daddr_t start_lbn;
int len;
daddr_t lbn;
{
struct cluster_save *b_save;
struct buf *bp, *tbp;
caddr_t cp;
int i, s;
#ifdef DIAGNOSTIC
if (size != vp->v_mount->mnt_stat.f_iosize)
panic("cluster_wbuild: size %d != filesize %d\n",
size, vp->v_mount->mnt_stat.f_iosize);
#endif
redo:
while ((!incore(vp, start_lbn) || start_lbn == lbn) && len) {
++start_lbn;
--len;
}
/* Get more memory for current buffer */
if (len <= 1) {
if (last_bp) {
bawrite(last_bp);
} else if (len) {
bp = getblk(vp, start_lbn, size, 0, 0);
bawrite(bp);
}
return;
}
bp = getblk(vp, start_lbn, size, 0, 0);
if (!(bp->b_flags & B_DELWRI)) {
++start_lbn;
--len;
brelse(bp);
goto redo;
}
--len;
b_save = malloc(sizeof(struct buf *) * len + sizeof(struct cluster_save),
M_SEGMENT, M_WAITOK);
b_save->bs_bcount = bp->b_bcount;
b_save->bs_bufsize = bp->b_bufsize;
b_save->bs_nchildren = 0;
b_save->bs_children = (struct buf **)(b_save + 1);
b_save->bs_saveaddr = bp->b_saveaddr;
bp->b_saveaddr = (caddr_t) b_save;
bp->b_flags |= B_CALL;
bp->b_iodone = cluster_callback;
cp = bp->b_un.b_addr + bp->b_bufsize;
for (++start_lbn, i = 0; i < len; ++i, ++start_lbn) {
if (!incore(vp, start_lbn) || start_lbn == lbn)
break;
if (last_bp == NULL || start_lbn != last_bp->b_lblkno) {
tbp = getblk(vp, start_lbn, size, 0, 0);
#ifdef DIAGNOSTIC
if (tbp->b_bcount != tbp->b_bufsize)
panic("cluster_wbuild: Buffer too big");
#endif
if (!(tbp->b_flags & B_DELWRI)) {
brelse(tbp);
break;
}
} else
tbp = last_bp;
++b_save->bs_nchildren;
/* Move memory from children to parent */
if (tbp->b_blkno != (bp->b_blkno + bp->b_bufsize / DEV_BSIZE)) {
printf("Clustered Block: %d addr %x bufsize: %d\n",
bp->b_lblkno, bp->b_blkno, bp->b_bufsize);
printf("Child Block: %d addr: %x\n", tbp->b_lblkno,
tbp->b_blkno);
panic("Clustered write to wrong blocks");
}
pagemove(tbp->b_un.b_daddr, cp, size);
bp->b_bcount += size;
bp->b_bufsize += size;
tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI);
tbp->b_flags |= B_ASYNC;
s = splbio();
reassignbuf(tbp, tbp->b_vp); /* put on clean list */
++tbp->b_vp->v_numoutput;
splx(s);
b_save->bs_children[i] = tbp;
cp += tbp->b_bufsize;
}
if (i == 0) {
/* None to cluster */
bp->b_saveaddr = b_save->bs_saveaddr;
bp->b_flags &= ~B_CALL;
bp->b_iodone = NULL;
free(b_save, M_SEGMENT);
}
bawrite(bp);
if (i < len) {
len -= i + 1;
start_lbn += 1;
goto redo;
}
}