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/* $NetBSD: ld.c,v 1.26 2003/06/29 22:29:59 fvdl Exp $ */
/*-
* Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Andrew Doran and Charles M. Hannum.
*
* 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 NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* Disk driver for use by RAID controllers.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ld.c,v 1.26 2003/06/29 22:29:59 fvdl Exp $");
#include "rnd.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/device.h>
#include <sys/queue.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/endian.h>
#include <sys/disklabel.h>
#include <sys/disk.h>
#include <sys/dkio.h>
#include <sys/stat.h>
#include <sys/lock.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <sys/syslog.h>
#if NRND > 0
#include <sys/rnd.h>
#endif
#include <dev/ldvar.h>
static void ldgetdefaultlabel(struct ld_softc *, struct disklabel *);
static void ldgetdisklabel(struct ld_softc *);
static int ldlock(struct ld_softc *);
static void ldminphys(struct buf *bp);
static void ldshutdown(void *);
static void ldstart(struct ld_softc *);
static void ldunlock(struct ld_softc *);
extern struct cfdriver ld_cd;
dev_type_open(ldopen);
dev_type_close(ldclose);
dev_type_read(ldread);
dev_type_write(ldwrite);
dev_type_ioctl(ldioctl);
dev_type_strategy(ldstrategy);
dev_type_dump(lddump);
dev_type_size(ldsize);
const struct bdevsw ld_bdevsw = {
ldopen, ldclose, ldstrategy, ldioctl, lddump, ldsize, D_DISK
};
const struct cdevsw ld_cdevsw = {
ldopen, ldclose, ldread, ldwrite, ldioctl,
nostop, notty, nopoll, nommap, nokqfilter, D_DISK
};
static struct dkdriver lddkdriver = { ldstrategy };
static void *ld_sdh;
void
ldattach(struct ld_softc *sc)
{
char buf[9];
if ((sc->sc_flags & LDF_ENABLED) == 0) {
printf("%s: disabled\n", sc->sc_dv.dv_xname);
return;
}
/* Initialise and attach the disk structure. */
sc->sc_dk.dk_driver = &lddkdriver;
sc->sc_dk.dk_name = sc->sc_dv.dv_xname;
disk_attach(&sc->sc_dk);
if (sc->sc_maxxfer > MAXPHYS)
sc->sc_maxxfer = MAXPHYS;
/* Build synthetic geometry if necessary. */
if (sc->sc_nheads == 0 || sc->sc_nsectors == 0 ||
sc->sc_ncylinders == 0) {
if (sc->sc_secperunit <= 528 * 2048) /* 528MB */
sc->sc_nheads = 16;
else if (sc->sc_secperunit <= 1024 * 2048) /* 1GB */
sc->sc_nheads = 32;
else if (sc->sc_secperunit <= 21504 * 2048) /* 21GB */
sc->sc_nheads = 64;
else if (sc->sc_secperunit <= 43008 * 2048) /* 42GB */
sc->sc_nheads = 128;
else
sc->sc_nheads = 255;
sc->sc_nsectors = 63;
sc->sc_ncylinders = sc->sc_secperunit /
(sc->sc_nheads * sc->sc_nsectors);
}
format_bytes(buf, sizeof(buf), (u_int64_t)sc->sc_secperunit *
sc->sc_secsize);
printf("%s: %s, %d cyl, %d head, %d sec, %d bytes/sect x %d sectors\n",
sc->sc_dv.dv_xname, buf, sc->sc_ncylinders, sc->sc_nheads,
sc->sc_nsectors, sc->sc_secsize, sc->sc_secperunit);
#if NRND > 0
/* Attach the device into the rnd source list. */
rnd_attach_source(&sc->sc_rnd_source, sc->sc_dv.dv_xname,
RND_TYPE_DISK, 0);
#endif
/* Set the `shutdownhook'. */
if (ld_sdh == NULL)
ld_sdh = shutdownhook_establish(ldshutdown, NULL);
bufq_alloc(&sc->sc_bufq, BUFQ_FCFS);
}
int
ldadjqparam(struct ld_softc *sc, int max)
{
int s;
s = splbio();
sc->sc_maxqueuecnt = max;
splx(s);
return (0);
}
int
ldbegindetach(struct ld_softc *sc, int flags)
{
int s, rv = 0;
if ((sc->sc_flags & LDF_ENABLED) == 0)
return (0);
if ((flags & DETACH_FORCE) == 0 && sc->sc_dk.dk_openmask != 0)
return (EBUSY);
s = splbio();
sc->sc_maxqueuecnt = 0;
sc->sc_flags |= LDF_DETACH;
while (sc->sc_queuecnt > 0) {
sc->sc_flags |= LDF_DRAIN;
rv = tsleep(&sc->sc_queuecnt, PRIBIO, "lddrn", 0);
if (rv)
break;
}
splx(s);
return (rv);
}
void
ldenddetach(struct ld_softc *sc)
{
struct buf *bp;
int s, bmaj, cmaj, i, mn;
if ((sc->sc_flags & LDF_ENABLED) == 0)
return;
/* Wait for commands queued with the hardware to complete. */
if (sc->sc_queuecnt != 0)
if (tsleep(&sc->sc_queuecnt, PRIBIO, "lddtch", 30 * hz))
printf("%s: not drained\n", sc->sc_dv.dv_xname);
/* Locate the major numbers. */
bmaj = bdevsw_lookup_major(&ld_bdevsw);
cmaj = cdevsw_lookup_major(&ld_cdevsw);
/* Kill off any queued buffers. */
s = splbio();
while ((bp = BUFQ_GET(&sc->sc_bufq)) != NULL) {
bp->b_error = EIO;
bp->b_flags |= B_ERROR;
bp->b_resid = bp->b_bcount;
biodone(bp);
}
bufq_free(&sc->sc_bufq);
splx(s);
/* Nuke the vnodes for any open instances. */
for (i = 0; i < MAXPARTITIONS; i++) {
mn = DISKMINOR(sc->sc_dv.dv_unit, i);
vdevgone(bmaj, mn, mn, VBLK);
vdevgone(cmaj, mn, mn, VCHR);
}
/* Detach from the disk list. */
disk_detach(&sc->sc_dk);
#if NRND > 0
/* Unhook the entropy source. */
rnd_detach_source(&sc->sc_rnd_source);
#endif
/*
* XXX We can't really flush the cache here, beceause the
* XXX device may already be non-existent from the controller's
* XXX perspective.
*/
#if 0
/* Flush the device's cache. */
if (sc->sc_flush != NULL)
if ((*sc->sc_flush)(sc) != 0)
printf("%s: unable to flush cache\n",
sc->sc_dv.dv_xname);
#endif
}
/* ARGSUSED */
static void
ldshutdown(void *cookie)
{
struct ld_softc *sc;
int i;
for (i = 0; i < ld_cd.cd_ndevs; i++) {
if ((sc = device_lookup(&ld_cd, i)) == NULL)
continue;
if (sc->sc_flush != NULL && (*sc->sc_flush)(sc) != 0)
printf("%s: unable to flush cache\n",
sc->sc_dv.dv_xname);
}
}
/* ARGSUSED */
int
ldopen(dev_t dev, int flags, int fmt, struct proc *p)
{
struct ld_softc *sc;
int unit, part;
unit = DISKUNIT(dev);
if ((sc = device_lookup(&ld_cd, unit))== NULL)
return (ENXIO);
if ((sc->sc_flags & LDF_ENABLED) == 0)
return (ENODEV);
part = DISKPART(dev);
ldlock(sc);
if (sc->sc_dk.dk_openmask == 0) {
/* Load the partition info if not already loaded. */
if ((sc->sc_flags & LDF_VLABEL) == 0)
ldgetdisklabel(sc);
}
/* Check that the partition exists. */
if (part != RAW_PART && (part >= sc->sc_dk.dk_label->d_npartitions ||
sc->sc_dk.dk_label->d_partitions[part].p_fstype == FS_UNUSED)) {
ldunlock(sc);
return (ENXIO);
}
/* Ensure only one open at a time. */
switch (fmt) {
case S_IFCHR:
sc->sc_dk.dk_copenmask |= (1 << part);
break;
case S_IFBLK:
sc->sc_dk.dk_bopenmask |= (1 << part);
break;
}
sc->sc_dk.dk_openmask =
sc->sc_dk.dk_copenmask | sc->sc_dk.dk_bopenmask;
ldunlock(sc);
return (0);
}
/* ARGSUSED */
int
ldclose(dev_t dev, int flags, int fmt, struct proc *p)
{
struct ld_softc *sc;
int part, unit;
unit = DISKUNIT(dev);
part = DISKPART(dev);
sc = device_lookup(&ld_cd, unit);
ldlock(sc);
switch (fmt) {
case S_IFCHR:
sc->sc_dk.dk_copenmask &= ~(1 << part);
break;
case S_IFBLK:
sc->sc_dk.dk_bopenmask &= ~(1 << part);
break;
}
sc->sc_dk.dk_openmask =
sc->sc_dk.dk_copenmask | sc->sc_dk.dk_bopenmask;
if (sc->sc_dk.dk_openmask == 0) {
if (sc->sc_flush != NULL && (*sc->sc_flush)(sc) != 0)
printf("%s: unable to flush cache\n",
sc->sc_dv.dv_xname);
if ((sc->sc_flags & LDF_KLABEL) == 0)
sc->sc_flags &= ~LDF_VLABEL;
}
ldunlock(sc);
return (0);
}
/* ARGSUSED */
int
ldread(dev_t dev, struct uio *uio, int ioflag)
{
return (physio(ldstrategy, NULL, dev, B_READ, ldminphys, uio));
}
/* ARGSUSED */
int
ldwrite(dev_t dev, struct uio *uio, int ioflag)
{
return (physio(ldstrategy, NULL, dev, B_WRITE, ldminphys, uio));
}
/* ARGSUSED */
int
ldioctl(dev_t dev, u_long cmd, caddr_t addr, int32_t flag, struct proc *p)
{
struct ld_softc *sc;
int part, unit, error;
#ifdef __HAVE_OLD_DISKLABEL
struct disklabel newlabel;
#endif
struct disklabel *lp;
unit = DISKUNIT(dev);
part = DISKPART(dev);
sc = device_lookup(&ld_cd, unit);
error = 0;
switch (cmd) {
case DIOCGDINFO:
memcpy(addr, sc->sc_dk.dk_label, sizeof(struct disklabel));
return (0);
#ifdef __HAVE_OLD_DISKLABEL
case ODIOCGDINFO:
newlabel = *(sc->sc_dk.dk_label);
if (newlabel.d_npartitions > OLDMAXPARTITIONS)
return ENOTTY;
memcpy(addr, &newlabel, sizeof(struct olddisklabel));
return (0);
#endif
case DIOCGPART:
((struct partinfo *)addr)->disklab = sc->sc_dk.dk_label;
((struct partinfo *)addr)->part =
&sc->sc_dk.dk_label->d_partitions[part];
break;
case DIOCWDINFO:
case DIOCSDINFO:
#ifdef __HAVE_OLD_DISKLABEL
case ODIOCWDINFO:
case ODIOCSDINFO:
if (cmd == ODIOCSDINFO || cmd == ODIOCWDINFO) {
memset(&newlabel, 0, sizeof newlabel);
memcpy(&newlabel, addr, sizeof (struct olddisklabel));
lp = &newlabel;
} else
#endif
lp = (struct disklabel *)addr;
if ((flag & FWRITE) == 0)
return (EBADF);
if ((error = ldlock(sc)) != 0)
return (error);
sc->sc_flags |= LDF_LABELLING;
error = setdisklabel(sc->sc_dk.dk_label,
lp, /*sc->sc_dk.dk_openmask : */0,
sc->sc_dk.dk_cpulabel);
if (error == 0 && (cmd == DIOCWDINFO
#ifdef __HAVE_OLD_DISKLABEL
|| cmd == ODIOCWDINFO
#endif
))
error = writedisklabel(
MAKEDISKDEV(major(dev), DISKUNIT(dev), RAW_PART),
ldstrategy, sc->sc_dk.dk_label,
sc->sc_dk.dk_cpulabel);
sc->sc_flags &= ~LDF_LABELLING;
ldunlock(sc);
break;
case DIOCKLABEL:
if ((flag & FWRITE) == 0)
return (EBADF);
if (*(int *)addr)
sc->sc_flags |= LDF_KLABEL;
else
sc->sc_flags &= ~LDF_KLABEL;
break;
case DIOCWLABEL:
if ((flag & FWRITE) == 0)
return (EBADF);
if (*(int *)addr)
sc->sc_flags |= LDF_WLABEL;
else
sc->sc_flags &= ~LDF_WLABEL;
break;
case DIOCGDEFLABEL:
ldgetdefaultlabel(sc, (struct disklabel *)addr);
break;
#ifdef __HAVE_OLD_DISKLABEL
case ODIOCGDEFLABEL:
ldgetdefaultlabel(sc, &newlabel);
if (newlabel.d_npartitions > OLDMAXPARTITIONS)
return ENOTTY;
memcpy(addr, &newlabel, sizeof (struct olddisklabel));
break;
#endif
default:
error = ENOTTY;
break;
}
return (error);
}
void
ldstrategy(struct buf *bp)
{
struct ld_softc *sc;
struct disklabel *lp;
daddr_t blkno;
int s, part;
sc = device_lookup(&ld_cd, DISKUNIT(bp->b_dev));
part = DISKPART(bp->b_dev);
if ((sc->sc_flags & LDF_DETACH) != 0) {
bp->b_error = EIO;
goto bad;
}
lp = sc->sc_dk.dk_label;
/*
* The transfer must be a whole number of blocks and the offset must
* not be negative.
*/
if ((bp->b_bcount % lp->d_secsize) != 0 || bp->b_blkno < 0) {
bp->b_error = EINVAL;
goto bad;
}
/* If it's a null transfer, return immediately. */
if (bp->b_bcount == 0)
goto done;
/*
* Do bounds checking and adjust the transfer. If error, process.
* If past the end of partition, just return.
*/
if (part != RAW_PART &&
bounds_check_with_label(&sc->sc_dk, bp,
(sc->sc_flags & (LDF_WLABEL | LDF_LABELLING)) != 0) <= 0) {
goto done;
}
/*
* Convert the block number to absolute and put it in terms
* of the device's logical block size.
*/
if (lp->d_secsize == DEV_BSIZE)
blkno = bp->b_blkno;
else if (lp->d_secsize > DEV_BSIZE)
blkno = bp->b_blkno / (lp->d_secsize / DEV_BSIZE);
else
blkno = bp->b_blkno * (DEV_BSIZE / lp->d_secsize);
if (part != RAW_PART)
blkno += lp->d_partitions[part].p_offset;
bp->b_rawblkno = blkno;
s = splbio();
BUFQ_PUT(&sc->sc_bufq, bp);
ldstart(sc);
splx(s);
return;
bad:
bp->b_flags |= B_ERROR;
done:
bp->b_resid = bp->b_bcount;
biodone(bp);
}
static void
ldstart(struct ld_softc *sc)
{
struct buf *bp;
int error;
while (sc->sc_queuecnt < sc->sc_maxqueuecnt) {
/* See if there is work to do. */
if ((bp = BUFQ_PEEK(&sc->sc_bufq)) == NULL)
break;
disk_busy(&sc->sc_dk);
sc->sc_queuecnt++;
if (__predict_true((error = (*sc->sc_start)(sc, bp)) == 0)) {
/*
* The back-end is running the job; remove it from
* the queue.
*/
(void) BUFQ_GET(&sc->sc_bufq);
} else {
disk_unbusy(&sc->sc_dk, 0, (bp->b_flags & B_READ));
sc->sc_queuecnt--;
if (error == EAGAIN) {
/*
* Temporary resource shortage in the
* back-end; just defer the job until
* later.
*
* XXX We might consider a watchdog timer
* XXX to make sure we are kicked into action.
*/
break;
} else {
(void) BUFQ_GET(&sc->sc_bufq);
bp->b_error = error;
bp->b_flags |= B_ERROR;
bp->b_resid = bp->b_bcount;
biodone(bp);
}
}
}
}
void
lddone(struct ld_softc *sc, struct buf *bp)
{
if ((bp->b_flags & B_ERROR) != 0) {
diskerr(bp, "ld", "error", LOG_PRINTF, 0, sc->sc_dk.dk_label);
printf("\n");
}
disk_unbusy(&sc->sc_dk, bp->b_bcount - bp->b_resid,
(bp->b_flags & B_READ));
#if NRND > 0
rnd_add_uint32(&sc->sc_rnd_source, bp->b_rawblkno);
#endif
biodone(bp);
if (--sc->sc_queuecnt <= sc->sc_maxqueuecnt) {
if ((sc->sc_flags & LDF_DRAIN) != 0) {
sc->sc_flags &= ~LDF_DRAIN;
wakeup(&sc->sc_queuecnt);
}
ldstart(sc);
}
}
int
ldsize(dev_t dev)
{
struct ld_softc *sc;
int part, unit, omask, size;
unit = DISKUNIT(dev);
if ((sc = device_lookup(&ld_cd, unit)) == NULL)
return (ENODEV);
if ((sc->sc_flags & LDF_ENABLED) == 0)
return (ENODEV);
part = DISKPART(dev);
omask = sc->sc_dk.dk_openmask & (1 << part);
if (omask == 0 && ldopen(dev, 0, S_IFBLK, NULL) != 0)
return (-1);
else if (sc->sc_dk.dk_label->d_partitions[part].p_fstype != FS_SWAP)
size = -1;
else
size = sc->sc_dk.dk_label->d_partitions[part].p_size *
(sc->sc_dk.dk_label->d_secsize / DEV_BSIZE);
if (omask == 0 && ldclose(dev, 0, S_IFBLK, NULL) != 0)
return (-1);
return (size);
}
/*
* Load the label information from the specified device.
*/
static void
ldgetdisklabel(struct ld_softc *sc)
{
const char *errstring;
ldgetdefaultlabel(sc, sc->sc_dk.dk_label);
/* Call the generic disklabel extraction routine. */
errstring = readdisklabel(MAKEDISKDEV(0, sc->sc_dv.dv_unit, RAW_PART),
ldstrategy, sc->sc_dk.dk_label, sc->sc_dk.dk_cpulabel);
if (errstring != NULL)
printf("%s: %s\n", sc->sc_dv.dv_xname, errstring);
/* In-core label now valid. */
sc->sc_flags |= LDF_VLABEL;
}
/*
* Construct a ficticious label.
*/
static void
ldgetdefaultlabel(struct ld_softc *sc, struct disklabel *lp)
{
memset(lp, 0, sizeof(struct disklabel));
lp->d_secsize = sc->sc_secsize;
lp->d_ntracks = sc->sc_nheads;
lp->d_nsectors = sc->sc_nsectors;
lp->d_ncylinders = sc->sc_ncylinders;
lp->d_secpercyl = lp->d_ntracks * lp->d_nsectors;
lp->d_type = DTYPE_LD;
strlcpy(lp->d_typename, "unknown", sizeof(lp->d_typename));
strlcpy(lp->d_packname, "fictitious", sizeof(lp->d_packname));
lp->d_secperunit = sc->sc_secperunit;
lp->d_rpm = 7200;
lp->d_interleave = 1;
lp->d_flags = 0;
lp->d_partitions[RAW_PART].p_offset = 0;
lp->d_partitions[RAW_PART].p_size =
lp->d_secperunit * (lp->d_secsize / DEV_BSIZE);
lp->d_partitions[RAW_PART].p_fstype = FS_UNUSED;
lp->d_npartitions = RAW_PART + 1;
lp->d_magic = DISKMAGIC;
lp->d_magic2 = DISKMAGIC;
lp->d_checksum = dkcksum(lp);
}
/*
* Wait interruptibly for an exclusive lock.
*
* XXX Several drivers do this; it should be abstracted and made MP-safe.
*/
static int
ldlock(struct ld_softc *sc)
{
int error;
while ((sc->sc_flags & LDF_LKHELD) != 0) {
sc->sc_flags |= LDF_LKWANTED;
if ((error = tsleep(sc, PRIBIO | PCATCH, "ldlck", 0)) != 0)
return (error);
}
sc->sc_flags |= LDF_LKHELD;
return (0);
}
/*
* Unlock and wake up any waiters.
*/
static void
ldunlock(struct ld_softc *sc)
{
sc->sc_flags &= ~LDF_LKHELD;
if ((sc->sc_flags & LDF_LKWANTED) != 0) {
sc->sc_flags &= ~LDF_LKWANTED;
wakeup(sc);
}
}
/*
* Take a dump.
*/
int
lddump(dev_t dev, daddr_t blkno, caddr_t va, size_t size)
{
struct ld_softc *sc;
struct disklabel *lp;
int unit, part, nsects, sectoff, towrt, nblk, maxblkcnt, rv;
static int dumping;
unit = DISKUNIT(dev);
if ((sc = device_lookup(&ld_cd, unit)) == NULL)
return (ENXIO);
if ((sc->sc_flags & LDF_ENABLED) == 0)
return (ENODEV);
if (sc->sc_dump == NULL)
return (ENXIO);
/* Check if recursive dump; if so, punt. */
if (dumping)
return (EFAULT);
dumping = 1;
/* Convert to disk sectors. Request must be a multiple of size. */
part = DISKPART(dev);
lp = sc->sc_dk.dk_label;
if ((size % lp->d_secsize) != 0)
return (EFAULT);
towrt = size / lp->d_secsize;
blkno = dbtob(blkno) / lp->d_secsize; /* blkno in DEV_BSIZE units */
nsects = lp->d_partitions[part].p_size;
sectoff = lp->d_partitions[part].p_offset;
/* Check transfer bounds against partition size. */
if ((blkno < 0) || ((blkno + towrt) > nsects))
return (EINVAL);
/* Offset block number to start of partition. */
blkno += sectoff;
/* Start dumping and return when done. */
maxblkcnt = sc->sc_maxxfer / sc->sc_secsize - 1;
while (towrt > 0) {
nblk = min(maxblkcnt, towrt);
if ((rv = (*sc->sc_dump)(sc, va, blkno, nblk)) != 0)
return (rv);
towrt -= nblk;
blkno += nblk;
va += nblk * sc->sc_secsize;
}
dumping = 0;
return (0);
}
/*
* Adjust the size of a transfer.
*/
static void
ldminphys(struct buf *bp)
{
struct ld_softc *sc;
sc = device_lookup(&ld_cd, DISKUNIT(bp->b_dev));
if (bp->b_bcount > sc->sc_maxxfer)
bp->b_bcount = sc->sc_maxxfer;
minphys(bp);
}
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