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NetBSD/sys/dev/ld.c
tls 14cd9beeae Don't use BUFQ_FCFS. It degrades performance both for "smart" (Mylex 
ExtremeRAID with NV cache) and "dumb" (3ware 6410) ld providers.

Instead, use the default buffer queue policy.

With the 3ware adapter, using the read priority strategy instead of FCFS,
for three extractions of pkgsrc, took 329 seconds instead of 331 -- but
with a dramatic improvement in perceived system response (latency for
I/O outside the main stream).

With the Mylex adapter, the improvement was dramatic: using read priority
instead of FCFS yielded an improvement from 381 seconds to 135 seconds!
There was a less-noticeable improvement in perceived latency as well.

The other disk drivers currently hard-wired to FCFS or another policy
should probably be changed as well.
2004-03-22 17:30:33 +00:00

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/* $NetBSD: ld.c,v 1.27 2004/03/22 17:30:33 tls 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 1.27 2004/03/22 17:30:33 tls 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_DISK_DEFAULT_STRAT()|BUFQ_SORT_RAWBLOCK);
}
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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