Date: Sat, 22 Jan 2000 01:00:02 -0800 (PST) From: Bruce Evans <bde@zeta.org.au> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/15611: EIDE Large Disk Support, Newfs problem, File system corruption,IBM-DPTA-353750 Message-ID: <200001220900.BAA69068@freefall.freebsd.org>
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The following reply was made to PR kern/15611; it has been noted by GNATS.
From: Bruce Evans <bde@zeta.org.au>
To: rjbubon@bigi.com
Cc: freebsd-gnats-submit@FreeBSD.ORG
Subject: Re: kern/15611: EIDE Large Disk Support, Newfs problem, File system
corruption,IBM-DPTA-353750
Date: Sat, 22 Jan 2000 19:58:14 +1100 (EST)
On Tue, 21 Dec 1999 rjbubon@bigi.com wrote:
> If I split the drive down the middle, 2 partitions, Strange things happen.
> I can load the first partition down with data. If I start writing to the 2nd
> partition, I corrupt the first. It's like the sector indexing in the OS
> is broke at some large number. Maybe an overflow.
Addressing is broken in CHS mode for cylinder numbers >= 65536, since
cylinder numbers are blindly truncated mod 65536.
The following patches give proper brokenness for -current. Large
disks are truncated to 65536 cylinders (normally 33.8GB). This is
simple in wd.c. Unfortunately, dsinit() "helpfully" enlarges the disk
if necessary to cover the slice entries in the MBR. This was once
necessary to support MFM disks with > 1024 cylinders, but it is wrong
for disks that report their size.
Index: i386/isa/wd.c
===================================================================
RCS file: /home/ncvs/src/sys/i386/isa/wd.c,v
retrieving revision 1.217
diff -c -2 -r1.217 wd.c
*** i386/isa/wd.c 1999/12/10 09:40:29 1.217
--- i386/isa/wd.c 2000/01/22 08:22:07
***************
*** 1761,1764 ****
--- 1761,1772 ----
du->dk_dd.d_secperunit / du->dk_dd.d_secpercyl;
}
+ if (du->dk_dd.d_ncylinders > 0x10000 && !(du->cfg_flags & WDOPT_LBA)) {
+ du->dk_dd.d_ncylinders = 0x10000;
+ du->dk_dd.d_secperunit = du->dk_dd.d_secpercyl *
+ du->dk_dd.d_ncylinders;
+ printf(
+ "wd%d: cannot handle %d total sectors; truncating to %lu\n",
+ du->dk_lunit, wp->wdp_lbasize, du->dk_dd.d_secperunit);
+ }
#if 0
du->dk_dd.d_partitions[RAW_PART].p_size = du->dk_dd.d_secperunit;
Index: kern/subr_diskmbr.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/subr_diskmbr.c,v
retrieving revision 1.42
diff -c -2 -r1.42 subr_diskmbr.c
*** kern/subr_diskmbr.c 1999/11/09 21:35:10 1.42
--- kern/subr_diskmbr.c 2000/01/22 08:21:43
***************
*** 73,76 ****
--- 73,79 ----
u_long ext_size, u_long base_ext_offset,
int nsectors, int ntracks, u_long mbr_offset));
+ static int dssetslice __P((char *sname, struct disklabel *lp,
+ struct diskslice *sp, struct dos_partition *dp,
+ u_long br_offset));
static int
***************
*** 295,306 ****
--- 298,321 ----
secpercyl = (u_long)max_nsectors * max_ntracks;
if (secpercyl != 0) {
+ #if 0
u_long secperunit;
+ #endif
lp->d_nsectors = max_nsectors;
lp->d_ntracks = max_ntracks;
lp->d_secpercyl = secpercyl;
+ /*
+ * Temporarily, don't even consider adjusting the drive's
+ * size, since the adjusted size may exceed the hardware's
+ * addressing capabilities. The adjustment helped mainly
+ * for ancient MFM drives with > 1024 cylinders, but now
+ * breaks at least IDE drives with 63*16*65536 sectors if
+ * they are controlled by the wd driver in CHS mode.
+ */
+ #if 0
secperunit = secpercyl * max_ncyls;
if (lp->d_secperunit < secperunit)
lp->d_secperunit = secperunit;
+ #endif
lp->d_ncylinders = lp->d_secperunit / secpercyl;
}
***************
*** 320,335 ****
sp = &ssp->dss_slices[BASE_SLICE];
for (dospart = 0, dp = dp0; dospart < NDOSPART; dospart++, dp++, sp++) {
! sp->ds_offset = mbr_offset + dp->dp_start;
! sp->ds_size = dp->dp_size;
! sp->ds_type = dp->dp_typ;
! #ifdef PC98_ATCOMPAT
! /* Fake FreeBSD(98). */
! if (sp->ds_type == DOSPTYP_386BSD)
! sp->ds_type = 0x94;
! #endif
! #if 0
! lp->d_subtype |= (lp->d_subtype & 3) | dospart
! | DSTYPE_INDOSPART;
! #endif
}
ssp->dss_nslices = BASE_SLICE + NDOSPART;
--- 335,341 ----
sp = &ssp->dss_slices[BASE_SLICE];
for (dospart = 0, dp = dp0; dospart < NDOSPART; dospart++, dp++, sp++) {
! sname = dsname(dev, dkunit(dev), BASE_SLICE + dospart,
! RAW_PART, partname);
! (void)dssetslice(sname, lp, sp, dp, mbr_offset);
}
ssp->dss_nslices = BASE_SLICE + NDOSPART;
***************
*** 435,446 ****
continue;
}
! sp->ds_offset = ext_offset + dp->dp_start;
! sp->ds_size = dp->dp_size;
! sp->ds_type = dp->dp_typ;
! #ifdef PC98_ATCOMPAT
! /* Fake FreeBSD(98). */
! if (sp->ds_type == DOSPTYP_386BSD)
! sp->ds_type = 0x94;
! #endif
ssp->dss_nslices++;
slice++;
--- 441,446 ----
continue;
}
! if (dssetslice(sname, lp, sp, dp, ext_offset) != 0)
! continue;
ssp->dss_nslices++;
slice++;
***************
*** 459,462 ****
--- 459,501 ----
bp->b_flags |= B_INVAL | B_AGE;
brelse(bp);
+ }
+
+ static int
+ dssetslice(sname, lp, sp, dp, br_offset)
+ char *sname;
+ struct disklabel *lp;
+ struct diskslice *sp;
+ struct dos_partition *dp;
+ u_long br_offset;
+ {
+ u_long offset;
+ u_long size;
+
+ offset = br_offset + dp->dp_start;
+ if (offset > lp->d_secperunit || offset < br_offset) {
+ printf(
+ "%s: slice starts beyond end of the disk: rejecting it\n",
+ sname);
+ return (1);
+ }
+ size = lp->d_secperunit - offset;
+ if (size >= dp->dp_size)
+ size = dp->dp_size;
+ else
+ printf(
+ "%s: slice extends beyond end of disk: truncating from %lu to %lu sectors\n",
+ sname, (u_long)dp->dp_size, size);
+ sp->ds_offset = offset;
+ sp->ds_size = size;
+ sp->ds_type = dp->dp_typ;
+ #ifdef PC98_ATCOMPAT
+ /* Fake FreeBSD(98). */
+ if (sp->ds_type == DOSPTYP_386BSD)
+ sp->ds_type = 0x94;
+ #endif
+ #if 0
+ lp->d_subtype |= (lp->d_subtype & 3) | dospart | DSTYPE_INDOSPART;
+ #endif
+ return (0);
}
Bruce
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