[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]
Re: kern/54470: Adapt FFS to work with HP-UX UFS1 variant
The following reply was made to PR kern/54470; it has been noted by GNATS.
From: Konrad Schroder <perseant%hhhh.org@localhost>
To: gnats-bugs%netbsd.org@localhost, kern-bug-people%netbsd.org@localhost,
gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, perseant%netbsd.org@localhost
Subject: Re: kern/54470: Adapt FFS to work with HP-UX UFS1 variant
Date: Sat, 17 Aug 2019 17:30:46 -0700
Do we have a way to construct a file system that works with NetBSD,
which has a physical sector size other than DEV_BSIZE?Â If so, I can
test against it.
Note too that the macros in question exist only within the scope of the
fsck_ffs utility.Â The other userland programs that I adapted didn't
need them, and the kernel uses macros that depend on struct ump and
could easily be special-cased for HP-UX or other old file systems if
need be.Â Come to think of it, in fsck_ffs we could just do something like
Â Â Â exter daddr_t dev_bshift;
Â Â Â daddr_t dev_bshift = DEV_BSHIFT;
Â Â Â #define BTODB(size) ((size) >> dev_bshift)
Â Â Â #define DBTOB(size) ((size) << dev_bshift)
and change the value of dev_bsize, if necessary, in the setup.Â The
kernel would do the same, but storing the dev_bshift value in struct
ump.Â Would this address your concern?
On 8/17/2019 4:20 AM, Michael van Elst wrote:
> The following reply was made to PR kern/54470; it has been noted by GNATS.
> From: mlelstv%serpens.de@localhost (Michael van Elst)
> To: gnats-bugs%netbsd.org@localhost
> Subject: Re: kern/54470: Adapt FFS to work with HP-UX UFS1 variant
> Date: Sat, 17 Aug 2019 11:15:28 -0000 (UTC)
> perseant%hhhh.org@localhost (Konrad Schroder) writes:
> >Can you be more specific?Ã?Â It gives the right values for my HP-UX image,
> >and for existing NetBSD file systems.
> >> >+#define BTODB(fs, size) ((size) >> ((fs)->fs_fshift - (fs)->fs_fsbtodb))
> >> >+#define DBTOB(fs, bc) ((bc) << ((fs)->fs_fshift - (fs)->fs_fsbtodb))
> The original BSD code used definitions like these above as a 'disk offset'
> referred to physical block numbers. This is still used that way in
> NetBSD disk drivers always use logical block numbers for a block size
> of 512 bytes (DEV_BSIZE) and filesystems ignore the superblock values when
> translating between filesystem block numbers and disk block numbers.
> For FFS the macros FFS_FSBTODB / FFS_DBTOFSB are used to do this conversion.
> They are differently defined for kernel and userland to address the different
> btodb / dbtob are originally MD macros (then unified) that always used
> a platform specific unit, i.e. DEV_BSIZE, to specify disk offsets. This
> unit is independent of a particular filesystem and the physical blocks of
> a specific device.
> Now what unit does di_blocks use, it's only used for reporting and quota
> calculations ? The original code used btodb(file_length), i.e. the values
> used the platform-wide DEV_BSIZE as a unit and that's what we still use
> Your patch changes that and di_blocks is now using the physical block
> size of the particular disk (recorded in the superblock) as the unit.
> Apparently that's what HP-UX is doing.
> I see two issues: you added another view on disk offsets and you break
> existing filesystems that use a physical sector size != 512.
> Apparently we need conditional code to handle di_blocks for the
> different systems.
> Michael van Elst
> Internet: mlelstv%serpens.de@localhost
> "A potential Snark may lurk in every tree."
Main Index |
Thread Index |