On Sat, Jan 08, 2011 at 05:00:59PM -0500, Ted Ts'o wrote:
> On Sat, Jan 08, 2011 at 09:05:20AM +0100, Rogier Wolff wrote:
> > Although those two numbers are equal right now, there is no reason to
> > assume that they will remain so in the future. So if the superblock
> > size (or the offset) changes in the future, it's much better to have
> > programmed this so that it will keep on working as opposed to getting
> > to deal with ugly bugs in code that hasn't changed in years...
>
> No. The superblock nor its offset will never change. It's like the
> syscall ABI, only worse. If we changed it would break *everybody*.
> Fortunately there is a huge amount of space left over in the 1024 byte
> superblock.
It's called defensive programming. It prevents bugs before they
happen. By your reasoning you could've written 2048 or 0x800 there.
My version:
- documents why something is subtracted from the blockszize and how
much.
- keeps on working even if the superblock would oddly change size
in the future. Even if now you don't expect that to happen ever.
Roger.
--
** R.E.Wolff@xxxxxxxxxxxx ** http://www.BitWizard.nl/ ** +31-15-2600998 **
** Delftechpark 26 2628 XH Delft, The Netherlands. KVK: 27239233 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
Q: It doesn't work. A: Look buddy, doesn't work is an ambiguous statement.
Does it sit on the couch all day? Is it unemployed? Please be specific!
Define 'it' and what it isn't doing. --------- Adapted from lxrbot FAQ
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
