Re: mkfs.minix V3 is broken

[Karel Zak <kzak@redhat.com>]

On Sun, Nov 27, 2011 at 11:03:38PM +0100, Davidlohr Bueso wrote:
> On Tue, 2011-11-22 at 10:03 +0100, Maurizio Lombardi wrote:
> > On Mon, Nov 21, 2011 at 11:06 PM, Davidlohr Bueso <dave@gnu.org> wrote:
> > >
> > > Most of the work I did on supporting v3 was based on the kernel's
> > > implementation and the mkfs shipped with minix (by ast), so a lot of
> > > what you say makes sense. I've taken a quick look at the changes and
> > > most are bugs are pretty straightforward, except:
> > >
> > > - mkfs.minix: The total number of zones is limited to 65536 only on V1
> > > filesystems
> > >
> > > Unless I'm missing something, this doesn't really change any logic.
> > 
> > Sorry, probably the commit message is not very well written... However
> > this commit fixes a very nasty bug, let me explain why....
> > Look at what the code did *before* my patch:
> > 
> > if (fs_version == 3)
> >      magic = MINIX3_SUPER_MAGIC;
> > if (fs_version == 2) {
> >      if (namelen == 14)
> >        magic = MINIX2_SUPER_MAGIC;
> >      else
> >        magic = MINIX2_SUPER_MAGIC2;
> > } else {
> >     if (BLOCKS > MINIX_MAX_INODES)
> >        BLOCKS = MINIX_MAX_INODES;
> > }
> > 
> > Can you see what happens if fs_version is == 3 ?
> > The total number of blocks is restricted to a maximum of 65536 both
> > with V1 and V3 filesystems, this is wrong because the total number of
> > blocks in V3 is a 32 bit number (the same of V2). With this
> > realization, it is really simple to fix the bug, and this is exactly
> > what I did:
> 
> Oh, yes, my bad, we should definitely have more blocks with v3. 
> 
> I made a couple of filesystems with your changes and things look good,
> specially incrementing the amount of inodes. The 60 character filename
> was already featured but it's good to specify it explicitly as well.
> 
> Karel, unless you have any objections please pull these changes in.

 Merged, thanks!

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com