Re: mount dos-partition bug

Re: mount dos-partition bug

[Andries Brouwer]

Andreas Huppert wrote:

> > I have been trying to mount the dos-partition /dev/hdb1 on /dos/d for
> > three years and it fails:

Yes. It has 805998 data sectors, which require 50374 clusters,
but the fat16 has room only to describe 39168 clusters.
The kernel mount code considers this an error.

You can remove the check in linux/fs/fat/inode.c
and write something like

                error = !sbi->fats || (sbi->dir_entries & (MSDOS_DPS-1))
#if 0
                        || sbi->clusters+2 > fat_clusters+ MSDOS_MAX_EXTRA
#endif
                        || (logical_sector_size & (SECTOR_SIZE-1))
                        || !b->secs_track || !b->heads;

(the current layout is somewhat uglier).
I would expect that afterwards things work.

If you use this under Windows, do you get over 400 MB on this disk?
Or was part of this partition effectively lost?

Andries
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Re: mount dos-partition bug

[Rogier Wolff]

Andries Brouwer wrote:
> Andreas Huppert wrote:
> 
> > > I have been trying to mount the dos-partition /dev/hdb1 on /dos/d for
> > > three years and it fails:
> 
> Yes. It has 805998 data sectors, which require 50374 clusters,
> but the fat16 has room only to describe 39168 clusters.
> The kernel mount code considers this an error.
> 
> You can remove the check in linux/fs/fat/inode.c
> and write something like
> 
>                 error = !sbi->fats || (sbi->dir_entries & (MSDOS_DPS-1))
> #if 0
>                         || sbi->clusters+2 > fat_clusters+ MSDOS_MAX_EXTRA
> #endif
>                         || (logical_sector_size & (SECTOR_SIZE-1))
>                         || !b->secs_track || !b->heads;
> 
> (the current layout is somewhat uglier).
> I would expect that afterwards things work.
> 
> If you use this under Windows, do you get over 400 MB on this disk?
> Or was part of this partition effectively lost?

I'd expect that IF you try to use more than 39k clusters, your
filesystem will be toast. Even if Windows doesn't have the "sanity
check" that Linux has.

				Roger. 

-- 
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