[BUGS] mountmsdosfs(): disk too big, sorry

[Jerahmy Pocott]

On 15/03/2008, at 5:18 PM, Trevor Roydhouse wrote:

> Trevor Roydhouse wrote:
>> Jerahmy Pocott wrote:
>>
>>> Any ideas?
>>
>> The source code (msdosfs_vfsops.c) suggests:
>>
>>                         error = EINVAL;
>>                         vfs_mount_error(mp,
>>                            "Disk too big, try '-o large' mount  
>> option");
>>                         goto error_exit;
>>
>> (I'm running FreeBSD 7.0-STABLE amd64, so this option might not be
>> available to you. It's not documented in the man page for  
>> mount_msdosfs
>> btw.)
>
> I should have read further whereupon there is a significant caveat:
>
>         /*
>          * Experimental support for large MS-DOS filesystems.
>          * WARNING: This uses at least 32 bytes of kernel memory  
> (which
> is not
>          * reclaimed until the FS is unmounted) for each file on disk
> to map
>          * between the 32-bit inode numbers used by VFS and the 64-bit
>          * pseudo-inode numbers used internally by msdosfs. This is  
> only
>          * safe to use in certain controlled situations (e.g. read- 
> only FS
>          * with less than 1 million files).
>          * Since the mappings do not persist across unmounts (or
> reboots), these
>          * filesystems are not suitable for exporting through NFS, or
> any other
>          * application that requires fixed inode numbers.
>          */
>         vfs_flagopt(mp->mnt_optnew, "large", &pmp->pm_flags,
>           MSDOSFS_LARGEFS);

So what is the largest msdosfs supported?

Read-only doesn't sound terrible useful..