On 16 May 1999, H. Peter Anvin wrote:

> Followup to:  <373C868C.10EB@mail1.bet1.puv.fi>
> By author:    "A. Wik" <aw@mail1.bet1.puv.fi>
> In newsgroup: linux.dev.kernel
> >
> > It's impossible to rename a file on a VFAT filesystem if
> > the only difference between the old and new names is case
> > (eg. longfilename and LongFilename).  The operation is
> > cancelled in fs/namei.c because the lookups return the
> > same dentry for both names.  What would be the most
> > reasonable way to fix this?
> > 
> 
> Clearly the VFS isn't the right place to make this kind of decision,
> at least if the strings don't compare identical.

It's worse than you think.
a) we should *never* allow several dentries for the same directory.
b) POSIX explicitly requires rename(foo,bar) to do nothing and just return
0 if foo and bar are the same filesystem object.
c) VFAT prohibits simultaneous existance of names that differ only in
capitalization.
d) usual interpretation of (c) being: all such names are equivalent.

Each of (b), (c) and (d) is a bug in itself. POSIX, Microsoft and DEC 
resp.

You can mount it with 'check=strict' (i.e. kill (d)). That should fix the
problem (i.e. allow such renames). But then you lose case-insensitivity.



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