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Date: Sat, 21 Oct 2006 13:24:31 -0700
From: Andrew Morton <akpm@osdl.org>
To: Damien Wyart <damien.wyart@free.fr>,
       OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       Nick Piggin <npiggin@suse.de>
Subject: Re: 2.6.19-rc2-mm2 : empty files on vfat file system
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On Sat, 21 Oct 2006 13:19:32 -0700
Andrew Morton <akpm@osdl.org> wrote:

> On Sat, 21 Oct 2006 19:38:49 +0200
> Damien Wyart <damien.wyart@free.fr> wrote:
> 
> > > --- a/fs/fat/inode.c~fs-prepare_write-fixes
> > > +++ a/fs/fat/inode.c
> > > @@ -150,7 +150,11 @@ static int fat_commit_write(struct file 
> > >  			    unsigned from, unsigned to)
> > >  {
> > >  	struct inode *inode = page->mapping->host;
> > > -	int err = generic_commit_write(file, page, from, to);
> > > +	int err;
> > > +	if (to - from > 0)
> > > +		return 0;
> > > +
> 
> That should have been
> 
> 	if (to - from == 0)
> 		return 0;

otoh, it's still wrong that we're not updating i_size.  We happen to know
that the caller will retry without dropping i_mutex, but it's a bit
incestuous.