Re: vfat vs msdos and -o flush

[Chris Mason <chris.mason@oracle.com>]

On Wed, Mar 03, 2010 at 10:36:21PM +0900, OGAWA Hirofumi wrote:
> Christoph Hellwig <hch@lst.de> writes:
> 
> > Commit ae78bf9c4f5fde3c67e2829505f195d7347ce3e4 added a -o flush
> > option to the fat driver back in 2006, which causes asynchronous
> > writeout after I/O operations ASAP.  This already is quite hacky
> > and not something I like very much, but even worse the option
> > is accepted when using the more common vfat filesysten type, but
> > only actually implemented for the less common legacy msdos
> > filesystem type.
> >
> > This tells us two lessons:
> >
> >   - the -o flush option probably never got a whole lot of exposure
> >     and users didn't notice it doesn't work.  We might as well just
> >     remove it again
> 
> Sigh. Chris, could you handle this?

I'm not against removing it.  The option was added to handle desktop
workloads where mount -o sync was too slow but people still wanted to be
able to rip out the usb stick..  Added Jeff to the cc list, is this still
in use?

Now that we have per-bdi dirty accounting, I think we're much much
better off to set the dirty limit on the bdi to 1 byte or something and
just let the page cache code do it all for us.

-chris