Re: [PATCH] direct-IO API change

[Badari Pulavarty]

> 
> 
> On Fri, 4 Oct 2002, Andrew Morton wrote:
> > 
> > > Especially since I thought that O_DIRECT on the regular file (or block
> > > device) performed about as well as raw does anyway these days? Or is that
> > > just one of my LSD-induced flashbacks?
> > > 
> > 
> > Now we're not holding i_sem for O_DIRECT writes to blockdevs,
> > I don't think the raw driver offers any advantages at all.  It's
> > a compatibility thing to save people from having to add "|O_DIRECT" to
> > their source and then typing `ln -s /dev/hda1 /dev/raw/raw0'.
> 
> Maybe the raw driver could become a shell that just adds the O_DIRECT? 
> Unless it can do something more, of course..
> 
> 		Linus
> 
> 

Only issue would be the alignment restriction on blockdev versus raw device.

raw allows 512 byte alignment on userbuff, offset and length.

blockdevice might need  1024/2048 byte alignment.

If we get the alignment patch for DIO, this is not an issue.
(alignment patch - in case of defualt alignment problem,
go down to blkdev_hardsect_size() alignment.)

- Badari