Re: dd PATCH: add conv=direct

[Andy Isaacson]

On Wed, Apr 07, 2004 at 11:18:41AM -0700, Andrew Morton wrote:
> Andy Isaacson <address@hidden> wrote:
> > > While you're there, please add an fsync-before-closing option.
> > 
> > Easy enough.  How does this look?  Note that C_TWOBUFS ensures the
> > output buffer is getpagesize()-aligned.
> 
> Looks nice and simple.  You'll need an ext2 filesystem to test it under 2.4.

I tested against a block device.  Easier to just "swapoff /dev/hda2"
than to find space to make a new filesystem.

> Be aware that it's rather a challenge to actually get the O_DIRECT #define
> in scope under some glibc versions.  I think you need to define _GNU_SOURCE
> or something like that.

Yeah, I had to -D_GNU_SOURCE to build standalone, but coreutils'
makefile seems to do OK.

Would there be any reason to allow O_DIRECT on the read side?

-andy