Re: Proposal for "proper" durable fsync() and fdatasync()

[Ric Wheeler]

Jeff Garzik wrote:
> Jamie Lokier wrote:
> > By durable, I mean that fsync() should actually commit writes to
> > physical stable storage,
>
> Yes, it should.
>
>
> > I was surprised that fsync() doesn't do this already.  There was a lot
> > of effort put into block I/O write barriers during 2.5, so that
> > journalling filesystems can force correct write ordering, using disk
> > flush cache commands.
> >
> > After all that effort, I was very surprised to notice that Linux 2.6.x
> > doesn't use that capability to ensure fsync() flushes the disk cache
> > onto stable storage.
>
> It's surprising you are surprised, given that this [lame] fsync behavior 
> has remaining consistently lame throughout Linux's history.

Maybe I am confused, but isn't this is what fsync() does today whenever 
barriers are enabled (the fsync() invalidates the drive's write cache).

ric
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