Re: ext3 and SPEC SFS Run rules.

[Theodore Ts'o]

On Mon, Jul 26, 2004 at 10:12:01AM +0100, Tigran Aivazian wrote:
> On Mon, 26 Jul 2004, Andrew Morton wrote:
> > ext3 should be fully syncing data and metadata for both fsync() and O_SYNC
> > writes in all three journalling modes.  If not, that's a big bug.
> 
> Ok, so, can I conclude that you are therefore saying that ext3 (with 
> default mount options) is compliant with SPEC SFS Run rules wrt NFS 
> protocol requirements:

This is up to the NFS server, not to the underlying filesystem.  It
would be insane for every single local write() to have mandatory
O_SYNC semantics, even if it is required by the NFS protocol.  

In modern Linux implementations of the NFS server, you can specify
whether or not the synchronization semantics as demanded by the NFS
protocol, or whether the more relaxed async writebacks are done.
Obviously, this has some pretty serious performance vs robustness
implications.

						- Ted
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