Re: [PATCH 5/6] NFSD: leverage DIO alignment to selectively issue O_DIRECT reads and writes

Christoph Hellwig
2025-06-12T07:32:15Z

On Wed, Jun 11, 2025 at 11:44:29AM -0400, Jeff Layton wrote:
> XFS, for instance, takes the i_rwsem shared around dio writes and
> exclusive around buffered, so they should exclude each other. If we did
> all the buffered writes as RWF_SYNC, would that prevent corruption?

The big issue is memory mapped I/O, which doesn't take any locks.
I guess you could declare using a nfs exported file locally as a bad
idea, but I know plenty of setups doing it.