On Wed, Jan 29, 2025 at 11:59:53AM +1100, Dave Chinner wrote: > Sure, but we don't think we need full file offset-scope IO exclusion > to solve that problem. We can still safely do concurrent writes > within EOF to occur whilst another buffered append write is doing > file extension work. Sure. The previous mail just sounded like you'd want to do away with exclusion for assigning the offset. > IOWs, where we really need to get to is a model that allows > concurrent buffered IO at all times, except for the case where IO > operations that change the inode size need to serialise against > other similar operations (e.g. other EOF extending IOs, truncate, > etc). > > Hence I think we can largely ignore O_APPEND for the > purposes of prototyping shared buffered IO and getting rid of the > IOLOCK from the XFS IO path. I may end up re-using the i_rwsem as > a "EOF modification" serialisation mechanism for O_APPEND and > extending writes in general, but I don't think we need a general > write IO exclusion mechanism for this... That might be a chance to also fix O_DIRECT while we're at it..
